Bruceynz
Well-Known Member
I can't recall what vac is, will need to check next time I am driving car.
408 Stroker build who's keen to watch this one :)
- Thread starter Bruceynz
- Start date
Oldiron440
Well-Known Member
You should pick up a book on tuning the Holley carb, here is a few.
The Holley Carburetor Handbook 4150 and 4160 : Selection, Tuning and Repair by Mike Urich (1987, Paperback) | eBay
One more
SA Design David Vizard's How to Super Tune and Modify Holley Carburetors SA216
Money well spent.
The Holley Carburetor Handbook 4150 and 4160 : Selection, Tuning and Repair by Mike Urich (1987, Paperback) | eBay
One more
SA Design David Vizard's How to Super Tune and Modify Holley Carburetors SA216
Money well spent.
These two figures can make a big difference.
If current power valve is at 8.5 (which opens at 8.5 inch of vacuum) and vacuum at idle is at say 9 (inches of vacuum) then it won’t take much for power valve to open – making it richer.
For stock engines, the power valve is about right, out of the box.
For non-stock engines – it is one of many things to play around with to make it right.
I agree with Oldiron440. Get a book (or two) and read up. It might make things a bit more understandable.
BudW
Oldiron440
Well-Known Member
A rule of thumb is a power valve with a number value half of the manifold vacuum at idle in drive. So if you have 12 in of vacuum you would need a 5.5 power valve.
AJ/FormS
Well-Known Member
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Here's my 2cents
You want power at take-off right,
and don't care about track times, right.
You need torque and lots of it, or you need TM(Torque Multiplication). That's all there is to it.
So you can do it with engine, or you can do it with TM and stall.
You gotta stop equating Horsepower at 5500 rpm as being meaningful to a streeter. You are only gonna hit peak power once on the way to the speed limit, and it comes at around 40mph. That is a useless target, when all that beast will do is chirp the tires off idle Am I right?
No; you want mega ftlbs on the start-line, ready to roast the tires, and if the tires light up right away, then that is a pleasure to deal with. So forget about 400hp at 5500,(or whatever). Instead concentrate on 250/300ftlbs at stall. Who cares about power after that, cuz we're spinning,wheeee!
One of the reasons everyone wants 400hp is cuz that combo can pull some big Mph number in the quarter. The fact is that it takes lotsa horsepower to push thru the air at 100 plus mph, but it takes 1/4 as much to hit 60mph as compared to hit 120. Excess power goes to tirespin, and tirespin while addictive, is slower than hooking.And if you can't use all of the power, then you might as well have a smaller engine.
So, IMO, fogetabowd a horsepower target at all, and just optimize what you got.
Like your friend says, give your current combo a chance.
Another 2cents;
Any cam you put in that 360, with no other changes, that is bigger than the current cam, and from the same manufacturer, will trade away low rpm torque for higher rpm power. There is no way around this. IMO,If you can't boil the hides,this is a step in the wrong direction. I don't like 112LSA cams for this type of application, and I especially don't like a cam like yours in an 8.8 Scr360; it just bleeds cylinder pressure, and sucks gas. That doesn't mean your combo can't be made to smoke the tires with it; it just means I don't like it,lol.
Your Dcr/ cylinder pressure , works out to 7.34/144, which, IMO, is on the low side. So the first thing I would do is a compression test with a known accurate gauge to verify that pressure. It's not the end of the world if your pressure is down there, it just means a few less ftlbs on the dyno, which we have to make up for, with TM.
And more opinion.
No dyno graph?
Get yourself a windshield mounted accelerometer. Now you can quantify every change you make to your car.
Now
I didn't read the whole thread so I may be repeating some things here.
The first step to smoking the tires, if you had a clutch would be to rev it up and dump it. The flywheel which has stored the energy in it, will break the tires loose, and once they are spinning, you only need to keep them spinning until the engine reaches equilibrium with tireslip, and then she's off like a bolt of lightning.
With an automatic, the way to do that is with convertor stall.
More opinion.
With typical 15" street tires you need about 1500ftlbs to the road to break traction. Then you just rev it up some to keep them spinning. Obviously the more power your engine has,at low rpm, the easier this will be both to initiate and to maintain.
The math
If you have say 3.23s, a typical street rear gear, then 1500/3.23=464 ftlbs out of the transmission is required. With a 2.45 low gear, this would be 464/2.45=190ftlbs . So then you look on your horsepower graph to see at what rpm 190ftlbs comes, and order a TC with at least that much stall. But you will quickly find out that as soon as the tires heat up a bit, they won't want to continue spinning. And you really want to annihilate them. So lets say you add 30% to the ftlbs giving you a nice bit of headroom. So then 190 plus 30%=250ftlbs. Look on the graph, find the rpm where 250 first occurs, and order up a TC with that stall rating, in rpm.
But what if you have 3.91s?
Same trick; 1500/(3.91x2.45)x 1.3=200ftlbs now. Look on your power-graph and order a TC with at least that much stall.
But say you have a 2400TC, and want to keep it. Then you look on the graph, find the ftlbs at 2400 and rearrange the equation to spit out a minimum rear gear. Say you found 220ftlbs at 2400.
(1500x1.3) /(2.45x220)= 3.55s..
No dyno graph? Get the accelerometer.
Or you could do what I did; 2800TC and 4.30s is guaranteed to put the biggest stoopid grin on your face that a week of sex is barely gonna affect.
Ok so now you know how to get the tires spinning. That 112Lsa cam will plateau on the power curve early, but with good heads, will carry the power for a long,long, ways. If you hit the TM target right, you might find yourself in the situation of having a preponderance of low-rpm power. If that happens to you, you can trade some away for another 100rpm or perhaps 150, by retarding that cam. In at the recommended 108, she's gonna be hard on gas. Between those two, retiming to 110 will help, a lil.
Now
as for me, I'm more interested with having power at 30mph, to blast off with. At 30, the 1500ftlbs is no longer adequate. Say you have settled on 3.55s. Your rpm at 30 in first gear will be about 3400, so the TC ain't slipping much anymore. So look on your graph at 3400 and find the available torque at that rpm. I bet it will be 95% of the peak, so lets say 360ftlbs. Doing the math; 360x2.45x3.55=3130 to the road. This should be enough to break traction with any street tire and no traction aider. I know it would make me happy,lol.
With 2.76s the number is 2540, and it will be considerably more difficult. The 600VS IMO, I doubt will do it. You need to shock the tires with with all 4 bbls, instantly; enter the Double-Pumper.
What I like
about double pumpers, is I get more control. I decide how much power to dial in. The Vs carbs were just too slow and too ambiguous, for my driving style. But they don't always work well on TM-handicapped combos. If the engine is at low-rpm but above stall you might/probably will, get a hesitation, and the more towards hiway that the gears are biased, and the slower the transmission is to kick down,the worse the hesitation can get.
As to which carb from your collection, YOU use:
again this is dependent on the TM, and between say 3500 and about 5000, makes as good as zero difference to a streeter...... except if you can't delay the secondaries to prevent a bog. The smaller the carb, the faster and sooner the secondaries can be opened, and a 600carb at 5000rpm, with 3.55s, will be doing ~44mph; almost time to shift with that cam. Your 600 is mathematically big enough for over 5000rpm. The thing is, if your engine can only pull in 500cfm no matter what, then there is not much point in bolting on a 770. It will only make problems for you at low-rpm.
And more opinion
If your engine was my engine, I wouldn't be satisfied with 144psi cylinder pressure.I know you said your best gas was like our 87. But is it really? My research shows that your gas is really just a more strenuous test protocol and a rebadging at the pumps. But the fuel is exactly the same. So an engine that runs detonation-free on 91 here, our best pumpgas, should run detonation free on your best pump gas.
I don't know if that is true (you need to research that yourself,for your own piece of mind);
But IF THAT IS TRUE,THEN..... then you should be able to run much more cylinder pressure, up to 160psi depending on your Quench and chamber, and other various parameters, but at the very least, at 155psi.
Of course the higher Dcr required to achieve this will reshape your powercurve with more ftlbs throughout the rpm band, but specifically at low-rpm. And that means a lesser stall-speed requirement, and/or a lesser rear gear.
Parting shot
Or you could just do what I did; throw 4.30s and a 2800 at it, that will fix anything, and call it done,lol. Be sure to go home once in a while; wives like that.
You want power at take-off right,
and don't care about track times, right.
You need torque and lots of it, or you need TM(Torque Multiplication). That's all there is to it.
So you can do it with engine, or you can do it with TM and stall.
You gotta stop equating Horsepower at 5500 rpm as being meaningful to a streeter. You are only gonna hit peak power once on the way to the speed limit, and it comes at around 40mph. That is a useless target, when all that beast will do is chirp the tires off idle Am I right?
No; you want mega ftlbs on the start-line, ready to roast the tires, and if the tires light up right away, then that is a pleasure to deal with. So forget about 400hp at 5500,(or whatever). Instead concentrate on 250/300ftlbs at stall. Who cares about power after that, cuz we're spinning,wheeee!
One of the reasons everyone wants 400hp is cuz that combo can pull some big Mph number in the quarter. The fact is that it takes lotsa horsepower to push thru the air at 100 plus mph, but it takes 1/4 as much to hit 60mph as compared to hit 120. Excess power goes to tirespin, and tirespin while addictive, is slower than hooking.And if you can't use all of the power, then you might as well have a smaller engine.
So, IMO, fogetabowd a horsepower target at all, and just optimize what you got.
Like your friend says, give your current combo a chance.
Another 2cents;
Any cam you put in that 360, with no other changes, that is bigger than the current cam, and from the same manufacturer, will trade away low rpm torque for higher rpm power. There is no way around this. IMO,If you can't boil the hides,this is a step in the wrong direction. I don't like 112LSA cams for this type of application, and I especially don't like a cam like yours in an 8.8 Scr360; it just bleeds cylinder pressure, and sucks gas. That doesn't mean your combo can't be made to smoke the tires with it; it just means I don't like it,lol.
Your Dcr/ cylinder pressure , works out to 7.34/144, which, IMO, is on the low side. So the first thing I would do is a compression test with a known accurate gauge to verify that pressure. It's not the end of the world if your pressure is down there, it just means a few less ftlbs on the dyno, which we have to make up for, with TM.
And more opinion.
No dyno graph?
Get yourself a windshield mounted accelerometer. Now you can quantify every change you make to your car.
Now
I didn't read the whole thread so I may be repeating some things here.
The first step to smoking the tires, if you had a clutch would be to rev it up and dump it. The flywheel which has stored the energy in it, will break the tires loose, and once they are spinning, you only need to keep them spinning until the engine reaches equilibrium with tireslip, and then she's off like a bolt of lightning.
With an automatic, the way to do that is with convertor stall.
More opinion.
With typical 15" street tires you need about 1500ftlbs to the road to break traction. Then you just rev it up some to keep them spinning. Obviously the more power your engine has,at low rpm, the easier this will be both to initiate and to maintain.
The math
If you have say 3.23s, a typical street rear gear, then 1500/3.23=464 ftlbs out of the transmission is required. With a 2.45 low gear, this would be 464/2.45=190ftlbs . So then you look on your horsepower graph to see at what rpm 190ftlbs comes, and order a TC with at least that much stall. But you will quickly find out that as soon as the tires heat up a bit, they won't want to continue spinning. And you really want to annihilate them. So lets say you add 30% to the ftlbs giving you a nice bit of headroom. So then 190 plus 30%=250ftlbs. Look on the graph, find the rpm where 250 first occurs, and order up a TC with that stall rating, in rpm.
But what if you have 3.91s?
Same trick; 1500/(3.91x2.45)x 1.3=200ftlbs now. Look on your power-graph and order a TC with at least that much stall.
But say you have a 2400TC, and want to keep it. Then you look on the graph, find the ftlbs at 2400 and rearrange the equation to spit out a minimum rear gear. Say you found 220ftlbs at 2400.
(1500x1.3) /(2.45x220)= 3.55s..
No dyno graph? Get the accelerometer.
Or you could do what I did; 2800TC and 4.30s is guaranteed to put the biggest stoopid grin on your face that a week of sex is barely gonna affect.
Ok so now you know how to get the tires spinning. That 112Lsa cam will plateau on the power curve early, but with good heads, will carry the power for a long,long, ways. If you hit the TM target right, you might find yourself in the situation of having a preponderance of low-rpm power. If that happens to you, you can trade some away for another 100rpm or perhaps 150, by retarding that cam. In at the recommended 108, she's gonna be hard on gas. Between those two, retiming to 110 will help, a lil.
Now
as for me, I'm more interested with having power at 30mph, to blast off with. At 30, the 1500ftlbs is no longer adequate. Say you have settled on 3.55s. Your rpm at 30 in first gear will be about 3400, so the TC ain't slipping much anymore. So look on your graph at 3400 and find the available torque at that rpm. I bet it will be 95% of the peak, so lets say 360ftlbs. Doing the math; 360x2.45x3.55=3130 to the road. This should be enough to break traction with any street tire and no traction aider. I know it would make me happy,lol.
With 2.76s the number is 2540, and it will be considerably more difficult. The 600VS IMO, I doubt will do it. You need to shock the tires with with all 4 bbls, instantly; enter the Double-Pumper.
What I like
about double pumpers, is I get more control. I decide how much power to dial in. The Vs carbs were just too slow and too ambiguous, for my driving style. But they don't always work well on TM-handicapped combos. If the engine is at low-rpm but above stall you might/probably will, get a hesitation, and the more towards hiway that the gears are biased, and the slower the transmission is to kick down,the worse the hesitation can get.
As to which carb from your collection, YOU use:
again this is dependent on the TM, and between say 3500 and about 5000, makes as good as zero difference to a streeter...... except if you can't delay the secondaries to prevent a bog. The smaller the carb, the faster and sooner the secondaries can be opened, and a 600carb at 5000rpm, with 3.55s, will be doing ~44mph; almost time to shift with that cam. Your 600 is mathematically big enough for over 5000rpm. The thing is, if your engine can only pull in 500cfm no matter what, then there is not much point in bolting on a 770. It will only make problems for you at low-rpm.
And more opinion
If your engine was my engine, I wouldn't be satisfied with 144psi cylinder pressure.I know you said your best gas was like our 87. But is it really? My research shows that your gas is really just a more strenuous test protocol and a rebadging at the pumps. But the fuel is exactly the same. So an engine that runs detonation-free on 91 here, our best pumpgas, should run detonation free on your best pump gas.
I don't know if that is true (you need to research that yourself,for your own piece of mind);
But IF THAT IS TRUE,THEN..... then you should be able to run much more cylinder pressure, up to 160psi depending on your Quench and chamber, and other various parameters, but at the very least, at 155psi.
Of course the higher Dcr required to achieve this will reshape your powercurve with more ftlbs throughout the rpm band, but specifically at low-rpm. And that means a lesser stall-speed requirement, and/or a lesser rear gear.
Parting shot
Or you could just do what I did; throw 4.30s and a 2800 at it, that will fix anything, and call it done,lol. Be sure to go home once in a while; wives like that.
Last edited:
Oldiron440
Well-Known Member
AJ, I agree with some if not most of what your saying but one thing I'd like to address is carb size.
My little Ford is 292 CID or less than 5 litters. Now going by the dyno sheets it only uses 518 cfm at 6500 rpm with a 750 DP. And it made a peek hp of 455 and peek tq of 445. Now just looking at the dyno sheet you might think the carb is to large and maybe a 600 would be closer to its needs. But on the dyno the 600 DP made a little more than 8 hp less and 6 ftlb less on torque.
You can't use air cfm as a absolute on determining carb size. Just look at every six pack motor mopar ever built, it takes a stout motor to need 1000 cfm in carbs.
My little Ford is 292 CID or less than 5 litters. Now going by the dyno sheets it only uses 518 cfm at 6500 rpm with a 750 DP. And it made a peek hp of 455 and peek tq of 445. Now just looking at the dyno sheet you might think the carb is to large and maybe a 600 would be closer to its needs. But on the dyno the 600 DP made a little more than 8 hp less and 6 ftlb less on torque.
You can't use air cfm as a absolute on determining carb size. Just look at every six pack motor mopar ever built, it takes a stout motor to need 1000 cfm in carbs.
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I’m not a 6-pack expert – but I thought a 440 6-pack had closer to 1,200 CFM rating (but not sure).
Whatever the exact CFM number is – it is way more than engine will ever need. Even in the early ‘70’s, people were altering them from vacuum to mechanical secondary’s for the pursuit for more power. I always thought it was pointless to have mechanical secondary’s on a 6-pack – with no additional shot of fuel (additional accelerator pumps) to get things going – but I digress. That is not the topic here.
AJ/FormS – well put and thought out.
I like it when someone can give their opinion and then back it up with data (numbers, in this case).
My question is – where did you get the “1,500 foot/pounds to break traction” figure from? I’m not disagreeing with it – I was just wondering.
For those racing, a detailed log (notebook) that also notes every single change made, is a requirement for those wanting to win. No two changes are to be made at same time.
https://www.forfmjbodiesonly.com/classicmopar/threads/performance-meter.5547/ talks about one I purchased. I didn’t make comment about it, but I took my wife’s 2002 minivan (3.8L) out for a “test” and the windshield mount fell apart on me. This company doesn’t tell the parts for the windshield mount for that model any longer – so I shelved that project. The newer models work better and give more details – so I may put that on my Christmas list for next year.
A couple of months ago I replaced wife’s van with a 2010 version with the 4.0L engine. That thing is a missile with comfortable seating for seven – because of the way the 6-speed automatic transmission keeps the engine in the powerband. The 4.0L is the exact same engine as the 3.5L engine used in the Charger/Challenger/300’s, except bored out a bit more.
BudW
Whatever the exact CFM number is – it is way more than engine will ever need. Even in the early ‘70’s, people were altering them from vacuum to mechanical secondary’s for the pursuit for more power. I always thought it was pointless to have mechanical secondary’s on a 6-pack – with no additional shot of fuel (additional accelerator pumps) to get things going – but I digress. That is not the topic here.
AJ/FormS – well put and thought out.
I like it when someone can give their opinion and then back it up with data (numbers, in this case).
My question is – where did you get the “1,500 foot/pounds to break traction” figure from? I’m not disagreeing with it – I was just wondering.
One of the best things I can recommend. Get a notebook and document all changes. Going by “the seat of your pants” or going by tire life is not the best way to determine what is best for your needs.
For those racing, a detailed log (notebook) that also notes every single change made, is a requirement for those wanting to win. No two changes are to be made at same time.
https://www.forfmjbodiesonly.com/classicmopar/threads/performance-meter.5547/ talks about one I purchased. I didn’t make comment about it, but I took my wife’s 2002 minivan (3.8L) out for a “test” and the windshield mount fell apart on me. This company doesn’t tell the parts for the windshield mount for that model any longer – so I shelved that project. The newer models work better and give more details – so I may put that on my Christmas list for next year.
A couple of months ago I replaced wife’s van with a 2010 version with the 4.0L engine. That thing is a missile with comfortable seating for seven – because of the way the 6-speed automatic transmission keeps the engine in the powerband. The 4.0L is the exact same engine as the 3.5L engine used in the Charger/Challenger/300’s, except bored out a bit more.
BudW
Bruceynz
Well-Known Member
Found this in graph form, it's simulated but shows what is going on like AJ says.
It is not for everyone, but driving a car (any car) with 3.7, 3.9 or 4.1 gears will put a huge grin on anyone (. . . still breathing, that is).
The downside is it is hard to drive long distances with low gears.
I prefer to use the term for 3.7, 3.9 or 4.1 gears “city gears” and 2.2, 2.4 or 2.7 “highway gears”.
2.9 and 3.2 are in the middle and where I recommend and point towards for most FMJ owners to obtain, for daily use.
I haven’t found any difference in fuel mileage for city usage between 2.2 and 2.9 gears. For those who mainly drive on highways, then yes, highway gears are great for fuel mileage – but most of us drive in the city.
If you drive your FMJ on some highway - but in areas with stop and go traffic on highways (rush hour), then it helps to have 3.5’s. I’ve been in stop and go highway traffic in Dallas and Houston TX (during rush hours). You are either standing on gas (WOT) OR standing on your brakes – or other cars (like . . . all of them) will cut right in front of you during those 0-60-0-60-0 moments.
BudW
The downside is it is hard to drive long distances with low gears.
I prefer to use the term for 3.7, 3.9 or 4.1 gears “city gears” and 2.2, 2.4 or 2.7 “highway gears”.
2.9 and 3.2 are in the middle and where I recommend and point towards for most FMJ owners to obtain, for daily use.
I haven’t found any difference in fuel mileage for city usage between 2.2 and 2.9 gears. For those who mainly drive on highways, then yes, highway gears are great for fuel mileage – but most of us drive in the city.
If you drive your FMJ on some highway - but in areas with stop and go traffic on highways (rush hour), then it helps to have 3.5’s. I’ve been in stop and go highway traffic in Dallas and Houston TX (during rush hours). You are either standing on gas (WOT) OR standing on your brakes – or other cars (like . . . all of them) will cut right in front of you during those 0-60-0-60-0 moments.
BudW
Oldiron440
Well-Known Member
I guess I'm more generous with rear gearing than that, if I had a vehicle that was stock and I wasn't looking to increase performance the two series gears would cut it but if I were building a mild small block and couldn't get the lower first gear I would go with a 3.25 to 3.55 gear set. The 3.55 is probably my favorite daily hotrod gear depending on tire size.
One thing to consider is if you have a higher than stock stall converter if you use a 3.0 gear instead of a 3.73 gear you will be working the converter much harder in traffic. Building more heat by forcing the converter to slip with no advantage in efficiency.
One thing to consider is if you have a higher than stock stall converter if you use a 3.0 gear instead of a 3.73 gear you will be working the converter much harder in traffic. Building more heat by forcing the converter to slip with no advantage in efficiency.
Bruceynz
Well-Known Member
I have a deep pan dish on my trans, it took a lot of trans fluid, I mean lot, the thing is huge! So lots of oil to spread heat over!
Oldiron440
Well-Known Member
An external trans cooler is needed also, I ran it through the rad and a external as well. Larger the better .
Dodge and Jeep 4-speed overdrive transmissions (A904 versions: A500, 40RH, 42RH. 40RE, 42RE and 44RE, and A727 versions: 46RH, 46RE, 47RH and 47RE) have a deeper transmission pan because the valve bodies are thicker (more valves) and of added electronics inside.
I encourage anyone with an FMJ automatic transmission to increase transmission fluid (ie: deeper oil pan) and transmission cooler size for several reasons.
The 4-speed oil pans are fairly inexpensive (well . . . except for freight to get one down under).
Even Dorman is making new (deep) pans at a reasonable price ($21 (US) plus freight on rockauto.com), part number 265-839 (A904/A999 4-speed version).
Someone else is making new (deep) pans for the A727 4-speed version for $22 (US) plus freight, also from rockauto.com.
Either version can be obtained with a drain plug – but for a lot more $.
A couple pieces of advice on using deep oil pans: Try to keep the filter on lower portion of oil pan – if at all possible. In the case of the 4-speed pans, this will require a spacer and longer filter bolts, that looks like this:
Note: there are several versions of these out there. Which version doesn’t matter – just use one.
The transmission filter to use is one that looks like this:
This style doesn’t fit (for the newer transmissions) and causes problems (unless you are using a 4-speed).
Also, I recommend using a Dodge re-usable pan gasket – for they seam to not leak as much: 4295875ac – A904/A999 (MSRP is $26.00 (US) as of 11/27/2018), or 2464324ac – A727 (MSRP is $40.75 (US) as of 11/27/2018) – but might be available cheaper on RockAuto.com or other places.
The magnet that fits in the transmission pans is also recommended – but not required. It does stop a lot of metal from floating around inside of the transmission
The transmission cooler, that is inside of the radiator, is not described accurately. It can cool fluid down but is more of a fluid heater than anything else. Transmissions like to have its fluid operate within a narrow temperature range – and the "in-radiator cooler” does just that . . . well, under normal conditions.
The police, taxi and HD towing packages had an external transmission cooler installed.
To back up a bit, the torque converter is the primary source (the only source?) of heat coming from an automatic transmission. The more the torque converter is placed in a “stall” condition, or into “torque multiplying” condition, it generates a TON of heat. For those with a heavy foot (finger pointed towards myself), drag racing, road racing, or anytime transmission is in a “Stall” or “torque multiplying” condition more than an ordinary driver would be – then you had better be installing an external transmission cooler . . . VERY SOON.
Several versions are out there – but if you have a transmission that is using lockup – I do highly recommend limiting rubber hose usage to a bare minimum – or leakage will occur. The factory used 100% metal tubing (or on some cars 98% metal with two pieces of 3-inch hose at the radiator – to prevent fluid leakage.
Non-lockup converters do not have transmission cooler line/hose leakage problems as much – sense there is only about 10-20 PSI pressure. Lockup cooler lines have 80-90 PSI pressure (when in lockup mode).
Bruce, if you plan on having a tire-roasting car, I would get as large of a transmission cooler that you can attach in front of the radiator (or A/C condenser – if present) that will fit.
BudW
Bruceynz
Well-Known Member
whats the lowering block called so I can find it on ebay or its part number
This is a picture of an old Mopar Performance deep pan (for a A727) from 20-30 years ago. This had a flimsy steel pedestal (white arrow) that went between the filter and the valve body.
I looked and couldn’t find any pictures of one in place. When you are installing the filter, the screws (longer screws, in this case) are going through the filter, the extension and into the valve body. The above picture also has a gasket that goes between the pedestal and the valve body.
It helps to have the filter at lower section/portion of the oil pan – which is what the filter extension is doing.
Think of it this way, you have a glass of a favorite beverage (some random picture I found on internet, below), would you rather use a straw that ends at the black line or ends at the white line? Note: for illustration purposes – mentally, YOU ARE using a straw – just in case you don’t, normally).
Go to eBay and perform a search using “727” and “filter” and scroll down quite a bit, and you will find several for sale. The material it is made of is not important.
A person could make yourself, one out of wood, if one so wanted to . . . (I wouldn’t, though).
BudW
I looked and couldn’t find any pictures of one in place. When you are installing the filter, the screws (longer screws, in this case) are going through the filter, the extension and into the valve body. The above picture also has a gasket that goes between the pedestal and the valve body.
It helps to have the filter at lower section/portion of the oil pan – which is what the filter extension is doing.
Think of it this way, you have a glass of a favorite beverage (some random picture I found on internet, below), would you rather use a straw that ends at the black line or ends at the white line? Note: for illustration purposes – mentally, YOU ARE using a straw – just in case you don’t, normally).
Dodge/Mopar Performance only sold the pedestal/extension/block as part of the deep pan set, so I don’t have a part number.
Go to eBay and perform a search using “727” and “filter” and scroll down quite a bit, and you will find several for sale. The material it is made of is not important.
A person could make yourself, one out of wood, if one so wanted to . . . (I wouldn’t, though).
BudW
Bruceynz
Well-Known Member
does the 727 filter extension fit the 904?
The A904 and A727 filters (and filter extensions) are the same - from '66 to mid '90's.
Yes, the one above will work.
Yes, the one above will work.
AJ/FormS
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Ok firstly , Op does not care about WOT power.
Secondly At Wot, So long as the carb can physically pass whatever cfm the engine requires it's big enough as you found out. Putting a bigger carb on it might find you a couple more Hps , but all that is happening is that the velocity of the air is dropping as it moves thru the bigger carb. You can keep on increasing the carb size all day, but power will not change a whole lot. So by the time you have doubled the carb size at WOT and found no real advantage you quit looking for power.
But what happens now at part throttle? The velocity thru the carb is so slow, that it doesn't meter properly, and the car becomes undriveable.
I think the formula is pretty close for most of us, if we adjust the end result to reflect VE.
For instance, the formula predicts 292x6500/3450=550cfm, and you pulled 518, so that's daymn close. Now if your engine was pulling a VE of 1.1, then 1.1x550=605. So a 600 would be a good starting point. And as you probably know 8hp is well within the realm of tuning. Could your 600DP have made another 8hp. I doubt it cuz then you would have gone hunting for it, and wouldn't have this great story to tell, right?
As for 340s and 1000 cfms; just because that engine had a total rated carb capacity of "1000" , doesn't mean it ever pulled that right? I mean I have put 850TQs on 318s that were almost maxed out on the 2bbl and it ran just fine with the TQ. But I bet it didn't pull 400 thru it. Same with those 6-packs. The standard AVS carb was rated at 580cfm and it made "275hp" on that. The TQ engines were rated at 290 IIRC, and the 6-pacs at 305IIRC. Otherwise the engines were all the same. So was there more power in the bigger carbs. It looks like it. But think about it. From 580 to 1000 is a difference of 420cfm, and it made just 30hp more. The formula predicts a requirement of 340x5800/3450=572. But those engines never hit 100% VE; maybe 90% at best, so 272x.9=515cfm. So who's zooming who as regards the power numbers?
It is commonly said that the 275 power number was a joke.
And it is commonly held that 340s built to OEM specs make a tic under 300.
IDK if that has any credence.
But if it does, then maybe they were making the power numbers up....... all of them. IDK
I know this; that NHRA factored all those hi compression 1971-340s to 330hp at 11.5Scr, without any regard to carburation used. What does mean? IDK, but it looks like the NHRA was not fooled.
When I showed up at the track in 1971 with my 1970Swinger 340 AVS equipped, they put me in G-stock. As I recall that is 10pounds per horsepower. My car scaled at 3200. I got a trophy that day.
Oldiron440
Well-Known Member
I have always tuned a performance build for wot power then tuned for drivability. Then its sqirter size, power valve or accelerator pump agustment but to detune or not tune for maximum power is ridiculous. If that's the case don't build for performance in the first place. We're talking vacuum secondary carbs here, the carb will only get as big as you let it.
One thing AJ on this carb you have a hard opinion and you don't know the cam yet.
One thing AJ on this carb you have a hard opinion and you don't know the cam yet.
AJ/FormS
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I made it up,lol
My combo is a dump-it-and-go deal. I tap the gas, and let out the clutch, and let the flywheel break traction,then drive away. I'm guessing 1500rpm more or less will do it. And the carb is barely open. My starter gear is 3.09x3.55=10.97. Estimating 140ftlbs at the crank, this maths out to 140x10.97=1536 to break traction. These are used BFG 295/50-15s. It 60fts in the 2.4plus range. Sometimes I floor it when I hear the chirp,lol.
So, you might be asking just 140 ft lbs? Where did I get that number?
I made it up.
What? well years ago I had one of those dash-mounted accelerometers that datalogs. So I made a graph from the data, and of course it's at WOT right, so not much help. The thing is I had a primaries only graph that started at 2000rpm/WOT. Still not much help.
But here is something to think about; as you know when you cam up, you trade away bottom end torque to get topend power. So eventually a 360 below 2000rpm looks almost exactly like a 318.....which is why we increase the TC stall.
So below is a teener graph. Notice at 1600 it is making~ 265ftlbs/WOT,with a 2bbl. I don't think it's much of a stretch to suggest that at 1/2 throttle it might be making 140.
Now for me the clincher is this; With the line-loc set, I can just modulate the gas and clutch still well below 2000rpm, break traction, let the clutch out all the way, and then bring the rpm waaaaaay down to hear the BFGs howl. I've never actually looked at the tach, cuz usually we all are splitting our sides with laughter that this is even possible. If I had to guess, it would be well under 1600, with the throttle barely open. It's hard to imagine my 367 would have much more than 140ftlbs,lol.
Waitaminute, I'm at 185psi cranking pressure; maybe it is more than 140! Hah, I knew that pressure was good for something,lol.
Anyway. like I said, I made it up.
I used to have a 2.66x3.55=9.44 starter gear, and the engine was one cam size smaller. And on that one I ran 245/60-14s (sick I know, but I was tapped out at the time). It was the same thing.
And that is my starting style, you won't hear my combo sounding like an old Mustang.
And now you know why I couldn't hardly wait to get rid of my first cam, the mighty 292/292/108. With the same 9.44 starter,and even at 11.3Scr, it couldn't do that.POS.
Well not POS exactly, cuz after 5000 it was gangbusters, all the way to 60mph, still in first gear,lol..
Having thought about it,Maybe 140 is a little soft. Maybe 1500 is not quite enough. But the 30% wiggle room I added should cover it for those that do NOT have 185psi........
Also note, I qualified it as 1500 to the road. With 26.5" tires, your crank torque would have to be grossed up by 26.5/24=plus 10.4%, so the 1500 would actually be 1656.
