C3-1971 Engine Rebuild Advise

[Greg F.]

Pending a Compression/Leak Down test, I may be rebuilding my stock 350/270 HP engine. If the results lean towards an engine rebuild, I'd like to get some advise from you guys and "Do's and Don'ts". I have a Corvette mechanic that will do the job for me. I wanted to reach to the Discussion Board before I start discussing the topic with him.

My 71 is a very nice driver and I'm constantly moving towards Top Flight Judging some day. Anytime I replace parts, I get the most original as possible. I drive the car about 2/K miles per year (live in Florida). I don't want to reinvent the wheel - I want parts that some else has experienced proven reliability. I don't need 400 hp. I'm fine with the same or little more hp. I use the car at local car shows and cruises mostly. I like to enjoy it by driving it.

Can I get suggestions "Do's and "Don'ts" from you guys?

1. Do I need to have it Bored (regardless if it doesn't need it)?
2. I know I WILL NOT deck the block
3. Any suggestions on the internal parks that have shown the "proven reliability" I want?
4. Any special questions or request I should approach the engine builder with?


I know I will NOT get the block decked!

Thanks in advance,
Greg

[Joe L.]

Re: C3-1971 Engine Rebuild Advise

Pending a Compression/Leak Down test, I may be rebuilding my stock 350/270 HP engine. If the results lean towards an engine rebuild, I'd like to get some advise from you guys and "Do's and Don'ts". I have a Corvette mechanic that will do the job for me. I wanted to reach to the Discussion Board before I start discussing the topic with him.

My 71 is a very nice driver and I'm constantly moving towards Top Flight Judging some day. Anytime I replace parts, I get the most original as possible. I drive the car about 2/K miles per year (live in Florida). I don't want to reinvent the wheel - I want parts that some else has experienced proven reliability. I don't need 400 hp. I'm fine with the same or little more hp. I use the car at local car shows and cruises mostly. I like to enjoy it by driving it.

Can I get suggestions "Do's and "Don'ts" from you guys?

1. Do I need to have it Bored (regardless if it doesn't need it)?
2. I know I WILL NOT deck the block
3. Any suggestions on the internal parks that have shown the "proven reliability" I want?
4. Any special questions or request I should approach the engine builder with?


I know I will NOT get the block decked!

Thanks in advance,
Greg

Greg------


1) It's possible the engine could be rebuilt at standard bore. It depends upon wear in the cylinders. If there's a "ridge" at the top, you know the engine has to be bored without even measuring the bores for wear.

Keep in mind that even if only 1 cylinder shows wear or damage, all cylinders will have to be bored; you can't just bore one cylinder and leave the others standard.

NEVER, EVER have an engine bored more than required. Most engine builders will want to go right to 0.030" over. However, usually 0.020" over will do and 20-over pistons are available.

3) I would use name-brand internal parts. I recommend Keith Black pistons, Sealed Power/Speed Pro piston rings, Federal-Mogul bearings.

[Greg F.]

Re: C3-1971 Engine Rebuild Advise

Thanks Joe for the "advice" (I noticed I spelled it wrong in my title).

Anyone else, please chime in if you have additional recommendations with anything regarding a rebuild.

Thanks,
Greg

[James W.]

Re: C3-1971 Engine Rebuild Advise

Thanks Joe for the "advice" (I noticed I spelled it wrong in my title).

Anyone else, please chime in if you have additional recommendations with anything regarding a rebuild.

Thanks,
Greg

Greg

I went with double roller timing chain, Roller cam and lifters (not rockers), ARP studs and bolts and DuraBond main and connecting rod pistons. Single moly rings and there's a newer forged piston that doesn't expand as much as the old ones do, so clearances can be tighter (no cold piston slap). You might consider some port mathcing and mild pocket porting, along with a three-angle valve job (some people go with a five-angle), hardened exhaust seats and having the rotating assembly balanced. I did this on my 71 454 and it idled like stock, but made 427HP and 480lb/ft torque.

Jim

[Paul O.]

Re: C3-1971 Engine Rebuild Advise

Greg if you intend to go for a Top Flight just be careful on upping the HP during Ops if there is to much cam and the judges will pick that up. On the engine paint I know its hard but try to keep the paint thin on the lower part of the block and oil pan Chassis judges will like that. Paul 18046

[Jim T.]

Re: C3-1971 Engine Rebuild Advise

How many miles are on your 71's engine? You mentioned doing the leak down test. You may have a lot of miles left on this engine and only need new oil seals for the the valves. My 70 had a 160K on it and was running fine when I removed it to install a GM ZZ crate engine with more horsepower. I did a lot of oil/filter changes to help keep it running good.

[Duke W.]

Re: C3-1971 Engine Rebuild Advise

Use only OE replacment parts - brands like Sealed Power that you can buy at NAPA. You can use the NAPA online catalog to look up the number for any needed replacement parts. Proper engine restoration including internal modifications for more power have been discussed extensively.

If you want more torque and power raise the CR to 9.8:1, which will require premium fuel. (The engine was designed to run on regular). Keith Black makes a domed piston that will achieve this CR with the 76 cc heads and proper head gasket selection.

If you want maximum top end power, "massage" the heads and have a multiangle valve job done with a backcut on the inlet valves. See archives. This has been discussed in great detail.

Another option is to retard the OE replacement cam four degrees. The loss of low end torque will be more than made up by the increased compression and with proper head work it will make nearly the same power as a Flint-built L-46 at 5500+ without effecting idle characteristics or low end torque.

Duke