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How does CID affect cam selection and performance ????

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Old Aug 23, 2004 | 12:19 PM
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Yelo's Avatar
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Default How does CID affect cam selection and performance ????

OK...alot of us are stuffing REALLY BIG (T-ReX, etc..) cams into 346cid motors with fairly good results....how would those same cams react in a 364cid (or bigger) motor ??

I am currently searching for a 6.0 block (a second one...the one in my truck is getting used and CAN'T have any downtime), I plan on keeping the stock bore and stroking it to 4.00 (402 cid), how does the displacement affect cam selection ??......When the displacement was going to stay stock at 364 I was looking at the Comp 212/218 XE High-lift for it's good street manners and good low-end (It's a truck...5600lbs...I NEED torque) even with a stock converter, now that I have a Yank TT2600 converter waiting to be installed I was looking a little more radical like a TR224 or so.

Now that I have decided to go with a stroker motor how big a cam can I run and still retain 100% driveability and reliability ???....by that I mean I want a cam that can be tuned to operate like stock (no stalling, surging, etc....)

I realize I've asked like 3 different questions here so bear with me answering them....I guess what I REALLy want to know is: assuming a given cam spec, how would that cam behave in say a 5.7, 6.0, and 6.6 ??

this is a long term project....don't expect to hear much on this for 6 months or so
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Old Aug 23, 2004 | 01:09 PM
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In simple terms, the more CID you have, the more camshaft you'll need to make the same power band. A bigger motor will 'eat-up' a camshaft designed for a smaller CID motor very quickly. The bigger the motor the more CFM it needs to reach 100% VE, so you'll need more camshaft to get more air to your combustion chamber. There are other variables in that equation, but that's a good general rule of thumb.

As far as finding a cam that doesn't surge or stall, there are a few variables in there that will determine just how big you can go. The two biggest factors are camshaft selection and tuner selection. A properly selected camshaft will have good street maners, no matter the advertised specs. The other factor is your tuner. An experience tuner will make all of the difference in the world. The combination of a properly selected camshaft and an experienced tuner are the two biggest factors for reaching your goals.

There are a couple of sponsors on this board that can help you select the right camshaft for your application. Check out some of the links over to the right and give some of them a call.

Good luck with the project.
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Old Aug 23, 2004 | 05:22 PM
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Check out the Small duration-narrow lda thread posted earier.That cam(THE 212) would make real good low-end!
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Old Aug 23, 2004 | 09:29 PM
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From what I vaguely remember when hotrodding small block Chevys, a cam in a 350 could be bumped up approximately 10 degrees in duration and act the same in a 383. 383-350=33 ci difference. 364-346=18 ci diff. which is approx 1/2, therefore a 5 degree bump in duration from a 346 cam should act the same in a 364. How's that for pulling numbers out of my ****, LOL! Nah, seriously though I think my estimate would be pretty close to real world. Other stuff that I did not consider was the stroke differences and resultant piston speed changes. But I'll leave that to the geniuses that frequent this forum. Good luck!
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