Project Tire Fryer

[kkritsilas]

Factory low stall speed converter and a cam intended for high RPM/high compression do not make for tire burning take offs from a stand still.

Before taking anything apart, if you can get a vacuum gauge on there, and see what the reading is at lets say, idle, 2500 RPM, and maybe 3500-4000 RPM, we may be able to figure out an approximation of how aggressive the cam is. I think this is just about the easiest way to get an idea of where you are. Low vacuum at idle is a good way to see how much overlap you have, which is an indirect way of seeing how much dynamic compression is being lost.

 

[AJ/FormS]

It's been said several times;Compression test.
And Stall test.
Vacuum test.
prove rear gear.
Until the results are in,it's all just so much speculation. Forget about cam timing for a bit.
Some of us have seen this sorta thing many times.KKritsilas summed it up pretty good in his opening comment,above.

Dropping a 340 cam(268/276/114) into an 8.0 teener will drop the Dcr into the basement, around 6.3 to one,117psi cylinder pressure. That makes a super-doughy torque up to around 3000/3600rpm.With a factory stall around 2100, now probably 1800 with the doughy down-low, trying to get going is like trying to push a rope! Couple that with a hiway gear,and slow heads, and you get; what you got.So do the tests, and then we can formulate a cure.6.3Dcr is like LawnBoy lawnmower territory

 

[BudW]

Big (intake) ports and high RPM go well together,
Small ports and low/mid RPM also go very well together.
They just don’t like to be mismatched.

Case in point.
The early ‘60’s Chrysler came out with the Max Wedge. Intake ports big enough to stick your fists into and not scrape the skin. Those engines were rockets once RPM’s reached 5k and higher. Before then, forgetaboutit – you got nothing.

If a person was to put a Max Wedge into an FMJ car, with 2.2 gear ratio, a bicycle would beat you until you got up to 60 MPH or so. I think a person walking could pass you until engine got up to speed. Those engines felt at home with 4.56 or 5.30 gears (not practticle for street driving).

I think you are on the correct path, with one possible wrinkle.
I don’t think it will make a difference on which chamber cylinder heads you use, so if you have a pair of heads, great – use them.
Then, Instead of milling or cutting down the cylinder heads, block and intake (to match), I would recommend getting or looking into getting the correct pistons, instead of milling.

Compression ratio is very important to get correct.
Too much is as bad as not enough. Most FMJ’s have “too little” compression.

I had two sets of custom pistons made for my pair of big blocks. Not only do they get me the exact compression ratio I want, but I also got them coated. The piston tops are coated with a heat resistant finish. The sides are coated with ant-scuff (and something else) coating.
The coatings are optional –but sense I plan on driving my cars, if felt like the right thing to do.

At least think about pistons, before cutting and/or milling the other engine parts.
You can't bring back, what you cut off.

BudW

 

[MBDale]

How hard could it be? a 360 with X or j heads @2.02 valve size,a decent 9.5-1 piston, you've basically got a mid 13 second car.

 

[kkritsilas]

It is not that difficult to screw up a combination. Use a cam optimized for low RPM with a large valve/high compression engine, and you leave a ton of horsepower on the table. Use a cam that is optimized for high RPM power on a stock, low compression car with small valves, and the car won't be able to get out of its own way. In both cases, have an improperly adjusted carb, or timing that is off by a significant amount, and the engine won't make the power that it could, even if everything else is right. I personally think it is just as easy, if not easier, to get things wrong than it is to get things right.

 

[Bruceynz]

Carb tuned by mechanic who specializes in them,(40+ years experience) he rejetted it to suit my engine, timing is at 34 degrees,(checked by mechanic) cam is unknown, my friend who has lived mopar all is life said its got good power approx. 2000rpm to 4700rpm, but doughy down low, mechanic said it is slug off the line he to suspected low comp he has been the mechanic for drag racing, circuit racing, power boats and more. um trying to think what vacuum was, I think at idle 11, I would need to check again, has edelbrock performer intake, 600 holley vac secondary's, cam is unknown at this stage, friend said it sounds like a 340 manual type grind to him, not big but you can hear its got a cam. Just remember this is a ROAD car not a 1/4 mile race machine, its an auto not a manual, its got an open rear end, it doesn't have a trans brake. Big valves, big flow is great for high RPM horse power but what use is that to me driving on the road, I have learned that when USA guys talk about cars they always talk drag racing, its almost like no one drives a car on the street. I want tire spinning power off the line, I don't want to drive my car at 125mph at 6000rpm. I dunno what your speed limit in the USA is, I suspect 100mph, In NZ we are 60mph. So if I can get the thing to turn at 4700rpm - 4800rpm with 318 heads and compression to match its gota be better for what I want. More comp, more efficiency, 318 heads is high velocity air flow as well! Gas is $8 a gallon in NZ!

 

[Bruceynz]

Remember that I am fighting with a low comp smog engine, its got the pistons at least 120thou down the bore, I know the best way is to pull the engine and put new pistons in it and have it rebalanced, would make life easy

 

[brotherGood]

Have you upgraded the gears? that'll help that thing get going. I've got a strong 318..and didn't shave anything off. Still have the smog block, original pistons, etc. just good flowing heads and a mild cam. I personally think that you're over thinking your build. I wouldn't be worried about shaving the heads or the block unless you plan on racing it. stick some good heads on it, a cam that has an operating range in the low end, stick some gears in it with a sure grip and you'll be good.

 

[Bruceynz]

changed from 7.25" 2.2:1 to a 8.25" 3.21:1

 

[AJ/FormS]

That's a 45% improvement right there. Unfortunately it helps you not one bit at zero mph.Put a performance TC in it and call it done. Wind that puppy up to where the footpounds are and it will slingshot off the line. Then with the new gears, it will wind up from the torque peak to the power peak waaay faster than before. Put some valve springs on it so it don't float the valves, and you can hit 5800@ 60mph,with the right tires.Badaboom/done!

Keep the 360 heads on it, cuz those smallport heads will be a real choke at the higher revs, especially with a non-stock cam. If anything, put the stock 360 2bbl cam back in, or even a teener cam in there,to pump up the Dcr and improve the doughy bottom end.Then maybe you can keep the factory TC.

See zero to 60 is not a 2 gear run unless you have race gears in it and even then it will not be optimum. So if it's a one gear run, you will have to match the cam to the gear first;that's the number one priority. Like it or not, you are wanting a race engine. Then you have to trick the car into believing it has less mass,with the TC and/or the compression.
So with a 340 type cam, you might want to gear the car to hit 5800@ 60mph. This is several hundred rpm past the power peak. But that's OK cuz the power peak with that cam is pretty flat. Ok so 5800 requires a tire about 27.35 in diameter, with your 3.21s. You got this part nailed.
Now this 340type cam will start pulling maybe around 3400 or so. With an automatic and a 2.45 low gear, this will be around 35 mph. So your teener heads are just starting to give up around here.They will be done around 40/45 mph. That's why I say keep the big-port heads.
OK so now you have to figure out how to get to 3400 rpm in a hurry. This will take a performance TC. How quick do you want to get to the torque? A 2200(factory) is slow. A 2600 is medium, and 3000 is fast, and a 3400 is of course, in your case, lightning.
Now notice that with these performance TCs, nowhere during acceleration will the engine be spending any significant time below 3000rpm. And the mods you are contemplating are all geared for that sub 3400 zone; so, now, those mods are a complete waste of time.

So now let's talk about those pistons being .120 in the hole.My math puts this right near 8/1Scr, with the virgin 360 heads, maybe a little less. But for ease of calculation I'm gonna call it 8. OK so, with a 340 cam of 268/276/114 This makes a doughy Dcr of 6.36 and cylinder pressure of around 118psi. Swapping in the 360-2bbl cam of 252/260/114, this becomes a little less doughy at 6.73/127psi. And the teener cam of 240/248/114 brings it up to 6.98/134psi; almost bearable.
With each successive cam size down, the torque peak will drop a couple to several hundred rpm, just what you need for a tire fryer. Unfortunately, the power peak drops with the torque peak, So the loss at the top has to be kept in mind with the gain at the bottom. For you, who insist that you're not looking for rpm, this is almost a no-brainer,stuff one of those smaller cams in there.You will immediately feel the torque increase,far in access of your proposed head mods. And the drop-off at the other end will also be much less severe. And by-golly, without all that machining, the parts fit together,just like at the factory.
So to recap, keep the 360 heads, get rid of that big cam, and drop in a 2800 type TC;Shazzam!
You are already correctly geared with the 3.21s, or at least close.Run a tire of maximum diameter that will fit in the wheelwells to keep the rpm down. A 28 incher will hit 5660 plus TC-slip, at 60mph.
In case you are wondering; yes the teener cam will spin 6000 plus rpm. It just needs some springs.And mine did quite well with dual 3 inch all-the-way pipes and TTI headers.I ran a big TQ, and had a lot of fun. Mine was only a teener with a 9.73 starter gear, and a 2400TC.You will be running a starter gear of 3.21x2.45=7.86,which is 19% less, but your engine is 12% larger, and with a 2800TC your combo will be way quicker off-the-line than mine was, on account of that long stroke makes the torque.
So to recap, keep the 360 heads, get rid of that big cam, and drop in a 2800 type TC;Shazzam!
Yeah so, that's my opinion. Good luck!
Oh yeah, big cams in little engines,are for big rpm,and thus for racing.If you can hear it in a low-compression 360 it is approaching big;probably bigger than that 268* 340cam.But I tell you what, If you ran a 268/276/106 cam,(same 340 cam but on a 106 LDA), then your DCR/compression would come back up to where it was with the original 360-2bbl cam(6.98/134psi); both can be installed with the same ICA. And It is the ICA (Intake Closing Angle) that determines when compression actually begins,and thus the DCr,and thus how doughy the bottom end feels.With the overlap increased to 60 degrees from 28, headers will actually work;especially as the rpm goes up.

 

[Bruceynz]

Hello

Very interesting, I found your calculations of the compression ratio quite interesting and how low it drops! When you put 318 heads on a 360 with the 1.88 and 1.6 valves, what sort of RPM did you notice it choked at?

Thanks
Bruce

 

[jasperjacko]

How hard could it be? a 360 with X or j heads @2.02 valve size,a decent 9.5-1 piston, you've basically got a mid 13 second car.

Pretty much my combo. 360 9:1 cp pistons, 40 over, j head stock valve size, no port work, performer intake no gasket matching, big block thermo quad, 165 psi cranking pressure, 3.55, 2500 stall, 1 5/8 headers into single 3' exhaust, 13.65 e.t.. I'm sure there's plenty more to be had.

 

[Bruceynz]

Hi Guys,

Before we start I have not bolted on the 318 heads to my engine, I do have a set in my garage from my old 318, so I am still trying to work out the best option. AJ/FormS has provided lots of info on this topic and I find the math interesting.

Ok I have some time to write some more, the factory rating on the 340 HP was 275hp at 5000 rpm, and 340 lbs/ft at 3200 rpm. Now that being said that cam in a 360 I suspect all the max figures would come in at a lower rpm. I do note that the 340 had 2.02 valves.

So my thought is this, 318 heads with 360 valves,(1.88 and 1.6) plain 20 thou of the heads, port match and remove any flashings. Use the .027/.028 head gaskets my calculations say I should be in the 9.4:1 with the pistons 120thou down the bore.

I can't give accurate CR until I have CC the heads and removed the heads to check exactly how far the pistons are down the bore, I did put a camera down the plug who to see that the pistons are down and they look flat tops. Still need to verify.

So with those mods with 318 heads will the engine rev to 5000rpm, I say yes and I will give my reasoning. The edelbrock performer intake I have on my engine now has the 318 size ports on it (.97" x 1.95"). I measured my 318 intake ports at 1.96" x .90". So that means the bottle neck for air flow is the intake manifold, the current set up will rev over 5000 rpm, I have had it to 5500rpm.(edelbrock performer, 600 holley)

So mes a thinking that 318 heads are going to up the compression, the 360 valves are going to give me the same flow as I have now as the restriction is the intake manifold.

Eddy intake manifold specs attached below for reference.

Thanks
Bruce




Edelbrock Perfromer 2176 Details

Chrysler 318-360ci Small Block V8


Designed for street 318-340-360ci Chrysler V8s. This intake manifold is for 318-360ci V8s with OEM 4-bbl. carb.; 1966-72 (1973 non-CA); except stock equipped EGR. (Intake manifold p/n 350-3776 is for same V8's with OEM 4-bbl carb; 1972-87.) This manifold is not for use on marine engines used in salt water.

Installation Notes:
Port exit dimensions: .97" x 1.95"

 

[AJ/FormS]

Hello

1)Very interesting, I found your calculations of the compression ratio quite interesting and how low it drops!
2)When you put 318 heads on a 360 with the 1.88 and 1.6 valves, what sort of RPM did you notice it choked at?

Thanks
Bruce

As to #1 above;That's not quite right;
the "compression ratio" doesn't drop.When we use the term "compression" we are usually referring to the Static Compression Ratio or Scr. This is written in iron, the moment the heads are bolted on. The Dynamic Compression Ratio, is calculated from the moment the intake valve closes, and is always less than the Scr, because the Intake Closing Angle(ICA) is always well after BDC, typically from around 50* to 80* ABDC.The teener cam closes at about 52*, the 360 2bbl cam at 58*, and the 340 cam at about 66*, and the 292/508/108 cam,at about 74*.
As to the second above;my teener was never dynoed, so it would be a seat-of-the-pants guess. But I can tell you that as long as you don't float the valves/pump up the lifters it will rev to past 6500. There is no reason to go there however cuz the power is long gone; I just wanted a safety margin for my stick-car without a rev-limiter. I usually shifted it at 5000,occasionally a little higher, but again, I was geared to hit 60mph at 5100 in second gear.I had the big TQ on top, and practically zero psi back-pressure on it.
OOPs, wrong question
I never put teener heads on a 360. I did put them on a 340 along with the rest of the teener top-end and with the teener cam, but with 340 springs. I stuffed this into a 65 V-100 Wagon, with a 904 and fenderwell headers.60mph was about 5300 at the top of first gear.Since the 340 pistons were quite high, the compression was pretty good. At the time I was a kid,(very early 70s), broke,and full of ideas. This one worked out pretty good as the little long-roof was a ripper.That Valiant was very light weight, and from a standing start,smoked the skinny tires all the way to the speed limit. So as where the power dropped off that would be too hard for me to remember, much less,say.I called it my big-bore teener,on account of that was all it was. I had compression on my side. And skinny tires, that let loose pretty easy.
As to #3,not found here;
If you machine the heads;both the bottoms and the sides, and also machine the decks, you better have a dead-nuts-accurate machineshop, or nothing will fit. The heads will end up going this way and that way and some pistons will be up and some will be down and the intake won't seal no how. During the cam break- in you will be going crazy with fear of a major melt down, as you can plainly hear the vacuum leaks. So do yourself a favor and put pistons in it, and leave the surfaces virgin.And then,leave the teener heads under the bench.And don't line-hone it unless you absolutely have to, and you trust your shop.
That's my opinion.
That 340/318 was a hoot tho. I mightabin 21?

 

[Bruceynz]

AJ/FormS - Ok but when you have put 318 heads on a 360 what was the RPM it choked at?

 

[AJ/FormS]

Pretty much my combo. 360 9:1 cp pistons, 40 over, j head stock valve size, no port work, performer intake no gasket matching, big block thermo quad, 165 psi cranking pressure, 3.55, 2500 stall, 1 5/8 headers into single 3' exhaust, 13.65 e.t.. I'm sure there's plenty more to be had.

That's a lot like my first iteration. Well not really but 165psi s right on with iron heads.

 

[AJ/FormS]

With no load on the engine, she will rev til the lifters pump up. On the stock teener I have seen this happen at 4500. On a stock 340, I have seen this as early as 5600.I have also been in a 340 car that had pump-up at 5500 at the top of second gear.
Unless your 360 with teener heads is powering up an Imperial, you will be hard pressed with 3.21s to feel it nose over.In an A-body360 with a nice TC, zero to 60 is about 5 seconds, maybe a tad more.You may not catch it. But when you hammer down at 30mph, and nothing happens, that's when it's back to the drawing board.And not applicable to you,I know, but you will feel it die at the top of second, and fugetabowd third.
I think you are too focused on gaining compression, at the expense of power. And torque a little higher where you need it. You can overcome the doughy bottom with a TC far cheaper.
But I recall you mentioned $8/gallon;a couple of times. So I can see your reasoning;I'm no stranger to that line of thinking.So if you want to build a tractor you are on the right track.But then get rid of that cam first and recalculate your Dcr, with the teener heads. If it gets too high you will have nothing but detonation problems.And when the cam is gone, the original 2bbl will be big enough, and so will be the TC.And maybe even the single exhaust.And you will fry the tires for a long,long ways.
Cuz you have built a very big-bore Hi-comp teener, with lightning runners that run out pretty early.A tractor.It will be dynomite around town, and return excellent fuel economy.I can hardly wait, so I'm gonna keep an eye on this thread, Cuz I haven't seen anybody do this since 1975ish,lol.

 

[Bruceynz]

AJ/FormS,

With 318 heads port matched to the edelbrock performer intake fitted with 1.88/1.60 valves will we see 5000rpm under load on a 360 with lets say a manual 340 grind type cam.

Yes or No?

Thanks
Bruce

 

[AJ/FormS]

Of course; it will rev 'til the springs lose control,or it can't pull any more air in, or the ignition craps out. But there's just no sense in putting a cam in that pulls hard to 6000, and then short shifting it at 5000 rpm.
You're asking a silly question.Go run around the block as fast as you can. Now do it again, but pinch your nose closed and suck through a straw.

 

[brotherGood]

Is there a reason youre so incredibly dead set on using the 318 heads? Ive seen multiple posts about how thats not your best move..yet you continue to come back to it.

If you want the 318 heads that bad, go the magnum route. I promise you wont be dissapointed. Otherwise, stick with the 360s