Thread: Engine Advice!!!!

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I recently acquired a 1971 Chevelle from my dad!!!! The engine sounds real good but I think the combination of parts are hurting the engine more than they are helping. I built the engine when I was 18 (12 yrs ago) and didn't have the first clue as to what I was doing. Dad knew how to put an engine together so that is exactly what we did. Now at I look back at some parts I used and I think we made a few mistakes. The engine block is a 1980 - 1985 350sbc Casting number 14010207 bored .40 over. The heads are Vortec Heads Casting number 12558062 (milled), The intake is a Edelbrock Performer 2116. The carb is a Edelbrock Performer 1406. The cam is a Crane Cam with a 516 lift (I think the lift is way to high for these heads). Stock 350 crank that I had checked by a machine shop. I don't remember the brand of pistons but I do remember they were flat top style and a compression ratio of like 10:1. The reason I think the cam lift is to big is because I have bent a couple pushrods in the engine and I read on a website where the heads were only rated for like a 470 lift or something like that (I could be wrong on that). I plan to go back through this engine and try and get all the right parts that I need to produce the best HP.

Maybe have some pistons clunking the valves???? Curious to see what you find inside. Cams have changed considerably over the years, so many good grinds on the market now, and should you go to a hydraulic roller things can even get better!!!

Welcome to CHR, good having you here, put up some pics of your Chevelle someday, been in the family for quite awhile!!!! Heck, I don't even keep wives that long!!!!

Hey Dave, thanks for the quick response. The engine fires right up and idles good. The only problem is from time to time it will bend a pushrod so I thinking the lift on the cam is to much for the heads. I'm not sure what you mean by " the pistons clunking the valves". I just added a photo to the garage section of this forum, go check it out and let me know what you think!! The interior is in bad shape but it wouldn't be a project car if I had nothing to do to it right!

Push rods being to long could hold valves open long enough for pistons to hit them.

Originally Posted by cffisher

Push rods being to long could hold valves open long enough for pistons to hit them.

How can I determine the length of pushrods I will need? Is there a way to measure this? I am no mechanic by no means but I think I have enough common sense to follow direction. I got a whopping when I was kid for not doing that, lol

does this happen after a few wide open throttle blasts ? .. normal driving for 12 years shouldn`t cause a bent pushrod . or i mean a bent pushrod or two over 12 years does`nt mean a problem is there ..

I want to pull the engine to have some head work done and while I have it out I want to change out some parts to maximize the horse power I can get from the engine. I am wanting to port the heads and change out the valve springs, adds some new lifters and rocker arms. I want to keep the block and heads but may change out the cam, intake, carb and pistons if this will help me. Just looking for some guidance from people with more experience on this subject than myself.

Originally Posted by HOSS429

does this happen after a few wide open throttle blasts ? .. normal driving for 12 years shouldn`t cause a bent pushrod .

This happens only when the car is being ran hard! The car hasn't drove more than 10 miles in the past 6 years.

Probably a bit of valve float at higher rpm's and or the lifters are pumping up and closing the distance on piston to valve clearance.

Originally Posted by Dave Severson

Probably a bit of valve float at higher rpm's and or the lifters are pumping up and closing the distance on piston to valve clearance.

How can I fix that?

Very nice looking Chevelle!

When you have the engine apart, checking piston to valve clearance, coil bind, pushrod length and many other things are all part of the mock-up prior to final assembly.....

Do you think the lift on the cam is to much for the type heads I have on the engine or do you suggest another cam that would produce more power with the heads? I can't remember the duration of the cam installed. I read somewhere that if your parts don't match then you will lose power. I don't know if my parts match....lol

[QUOTE=Dave Severson;478693]Very nice looking Chevelle!


Thanks!!! I was very excited when dad told me to take it home with me!

I'm by no means one of the sbc guru's on here, but I do think that's way too much cam for those heads!!!! You're right on the engine parts, they do have to match!!! Regardless of the brand, over-camming and over-carbing are probably the two most common mistakes on engine builds..... All the components have to compliment each other to get the most out of an engine.