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My Headache 350 SBC

General engine tech -- Drag Racing to Circle Track

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econo racer
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My Headache 350 SBC

Post by econo racer » Fri Mar 13, 2020 5:07 am

Many years ago I built a 350 for my bracket foot brake car.Was looking for about 8.0 1/8th. Block was bored out. Everything machine. Deck cut approx. 20 thous. I used a new cast Eagle 350 crank, New factory GM powdered rods. Then I put Keith black pistons in. Flat top with 2 recesses. Have 0 deck height. I used a new vortec rpm intake. I bought a new vortec head package. Left heads stock except for the valve springs just a little stronger. I used a Comp 268 Extreme Hydraulic flat tappet. Motor smoked a little. went to do the burnout and it popped and cut off. opened the hood and the distributor bolt broke in half. And the distributor was popped up. WOW :shock: I used a longer distributor bolt. set timing. I don't remember the exact ET. maybe 8.30. Smoking worse now. Put it on the trailer took home and pulled the motor. Intake not sealing on the sides. I put a flash light under the intake and set it back on. Light coming out everywhere. Great :( The distributor gear was worn thin that fast. I pulled the heads and there was almost witness marks on the pistons. Wow valves real close to hitting with such a little cam. Stock vortec self aligning rockers were used. Oh I used factory thin head gaskets. I'm pretty sure they were 27-28 thous thick. I gave up and left it on the stand. Still have. Only motor I ever built to give me a hard time. I don't know what to do to fix it. #-o Any ideas?

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Re: My Headache 350 SBC

Post by mag2555 » Fri Mar 13, 2020 6:14 am

seems like you had luck on your side for the other motor builds that worked out because the root of your oil / smoke issue was the valves knocking the Pistons around and unseating the rings in all likelihood!

Your poor Intake sealing that made for sucking air and oil did not help any either.

If you would have double or tripled checked your piston to valve clearance as good builder do then would be different do you not agree?

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Re: My Headache 350 SBC

Post by BillK » Fri Mar 13, 2020 6:57 am

It sounds to me like either the block has been decked too much or the intake has been cut, or both. You need to measure the actual block deck height first. Not the depth of the pistons but the actual block dimension.

If you have not taken it apart yet maybe try a different manifold. Preferably one that is new or that you know for sure has not been milled.

Sounds like the distributor might have been bottomed out in the oil pump ? This should have been noticeable when you first installed it. It probably was not even touching the intake manifold.

Sounds like you just need to take it all apart and start from scratch and check everything properly as you reassemble it. Impossible to tell you what is wrong without looking at it in person.
Bill Koustenis
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Re: My Headache 350 SBC

Post by econo racer » Fri Mar 13, 2020 7:41 am

Oh Bill the machine shop put those screw in oil baffles in the lifter valley. I took all of them out. Did not look right to me. Stock pump and pan. I would never thought the valves would be that close on that little lift of a cam. What little I let it run-It was a Grunt Master-felt like it would pull some weight. When I get time I want to lay a stock old chevy head with gaskets and see what the gaps look like :shock: Maybe it don;t want vortecs.

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Re: My Headache 350 SBC

Post by econo racer » Fri Mar 13, 2020 7:46 am

Bill trust me I am soaking up what your saying. I have lived in Alabama along time now but lived in your area for many yrs to. I lived in Manassas- raced Old Dominion and the duck and Mir. My old boss bought MIR . A lot of good people raced in them days. Like family. :D

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Re: My Headache 350 SBC

Post by tenxal » Fri Mar 13, 2020 8:12 am

Let's start with the basics.

-If the block is really at '0' deck and your head gasket is .027-.028 thick, the pistons will kiss the heads. You're going to need a minimum of .032. And .034 is better for a bit of insurance.

- The distributor is no doubt bottomed out on the oil pump shaft. Extra distributor gaskets solve that.

-It's not just the cam lift that can get you into v-p clearance issues.....it's the when that lift occurs. If you didn't degree the cam, you've got no idea where it's at relative to the piston.

-The intake not sealing to the heads is pretty basic stuff. If the block/heads have been cut, you'll generally need to cut the intake to fit properly....assuming a proper fit in the first place. A good rule of thumb is a 1.2:1 ratio (.020 total cut gets you .024 intake cutting).

Basic 'Engine Assembly 101' stuff.....

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Re: My Headache 350 SBC

Post by BillK » Fri Mar 13, 2020 9:25 am

econo racer wrote:
Fri Mar 13, 2020 7:41 am
Oh Bill the machine shop put those screw in oil baffles in the lifter valley. I took all of them out. Did not look right to me. Stock pump and pan. I would never thought the valves would be that close on that little lift of a cam. What little I let it run-It was a Grunt Master-felt like it would pull some weight. When I get time I want to lay a stock old chevy head with gaskets and see what the gaps look like :shock: Maybe it don;t want vortecs.
I agree with taking out the oil baffles on a flat tappet cam even though all of the dirt track guys use them and dont seem to have a problem.

As far as the Vortec heads they are the way to go in my opinion. They flow like crazy and are the same dimensions as the old school heads so there really should not be a problem due to them. One thing I will say about the vortec heads is that the deck is very thin and I would be hesitant to use a real thin steel head gasket with them.

As far as valve to piston clearance goes I have found that .500 lift is pushing your luck with a stock type piston and big valves. And that is without milling the block deck. So I amnot a bit surprised that you are too close with the block being decked and using a thin head gasket.
Bill Koustenis
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Waldorf Md

www.enginerepairshop.com

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Re: My Headache 350 SBC

Post by BillK » Fri Mar 13, 2020 9:25 am

BillK wrote:
Fri Mar 13, 2020 9:25 am
econo racer wrote:
Fri Mar 13, 2020 7:41 am
Oh Bill the machine shop put those screw in oil baffles in the lifter valley. I took all of them out. Did not look right to me. Stock pump and pan. I would never thought the valves would be that close on that little lift of a cam. What little I let it run-It was a Grunt Master-felt like it would pull some weight. When I get time I want to lay a stock old chevy head with gaskets and see what the gaps look like :shock: Maybe it don;t want vortecs.
I agree with taking out the oil baffles on a flat tappet cam even though all of the dirt track guys use them and dont seem to have a problem.

As far as the Vortec heads they are the way to go in my opinion. They flow like crazy and are the same dimensions as the old school heads so there really should not be a problem due to them. One thing I will say about the vortec heads is that the deck is very thin and I would be hesitant to use a real thin steel head gasket with them.

As far as valve to piston clearance goes I have found that .500 lift is pushing your luck with a stock type piston and big valves. And that is without milling the block deck. So I am not a bit surprised that you are too close with the block being decked and using a thin head gasket.
Bill Koustenis
Advanced Automotive Machine
Waldorf Md

www.enginerepairshop.com

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Re: My Headache 350 SBC

Post by econo racer » Fri Mar 13, 2020 10:18 am

Bill everything was new out of the box. Nothing milled. Just the block. If I put a 52 thous. cometic do you think that would get it sealed?

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Re: My Headache 350 SBC

Post by Little Mouse » Fri Mar 13, 2020 10:00 pm

So my question your not sure of the head gasket compressed thickness and you say used factory thin head gaskets. Original iron head sbc used .018 compressed steel shim gasket and the pistons were below the deck around .025. So what do you really have for head gaskets ? Most people if they zero the deck use
.036 or .041 compressed gaskets. Never used vortech heads but are those heads if off the pickups limited to about .465 valve lift after that they can slam the retainer into the top of the valve guide.

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Re: My Headache 350 SBC

Post by econo racer » Fri Mar 13, 2020 11:51 pm

I used Chevrolet Performance part #10105117. It is a composite head gasket with .028 compressed thickness. And the factory vortec intake gasket that come with the head package. All top end was from the Chevrolet Dealer.

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Re: My Headache 350 SBC

Post by rfoll » Sat Mar 14, 2020 3:17 pm

If you have a protractor, the angle face to face on the intake side should be 110 degrees. I have found this to be off many times on Edelbrock intakes.
So much to do, so little time...

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Re: My Headache 350 SBC

Post by Little Mouse » Sat Mar 14, 2020 3:57 pm

If your anywhere near zero deck. .028 gasket not near enough.

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Re: My Headache 350 SBC

Post by stealth » Sat Mar 14, 2020 5:28 pm

If your frustrated and not feeling confident why not find a reputable machine shop to help you get this fixed up. Likely we’ll worth a few bucks.
The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man.

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Re: My Headache 350 SBC

Post by the rain maker » Mon Mar 16, 2020 1:00 pm

Stock timing chain and gears or multi-keyway timing set?
David Hammons

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