Inliners International Forums General Discussion Hi Performance Hybrid Head For A 250

Am about to try the "V8" Hybrid Head" for on my 244cu in 250 block. Whats everybody thoughts on the project? The engine is in my 39 Chevy Vintage Dirt Modified. All Pros and Cons gladly appreciated.

Ok first question is how did you get 244cu in 250 block????
But anyway here it goes. First off doing this to a head is not cheap.All the time it will take to cut & weld the head up. Then there is redrilling and filling holes in the block. Special head gasket,Custom valve cover&gasket You will also need to make New side lifter covers Because now the push rods are now out side the block.And last but not least custom exhaust and Intake. So after
all that you now have a 4in combustion chambered
head, On a now less then 4in bore block.This could now leave a issue with valve to block cleance depending on the lift of the cam.And on a
Low deck motor(250) there is not as much meat
(persay) to the top of the block like the 292s
because they are taller/Thicker over the water
area if you was to look at the face of the block.
The whole top deck is thicker.
Yes more is to be had,But as to how much?That i do not know.
Have you lump ported Your stock L6 head? If not
maybe you should.This to will give you more power
and a much better air flow.

What Larry said.

Larry, 3.25" crank on a 4" bore. That gives you an excellent bore stroke ratio of 1.72, and the advantage of a wide assortment of pistons to use. Cylinder bore spacing on a V8/V6/I4 is the same, so that opens a lot of possible head options, some are easier to do, with the V8 set looking to be the best choice. Yes, there is machining work to do, but that is not a problem. The 292 block is stronger in the top than a low deck, but that long rod and long stroke doesn't like to stay together too long at 7500 to 8000 rpm. Yes ,I do have a head with lumps, now its time to try something different. Remember this is not a street engine but a full race 3/8 to 5/8 mile dirt and asphalt engine. Flyer, what do you mean by "What Larry Said"? Lets hear somemore one way or the other

the deck of the block will also be severely weakened. i would also tell you to not pursue the hybrid head.

tell us more about your combo and what you want out of it. maybe there is still life in that old head. tom

OK, all I know about these heads is what I read in Leo's book. I am amazed that anyone figured this out in the first place, the whole "mother of invention" stuff. It sounds like you've given this a lot of thought and have run the other options. Machine work is not a problem ,it's a race engine, go for it! Let us know how it's going, posts ,pics, etc.

I found out that Douglas milled the deck on his 250 block .300 then bored to 4.0"
IIRC 15 to 1 compression?
Runs 12 flat in the 1/4

MBHD

Albee47

Have you thought about cutting the whole upper part of the head out and Rasing the floor even more to make a much straighter run. Cut it clean
back to the Valve cover gasket rail. And also widen the ports at the sametime.

I meant that I agree with Larry's advice about using a six head with lump ports and the pitfalls associated with a hybrid, especially durability and money wise. But if you have already done this (and if you did it right you should be pulling something close to 400 HP @ 8000 RPM) and are ready to move on up then do not rule out something other than SBC heads for your hybrid. I've seen Chryseler W6, W7 hybrids and Ford SVO 4.5 V6 NASCAR/Busch aluminum hybrids, and also the later LS1 heads. These may be easier to fit up with better end results. Keep us updated on your final decision / progress.

Hey guys, My bore/stroke ratio 1.72 was wrong, it should had said 1.23. The rod/stroke ratio is 1.75 which is considered the best to use. In the late 1960's, there was 3 guys that ran V8 head converstions on their 6cyls. at our local dirt tracks. Two were Chevy and one was a Ford. Nobody around remembers how or who did them. I was hoping maybe someone else had tried this "out of the box" idea. Other than "LEO's article, has anything else ever been seen about this? TLOWE, looked at your pics. Lots of thought and work has gone into your project, looks great.

email me, Armond

Sure , I know of lots of guys who have built hybrid heads.

They all seemed to have two things in common:

1) They made lots of power.

2) Iron or aluminum, they all were fragile, high maintenance pieces, requiring frequent head removals to fix leaks, cracks, and valvetrain. Add in head gasket sealing issues and you begin to understand the formidable challenges you face. But one man's challenges are another man's motivation.

That is the reason the prominent drag racing teams have switched to one-piece billet aluminum heads.

Not to be contrary but we have never had head gasket problems, even at 25# of boost (at least not in the 5 years I've been wrenching with Leo). This last season, the head never came off, nor did the engine leak or crack anything, the valve train is just fine, as it always has been. Yes, this is not for the faint of heart but there are no problems that can't be overcome. Yes, there are better choices for the head but you pick the head to do the job at hand. An awfully lot of it depends simply on the fabrication of components, good machining and assembly techniques. Don't machine where it will weaken the block or expect silicon to bridge a quarter inch gap. Simple stuff.

I know of one hybrid (351)on 300 Ford and it has been reliable in a drag car.

If you could adapt the L92 Caddy LS2 heads, that would be great.
Those are cheap price wise(considering how much they flow),& my friend has a CNC program to make them flow even more.
http://www.proheads.com/WCCH%20L-92.html
http://www.proheads.com/
The head bolt pattern is off though.
These heads flow awesome!!!

MBHD

Well that is what's good about this board - you get several opinions for the price of none. I admit that I have never personally run a hybrid head and it sounds like those of us who have had recent success with them have overcome any durability issues common in the past. Aluminum heads are better candidates in my opinion for ease of repair / fab. And try to find a head to use with the same bore spacing as your block as offsetting the valve guides vis-a-vis the bore centers even a few hundredths of an inch can greatly affect flow.

Good luck on your project.

Don’t be discouraged, if you have tried everything ells on your head then I would look at a hybrid head. There’s a car that that drag races out here that has Chevy SB2.2 heads welded together. The last few times I have seen it run it fast. With the NASCAR boys going to the new Chevy this year you can get those very cheap, and considering how they flow it’s a bargain. Doug Robinson built a head for his GMC 302 by welding some NASCAR Ford Yates D3 heads together. As Armond mentioned if built right I wouldn’t worry about reliability. I have a friend that has been running his Boss 302 hybrid head conversion Ford 300 since he got the head in the early seventies without any problems.

Albee47
Why not get Two of the true 8 port marine heads
(and does not share the ports Like the other 4cyl
head or our L6)and weld them together. You would then have a True bolt up with much less Mods to the block AND it uses our same L6 head bolt holes. And to my understanding IT came with Stock 1.94 valves. At Least the one i have sitting here
is a Stock 1.94 valved head.

What are the recommended minimum wall thicknesses for the 250 engine, street and race? Being able to use the 4" Chevrolet 327 hypereutectic cast aluminum piston (short compression height version) with a 6" rod would be nice if possible.

Larry:
I've made the same case about the marine head too. Now they make them here and are of better quality than the Mexican heads from GM. Cast iron is not an easy material to weld. A set of new castings and Furnace-brazed together would be the ticket. Hey, I need to get a set of lumps from you. Heading to you site now!!!!!!!

I'd have to look again BUT??? I think the 4cyl marine head i have here is a Mexician head.
I think you would be better off doing tig with nickel then to Brazing it together, But I honestly don't know for sure I haven't done much digging into that just yet.I have had a head tigged once before and Never had any problems But it was just the stud Bosses.

Has anyone taken a look at using one of Ryan Falconer's V-12 aluminum (cross flow) heads - presumably the "driver's side" unit to align the valve train up to the Chevy I6 block layout? If I recall the article I read about them, his V-12 block is based on a 4.40 cylinder bore spacing (as used by the SBC V8) so I believe the head would align with the I6 in that respect. I'm sure one of these heads would NOT be cheap (and Falconer may not part with a single head at any price) but using it would at least eliminate the head fabrication part of the project, and therefore some of the problems others in this post have pointed out. I'm assuming all the block work (fasteners, water ports, and closing in the valve train where necessary) would be pretty much the same as is needed for a composit (hybred) head. If there is any interest, you can take a look at Falconer's web site. Perhaps the folks at Falconer would part with a head gasket (for a price) to help assess the various alignment issues? Just a thought . . .

I forgot all about Falconer's 12. Neat engine in concept (a 600 CID V 12 with common SBC wear parts). Is he still producing them? I remember the Thunder Mustang kit plane was supposedly using that for power, but haven't heard anything since.

falconer will not sell his parts, only complete engines. he also offers a inline 6 model. overhead cammed also. tom

Just plug and play...I like that

Base Price OUCH but yeah I bet it kicks butt. Just I will never have that kinda money,Not to waste on a Hobby toy/Play/Fun. I'll just stick with the stone age as One mit say.

Larry, at my age I try not to think of it as stone age....we are just using the technology that we have access to....besides thats the route (cut and try) that got us to where we are today. I've still got one in college so I have a lot more "sweat equity" available than money! Thanks for all your great input...fats

The stone age thing was just a Joke. But anyway it looks sweet to have But just waaaaaaaayy to high tech for my pockets.I am like you and many others who have more Sweat equity then money.

I HAVE A 12-ALUM.INLINE 6 HEAD FOR SALE ON INLINER AD.
THAT WILL BOLT TO YOUR BLOCK AND AD 100HP.

HEY JOE/WALTER

Is that another buyer beware item? And if you really have one OR?? some how much for a ready to go bolt on head??And how much down?? And can it be used with water??

Really, is this guy related to Joe Deppe?

Yeah Hank That is MR.Joe/Walter Deppe

I thought he sold all of his inventory & is out of business.

MBHD

Yeah well it does kinda make one wonder huh????

1# I DON'T NEED YOUR SMART MOUTH

2# I HAVE 10 HEADS READY TO SHIP

3# I HAVE THEM WITH OR WITH OUT WATER

4# IT IS CASH AND THAT MIGHT BE HARD FOR YOU TO COME UP WITH

5# ANYTHING ELSE GIVE ME A CALL DON'T PLAY GAMES
ON YOUR KEY BOARD WITH ME.

Why not post how much your heads cost & flow numbers?

MBHD

Just a note - for the cost of a hybird head + $800 one could get a 4200 vortec ($500 on ebay)- add race cams ($1200 - 1400),headers and an intake make 500HP all day long and not have the headache of trying to keep a hybird head sealed....

500 HP all day,used Ebay engine with just adding cams,headers & intake,,,,,,,,,,seems unbelievable,yes,no?

MBHD

Bone stock the '06 and later motors make 290HP in full emissions dress. This is with TINY camshafts like 190 deg@50 and .400" lift... The head on this motor is really that good with a little bit of head porting - mainly on the exhaust side. Add 80-90 deg duration @50 and .100" lift.

We'll find out in Aug.. what a good NA LL8 is good for. And hopefully sooner for the turbo version..

Hey if you don't like what is said then talk a walk. Many know your about as crooked as one may come.Yeah you may have some happy people out there But i haven't heard of any as of yet.So i am just stating my Facts. And if you don't like what i have to say then just don't read it. have a good day.If you have any happy customers I'll be happy to talk with them,to change my facts.OH and are you a Paid member in good standing?