350 Head Gasket

Dave Gantz · 12-28-2013, 08:49 AM

Thanks for the information, guys. I should've mentioned that the .028" gasket is a composite. I'm going to go with that one.
Before I took it apart, I was "assuming" it would have a .039", or so gasket, thinking that what Chevy used is about the same as aftermarket. I ordered the .028" figuring I would at least pick up a little, maybe a half a point. Turns out I'll lose a little.
The engine is out of a 8500# step van, used for work. It got 8 mpg when I bought the truck 4 years ago. (The truck is a '75. The engine is a Mexican 2 piece rear main seal crate.) I put 1 1/2 diameter headers, dual exhaust and played with the distributor curve. Now it gets 8-9 mpg. I just figure that at 8500#, it's not going to get much better. But, being a tinkerer, while I have it apart to stop leaks, I am trying: Advancing the cam 6*, using 1.6 rockers, and I was going to try bumping the compression a little. It's not worth machine shop time to me though. For one, I wouldn't know where to get machine work done where I live now, and mostly, I need the truck!

Rsmith38 · 12-28-2013, 09:24 AM

On my 78 C20 I started at 8 MPG but was able to get it up to 13+ (on highway) Advance weights were frozen, used light springs; but the greatest improvement was the adj vac advance. I beleive I ended up at 41 degrees - just kept increasing it until it pinged.

Alan Roehrich · 12-28-2013, 10:18 AM

I would not advance the cam 6 degrees.

Were I you, I'd consider a mild camshaft and a really good timing set instead, with a new set of valve springs and seals. I've had really good luck with some of the budget cams that Speed Pro sells, as well as one of the small Melling cams. I buy them in kits, with lifters, they are pretty inexpensive. I usually put something simillar to the old stock Z-28 spring on them, they're inexpensive, too. A really good timing set will prevent the near instant slack you get with the cheap ones, and the stock ones, because the sprockets are not heat treated. You can often do the whole job for under $250, and you probably have it apart far enough to do it all easily.

A real good tune, as suggested above, will do a lot.

cad · 12-28-2013, 10:53 AM

The 10067353 Goodwrench engine is 8.5:1.
My old 383 was based on that block...we did deck the block during the overhaul and the block deck was terrible. Putting a tin head gasket on may be asking for trouble.

Here are the specs for reference.
http://www.jegs.com/i/Chevrolet+Perf...67353/10002/-1

Dave Gantz · 12-29-2013, 12:09 PM

Alan:
Could you be more specific as to why you wouldn't advance the cam 6*? I did it using a roller chain from Trick Flow. It adjusts at the crank gear. I didn't use a degree wheeI. I don't like the method of advancing the cam where you drill the cam gear dowel hole and install an offset bushing. Sloppy. It's still on the stand, cover and pan are on. I could change it if need be. I wasn't going to try a cam because I thought at 8500#, anything but the original would give up bottom end. Also, the original chain wasn't really bad, but was defintely retarding.
Main thing is, I need to get this runnning again. I see now, I should've brought this up before I pulled it apart.

Cad: The .028 gasket I'm going to use is a composite. I thought the same thing about a steel gasket. The only reason I pulled the heads is because one was leaking oil at the back. I agree, composite is the way to go.

Rsmith38: I installed a new distributor, the mechanical advance stuff was worn and sloppy. I also limited the mechanical advance, used lighter springs and have an adjustable zacuum can. I never saw much from it. I should fiddle with it more.

gbur · 12-29-2013, 02:16 PM

Victor Reinz from Carquest

Alan Roehrich · 12-29-2013, 03:01 PM

Quote:

Originally Posted by Dave Gantz

Alan:
Could you be more specific as to why you wouldn't advance the cam 6*? I did it using a roller chain from Trick Flow. It adjusts at the crank gear. I didn't use a degree wheeI. I don't like the method of advancing the cam where you drill the cam gear dowel hole and install an offset bushing. Sloppy. It's still on the stand, cover and pan are on. I could change it if need be. I wasn't going to try a cam because I thought at 8500#, anything but the original would give up bottom end. Also, the original chain wasn't really bad, but was defintely retarding.
Main thing is, I need to get this runnning again. I see now, I should've brought this up before I pulled it apart.

Cad: The .028 gasket I'm going to use is a composite. I thought the same thing about a steel gasket. The only reason I pulled the heads is because one was leaking oil at the back. I agree, composite is the way to go.

Rsmith38: I installed a new distributor, the mechanical advance stuff was worn and sloppy. I also limited the mechanical advance, used lighter springs and have an adjustable zacuum can. I never saw much from it. I should fiddle with it more.

If you need to, or gain from, moving a cam 6 degrees, the cam is way wrong. But you're just not going to gain anything from moving the stock cam to 6 degrees advanced. It is already too small to begin with.

I've never used a Trick Flow set. I usually use Cloyes. If there is not obvious heat treating on both sprockets, the sprockets will wear within 5K miles, or less, and you'll be back to slop and slack.

Dave Gantz · 12-29-2013, 04:09 PM

Thanks Alan.
I wasn't looking at it from a too small perspective, just hoping it might help move the barge.
I wasn't looking for any evidence of heat treating, it looked well made, though.
As I said, it's all buttoned up, so I'll give it a go.

Thanks to all who posted. "Duly noted."

12-28-2013, 08:49 AM	#1
Dave Gantz Senior Member Join Date: Nov 2005 Location: Verrry South Jersey Posts: 537 Likes: 134 Liked 251 Times in 125 Posts	Re: 350 Head Gasket Thanks for the information, guys. I should've mentioned that the .028" gasket is a composite. I'm going to go with that one. Before I took it apart, I was "assuming" it would have a .039", or so gasket, thinking that what Chevy used is about the same as aftermarket. I ordered the .028" figuring I would at least pick up a little, maybe a half a point. Turns out I'll lose a little. The engine is out of a 8500# step van, used for work. It got 8 mpg when I bought the truck 4 years ago. (The truck is a '75. The engine is a Mexican 2 piece rear main seal crate.) I put 1 1/2 diameter headers, dual exhaust and played with the distributor curve. Now it gets 8-9 mpg. I just figure that at 8500#, it's not going to get much better. But, being a tinkerer, while I have it apart to stop leaks, I am trying: Advancing the cam 6*, using 1.6 rockers, and I was going to try bumping the compression a little. It's not worth machine shop time to me though. For one, I wouldn't know where to get machine work done where I live now, and mostly, I need the truck!

12-28-2013, 09:24 AM	#2
Rsmith38 Member Join Date: Mar 2011 Posts: 186 Likes: 0 Liked 28 Times in 15 Posts	Re: 350 Head Gasket On my 78 C20 I started at 8 MPG but was able to get it up to 13+ (on highway) Advance weights were frozen, used light springs; but the greatest improvement was the adj vac advance. I beleive I ended up at 41 degrees - just kept increasing it until it pinged.

12-28-2013, 10:18 AM	#3
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,126 Likes: 1,583 Liked 1,893 Times in 423 Posts	Re: 350 Head Gasket I would not advance the cam 6 degrees. Were I you, I'd consider a mild camshaft and a really good timing set instead, with a new set of valve springs and seals. I've had really good luck with some of the budget cams that Speed Pro sells, as well as one of the small Melling cams. I buy them in kits, with lifters, they are pretty inexpensive. I usually put something simillar to the old stock Z-28 spring on them, they're inexpensive, too. A really good timing set will prevent the near instant slack you get with the cheap ones, and the stock ones, because the sprockets are not heat treated. You can often do the whole job for under $250, and you probably have it apart far enough to do it all easily. A real good tune, as suggested above, will do a lot. __________________ Alan Roehrich 212A G/S

12-28-2013, 10:53 AM	#4
cad Senior Member Join Date: Apr 2009 Location: Omaha, NE Posts: 703 Likes: 203 Liked 93 Times in 52 Posts	Re: 350 Head Gasket The 10067353 Goodwrench engine is 8.5:1. My old 383 was based on that block...we did deck the block during the overhaul and the block deck was terrible. Putting a tin head gasket on may be asking for trouble. Here are the specs for reference. http://www.jegs.com/i/Chevrolet+Perf...67353/10002/-1

12-29-2013, 12:09 PM	#5
Dave Gantz Senior Member Join Date: Nov 2005 Location: Verrry South Jersey Posts: 537 Likes: 134 Liked 251 Times in 125 Posts	Re: 350 Head Gasket Alan: Could you be more specific as to why you wouldn't advance the cam 6*? I did it using a roller chain from Trick Flow. It adjusts at the crank gear. I didn't use a degree wheeI. I don't like the method of advancing the cam where you drill the cam gear dowel hole and install an offset bushing. Sloppy. It's still on the stand, cover and pan are on. I could change it if need be. I wasn't going to try a cam because I thought at 8500#, anything but the original would give up bottom end. Also, the original chain wasn't really bad, but was defintely retarding. Main thing is, I need to get this runnning again. I see now, I should've brought this up before I pulled it apart. Cad: The .028 gasket I'm going to use is a composite. I thought the same thing about a steel gasket. The only reason I pulled the heads is because one was leaking oil at the back. I agree, composite is the way to go. Rsmith38: I installed a new distributor, the mechanical advance stuff was worn and sloppy. I also limited the mechanical advance, used lighter springs and have an adjustable zacuum can. I never saw much from it. I should fiddle with it more.

12-29-2013, 02:16 PM	#6
gbur Member Join Date: May 2013 Location: Spotsylvania,Va Posts: 354 Likes: 0 Liked 1 Time in 1 Post	Re: 350 Head Gasket Victor Reinz from Carquest

12-29-2013, 04:09 PM	#8
Dave Gantz Senior Member Join Date: Nov 2005 Location: Verrry South Jersey Posts: 537 Likes: 134 Liked 251 Times in 125 Posts	Re: 350 Head Gasket Thanks Alan. I wasn't looking at it from a too small perspective, just hoping it might help move the barge. I wasn't looking for any evidence of heat treating, it looked well made, though. As I said, it's all buttoned up, so I'll give it a go. Thanks to all who posted. "Duly noted."