Cylinder Head Digest

[WyoSyclone]

I've put some effort into building a 'cylinder head digest' on my photobucket page. It's divided into LB4, L35, and Vortec sections. I've tried using pictures only where I can see the actual casting number on the head.

See here: http://s137.photobucket.com/home/wyosyclone/allalbums Click on the individual LB4, L35, and Vortec headings under "Cylinder Head Digest".

I've relied on the Doug Anderson information as published here:

http://www.enginebuildermag.com/Article/2427/rebuilding_the_new_chevy_262.aspx

I'll keep adding to this as I find more pics of different head casting numbers. Doug's info has become a little outdated as his research kind of trails off ending in 1998. My photobucket page shows some of the newer heads he doesn't talk about, in the Vortec section. If upgrading to L35s read Doug's info carefully regarding the 10238181 and 10240209 casting numbers, and the differences between the '92-93' versions, and the '94 version...looks like the '94 would be the desirable head but probably hard to find.

Hope this helps those looking to upgrade heads.


Keywords: LB4, L35, Vortec, LB4 heads, L35 heads, Vortec heads, cylinder heads, which heads to get, casting numbers, cylinder head casting numbers, cylinder head questions

 

[It's just a six]

Re: Cylinder Head Digest

Nice & thanks!

So what are the best flowing L-35 heads? PN?

 

[WyoSyclone]

Re: Cylinder Head Digest

Nice & thanks!

So what are the best flowing L-35 heads? PN?

I'm not sure.... I've got links to a few sites with a lot of flow info.. I'll try to get that integrated on the heads we'd be interested in (I know Tooky has some good flow info as well).

 

[It's just a six]

Re: Cylinder Head Digest

IIRC, when Tooky ported his own heads,they actually flowed worse & or not much better & he put a lot of time in porting them.

But when you are forcing air through the heads,flow numbers do not matter as much,more so on a normally aspirated engine,is when you will see a loss in power when heads are not ported properly.

 

[Maxtor]

Re: Cylinder Head Digest

I would really like to see a source that lists casting numbers for Vortec heads that have hardened valve seats. I think that all marine castings came that way, but none of the automotive ones did. I've never been able to find a source that lists the marine castings.

FWIW, the casting number of my heads is 12557107 and they do have hardened valve seats.

 

[WyoSyclone]

Re: Cylinder Head Digest

I would really like to see a source that lists casting numbers for Vortec heads that have hardened valve seats. I think that all marine castings came that way, but none of the automotive ones did. I've never been able to find a source that lists the marine castings.

FWIW, the casting number of my heads is 12557107 and they do have hardened valve seats.

That's a good question.... I'll do some searching.

Thanks for the info, too. Of course your casting number is one I don't have listed! Since they start out with a '12' I assume they're a Vortec.. do you have pics? I would imagine they're a Marine head. I'll add your info to the digest once I get some more details.

 

[WyoSyclone]

Re: Cylinder Head Digest

I would really like to see a source that lists casting numbers for Vortec heads that have hardened valve seats. I think that all marine castings came that way, but none of the automotive ones did. I've never been able to find a source that lists the marine castings.

FWIW, the casting number of my heads is 12557107 and they do have hardened valve seats.

I did just find this on the web... from a guy who did a 4.3 build...

"A couple days later, I started calculating what the cost of the heads would be, and was looking around to just exchange them at one of the head exchange places, one is near my house that I've used before for head jobs, never had problems with them. But then, I found these really nice brand new Vortec heads, casting number 12557107, supposedly the same as the 772 casting found on 96-97 heads, but with a hardened exhaust seat. Brand new painted, finished with stock valves, seals, springs, keepers, locks for $275 to my doorstep. So I bought those and went and picked up my old heads at the machine shop. I can't find much information on this casting number, I had my brother who works for General Motors attempt to lookup the application for that number, he said he could find much of anything, he did find it was a valid number, but other than that, just some chmafer specs and wall thickness. Looking at some specs for stock 350 heads from an old drawing I had kept from the mid-90's for a 97 head when I used to work at a tooling shop as a process engineer, they specify a wall thickness, then note marine heads got a tad thicker casting, and the thickness they mention matched the thickness of the heads I got. That, and the fact that they are painted from the factory as a bare head, kinda of tells me that they are marine heads. But it's a little intriging because all the Mercruiser heads I find are the same casting numbers as automotive applicaiton, I thought they stopped making marine specific block and heads back in the early 80's."

 

[Maxtor]

Re: Cylinder Head Digest

I have some pictures on my HD at home. I'll try to upload them tomorrow. I don't think it is widely understood that as you increase power to appreciable levels using cast heads with non-hardened valve seats you are asking for cracks. If you are going to do the conversion it is just as easy to grab a set that has the hardened seats assuming you can find them. I have also read that there may be subtle changes in the thickness of the casting in certain areas which is stated in the paragraph you found. Not sure what benefit that may bring to our application but it was obviously done on the marine head taking into account variables such as heat and duty cycle.

I learned the hard way several years ago to stay away from cast heads without hardened valve seats and was rewarded with a very expensive boat anchor.

 

[It's just a six]

Re: Cylinder Head Digest

All the newer GM heads,cast iron,have induction hardened exhaust seats,(IIRC)meaning there are no exhaust seats installed,they are not necessary,the material is really hard.

 

[syclone rider]

Re: Cylinder Head Digest

Mine came off a 97 and they had the hardened seats because my head dude cut the biggest seat he could without cutting out all the hardened seat.Sorry do not have the casting numbers because they are still at the head shop.

 

[Maxtor]

Re: Cylinder Head Digest

I found some pictures of my heads. Rob - hope this isn't hijacking your thread, just trying to contribute.


My current heads 12557107 casting:

Before porting, easy to see the hardened seats in this pic:

And the result I experienced a few years back without hardened seats. I don't know that I am an advocate of the big valves with a cast head at this point considering forced induction. Not sure the trade off is worth it. I think a set of properly ported heads with a stock diameter valves (or just slightly larger) would probably not slow it down one bit....

 

[It's just a six]

Re: Cylinder Head Digest

I can't see what you are describing.
Maybe need a better close up?
I inlarged my screen to 400%.

You can have the seats cut then induction hardened again w/out the need to install hardened seats.

 

[Maxtor]

Re: Cylinder Head Digest

I can't see what you are describing.
Maybe need a better close up?
I inlarged my screen to 400%.

You can have the seats cut then induction hardened again w/out the need to install hardened seats.

In which picture? Yes, you can have it done with any set of heads. I only spoke up because many people here don't understand or value the need to take this step.

 

[Maxtor]

Re: Cylinder Head Digest

in picture 2 you can see the hardened exhaust valve insert poking our around the valve, it is a different color. In picture 3 look for the crack at 3 o'clock.

 

[WyoSyclone]

Re: Cylinder Head Digest

Hey Mark, those are great pics.. I can see the hardened seats poking out beneath the seats in that one pic. That's what I really like about this site... people actually take the time out of their day to contribute so that others may benefit :tup: If you don't mind I'll post those pics over on my photobucket site too.
Thanks, Rob

 

[It's just a six]

Re: Cylinder Head Digest

In which picture? Yes, you can have it done with any set of heads. I only spoke up because many people here don't understand or value the need to take this step.

That 3rd pic was not there @ first,I see the crack.They were all the same pics @ first,but now they are 3 different pics.

I really do not think most guys need to use a 2.02" intake,they will definatley have a tendancy to crack because of the little material left between the valves.

Probably could get close to the same flow numbers w/a 2.0" intake & have more meat between the intake & exhaust valves. :2cents:

 

[Maxtor]

Re: Cylinder Head Digest

That 3rd pic was not there @ first,I see the crack.They were all the same pics @ first,but now they are 3 different pics.

I really do not think most guys need to use a 2.02" intake,they will definatley have a tendancy to crack because of the little material left betwqeen the valves.

Probably could get close to the same flow numbers w/a 2.0" intake & have more meat between the intake & exhaust valves. :2cents:

Completely agree. The risk of using the bigger valves in our application probably outweighs the small gain. I would only add that calculating the benefit of better flowing heads on a forced induction motor is complicated... but it is well understood that getting the last ounce of flow out of a head is not as important as a N/A motor. Using a slightly smaller valve and ensuring the exhaust seats are hardened will definitely increase the liklihood you won't have to use curse words later. Ultimately there is a point where you are making enough power that cast heads of this type shouldn't be used but you can push that point by taking these actions.

Rob - Feel free to use the pictures. Thank you for posting the thread.

 

[WyoSyclone]

Re: Cylinder Head Digest

I also just noticed the difference in the size of the coolant passage ports between the L35 and Vortec.. I would think those larger ports would just have to help getting rid of CC heat in the Vortecs.... I need to go look at the block in my shop and see what those ports look like. Could be that opening up those ports in the head during a simple rebuild on a stock motor may help with preignition on the LB4's.

 

[turbodig]

Re: Cylinder Head Digest

Completely agree. The risk of using the bigger valves in our application probably outweighs the small gain. I would only add that calculating the benefit of better flowing heads on a forced induction motor is complicated... but it is well understood that getting the last ounce of flow out of a head is not as important as a N/A motor. Using a slightly smaller valve and ensuring the exhaust seats are hardened will definitely increase the liklihood you won't have to use curse words later. Ultimately there is a point where you are making enough power that cast heads of this type shouldn't be used but you can push that point by taking these actions.

Rob - Feel free to use the pictures. Thank you for posting the thread.

Not to mention, I think the knife-edge that gets created between the valves would make for more deto - that thin area would glow like crazy.

I don't think the extra valve area helps much either, particularly on a bore less than 4.100.

I've got some misc castings at home too, Rob, I'll snap a pic or two.

Have a friend that had some nice Marine castings... will see if he has pics.

I suspect that heads with inserts would/could have had the same casting # as without, but would have different P/Ns depending on how they were finished.

It would be nice to get the Brodix/Pontiac/Bowtie/Canted/Dart options pictured. A lot of these have been shown here over the years via for sale ads and such, but they've never been all in the same place.

 

[WyoSyclone]

Re: Cylinder Head Digest

Not to mention, I think the knife-edge that gets created between the valves would make for more deto - that thin area would glow like crazy.

I don't think the extra valve area helps much either, particularly on a bore less than 4.100.

I've got some misc castings at home too, Rob, I'll snap a pic or two.

Have a friend that had some nice Marine castings... will see if he has pics.

I suspect that heads with inserts would/could have had the same casting # as without, but would have different P/Ns depending on how they were finished.

It would be nice to get the Brodix/Pontiac/Bowtie/Canted/Dart options pictured. A lot of these have been shown here over the years via for sale ads and such, but they've never been all in the same place.

Thanks Dig... I did just add a new page for the Brodix and added the pics of my -10's.