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torque engine build

Posted By: rbstroker

torque engine build - 09/05/11 05:29 PM

I am trying to get some ideas on setting up my current 440 stroker (496") to get maximum low end torque and driveability. It has 10:1 compression, reworked 906 heads, currently TM7 intake and 750DP (changed from 6 pack), stock '68 GTX manifolds and full 2 1/2" dual exhaust, stock 833 manual trans, 3.23 gear and 30" tires. My current Racer Brown SSH-25 leaves a lot to be desired in the driveability area. I am thinking about a Comp 260H. I came up with this by looking at recomendations for a Cadillac 500" engine. Am I on the right track or way out in left field. The Comp Cams simulator shows 381hp @ 4500 and 540# @ 3000rpm in the stroked 440.
Posted By: goldmember

Re: torque engine build - 09/05/11 05:44 PM

If you want more idle vac I'd try a 2 plane performer RPM intake,that should really boost lower rpm performance without digging into the engine. Proper ignition and carb tuning will also go a long way to clean it up down low. With your compression I would not go to a cam as small as the comp 260H. I wouldn't use Campquest to make a cam choice. If you feel you must change the camshaft just call Tim @ bullet cams. I have given up giving cam suggestions,just too many guru's on the interweb.
Posted By: JohnRR

Re: torque engine build - 09/05/11 06:00 PM

Quote:

If you want more idle vac I'd try a 2 plane performer RPM intake,that should really boost lower rpm performance without digging into the engine. Proper ignition and carb tuning will also go a long way to clean it up down low. With your compression I would not go to a cam as small as the comp 260H. I wouldn't use Campquest to make a cam choice. If you feel you must change the camshaft just call Tim @ bullet cams. I have given up giving cam suggestions,just too many guru's on the interweb.



What he said, it seems you have a large mismatch of parts so it's not surprising that drivability is less than stellar.

You can also call Dwayne Porter , fast68plymouth , he is very well versed in cams for large engines using stock exhaust manifolds .
Posted By: rbstroker

Re: torque engine build - 09/07/11 01:36 AM

I wonder what simply changing the intake centerline from the recomended 106* to about 111* would do.
Posted By: 71X-mark

Re: torque engine build - 09/07/11 02:21 AM

The 3.23 gears with 30" tires could also hinder the engine from developing the torque response you seek.
Posted By: ahy

Re: torque engine build - 09/07/11 02:47 AM

The Racer Brown cam you have looks like it has 238 degrees intake duration at .050". The 260 H is 212. A big reduction.

238 degrees isn't a big cam for 500". I would expect it to pull well from 1800-2000 RPM and hit its sweet range from 3000-5000 RPM. It may be a little sketchy accelerating below 1800 RPM with a manual transmission. I wonder if there are some other issue affecting driveability as others have posted. What are the drivability issues? Was the carb swap done to improve the situation?

If you can post some more details it may help.
Posted By: Belvedere2

Re: torque engine build - 09/07/11 03:05 AM

I run the same cam in my 340. No problems and I run an auto trans. I do have 4.10s though.
Posted By: 383man

Re: torque engine build - 09/07/11 03:07 AM

Quote:

I wonder what simply changing the intake centerline from the recomended 106* to about 111* would do.



Advancing the cam will help low end. If you do decide to change cams I agree with calling "Dwayne Porter". He speced my cam for my 493 and it works great. Its big enough to make good power but still idles nice enough and sounds great with just enough rump rump. My cam is 264 and 270 at .050 with .634 and .630 lift with 1.6 rockers. I only run 10.6 comp but I use a very fast advance and it has nice low end. I also use the Indy dual plane intake. With standard 906 ports the Performer RPM would work good for you. Ron
Posted By: Dabee

Re: torque engine build - 09/07/11 03:37 AM

Get one of these. It works great in my 511 and pulls hard from 2000 rpm in third gear with the Gear Venders in overdrive. Brute torque!!!

Attached picture 6814438-DaBeeCamCard003.jpg
Posted By: rbstroker

Re: torque engine build - 09/07/11 12:15 PM

Quote:

The Racer Brown cam you have looks like it has 238 degrees intake duration at .050". The 260 H is 212. A big reduction.

238 degrees isn't a big cam for 500". I would expect it to pull well from 1800-2000 RPM and hit its sweet range from 3000-5000 RPM. It may be a little sketchy accelerating below 1800 RPM with a manual transmission. I wonder if there are some other issue affecting driveability as others have posted. What are the drivability issues? Was the carb swap done to improve the situation?
If you can post some more details it may help.



The cam does indeed spec out at 238* @ .050 on both intake and exhaust. Valve lift is .485 for both. The centerline is actually 105* with a lobe separation of 108*. I have a surging issue at cruise (about 1500-2000rpm), absolutely no power to pull from a stop unless bringing the RPM up and slipping the clutch, that I thought might be caused by the six pack. I then changed to a TM7 and a 750DP carb and still had the same issue. Pulled the MP tach drive distributor in favor of a stocker. Problem got worse when the vacuum advance was hooked up. Set initial at 5* from the original 15*. Helped a bit. Changed the carb to a 650 Eddy. Same thing. Notice that most of the cams out there have a recomended centerline of 110-112*. Therefore, my question about advancing the cam. Looked at Cadillac 500" engine cam recomendations (longer stroke but about the same cubes). MTS series 5 cam is recomended by a Caddie builder as having a peak cruise RPM of 2200-2500 RPM and specs at 208/215 @ .050 and .495/.510 lift. Thing is supposed to have nearly 600ft/lbs @ 2500. That's what prompted my question about the Comp 260H. I just want to be able to take advantage of my large displacement and not "shake, rattle, and roll" at idle.
BTW, I'm sure that it is obvious that camshaft technology is not my area of expertise. If you gave me a dollar for all I know, I would owe you money.

Posted By: ahy

Re: torque engine build - 09/08/11 01:59 AM

I'm no expert on cams either Since I run a roughly similar combo I feel somewhat qualified to comment though. Mine's an Ed headed 496, 243@.050 .55" lift cam, 108 cl, manual transmission, MP single plane intake, 3.23 rear and 25" tire. It's a little tender launching but does fine with practice. It will accelerate cleanly in high gear from 1200 RPM with part throttle but still may buck a little if I try to run it steady at say 1500. In that situation, I just pull the next gear. With a 30" tire it would possibly be too "tender".

With 10:1 (true measured) compression you may be limited in reducing cam duration much as you can run into detonation problems. You are doing well not to have problems now. Also, I think there is a good chance you can get it smoothed out without a cam change or at least without a lower duration cam with the suggestions posted above and one or two more. If you do change cams a wider LSA with about the same duration would be in the right direction. Advancing is worth a try; a lot of the rest is tuning so if you are going to advance it, start with that first. Surging at low RPM may be the result of a lean mixture, excessive advance and/or a big tight CL cam. A dual plane intake should help. Getting it to behave in the 1200-2000 range also takes a lot of tuning. I'm a little surprised reducing spark advance to 5 degrees helped... most moderatly performance cammed strokers like 15-20 initial. It makes me wonder if the rest of the timing curve is off somehow. I'd suggest an initial timing of 15 degrees and a slow advance to 34 degrees at 2800-3000 RPM. Add or re-connect the vacuum advance after you get it smoothed out without vacuum. Vacuum advance will help the engine burn clean and improve fuel economy if you can get it sorted out. The carb likley will need tuning and I'm not a carb guy, mine's EFI and has taken a lot of fiddling to get it to behave reasonably well at low RPM. 750 is a bit small for a 500" engine but may be ideal for your application to help response and low RPM drivability. A vacuum secondary carb is usually considered more street friendly than a DP. It would be worth looking for somebody in your area that's good at tuning carbs.

If all of that helps, but doesn't quite get there, a step or two up in rear gear will help. 3.55 isn't much of a change so 3.7x may be the best bet with 30" tires.

Good luck!
Posted By: TinCuda

Re: torque engine build - 09/08/11 02:15 AM

Lunati voodoo cam p/n 60303 and Rhoads lifters p/n 2018. Just throwing it out there if you want to look at it.


.,
Posted By: dodgeboy11

Re: torque engine build - 09/08/11 03:56 AM

First start with a four hole spacer with a four hole gasket against the bottom of the carb. This will help with signal to the carb. If that helps, I would definitely get a performer RPM intake manifold and ditch that single plane. I personally would run the comp cam that has 231/237 @ .050" .525" lift and a lobe sep of 110. Install it at 108 or even 106 ICL. But first start with the carb spacer and gasket/ intake manifold. You may find yourself happy with the performance that will gain you in the lower rpm range. The single plane manifold isn't designed to run cleanly at that lower rpm. The runners simply are not long enough. You might find a small runner tunnel ram that'll make good lower rpm power, but it's hard to package that under the hood. Typically the longer the runner, the more tuned it'll be for low to midrange power. You can go excessive with some of those early cross ram manifolds chrysler had, and I would steer you away from them. The six pack is a good manifold but sometimes very difficult to get tuned.
Again, four hole spacer with four hole gasket against the carb to start and then possibly a Perf RPM intake manifold. It'll make it much more manageable.
Posted By: TinCuda

Re: torque engine build - 09/08/11 04:19 AM

If you are using a big cam, look into Rhoads lifters to calm down your idle and still get all the low end torque and all the power at higher RPMs.

I copied this from thier web site.

Orginal Rhoads Lifters reduce lift and duration at idle by approximately .010" to .020". Duration is reduced by approximately 10 to 15 degrees. Total lift and duration are restored at approximately 3500 rpm. Typical vacuum increases range between 1 to 3 inches.


I am a big fan and use them in my 512 stroker 440.

.,
Posted By: SomeCarGuy

Re: torque engine build - 09/08/11 04:55 AM

Scott Brown spec'd a cam for mine that tore the tires off. We camed for use with a small convertor and 3.23 gear. I remember 234 at 50 and .555 lift. Guy I sold it to ran more gear, can't remember but I think it was 3.91. Said the torque was killer for him, but not enough top end charge. Had an Eddy RPM intake and Eddy heads. 10.25 comp.

Just depends on what you want to do with it. Undercam for mostly street is a good route. Really all the way around going small is better for a car thtat is street used a lot.
Posted By: rbstroker

Re: torque engine build - 09/16/11 10:14 PM

I swapped the TM7 for a stock dual plane intake with surprising results. Still not perfect, but at least driveable. Hooking up the vacuum advance still causes the "bucking" at cruise. I still believe that the majority of my problems are cam related. I am listening to everybody's suggestions and I believe that a cam swap is in the cards for this winter.
Posted By: RapidRobert

Re: torque engine build - 09/16/11 10:34 PM

Quote:

Hooking up the vacuum advance still causes the "bucking" at cruise.

In your driveway w vac hooked up you might try duplicating the RPM and VAC NUMBER that you have on the hiway at cruise when it bucks & note what the total timing is at that point then unhook/plug the vac adv & bump the initial up so you get the same timing at the aforementioned RPM/Vac level & see if it still bucks & if not then it's a rotor phasing prob from the vac adv & if it still bucks the exact same it's not from rotor phasing but ideally to confirm you'd want to drill a 1/2" hole in the top flat of a dist cap & check by freezing it w a timing light & it's likely from either too much timing or lean/vac leak. If it's rotor phasing holler & we'll go from there and too large of a gap between rotor blade/underside of cap terminal(s) will exacerbate rotor phasing probs (rotor tip too far away from the underside cap terminal(s) & can solder the tip to extend it & I think Echlin has a .060" longer rotor part # MO 3000
Posted By: rbstroker

Re: torque engine build - 09/20/11 12:54 AM

Been doing a lot of camshaft reading and studying to the point of total confusion. I sure would appreciate some feedback to using a Mopar P4529270 cam which is a six pack replacement, in this stroker. The 228/241 degree duration @ .050 in addition to 115 LSA are great in the 440, but what effect will my extra 56 cubic inches have? I'd really like to be able to put the six pack setup back on yet keep the tall Mickey Thompson tires as well as the low (numerical) gear with the 4 speed. Winter will be here before we know it, and I want to make sure that the cam selection is going to be the correct one this time. Thanks to everybody for any and all input.
Posted By: ahy

Re: torque engine build - 09/20/11 02:38 AM

The extra cubes will lower the RPM range with that cam and boost peak torque. All in the direction you want to go.

The only thing I wonder about is pinging/detonation. I believe you posted you have 10:1 with iron heads. Is the 10:1 calculated with everything cc'd or based on the piston manufactures estimate? Piston manufacturers estimate high just like MOPAR did. If it is true 10:1 your current cam's higher duration may be keeping detonation at bay. Less duration may cause a problem but may not. The wider LSA actually helps prevent detonation (per comp's guidance) so it may be a wash.

Bottom line, I think the cam is a good fit. The 6 pack is also... its dual plane for good response at light loads running on a single 2 bbl. May be a little trickey to set up but good for what you want to do, a great runner and lots of fun.

It sounded like your current distributor was advancing too fast as well. I would get it checked out and adjusted. About 15 degrees initial advance and 19 mechanical advance (34 total mechanical) all in by 2800-3000 RPM should about right. This is a gentle advance curve for a heavy car and high pump gas compression ratio. An additional 15-20 degrees vacuum advance can be added on top for cruising.
Posted By: rbstroker

Re: torque engine build - 09/20/11 05:58 PM

The math for the compression ratio turned out to be exactly 9.9:1. Everything was exactly cc'd.
I do have a mild pinging issue if I roll into the gas a bit too hard in high gear at lower RPM. I use pump premium without ethanol. I also have the proper amounts of sta-bil and Marvel Mystery Oil in the tank. I believe that the MMO helps lubricate the valves without leaded gas.
This morning, I decided to replace my early 60's timing light, that I bought new about 1963, with a digital type so I can get some exact numbers. I am able to set my idle at 800 RPM. My initial was 8.4* and stayed that way through 1000RPM. At 1500 it went to 18.2* and maxxed out at 25* at 2000RPM. With the vacuum advance hooked up, I read 9.1* at 800RPM and I had 10# vacuum. At 1000RPM I had 20.5* and 15# vacuum. At 1500 the total was 38.3* and 18# vacuum.
Per suggestions, I set the initial at 18* at 950RPM. I watched as the mechanical advance maxxed out at 1880RPM. I read a total of 34.9* at 2000 RPM without any vacuum advance.
If the streets dry up a bit, I'll try this initial setting and then try with the vacuum advance hooked up.
Thanks again, I will keep you posted.
Posted By: Prince_Valiant

Re: torque engine build - 09/20/11 06:15 PM

Honestly, spec a cam ~ 228 @ .050 duration with a wider lsa of 112-114. This will give you peak torque in the ~-2500-3000rpm range, probably on the order of 550-ish ft-lbs.
Posted By: ahy

Re: torque engine build - 09/20/11 10:39 PM

Quote:

The math for the compression ratio turned out to be exactly 9.9:1. Everything was exactly cc'd.
I do have a mild pinging issue if I roll into the gas a bit too hard in high gear at lower RPM. I use pump premium without ethanol. I also have the proper amounts of sta-bil and Marvel Mystery Oil in the tank. I believe that the MMO helps lubricate the valves without leaded gas.
This morning, I decided to replace my early 60's timing light, that I bought new about 1963, with a digital type so I can get some exact numbers. I am able to set my idle at 800 RPM. My initial was 8.4* and stayed that way through 1000RPM. At 1500 it went to 18.2* and maxxed out at 25* at 2000RPM. With the vacuum advance hooked up, I read 9.1* at 800RPM and I had 10# vacuum. At 1000RPM I had 20.5* and 15# vacuum. At 1500 the total was 38.3* and 18# vacuum.
Per suggestions, I set the initial at 18* at 950RPM. I watched as the mechanical advance maxxed out at 1880RPM. I read a total of 34.9* at 2000 RPM without any vacuum advance.
If the streets dry up a bit, I'll try this initial setting and then try with the vacuum advance hooked up.
Thanks again, I will keep you posted.





If you can slow the mechanical advance so it is all in around 3000 RPM instead of 2000 you may reduce the pinging problem and smooth out operation below 2000 RPM. Marvel Mystery oil is a great lubricant but it does drop the octane a bit.
Posted By: DaytonaTurbo

Re: torque engine build - 09/21/11 04:50 PM

Try getting your timing curve setup properly first. Timing affects fueling, fueling does not affect timing. After your timing curve is dialed in properly, start looking at the carb to make sure you're not too right or too lean at cruise and start tuning from there.

Also, you have to be careful with cam choice or you will end up with too much cranking compression for pump gas. With a 10:1 500" engine, I wouldn't want to go with a cam with less than around 47* abdc or so valve closing angle. Anything much lower than that and you're going to start seeing your cranking compression go up over the ~180psi range and you may have difficulty getting it to run on pump octane without ping.
Posted By: patrick

Re: torque engine build - 09/21/11 05:34 PM

Quote:

I wonder what simply changing the intake centerline from the recomended 106* to about 111* would do.



I'd definitely swap the intake to an eddie RPM...

you'd want to go the other way-- move from 106 to say 102, to get the intake closing point earlier.


for a cam, I'd probably drop to a Lunati voodoo 60303 (IIRC, 268 adv, 226@.050 and about .5" lift), should still work reasonably well with your compression.

or maybe even a 60302 (~262 adv ~220.050, ~.475" lift)

add long tube headers, even 1 3/4" cheapies...should be an easy 20 lb-ft of torque throughout the rev range.

the wider LSA of the lunati cams (IIRC both are 112 degrees) will reduce overlap and smooth out the idle at the cost of peak midrange torque (torque curve will be flatter, but with a slightly lower peak)....the wider LSA also helps carry torque higher up in the rev range, offsetting the duration loss to help with upper RPM HP production
Posted By: rbstroker

Re: torque engine build - 10/03/11 04:23 PM

Quote:

The extra cubes will lower the RPM range with that cam and boost peak torque. All in the direction you want to go.

The only thing I wonder about is pinging/detonation. I believe you posted you have 10:1 with iron heads. Is the 10:1 calculated with everything cc'd or based on the piston manufactures estimate? Piston manufacturers estimate high just like MOPAR did. If it is true 10:1 your current cam's higher duration may be keeping detonation at bay. Less duration may cause a problem but may not. The wider LSA actually helps prevent detonation (per comp's guidance) so it may be a wash.

Bottom line, I think the cam is a good fit. The 6 pack is also... its dual plane for good response at light loads running on a single 2 bbl. May be a little trickey to set up but good for what you want to do, a great runner and lots of fun.

It sounded like your current distributor was advancing too fast as well. I would get it checked out and adjusted. About 15 degrees initial advance and 19 mechanical advance (34 total mechanical) all in by 2800-3000 RPM should about right. This is a gentle advance curve for a heavy car and high pump gas compression ratio. An additional 15-20 degrees vacuum advance can be added on top for cruising.




I received and installed a set of distributor springs and an advance limiter from 4 seconds flat this past weekend. Per advice given here, I set up my old tach drive distributor (no vacuum advance can) with the heaviest of the springs and a 20* mechanical limit. Installed everything with about 15* initial and a total of about 34* at full advance (over 3000rpm). No other changes. Drastically decreased the "surging" and I can now let out the clutch at a stoplight without having to bring the revs way up. Pinging seems to be minimized if not gone completely. A lot more driveable all in all. I think that I'll do a bit more tweeking and once satisfied, re-install the six pack. I find that the folks on this site are pretty darn knowledgeable and willing to help.
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