new member drifter-6 - Impala Tech
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post #1 of 5 (permalink) Old 01-10-2011, 08:19 PM Thread Starter
 
 
Join Date: Jan 2011
Location: Lexington Mo.
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new member drifter-6

Just joined, Looking forward to being a member. I live in Missouri, My wife and i currently own a 55 nomad 327 4 speed since 74 and a 62 chevy 2 conv. 194 powerglide since 95.My current project is a 69 427 335 hp complete engine less carb I have had for a while. I am ready to rebuild and have questions on heads valve seats, and compression ratio, I think 10.25 to 1 with todays fuel. I want to build an engine with good torque and a loping sound for cruising. No racing just riding. Would like to find a Impala to put it in. Ideas and info would be great.

Thanks Tim

drifter-6
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post #2 of 5 (permalink) Old 01-10-2011, 09:16 PM
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Welcome to the Team Tim!

The 335 horse is configured the same way as the 325 horse 396 is (the extra 10 horse comes from the extra 31 cubes of displacement). Your missing carb should be a 780 cfm Rochester QuadraJet carburetor (designed for a big block, not the smaller 650 cfm version found on small blocks) as the carb and distributor though interchangeable between small blocks won't deliver the full power it had new back in 1969.

Your 427 has oval port 230 cc intake runner and 118 cc open combustion chamber cast iron heads (versus the previous four years closed chamber "bath tub" design). It left the factory with 2.08" intakes and thick, heavy, steel 1.72" exhaust valves. These heads can be easily (note I said easily not cheaply) rebuilt with bigger valves (stiffer valve spring rate with dual coils to control the extra valve mass), new bronze valve guides for 11/32 inch valve stems with hardened 2.25 or 2.30 inch intake seats and 1.88" hardened exhaust valve seats to accept the correct size swirl polished stainless steel tulip style Manley valves. With a set of chromemoly push rods and light weight chromemoly spring retainer. Finally have the heads pocket ported and your 335 horse can be pumping out close to 600 horsepower with the right cam. (or you could save money and buy a new set of oval port aluminum aftermarket heads).

Your stock 10.25:1 pistons are cast, not forged if still original. That static compression ratio combined with the mild stock flat tappet hydraulic cam you should have if still stock, and cast iron heads; is a recipe for detonation. You not only want a lopey cam to make it "sound" good, you need one to bleed off some of your static compression. Normally for a street driven car I recommend a Thumper or VooDoo cam as it has the duration added to the exhaust side where it doesn't hurt performance as adversely as a long duration cam normally does. But you need to bleed off some compression to run the lower octane gas available today. So I am recommending a RV or high torque cam; which would be ideal for your application (one with higher than stock lift but only a little extra duration added for a slight lope).

Big Dave
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post #3 of 5 (permalink) Old 01-11-2011, 07:07 AM Thread Starter
 
 
Join Date: Jan 2011
Location: Lexington Mo.
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Thanks Big Dave Thats a lot of info. and will be great help to me.I am sure i will need more. thanks drifter-6
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post #4 of 5 (permalink) Old 01-11-2011, 07:32 PM
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I would also recommend upgrading to a roller cam. It's more money up front, but will save you money in the long run, and probably make a little more power too.

'69 Impala 4-door hardtop
'70 Impala Custom coupe
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post #5 of 5 (permalink) Old 01-11-2011, 08:03 PM
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Welcome to the site !!
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