Engine Advice!!!!

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10-27-2012, 03:44 PM
Clayton A

Engine Advice!!!!

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.
10-27-2012, 03:49 PM
Dave Severson

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!!!!:LOL::LOL::LOL:
10-27-2012, 03:59 PM
Clayton A

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!
10-27-2012, 04:01 PM
cffisher

Push rods being to long could hold valves open long enough for pistons to hit them.
10-27-2012, 04:05 PM
Clayton A

Quote:

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 :)
10-27-2012, 04:10 PM
HOSS429

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 ..
10-27-2012, 04:10 PM
Clayton A

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.
10-27-2012, 04:12 PM
Clayton A

Quote:

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.
10-27-2012, 04:14 PM
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.
10-27-2012, 04:20 PM
Clayton A

http://www.clubhotrod.com/garage_attachment.php?id=652
10-27-2012, 04:23 PM
Clayton A

Quote:

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?
10-27-2012, 04:39 PM
Dave Severson

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.....
10-27-2012, 04:46 PM
Clayton A

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
10-27-2012, 04:48 PM
Clayton A

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

Thanks!!! I was very excited when dad told me to take it home with me!
10-27-2012, 05:33 PM
Dave Severson

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.
10-27-2012, 07:09 PM
Clayton A

Quote:

Originally Posted by Dave Severson

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.

Any SBC gurus on here that could guide me to the cam that would work well with these heads?
10-27-2012, 07:27 PM
Clayton A

Quote:

Originally Posted by Dave Severson

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.

Maybe there will be a sbc guru that will be able to point me to the right cam for these heads!! Hint Hint
10-27-2012, 08:09 PM
glennsexton

Welcome to CHR Clayton:

I’ve read this thread and also your PM to me and I think you may have pretty good base but I have a couple questions and comments.
1. Do you know if you had the block squared? If so, do you know the finished deck height (it will be a 9.xx number).
2. You said that you had the heads milled. Why? Were they not square or were you looking to increase c/r?
3. What head gasket have you been using (how thick?)
4. You indicated that you had 10:1 c/r – how was that determined?
5. Is this an automatic or manual transmission?
6. Do you know the rear end ratio?

Couple suggestions:
1. Do not port these heads – you will not improve them and in all likelihood hurt performance. These are some of the best flowing factory heads ever made by GM.
2. You probably have too much lift, but need to know more about the cam to know if you’re “over cammed”. I would recommend something like this one - Summit Racing Street & Strip® Cam Kits SUM-K00042, 210/210 @050 and .440/.440 lift.
3. Edelbrock Performer is okay, Performer RPM manifold is better. The 1406 is also fine (IMO) but if you change to a Performer RPM, I’d go to a spread bore and use a Q-jet, but I like Q-jets and that big rush when the secondaries open.

As mentioned by others, your bent push rods may be valve float.

Regards,
Glenn
10-27-2012, 08:42 PM
Clayton A

Glenn, all this took place 12 yrs ago so I will try my best. :)

1. I know when I took the block to the machinist he bored the block .040 and checked it to see if it needed to be squared. I don't remember if he needed to do that or not (If it needed to be done he did it) so I don't have that 9.xx number.
2. I milled the heads because a friend suggested doing so to increase compression ratio. I will leave the ports alone if they are fine as is and paying to port and polish them will be a waste of money. Do you suggest I change the valve springs and rockers?
3. I probably bought some cheap head gaskets when I was 18 because I was broke so assume the worst. I can change those out to whatever they need to be.
4. I don't know the actual compression ratio in the engine itself but the pistons I bought said 10:1 C/R. Is there a way I can check the actual C/R?
5. I have a Turbo350 transmission with a 3000 stall.
6. The rearend was replaced with a stock 10 bolt (one wheel pulling) but I am planning on going with a eaton posi with 3.73 gears unless suggested otherwise.

I have headers on the engine that go back to dual 3" flowmasters.

I had all the specs on the cam when I built it but since lost all the information once I moved away from home. Will that cam you suggested still have a good sounding lope to it? I would like to have a good sound with the best performance.

I think my dad may have a Edelbrock Performer RPM manifold in his shop.

Is the carb you suggested for the RPM manifold a Qjet brand? Sorry for my lack of knowledge.
10-28-2012, 10:09 AM
HOSS429

intake or exhaust pushrod ?
10-28-2012, 12:49 PM
Clayton A

Quote:

Originally Posted by HOSS429

intake or exhaust pushrod ?

ummmm, not sure.:( It's the one that sits in the lifter and goes up to the rocker.....
10-31-2012, 10:03 AM
Clayton A

The cam that I have is a Crane Cam with 238 int / 244 exh @ 050 in lift with 0.502 int / .0516 exh lift lobe separation of 106 degrees. Now that I have the specifics on the cam lets say that the heads are just out of the box Vortec 12558062 heads with 1.94/1.50 valves with 64cc chambers. Would this be too much cam for these heads? I did have the heads milled to increase c/r but can't remember how much.
10-31-2012, 10:21 AM
jerry clayton

You need to go back to the basics to check out what you have and its total relationship with the other components of your engine---heads milled to increase compression-----effects valve to piston relationship (clearance)
Cam---cam timing to crank effects valve to piston relationship(clearance)
Heads---clearance between valve retainer, seal, guide effects how much cam lift can be used
Valve springs--spring pressure effects tappet following cam lobe and rpm---
10-31-2012, 02:27 PM
techinspector1

Quote:

Originally Posted by jerry clayton

You need to go back to the basics to check out what you have and its total relationship with the other components of your engine---

Thanks Jerry, that's pretty much what I told this young man on another forum. For instance, you can't choose another cam until you know the static compression ratio.
11-01-2012, 04:46 AM
Clayton A

Thanks guys, looks like I have my work cut out for me! :LOL: