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Old 07-09-2008, 03:34 PM
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Cam choice for quick car?

My dad recently got ahold of a 1984 Caprice Landau. We are putting in a rebuilt 350 chevy and 350 turbo tranny. He want to make this car pretty quick, but he doesnt want to dump a whole bunch of money into it. It has 2.73's in the rear end right now, but that will be changed. The heads have 1.94 Intake, 1.50 exhaust, and 76cc. I know the heads arent the best, but thats all we have to work with. What do you think will be the best cam for low end torque, and mid range power? He doesnt care for going over 100mph, He just wants to get there in a heart beat.

Thanks in advance,

~ Logan

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Old 07-09-2008, 04:55 PM
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Don't expect too much but you can increase power by a good amount with a few bolt ons. You can get around 275hp/350 ftlb out of a stock 350 with headers, small cam, and a 4bbl carb.

I would install a set of small tube tri-Y headers and a short duration cam, like a compcam 246PE (203/212 at 0.050") or 252H (206/206 at 0.050"). Use 2-1/4 dual pipes with dynomax super turbos. I would use a Q-jet and a stock gm q-jet intake. And run 15 degrees of initial timing with 38 total (mechanical) plus another 12 from the vacuum advance (50 total during light load).

The compression in that 350 is low so keep the cam duration low and maybe change to a 3.08 gear with a limited slip center section. If you are using an OD transmission (200r or 700r) then use a 3.42 gear.
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Old 07-09-2008, 05:43 PM
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We have hooker shortie 1 5/8 headers right now. And the car has 2 1/4 duals with an H pipe and cherry bombs. The motor has a edelbrock performer #2701 intake manifold with the original q jet on it. We had a cam with .480/.480 lift and a 287/287 duration. And it ran alright. But it didnt have any balls. So we are going to see if it runs better with a less duration cam.
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Old 07-09-2008, 06:12 PM
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Quote:
Originally Posted by logan__tille
We have hooker shortie 1 5/8 headers right now. And the car has 2 1/4 duals with an H pipe and cherry bombs. The motor has a edelbrock performer #2701 intake manifold with the original q jet on it. We had a cam with .480/.480 lift and a 287/287 duration. And it ran alright. But it didnt have any balls. So we are going to see if it runs better with a less duration cam.
Get some full length headers. You lose hp and torque with shorties as compared to full length. But shorties are much better than manifolds.

cherry bombs don't flow very well. Get a set of dynomax turbo mufflers. Plus they are much quieter. That is the sign of a good muffler, noise to flow ratio.

Yes, that cam is way too big. I would use one of the two cams that I listed above.

The stock gm intake will make more power under 3000 rpms as compared to the performer intake. Your car is heavy and would run better with as much low rpm torque as possible. But not a big difference.
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Old 07-09-2008, 08:03 PM
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Will changing the cam to something like the 252H be very beneficial? If its not going to make much of a difference, We would rather just save the money.
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Old 07-09-2008, 08:57 PM
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Your main limiting factors right now are compression and head flow, so a cam will help some, but not as much as you might think.

For comparison: That 252 or 256 cam should put you around 260-275 with headers and a good dual plane intake. Compare that to my 9.5:1 Vortec 350 with a stock marine cam (197/207) that is putting out just shy of 300.

Power is in the heads -- the cam, too, but heads are a bigger payoff than cams on the street.

Its not cheap, but you can do a vortec head swap if you get a vortec-style intake to match it. Figure $350 for a set of good heads and $100 for an ebay Edelbrock intake, then you have to figure on gaskets, materials, and other assorted tuning, but its a good way to get your power goals pretty easily. Then, later, a cam swap will really wake it up.

Before bolting on Vortecs, though, check to make sure you don't have domed pistons. If they're flat tops, Vortecs should put you right around 9.5:1 which is fine on 87 octane with most cams. The modern design of the chambers is much more tolerant to detonation. But if you have domes, you might be in really high compression territory. You can usually check pistons by pulling a plug and looking in there with a flashlight.
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Old 07-09-2008, 09:17 PM
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cam choice

i also need advice about cam choice i am changing to a 1978 s/b chevy the motor is stock i want low end power and alot of lope with out having to do head work i am curently running flowtec headders and flowmaster exaust w/stock 4bbl carb w/ manual tranny any help would be great
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Old 07-09-2008, 09:42 PM
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They are flat tops. The heads are off right now. So you think a set of vortecs are the way to go?
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Old 07-09-2008, 10:24 PM
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Quote:
Originally Posted by logan__tille
They are flat tops. The heads are off right now. So you think a set of vortecs are the way to go?
The Vortecs are absolutely the best bang for the buck. Probably a 30-40HP increase over what you have now. Then add a better cam with less duration & lift. Do a search on this site for tons of info on (Vortec heads).
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Old 07-09-2008, 11:58 PM
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Figuring a 0.030" overbore with rebuilder flat-top pistons and 76cc heads, the static compression ratio will be 8.3:1 and anything over a stock cam will result in a mushy bottom end. I'll also wager that the squish is 0.075" or greater and the only thing to keep it from detonating will be the 8.3 c.r.

Going to 64cc Vortec heads will raise the c.r. to 9.35 and with a wide squish, I can almost guarantee the motor will detonate, even with a longer cam.
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Old 07-10-2008, 02:05 AM
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Quote:
Originally Posted by techinspector1
Going to 64cc Vortec heads will raise the c.r. to 9.35 and with a wide squish, I can almost guarantee the motor will detonate, even with a longer cam.
Don't underestimate the vortec's chambers, even at wider quench heights. I'm running 9.5:1 with a 197/207 cam on 87 and absolutely no detonation, and that's without the benefit of EFI and spark retarding; just a holley 670 vac secondary. Timing is 10 initial and 34 total; right in the sweet spot for Vortecs. I didn't measure my quench, but its a stock reman, so its nothing special.
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Old 07-10-2008, 03:06 AM
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Figure in the price of a vortec style intake , just examples.
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Old 07-10-2008, 06:34 AM
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changing from a 252 degree cam from a 287 degree cam will make a HUGE difference in low rpm torque. That 287 cam is a dog until 3000 rpm. Plus that low compression is really hurting the torque on the 287 cam and the 2.73 gear is making it even harder on that cam.

a 252H cam works will with 8.5 cr, 2.73 gears, stock converter.

A 287 degree cam works well with 10:1 cr, 3.73 gears, and a 3000 stall converter.

A 252H or something similar in duration is a much better match for you setup.
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Old 07-10-2008, 08:47 AM
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Quote:
Originally Posted by techinspector1
Figuring a 0.030" overbore with rebuilder flat-top pistons and 76cc heads, the static compression ratio will be 8.3:1 and anything over a stock cam will result in a mushy bottom end. I'll also wager that the squish is 0.075" or greater and the only thing to keep it from detonating will be the 8.3 c.r.

Going to 64cc Vortec heads will raise the c.r. to 9.35 and with a wide squish, I can almost guarantee the motor will detonate, even with a longer cam.

What if he were to use the shim gaskets of .015 thickness. This will help with sqish and prvent Detonation. Shim gasket will probobly get .050 squish.
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Old 07-10-2008, 09:34 AM
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That could work, although some of the more experienced builders on this board have stated that the heads and block decks must be very flat in order for the shim gaskets to work properly. I'm sure someone will correct me if I'm wrong, but I think they've said within 0.0015" of parallel.

So, if a guy were going to cut the decks to insure flatness, he may as well cut them for zero piston deck height and use a conventional 0.039" to 0.040" composite gasket and have the squish set properly. I doubt that logan is gonna go to all that trouble and expense though.
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