396/325 - 68 Camaro - Team Camaro Tech
Engine General Engine Discussion.

 
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post #1 of 6 (permalink) Old Sep 7th, 04, 07:24 PM Thread Starter
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Finally getting ready to start on the engine and have a few questions. Please bear with me because I'm not an engine guru. I do not plan on racing.
My engine is an original 396/325 hp 68. I would like to retain the stock hp and torque as advertised from GM. I would also like to run on pump gas. My tranny is a Turbo 400 and rear is 3.31. The block casting is 3935440 and the heads are 3931063. Dates are wihin a week of each other so I assume these are the original combination. When speaking to the engine rebuilder, he suggested that I increase the size of the intake valves as one way to get the HP and torque with a 9.5 compression ratio. Can I get some suggestions from you, the more experienced, as to what I can do to achieve my goals with the engine?

EricE
68 Butternut Yellow
SS Coupe 396/325
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post #2 of 6 (permalink) Old Sep 8th, 04, 02:03 AM
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My 2 cts., if you like the performance from the engine now, and you stated you want to keep it stock, don't pad the rebuilder's pocket.

I would go for a 3 angle valve job, hardened exhaust seats, and a balance job. I would probably even purchase a new harmonic balancer. The OE one is 36 years old and the elastomer, the rubber material between the hub and rim, doesn't last forever. Granted, its probably okay, but its like buying a new oil pump, cheap insurance.

Yes, increasing the intake size does warrant some power increases, so does a healthier camshaft, bigger carburetor, alum intake, better ignition, bigger exhaust, more rear axle gear, and the list never ends.

I hope others here give there 2 cts.........

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post #3 of 6 (permalink) Old Sep 8th, 04, 02:53 AM
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I am with Everett on this one. Rebuild with the highest quality parts you can afford yet avoid changing valve sizes. The HP gain is not worth the cost.

68 Camaro, 555 big block, Doug Nash 5-speed, 3.54 gear.
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post #4 of 6 (permalink) Old Sep 8th, 04, 07:02 AM
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Your cam is really done before 5000rpm. No need for anything except stock although you might have some detonation problems if you leave the stock compression and that super mild cam.
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post #5 of 6 (permalink) Old Sep 8th, 04, 04:19 PM Thread Starter
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Thanks for the responses. I had a feeling about resizing the intake. So, if I want to run on pump gas, do I change the cam to get my 325 and 9.5:1? Any suggestions on a cam? Should I buy the parts and bring to rebuilder?
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post #6 of 6 (permalink) Old Sep 9th, 04, 01:28 AM
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Supplying the parts to the rebuilder will determine the amount of warranty he provides with the rebuild.

Case in point, if he supplies the parts, then he may give a 100% warranty for the whole event. If you supply the gasket set for example, and later, say 6 months, the oil pan gasket starts to leak, he can say it was a defective gasket when maybe, in reality, it might have been faulty workmanship. Then he can charge you for replacement parts and labor rather than absorbing the whole cost.

This is something you'll have to discuss with him before the procedure starts. You might offer him to pay for parts up front, if you decide for him to buy parts. This would be a good jesture.

Others here would give probably a better choice as to camshaft to use. The best advice is to call anyone of the camshaft manufacturer's Tech Section and ask for their suggestions. From you, they will need the weight of the car, rear axle ratio, type of transmission, and static compression ratio. If you have power brakes, be sure to tell them, this will also be a factor in determining the cam to use.

But, I would definitely include a balance job for the engine and good quality parts.

In your list of parts, be sure to include a radiator flush, if not a replacement, a new thermostat, hoses, and belts. Hate to see/read about getting it back together only for it to go up in smoke. Request to have the block water jacket steam cleaned/pressure washed to remove all the accumulated debris in the bottom of the block. Have the drain plugs replaced with petcocks in the block.
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