Anybody familiar with these custom heads? Back in the '70's there were some drag racers running Chevy Stovebolt straight sixes. Someone figured out that the head-bolt patterns for the V-8's and the sixes were the same. They then started creating cross flow heads by cutting off one cylinder each from two V-8 heads and welding them together. They also had other areas to plug and custom side covers to build to get the pushrods enclosed etc. NHRA finally banned them for whatever reason but not immediately. I would love to find one of these mongrels for my engine. However I am not going to pay stupid money just because they are rare when I could build my own for less. Any owners or leads out there that remember these things? I appreciate any help in finding one.
I almost fell out of my chair when your post popped up on my screen. Are you intentionally shouting by using large fonts? You are likely to be bombed. Others have been shot for not toning it down. Look at other posts and you'll get the idea. I have heard about this mod, but no references. Oh, yeah, welcome to the group.
Flathead guy, being the rookie I was just relating font size to what my normal word processor stuff would be. Thanks for the tip but no, not any kind of rant going on just asking questions.
Here is the exact thread I was mentioning. http://www.jalopyjournal.com/forum/showthread.php?t=644129&highlight=sissel+head Also, Making an inliner head from scratch http://www.jalopyjournal.com/forum/showthread.php?t=499123&highlight=sissel+head
I talked to a machinest friend about these a few years back, and he said he still made one every now and then. Usually for bonneville cars.
What you are talking about is the hybrid V8 headed inline six. Its not a easy thing to make. It takes two V8 aluminum heads with the end cylinder cut off each one, then some very tricky welding to get them all sealed together. After you get that done, you have to drill new head bolt holes ( they are not the same) in the block deck and seal the factory holes up. After all that, you need to have a side plate made since the V8 head is wider, the side plate seals the head to the block. If you get this far, you still need to make a intake manifold to fit the hybrid head along with a header, custom linkage, fuel lines, and cooling. Not sure if the old ones used coolant or not since they were alcohol burning race cars. Good luck! Joe
The only Chevy 6 head built from 2 V8 heads I have ever seen is hanging on the wall in Wes Rydell's shop. It was run in the Rydell, Hope, and Lang car. That car is currently being restored, check out the restoration thread here. http://www.jalopyjournal.com/forum/showthread.php?t=644129 It was just as popular to take Ford 351 Cleveland heads, cut them into 6 pieces, weld or braze them back together and bolt the conglomeration to the top of a 300 Six. Whether it is done for a Ford or Chevy, it is a very labor and machine work intensive process, and as such is not going to be cheap.
I think Frez is a little confused on the actual process he is asking about. The Chevy 6 engines used a Chevy V8 head at times, but it didn't have the same bolt pattern and wasn't an easy bolt-on mod as JoeH has pointed out. The Ford 240/300 six cylinder racers also did a similar mod using 351C cylinder heads. Either one takes tons of work and welding and fabbing, so yeah their going to be expensive, even if they were done 40 years ago.
found on craigslist I have a brand new never used Algon racing head for a GMC 302 6 cylinder head. One of only 6 built. Perfect for a bonneville race car. Very rare head. It's been known to get over 800hp with a supercharger on a 6 cylinder with this head. I also have titanium intake valves that go with it. I also a standard bore High Nickel GMC 302 6 cylilnder military block, aluminum timing cover and a rare aluminum oil pan. Please call if serious only 623-238-1511 Rare Algon Aluminum 6 cylinder racing head/engine - $15000 (Buckeye AZ)
instead of guessing and wondering, you could buy a copy of this, as it tells all about how to do it. http://www.amazon.com/Chevrolet-Inl...8&qid=1370368852&sr=8-1&keywords=leo+santucci
Guys, I have the six power manual book by Leo Santucci. That is where I found out about these things and got the brain turning. I know it would be a giant pain in the ass to build one. The book is very detailed in what you're up against to do it. However I have a friend that is as good a welder as there is so I'm confident he could pull this off. May be easier just to pull a modern six out of a Colorado or such but I'm old. I'd rather hot rod my '68 250. But I'll probably be dead before half my projects get finished at the rate I'm going. But hey, I can dream can't I? Thanks for all the replies so far.
Frez, a lot of advances have taken place in speed equipment for these engines since Leo's book was written more than 20 years ago. A modern LS style head is a much better cylinder head for anyone looking to create a hybrid head for the Chevy 6 than the traditional SBC heads are for many reasons. Look over on Inliners for anything you might need info for, especially in the cylinder head department.
I have two. Both are true performers and really made a huge performance difference. Both were completely reworked by Mike Kirby at Sissell's in West Covina, CA. The 292 shifts at 9,000 RPM and the 261 at 7,200 RPM. Both still are competitive too. Normbc9
Looks like an old thread. I have a 292 sitting in the living room and an LS is the shop in a customer car. This got me to thinking so I searched and found this thread. Currently I am working on putting a 351 Cleveland head on a Jeep 2.5 4 cylinder engine. I also want to do the same for the Jeep 6 cylinder engine by cutting and welding two heads together. My son has a truck with the 292 Chevy 6 and I looked at what it takes to put the small block Chevy heads on it. He also has the book. What a huge amount of modification to make it work. So needless to say, down the rabbit hole I go. The problem with the small block Chevy heads is that the valves are canted towards the intake side. This causes the rocker arms to be so far over that the push rods are outside of the block. The same problem with the LS head except you don't have the head bolt in the edge of the block problem. What this really needs is to have the intake remaining on the driver's side and have the exhaust go out between the pushrods. This keeps the valves canted the right way to have a compact head. It would mean casting a new head design but it might be worth it to free up the drivers side for better port spacing and dedicated ports instead of the siamese port with the head bolt boss in the middle of it.
Those are all common issues when creating a hybrid head to fit the 6 cylinder and even 4 cylinders. But, those types of mods have been done successfully for close to 50 years now. Also, there have been several application specific heads for the Chevy 250/292 6 cylinder for close to 50 years now, and the 4 cylinder little brother as well as far back as the mid-60's, and more recently in the later 80's from GM Performance, and later on the 8 Port Duggan style head. They are still out there if you look, but when they were available, people still tried to reinvent the wheel and create hybrid heads which brought with it many issues and problems instead of buying the bolt on performance heads made specifically for these engines. It just depends on what kind of power output you are looking for. Our NHRA Chevy 292 H/MP and Comp Eliminator engine made around 620 HP with a siamese head, naturally aspirated(Its in Leo's book multiple times). And i'd wager that nobody that has ever used a Sissell/Duggan 12 port head ever made that much or more power on their 6 cylinders than what is possible with a siamese head. And we raced and competed against and beat several top Ford 6 cylinder guys that did have the 351C hybrid heads on their engines. They truly were works of art, but our production GM siamese head 292 produced more HP than most of those top guys. Bruce Sizemore was one of them. So don't sell the siamese head short thinking you are upgrading to an exotic crossflow head, you might be disappointed.
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