MSD ignition conversion on my '88 5th Ave

BudW

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Father outwards (towards the L/F frame rail).

I’ll see if I can take some pictures to clarify.
 

MiradaMegacab

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Fairly sure – but not tested to confirm.
If you supply either a Nitrous or a blower, I can go find out – to confirm my theses?

It might be fun just finding out.
BudW
I've done it already........
Went from a 18.xx to a 13.01@104
Roots blowers love deep gears. The added torque pulls thru each gear. Stock engine, trans, and a 2.xx rear.......
 

MoparKidD-4

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Lots of info thanks guys... first off I did decide to do the rear end/gears swap before anything else, I'm going with 3.07:1. Quick question what are the ratios of my transmission? Everyone is saying it's a 904 so does that mean the regular 2.54-1.45-1 or does it have the deeper gearset with the 2.74 low, like the 998 or whatever?

Regarding the linkage I was really hoping I'd be able to find a factory setup for cheap but it sounds like that won't be easy. I did the Lokar throttle and kickdown cables on my '70 Duster, they are very nice but I don't feel like spending $160. Is it not possible to modify the factory 2-bbl linkage to make it work? I did a similar thing on my Duster when I first had it, "kind-of" worked but I'd be able to fab more parts myself now if needed to make it work better.
 

MoparKidD-4

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Since you got the MSD for free, yeah you might as well use it, but is way overkill.
Don't get carried away with the timing in that thing, or you will get into detonation pretty quick. The factory ELB computer did a pretty good job on the timing end of things. So much so that 5ths,up here, regularly get 25 mpgs on the hiway. That is 20mpgUS.
The new rear gears will be a tremendous improvement to 2.2s; almost 40% better. Your car will feel like it just got a turbo.
I would encourage you to get that installed first.
The 4 bbl will do nothing for you with those 2.2s, until over 40 mph, and it won't amount to much.
Whereas the gears will improve performance everywhere. With the new gears, the 4bbl will start to pull at around 30 mph.That is also a very nice improvement. Keep in mind that even on a hotrod engine, the secondaries only add about 8 to10% power. On a 300 hp engine this is 30hp. On your teener it might make 15hp difference and it won't make that until maybe 4500 or 56 mph in first with 2.21s.

If the MSD box turns out to be junk I'll look into a cheap less-overkill solution... I already know the distributor is good and I just bought a brand new MSD Blaster 2 coil to go with them I might as well use that too.

I don't deny the MPG capability, I just got back from a trip to Steamboat Springs (160 miles each way) and I know I easily broke 20. I also noticed how the fuel economy does indeed improve when using higher-grade gas; the difference between 85 regular and 87 midgrade (both E10) is staggering, 91 is a bit better but doesn't justify the cost it's 50-60 cents more expensive /gal when regular is $2.20/gal. I typically go with mid.

The 4-bbl won't just add aiflow from the secondaries, this stock 2-bbl is extremely small for this engine @BudW didn't you say it was like sub-200 cfm? The primaries alone will flow more considering it's a big-block TQ, I swapped in the smaller jets and bigger metering rods from a 360 TQ core I have as well. I'm not necessarily looking for more off-the-line tire-smoking type stuff, more like better passing power once the car is rolling. Hitting the kickdown at 65 mph or higher is a joke, almost pointless... just wheezes along waiting to shift back to 3rd lol
 

AJ/FormS

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Hitting the kickdown at 65 mph or higher is a joke, almost pointless... just wheezes along waiting to shift back to 3rd lol
I know exactly what you mean; My dad left me his 5th when he died.It was exactly like that. I never bothered to register it, and sold it for what the new tires on it were worth.

Your engine will not pull over 200 cfm until, well over 3000rpm,and that with a free-flowing dual exhaust, not the crippling factory single pipe.And when it does it is hardly gonna hit a wall, it will pull thru that little carb until it blows up.It will continue to pull no problem, until long after the cam is choking.So your 4bbl will not add any airflow until perhaps 3000 rpm at the earliest,which being what again? Oh yeah 34 mph with 2.74lowx2.4sx26tires,IIRC,lol. And if you haven't altered your timing curve, that teener may be ready to drop its skirts into the pan.Be very careful to stay out of detonation.
The big TQ has 1.5 primary blades, about the same as most teener 2bbls.
One thing you may have overlooked is that 2bbls and 4bbls are rated differently as to flow and are not directly comparable.IIRC 2bbls are flowed at 3 inches and 4bbls are at 1.5. And I have forgotten the conversion formula.
I once installed a BBD onto a 340 that easily pulled to 5500 and more. It was a dynomite combo with the rest of the pkg.

If you want passing power, the quickest way to get it is with gears.
If your engine is loafing along at 2060@65(2.45s) and you stomp it, she will kick down into second at 3170 plus slip,say 3330. How much torque is there? Lemme guess 115 ftlbs. If you had the 4 bbl open there, and if it added a whopping 10% horsepower, that would translate to about 10 ftlbs for a grand total of 125 ftlbs. Lets put this into perspective;
>125 at the crank times 1.54tranny gear x 2.45rear gear x12/13tire correction=424 road ftlbs. Now lets say your car weighs 4000 pounds with you in it.This then is 4000/424=9.43ftlbs per pound of car weight.This is about 1/100th of a performance car might have.
>Without the 4bbl it would have been 9.92.So this is an improvement of 5.2%
>Now lets remove the 4bbl and install those 3.07s
115 x 1.54x3.07x12/13=502 ftlbs, and 4000/502=7.97 ftlbs per pound.
This is an improvement of 9.92/7.97=plus 24.4%
I'll tell you a secret;3.07/2.45=25.3% improvement, so you can skip almost all the math.
Now lets put the 4bbl back on, and add back those 10 ftlbs at 3330rpm
(115+10)x1.54x3.07x12/13=545 ftlbs, and 4000/545=7.33 pounds per pound, a further improvement of 7.97/7.33=8.8%. Now the 4bbl is making a difference.
We have gone from 9.92 to 7.33, a total of 9.92/7.33=plus 35%@3330 rpm.
>Bottom line is;How is this gonna affect your passing power? I can't say; I have never been in this situation. I've never owned a 4000pound .......anything,lol. And if I wouldda, it wouldn't have had a teener in it,by the time it was road-legal.
BTW;
I chose 115 ftlbs not to be exactly representative of a real teener at 3330rpm. It doesn't matter what the true number might be,cuz I worked everything out in percentages, and those will not change no matter what you actually input as to torque.That is the beauty of percents, no initial accuracy required. I could have inputted 200 or 2000 ftlbs as a starting torque, the percent change would have remained the same. So, take heart, your particular teener may not be as anemic as 115ftlbs at 3330rpm.lol.
maybe I should have grossed it up some.............................................
I vote NOT going to any more than the 3.07s. These will get you 4170rpm at 65, and your cam was done several hundred rpm ago. So she will be done pulling real quick.Not done reving, but done pulling. The valve springs may be good to 4500 or a little less; watch for it!
 
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MoparKidD-4

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I know exactly what you mean; My dad left me his 5th when he died.It was exactly like that. I never bothered to register it, and sold it for what the new tires on it were worth.

Your engine will not pull over 200 cfm until, well over 3000rpm,and that with a free-flowing dual exhaust, not the crippling factory single pipe.And when it does it is hardly gonna hit a wall, it will pull thru that little carb until it blows up.It will continue to pull no problem, until long after the cam is choking.So your 4bbl will not add any airflow until perhaps 3000 rpm at the earliest,which being what again? Oh yeah 34 mph with 2.74lowx2.4sx26tires,IIRC,lol. And if you haven't altered your timing curve, that teener may be ready to drop its skirts into the pan.Be very careful to stay out of detonation.
The big TQ has 1.5 primary blades, about the same as most teener 2bbls.
One thing you may have overlooked is that 2bbls and 4bbls are rated differently as to flow and are not directly comparable.IIRC 2bbls are flowed at 3 inches and 4bbls are at 1.5. And I have forgotten the conversion formula.
I once installed a BBD onto a 340 that easily pulled to 5500 and more. It was a dynomite combo with the rest of the pkg.

If you want passing power, the quickest way to get it is with gears.
If your engine is loafing along at 2060@65(2.45s) and you stomp it, she will kick down into second at 3170 plus slip,say 3330. How much torque is there? Lemme guess 115 ftlbs. If you had the 4 bbl open there, and if it added a whopping 10% horsepower, that would translate to about 10 ftlbs for a grand total of 125 ftlbs. Lets put this into perspective;
>125 at the crank times 1.54tranny gear x 2.45rear gear x12/13tire correction=424 road ftlbs. Now lets say your car weighs 4000 pounds with you in it.This then is 4000/424=9.43ftlbs per pound of car weight.This is about 1/100th of a performance car might have.
>Without the 4bbl it would have been 9.92.So this is an improvement of 5.2%
>Now lets remove the 4bbl and install those 3.07s
115 x 1.54x3.07x12/13=502 ftlbs, and 4000/502=7.97 ftlbs per pound.
This is an improvement of 9.92/7.97=plus 24.4%
I'll tell you a secret;3.07/2.45=25.3% improvement, so you can skip almost all the math.
Now lets put the 4bbl back on, and add back those 10 ftlbs at 3330rpm
(115+10)x1.54x3.07x12/13=545 ftlbs, and 4000/545=7.33 pounds per pound, a further improvement of 7.97/7.33=8.8%. Now the 4bbl is making a difference.
We have gone from 9.92 to 7.33, a total of 9.92/7.33=plus 35%@3330 rpm.
>Bottom line is;How is this gonna affect your passing power? I can't say; I have never been in this situation. I've never owned a 4000pound .......anything,lol. And if I wouldda, it wouldn't have had a teener in it,by the time it was road-legal.
BTW;
I chose 115 ftlbs not to be exactly representative of a real teener at 3330rpm. It doesn't matter what the true number might be,cuz I worked everything out in percentages, and those will not change no matter what you actually input as to torque.That is the beauty of percents, no initial accuracy required. I could have inputted 200 or 2000 ftlbs as a starting torque, the percent change would have remained the same. So, take heart, your particular teener may not be as anemic as 115ftlbs at 3330rpm.lol.
maybe I should have grossed it up some.............................................
I vote NOT going to any more than the 3.07s. These will get you 4170rpm at 65, and your cam was done several hundred rpm ago. So she will be done pulling real quick.Not done reving, but done pulling. The valve springs may be good to 4500 or a little less; watch for it!

Nice math as always AJ... These cars aren't quite 4000 lbs btw, factory curb weight is 3750 so just about 3900 with me in it (I'm 6'1" but lanky like Richard Petty lol). I might try shaving 1-200 lbs. removing a bunch of the unnecessary heavy stuff these cars came with (bumper supports, driveline weights etc.) if I can. Aluminum 4-bbl intake will take off what like 25 lbs as well?

Even if this stock carb did flow 'enough' it still needs to be replaced; I checked the throttle shaft play and it is HORRIBLE, I can wiggle it up and down even in the bore and it always hiccups stepping on the gas off idle just like every other old worn-out carb I've driven. Also what you say regarding the difference in flow ratings is interesting, as in rating both the 2-bbl and 4-bbl at the same 1.5"Hg pressure drop would show the 2-bbl flowing even LESS. I do have free-flowing dual exhaust off the stock manifolds btw, first thing I did to this car literally the day after I got it to pass emissions was cut out all the factory exhaust from the manifolds back and make up my own dual pipes with side exits and a pair of brand new Dynomax Ultra Flo mufflers.

One more thing, reading about the output specs of these later 318s and how they came with the roller cam and improved heads the torque ratings shot up from 235 to 265 lb-ft which is quite a big improvement IMO going off 1980s standards. This leads me to believe these later 318s have more power/airflow potential in stock form than the older non-roller-cam 318s so I think a 4-bbl swap even with the stock cam should make a bit more noticeable improvement than doing the same to a 1977-spec 318, for example. Also this thing has pretty insane grunt, like peak torque is pretty much right off idle I know once I put those 3.07s in the back it'll start lifting the left-front fender pretty hard lol. I would say it'll spin the tires too but I have the giant 275/60-15s I swapped over from my Duster and the built 360 in that car could barely break these tires loose.

Overall I'd say this 318 runs wayyy better than the 318 that came in my '70 Duster when I first got it. Granted that engine was not in as good of shape (burned lots of oil) but this 318 is so much smoother and torquey in comparison, and it gets good gas mileage to boot. I don't think I ever managed even 20 mpg with the 318 in my Duster and it had 2.76 gears and weighed ~600 lbs less.
 

BudW

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A Carter BBD flows about 230 CFM.
Not sure about the Holley 2280/6280 - but would guess to be about the same CFM.

1-3/4” single exhaust will flow about 239 CFM.
1-7/8” single exhaust will flow about 278 CFM.
Most year 2-bbl M-bodies have 1-7/8” muffler inlet and 1-3/4” muffler outlet.

O’Reilly auto parts (who I use) shows three different mufflers, in two different sizes: 1-7/8” in/1-7/8” out as well as 1-7/8” in/1-3/4” out.

They also show one tail pipe, Walker 45614, which is 1-3/4” (I have a brand new one in my garage, free, if someone wants to pay for shipping for it).
BudW
 

AJ/FormS

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I was careful to say 4000 pounds with you in it, as most of us older fellas are dialing in at over 200.
A 100 pound error is 2.5%, and would make about .3 ftlb error in my calcs.

As to flowing, you got it backwards. If you take a 230 cfm 2 bbl that was rated at 3 inches and pull harder down thru it to pull 1.5 inches, it will flow more. A number just popped into my head, and I think the conversion factor is 1.67. So if that's right, then the 230 will become a 384, and the 650 would become a 389. If your engine cannot pull the vacuum, then you get what you get, in some other proportion. Most engines don't pull the numbers until way up the rpm band.
If your engine could pull 380ish through the 2bbl and also thru the primaries of the 4bbl, and you then floored it, the car would not go any faster, it would just share the airflow thru 4 boosters instead of 2.
See you don't put a 4bbl on an engine to go faster. You put a 4 bbl on the engine to support the other mods that you have done to the engine that have created a situation where the engine can breath more air. Things like hi-flow heads and a camshaft with a higher operating speed.
Think of it this way; grab a straw and blow thru it. Then fabricate a funel to double the inlet size and blow thru it again. Do you imagine any more air went thru that straw? That is the same idea with putting a 4bbl on an engine that is restricted in airflow due to heads cam or exhaust.
Try this, instead of blowing thru the one straw, blow thru two. Now you have delivered twice as much air. This is akin to a cam swap or headwork.
Your engine, if it is flow restricted, doesn't need a 4bbl until she is built so that the atmosphere can actually push more air into it.
Your engine is flow restricted partly cuz it is rpm limited by the rear gear.It is also restricted by the factory cam and valve springs.And partly cuz it is currently breathing thru log manifolds.And finally by the compression ratio.
But it makes a certain amount of torque, which we can multiply with gears to do a great deal of work. We can easily double it, That is 100% more. This would require 2.45 x 2=4.90 rear gears. This is an across-the-board increase of 100%, everywhere in the rpm and speed range.The trade offs are fuel economy,noise, and vibration.
A 4 bbl by itself, if it manages 15 hp at 4500 rpm is a poor excuse of an increase starting perhaps as early a 3000 rpm. What was that again;oh I remember; starting at 35 mph with a 1 hp increase, and every 200 rpm adding 1 hp to it, so that by 4500/52mph, you get the full effect, then you shift and the Rs fall to 2529, and the secondaries slam shut and you get to climb back up to 3000/62 mph when the secondaries just crack open again.So that 4bbl has a very narrow window of operation from 34 mph to 52 mph. And it starts off with a tiny increase, working up to a frenzy at 4500rpm.
Of course you can bring in the secondaries in earlier, at the risk of detonation, and enjoy the fractional increases in power. The engine will only pull in what it is able to. You could put 8 bbls on there and it would not pull any more power below that rpm that the current 2bbl is adequate to.And I'm estimating,nay guessing, your teener will pump up the lifters before that rpm is reached.
The formula is (cid x rpm)/3450 x VE . Do the math for a 318,4500rpm,and .75 VE. I get 311cfm. this is for 1.5 inches depression. correcting your 230 from 3 to 1.5 if my memory is right, you currently have a 230 x1.67= 384. So at 4500 you have a reserve capacity of 384 less 311 is 73 cfm which is 73/384=19%.
A 19% reserve capacity. hmm. Lets work the formula backwards
384x3450/318/.75VE =5700rpm. Hyup, thats about what my old 340 2bbl revved to with 318LA smogger heads on it and an early 318 2bbl cam in it and fenderwell headers with dual 2.00exhaust. So I'd call it close.
Now you can argue all day long about it feels stronger and it will pull the fender up etc , but I don't see you posting up before and after time slips, so your protestations ring hollow.
By the same token you never rode in my 65 long roof with the big-bore teener experimental engine, so for all you know I'm just a crackpot who knows a little math.
I get that.
But just hurry up and get that 3.07 under there, and you will be in a whole new world full of nothing but giddiness.
 
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MoparKidD-4

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Wait wait wait... I thought the pressure drop increased with flow, not the opposite?? Like if you have a 1.5" negative pressure on one side of an orifice and you try to push/pull more air through it the pressure differential will go up...??
 

MoparKidD-4

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Just did some quick searching I think you actually have it backwards AJ, everything is saying that conversion factor goes the other way (2-bbls have higher ratings than if they were flowed at 4-bbl pressure drop)...
 

BudW

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AJ’s math is mind boggling but all that I can tell is right on.

Replacing a 2-bbl with a 4-bbl (with no other mods) does help as much as one would expect.

The big issue is the 4-bbl helps out but with more RPM – but that is where valve float comes in.
Also, if you have more air coming in – you still have the bottle neck of the camshaft, exhaust manifolds and exhaust piping (cats, mufflers, etc).

If you replace the carburetor, intake (all necessary linkages: ie: kickdown linkage and throttle cable). Camshaft, valve springs, exhaust manifolds/headers, bigger exhaust system (single or dual) then you have a LOT more capability with overall power.
The same note, you just lost the low end torque the 318 is known for (replaced it with high end power).

AJ is correct is to change gear ratio first, then see if you want to make the other modifications.
If so, then the gears (which is needed for 4-bbl to be effective) is already there.


I have two stock 318’s with are identical except for gear ratios. My ’77 wagon (2.9 ratio gears) will run circles around my ’86 5th Ave (with 2.2 ratio). Well, I say identical, but close – my ’86 has Lean Burn/ESC on it – but otherwise the same.

I have a 8¼” differential out of an ’84 Gran Fury police car with 2.94 that I plan in putting into my 5th Ave, soon – for I can’t stand those 2.2 gears.
A passenger could literally get out, check tire air pressures and check oil level, while car is taking off from a stand still. Well, OK, maybe not, but you get what I’m saying.

The wagon is definitely more fun to drive. The problem with it, is I have to change a host of items on car (see notes from above) and at the end, the car will not be as fun to drive in in city driving – for I need that low end torque. City driving, with my 10 year old twins in the car, I don’t want to make high RPMS.

My ultimate fix (for me) is more cubic inches (about 200 more cubic inches . . .), but that is a conversation for another day.
BudW
 

AJ/FormS

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They say there is no substitute for cubic inches
And nowhere is this more applicable than starting from zero mph!
This is also why you couldn't give me a teener. By the time it is making decent midrange, the bottom is getting soft. And by the time the top-end is there, the bottom is all but gone. Then come the bandaids to get it moving off the line. Bandaids like Hi-stalls and gears.
Man just drop a 360 in it and call it done. Forty Two cubes, puts all the bottom-end in there you will ever need in a streeter.
Power them both up to 300 hp and as to the bottom end and even the midrange,the teener is sick in comparison.
This matters not much when the engine is wound up. But from a stop, the 360 needs nothing while the teener needs many dollars to keep up, and then it burns gas at an alarming rate around town.The only cure for this is for the teener car to go on a major weight loss program, so the teener doesn't have to have that stinking race-cam,lol.
No-sir, you couldn't give me 10 teeners for a performance 2nd gen A-body, or anything heavier.
Actually I would accept one with;
a 210ish cam,and a Dcr of about 8.6 in conjunction with a tight-Q
A free-flowing dual-exhaust,
small-port heads, a small-port intake, and a small 4bbl of 390 to 500.
Yes-sir, I could make that work with an A518, and 3.73/2400TC or 3.91s/2200TC. Hyup,I think that recipe is good.
So in conclusion, I stand corrected;
There is no substitute for cubic inches, when saddled with really poor gears and a lot of weight,lol.
 

MoparKidD-4

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They say there is no substitute for cubic inches
And nowhere is this more applicable than starting from zero mph!
This is also why you couldn't give me a teener. By the time it is making decent midrange, the bottom is getting soft. And by the time the top-end is there, the bottom is all but gone. Then come the bandaids to get it moving off the line. Bandaids like Hi-stalls and gears.
Man just drop a 360 in it and call it done. Forty Two cubes, puts all the bottom-end in there you will ever need in a streeter.
Power them both up to 300 hp and as to the bottom end and even the midrange,the teener is sick in comparison.
This matters not much when the engine is wound up. But from a stop, the 360 needs nothing while the teener needs many dollars to keep up, and then it burns gas at an alarming rate around town.The only cure for this is for the teener car to go on a major weight loss program, so the teener doesn't have to have that stinking race-cam,lol.
No-sir, you couldn't give me 10 teeners for a performance 2nd gen A-body, or anything heavier.
Actually I would accept one with;
a 210ish cam,and a Dcr of about 8.6 in conjunction with a tight-Q
A free-flowing dual-exhaust,
small-port heads, a small-port intake, and a small 4bbl of 390 to 500.
Yes-sir, I could make that work with an A518, and 3.73/2400TC or 3.91s/2200TC. Hyup,I think that recipe is good.
So in conclusion, I stand corrected;
There is no substitute for cubic inches, when saddled with really poor gears and a lot of weight,lol.

All true, but you only start losing bottom end when the cam is changed. All the "bolt-on" stuff just helps boost breathing at higher RPMs but doesn't take anything away from the bottom. Obviously you can only do so much until the engine is at its max airflow capacity with the stock cam/heads etc. and that's exactly where I want to take this engine. Maximize airflow and power with the stock long block and cam, and give the engine a break from having to lug the car around with absurdly high gear ratios.

BTW I like 318 because gas mileage lol. Sure a 360 will do OK with overdrive/tall gears, but a 318 will always do better set up similarly simply because it's smaller. The purpose of my 5th Ave is a cheap, comfy, reasonably fun-to-drive cruiser that can get over 20 MPG on the highway and go anywhere without worrying about something breaking down. Right now it does the cheap, comfy, and 20 highway MPG part with ease but fun to drive? Not really.
 

MiradaMegacab

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One way to overcome any of the above concerns and to disprove the "no replacement for replacement theory"
blower12.jpg
blower12.jpg
blower12.jpg
 

kkritsilas

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I have never heard of 3 superchargers in series, but have heard of 2 superchargers I think the 1930s Mercedes Benz SSK had those, and maybe an Alfa Romeo race car, but I think they were more common on piston engine fighter planes. I have also heard of a supercharger-turbo combination. That combination was used in the Lancia Delta rally cars, and there was a yellow Nova in the 1980s- earky1990s that used a supercharger feeding twin turbos. It was pretty famous as being the best street rod of that time. Both the Lancia rally car and the Nova used a supercharger for low end response, and then transitioned to the turbo (s) at higher RPM to make top end power.
 

AJ/FormS

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All true, but you only start losing bottom end when the cam is changed. All the "bolt-on" stuff just helps boost breathing at higher RPMs but doesn't take anything away from the bottom. Obviously you can only do so much until the engine is at its max airflow capacity with the stock cam/heads etc. and that's exactly where I want to take this engine. Maximize airflow and power with the stock long block and cam, and give the engine a break from having to lug the car around with absurdly high gear ratios.

BTW I like 318 because gas mileage lol. Sure a 360 will do OK with overdrive/tall gears, but a 318 will always do better set up similarly simply because it's smaller. The purpose of my 5th Ave is a cheap, comfy, reasonably fun-to-drive cruiser that can get over 20 MPG on the highway and go anywhere without worrying about something breaking down. Right now it does the cheap, comfy, and 20 highway MPG part with ease but fun to drive? Not really.

All the bolt on stuff is pretty much useless on a stock 8.0 teener, it is already close to its maximum breathing ability.
The stock teener might make peak power at 3900. And at 3900 it might pull 318x3900/3450 x .60VE=215cfm. The stock 2bbl is rated at 230cfm. 3900 rpm with a 2.2 axle is about 51mph with a 2.74 low gear. Who in their right mind holds their FMJ in first gear to 51mph?
Ok but say you stuck a 500 4bbl on it anyway. Well it doesn't matter if you put a 500 or a 600 or a 750 on it, the teener will only pull 215 cfm at 3900.The difference is now 4 barrels are flowing the same air as previously only 2 were.
And that teener might not even flow 215, thru the logs,the Y, the cats and the mufflers, etc.
OK so you get rid of that entire OEM exhaust, all of it. And you put some long-tubes on it.Ok firstly, the stock 240/112 cam has 20* of overlap, so the headers have nothing to work with.Zip,Nada, Zereo. About all they can do is not be a restriction. But yeah they might help evacuate the exhaust, what little there is of it. So let's say, at 3900 they increase the VE to .65, together with the 4bbl. the new cfm number is 318x3900/3450x.65= 231cfm. At 51 mph. At 51 mph. What else you want to bolt on. OOps sorry there is nothing else.
So let see, we gained 16 cfm. Gee, I wonder how much power that would be down on the starting line 1750rpm, the stock stall? I'll guess just enough to run the A/C compressor.
And finally, let's put a cam in it. Oh wait,let's not! Any cam that you stick in an 8.0 teener with a later closing intake valve will only make a bad situation worse. But let's say you are a sucker, and stick a little 262/110 in there.
Well firstly, this is not a cam-only deal. This cam will drop the Dcr so far down that an A-body slanty will put a hurt on you at the start line. So you are also gonna have to buy a bigger TC. And a 2400 may not be enough. And you will need some new springs so that cam can rev to it's working area. And you will need some headwork cuz the stock teener ones will more or less choke the 262/110. And probably some new pushrods. But by golly,after all that,the VE shot up to 70% now at 4800.So now we are pulling 318x4800/3450x.7=310cfm! Yippee! Now we are getting somewhere.
Well we are aren't we? 4800 with 2.2s are 63 mph in 2.74 low gear. So you have passing power.
But you sacrificed the entire bottom end to get it! All of it gone! And that 2800 is not real good at 65 mph, when the engine is spinning 1900rpm, with those 2.2s
Up-camming an 8.0 teener is a colossal waste of money, in most applications.
And if you don't cam it, the 4bbl is a waste.
And if she won't pump air, the headers sure look nice.

Ok that's all well and good you say, but you have 2.45 gears. Oh please; that is 11% more gear, and now your 3900rpm is 44mph in first gear. How often will you be keeping first gear to 44 mph?
But dropping in a 360 is an instant 13% increase in cubic inches. More torque and more power and a higher operating limit, and more potential to breath through a bigger top-end.
The 360LA comes with a 252/112 cam, and about 32* of overlap, still not much for the headers to work with, but that cam peaks several hundred rpm higher than the teener, maybe 4400. So, the cfm now is 360 x4400/3450 x.65guessing=298cfm, no headers no 4bbl, no cam, no TC, no springs, and no headwork. If you want to hold the 360 in low gear to 65 mph, it will be doing 5200@5% slip, with those same 2.2s.
Ok so lets compare.
The teener all dressed, pulled 310cfm, and the just-dropped-in 360-2bbl with 360 iron manifolds, pulls 298.That's 96%.
How much did you spend on that teener? Let's see now, headers,and complete exhaust,intake and 4bbl, cam kit, port work, a 2800TC, a little of this and that, and I see somewhere between $3000 and 4000USd.
And how much for the pic-a-part 360 with the monster torque that loves your 2.2s with a stock 1750TC? Ok add installation.

The absolute biggest favor you can do for your 318 in regards to performance is ditching those horrible hi-way gears, be they 2.2s or 2.45s, and swapping in at least 3.23s. this is a 46.8% improvement over 2.2s and a 31.8% improvement over 2.45s. This will make your engine feel correspondingly bigger. In fact, it will feel bigger than a 360 with the old gears. First gear at 3900 will now be 33mph, so you will get to use second for a good long way on the trip to 65mph, which will be about 4300. Then into Drive it goes, spinning 2670@ zero slip.
Yeah it will use more gas cruising the hiway, but I bet it does a lot better around town, in stop and go. So the general average may not be as bad as you imagine.
Ok if you just can't stand the extra gas at 65mph, 2.94s are a reasonable compromise.
Just please don't up-cam the teener without also upping the compression.
I'd say trust-me, but that is such a cliche. Look, put some gears in it first.At least 30% more than you got now.Then come back and say, AJ you suck! I dare you! You will forget all about bolt-ons.
30%. Can you imagine what that will feel like? Well,consider this; A turbo can add that much torque to your teener,maybe even up to 50% more torque. 30% is a LOT. A 413 engine is 30% bigger than a 318. It might send a few more footpounds into the pavement with the 2.2s than your teener with the 3.23s, but I bet it would be close.4.30 are 33% bigger than 3.23s, and you better believe 4.30s will be a fantastic improvement to 3.23s.
I have run teeners with almost every gear you can name. And I have up-cammed them without adding compression. And I have bolted on X-heads, and 340 cams and 850 TQs, and TTi headers and automatics and 4-gears. About the only thing I have never done is given even just one of them a boost in compression.
Without exception the nicest one I ever ran,had nothing but a 4bbl,headers, a 2800TC, and about a 10/1 starter gear. That was 3.09 x 3.55=10.97. Yeah it had overdrive;a 2.77 final drive. The headers were on it cuz they were already in the chassis;they belonged to the 367summer motor. The 4bbl went on cuz I love the sound of the TQ moan, and cuz with a 10/1 starter gear, the secondaries can actually be made to open at a low-enough rpm to do something besides moan.Hyup that was a fun winter.
Another winter, I ran that same engine with an A833od and the Gvod behind it, and 4.30s. Hyup, that was a fun winter.
Another winter, I ran the Gvod behind a 3.09low-A833 and again the 3.55s. Hyup,that was a fun winter.
Anoth, enough!
Teeners come alive with a starter gear of between 10/1 an 11/1, and very tight splits.If automatic, I can tell you that a 2800 is awesome.
One winter I ran the 2.74 auto and 2.76s. The starter gear was just 7.56. But that 2800 just made all the difference. No od on this combo, so I leaned out the TQ a tad, and I drove a little slower,lol.
Hyup those were good times.......
 
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MoparKidD-4

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AJ, man you like to go on lol always a good read... couple of assumptions still, I'm not sure if I said in this thread but I'm swapping in an 8 1/4" rear with 3.07 gears before any other performance stuff. My car has the 2.74 low first gear 904 btw, with 3.07 gears that gives the same starting ratio as an early 904 with 3.42 rear gears. I'm also not bothering with headers because like you said they don't do anything on an engine with little to no overlap in the cam.

If the carb on this engine was in better shape I might consider leaving it be but it's in bad shape. TONS of throttle shaft wear, like it actually has end play you can wiggle it up and down and the engine always stumbles off idle. Like I said before also, by going to the 4-bbl I'm not expecting to get any improvement in off-the-line acceleration or even up to 20-30mph, I want it for the extra passing power and acceleration once the car is already moving. I already have the carb and I'm looking for a good deal (<$180 US) on a Performer intake manifold. Over on FABO where I started the thread about hopping up this engine I got the impression that not too many people have done a TQ swap on a stock roller-cam 318 and it got me curious, I want to try it just to see what happens lol. More compression (rated 9.2:1 so probably around 8.5 in reality?), better heads, and roller lifters ought to be worth something. If it was an earlier flat-tappet 318 I would be less interested, I'd have bought a running 5.2L Magnum off Craigslist to swap in by now.

FWIW I hold this thing in first gear until 45mph or so when I'm entering the freeway. It's the only way to catch up to 75mph traffic because if it shifts into 2nd any sooner it just falls on its face (not like it's malfunctioning, just too big a drop in RPM and not enough torque at the wheels).
 
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