Thread: Cam and torque converter decision help

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Hi,

I am new to the forum and I have a 72 Chevelle I built a few years ago. At the time I plugged a Motor Home Mark IV 454 and matching TH400 transmission in it. The motor only had 25k miles on it and the only thing I have done other than cleaning it up is put edelbrock 750 carb/intake, Headers, HEI Ignition on it.

It has the peanut heads with motor home cam and etc on it. Sounds good but not great power so decided to start collecting top end build items but I am out of my league on selecting the right components to work well together.

The one thing I just got is a set of new aluminum large oval port cylinder heads with open style 115cc combustion chambers and 300cc intake runners. So looking for advice on Cam and torque converter. I like a lopey sound but do not want to get so aggressive that I have to build it for higher compression.

Was thinking a RPM range between 1800 to 6500 and keeping the stall converter around 2400 +/- but keep in mind I am a rookie at putting these components together.

Thanks and any advice is appreciated!!
Dave

Dave, As great and knowledgable as many of the members of this forum are, and there are several, I would highly recommend against joining any forum and taking a stranger I don't know advice on something as important as a cam spec, it ok to learn from them to gain knowledge about what you are about to purchase but I would call the cam manufacturers and ask their tech expert. Otherwise you might take the advice of somebody like myself who knows just enough to buffalo somebody that doesn't know much and end up with a piece of crap that is mismatched. Just my advice! This hobby is about having fun, and it's not fun and many quit when they get junk info and spend their hard earned bucks for something that doesn't work, the manufacturers butt is on the line, they are pros and they value their reputation and don't want to steer you wrong, call 3 companies, at least 2 companies should come up with similar specs, use that one and you will be happy I bet. For that matter you can do the same with your convertor. Don't fall for vendor techs (ex. Summit) use manufacturer techs also, trust me on this I learned for you!

solid advice Mattyj!

Will do that. Do you know if Howards has good resources for this type of advice? They seem to have been a round a while and economical. Thanks

Hi, Sorry I did not read your post thoroughly MattThy. I will call several and of course the will have tech experts. :-)
Late here on the east coast. :-) Thanks again!

Originally Posted by Mabel

Hi,

I am new to the forum and I have a 72 Chevelle I built a few years ago. At the time I plugged a Motor Home Mark IV 454 and matching TH400 transmission in it. The motor only had 25k miles on it and the only thing I have done other than cleaning it up is put edelbrock 750 carb/intake, Headers, HEI Ignition on it.

It has the peanut heads with motor home cam and etc on it. Sounds good but not great power so decided to start collecting top end build items but I am out of my league on selecting the right components to work well together.

The one thing I just got is a set of new aluminum large oval port cylinder heads with open style 115cc combustion chambers and 300cc intake runners. So looking for advice on Cam and torque converter. I like a lopey sound but do not want to get so aggressive that I have to build it for higher compression.

Was thinking a RPM range between 1800 to 6500 and keeping the stall converter around 2400 +/- but keep in mind I am a rookie at putting these components together.

Thanks and any advice is appreciated!!
Dave

"I like a lopey sound"
That right there will be your biggest problem, the same problem that thousands of other young fellows encounter. That lopey sound requires a fairly radical cam and a fairly radical cam requires some compression and "some compression" requires aftermarket pistons to raise the static compression ratio and raising the static compression ratio requires cutting the block decks to set the squish/quench to help prevent detonation, choosing a looser torque converter and stiffer gears and.....and.....and.....

The camshaft in a motor is not a stand-alone part. It requires support from all other areas of the motor, torque converter, transmission, rear differential gears and rear tires. The vehicle must be taken as a complete system that will work together as a system, not several individual parts just thrown together without a plan.

As soon as you get this "lopey sound" business out of your mind, you will be ready to begin setting up your combination for running well on the street on pump gas.

If I had caught you before you shelled out for those large runner aluminum heads, i would have strongly recommended keeping the iron oval port heads and building the motor as a high torque, low rpm street runner with a very mild cam, high-rise, dual plane intake manifold, headers, converter and rear gears. Using those aluminum heads will require taking a loan at the bank to build a supporting system for them. That's my opinion.
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It'll be a while before I'm done with this project but next on my list is a sound track loadable onto a smart phone that can be played thru car sterio system with some external underneath vehicle speakers that play a very deep rumble type sound -------It will have various tracks that the driver can learn the timing from so he knows when to wing the revs in time with the sound track----------hows that sound to you guys???????? rump,rump,whooome, rump rump

My smile for the day, Jerry, thanks.

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Techinspector,

Sounds like I need to step back from the lopey sound, which is fine. Like I said I am new to putting a motor combo together.

It was a impulse buy on the heads but I do not think I am upside down on them as I paid only $580 for the pair so if it does not make sense to use them, I think I can get my money back for them pretty easy. I would like to understand what you mean around "building a support systems around the Large runner heads".

Just looking for respectable HP without having to do much with the lower end. I suspect the timing chain on this motor home 454 is even retarded a bit so would do that regardless. The intake I have is the Edelbrock RPM 2.0 which I believe is dual planed. Will call some of the Cam and torque converter companies to get some guidance from them as mentioned above. Thanks

What he is saying about the heads is the same as what he is saying about the cam. Everything must function as a unit.

It brings to mind a motor I once sold: it had a larger cam, performance intake and full length headers, and ran pretty good.

The new owner called me up a week later, saying the motor ran extremely poor, did I have any idea why? Well he had stripped off all the performance parts, but didn't change the cam.

I had a less complete comprehension of an engine back then, but I told him the engine couldn't "breathe" and would never run well unless he put the other parts back on, else put the cam back to stock.

I get what you are saying.

I gave the details of what I have and trying to do so that I might get advice on what a good combo of components would be.

I called Howards and explained the motor, heads and my willingness to go with what ever tourque converter needed. They recommended a 2000-5800 RPM BBC Chevy Retro-Fit Hyd Roller 282/288 589"/601" 110° Cam if I go with a Hydraulic roller or a 1600-6000 RPM BBC 279/289 527"/533" 110° if I go Flat tappet. Definitely leaning toward going hydraulic roller though it is triple the price.

Neither of these seem to be so aggressive that I am falling into the "Lopey sound" pitfall. Does not mean there are not others out there for me to fall into. :-)

Will reach out to a few torque converter places tomorrow for their recommendations based on the rest of the components.

Thanks

I wonder if the valve spring pack and rockers could handle that much, over 1/2", lift, and 6 thou RPM.....

Originally Posted by Mabel

I get what you are saying.

I gave the details of what I have and trying to do so that I might get advice on what a good combo of components would be.

I called Howards and explained the motor, heads and my willingness to go with what ever tourque converter needed. They recommended a 2000-5800 RPM BBC Chevy Retro-Fit Hyd Roller 282/288 589"/601" 110° Cam if I go with a Hydraulic roller or a 1600-6000 RPM BBC 279/289 527"/533" 110° if I go Flat tappet. Definitely leaning toward going hydraulic roller though it is triple the price.

Neither of these seem to be so aggressive that I am falling into the "Lopey sound" pitfall. Does not mean there are not others out there for me to fall into. :-)

Will reach out to a few torque converter places tomorrow for their recommendations based on the rest of the components.

Thanks

Your static compression ratio is likely no higher than 8.75:1. That 282/288 cam will want a minimum of 10.0:1 static compression ratio. Call Howards back and ask to speak to someone who understands the relationship between static compression ratio and camshaft timing.

Their CL120235-10 cam and lifter kit (266/274, 213/221, 0.510"/0.538", 110 LSA, operating range 1200 to 5000) would be the wildest I would use and even it recommends that the motor should have a minimum of 9.0:1 static compression ratio, although Crane Cams recommends that grind for down to 8.75:1 static compression ratio.

If you want to use more cam than that, I don't see any way to do it without changing pistons, bottom line.

And by the way, using a flat tappet cam in a BBC is just asking for trouble.
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ABSOLUTELY agreed with Techinspector1 on the use of flat tappet in big block! Been a hobbyist for many years and been doing so with BBC's since early 1970s and do not place myself in the camp of many of our experts on the site, but their information/EXPERIENCE is invaluable.
With availability of just about anything you could ever want in roller cams you will save considerable exposure to cam failure by using one. Even so, I still use Joe Gibbs or similar oil as insurance. I still have a block or two that have the remnants of failed flat tappet cams in them!

Here's another vote for roller lifters in "Rat motors" - well, in any engine you can get one for these days. I played with "Rats" in the late sixties and early seventies, and all of them that I had pretty much ate cams for breakfast, lunch, and dinner, flat tappet cams, that is. I had one 396 that didn't even like the roller cam I gave it.

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