Inliners International Forums General Discussion Bench racing Hybred head for flat head Mopar

Since circumstances prevent me actually working on my project I’m doing it “mentally’ instead. I’ve been investigating chopping up a newer overhead valve head for use on the Mopar flathead. The problem I am running into is that all the heads I have looked at place the push rods too far away from the centerline of the bore to be compatible with the old Mopar which depending on type, only had a bore of 3 inches or so. Since most modern engines are about an inch bigger, the spot where the pushrods come up is too far out. The heads I have looked into were all Mopar because I have drawings to look at. Has anyone investigated this? Is the small block Chevy or Ford more compact? It looks to me like the magic number would be around 2 5/8 inches from centerline of bore to centerline of pushrods.

Leif

Man, I hate it when someone here starts thinking! My ADD/ ADHD & CMMOB all kicks in at once. SBC- 3 1/2", 292 Chevy 6- 2 1/2", Stude V8- 3 1/4" GMC 270 3 1/4" I don't have any heads off the Cadillacs. These are just tape measure quickies.

Are you thinking 2 V8 heads or some other 6 also? Stude, Ford, IHC, Chevy a ton of tractors. How about British 4s? Have you considered overhead cam to just avoid the push rod thing?
Did you see the pictures of the Edgerton conversion I saw at Bonneville? Someone posted a picture here. You are welcome to come work on some of my projects!

Would the overhead cam head off a straight 6 Jeep (Cherokee) fit?

I knew this was the place to ask! That Chevy 6 number looks pretty close and the OHC Jeep idea is a very interesting one! I had heard that the block they used was closely related to their flat head...you could use a belt to drive the cam which would be much easier to fabricate than a chain. Cam bearings might be an issue if I have to saw everything up to account for bore spacing...
thanks guys..this forum is the BEST!

Leif (Those mental wheels are spinning now!)

My brother used to have a '63 Jeep with an OHC 6. I think the called it a Tornado? I know his '55 had a Hurricane flat 6. I saw a crank from one those OHCs that had sat outside for years and it looked brand new! Lot of hard stuff. Good luck and keep us posted. When you get this figured out we can do the 413!

I've been told you can use the older AMC 6 crank to stroke the 4 Liter I6 (Jeep) into a real monster, so, that would at least suggest the cylinder spacing should be the same (as the AMC 6's). Don't know how that relates to the Mopar 6, but I thought that might be something you had access to (that and it's supposed to be a decent flowing head stock).

I would think cylinder spacing and clamping/bolting area would be more important than push rod/cyl. spacing. Rocker stands or studs might be able to be moved. Custom or stock rockers might be made to work. Water flow into the head is another concern. Maybe comparing head gaskets would be a help.

have you looked at the head from a chrysler australia 215/245/265 hemi inline 6??

not entirely stock though!

That is BAD! I saw one of those blowers on eBay recently. What years were those heads used? Thanks, Beater

the motor was produced ,in OZ,from '70 to the early '80's .lots of parts and speed equipment still being made.motors are still easy to get as well.check out e-bay(australia)just put in 'hemi' and most of the hemi ,in OZ, will be the hemi 6 cyl.

buickroadster, Do you have a picture you can post with the valve cover off? I would like to see how the rockers worked for the hemi design. Is it a true hemi design?

the hemi design is true ,but rather thanthe valves being opposed across the head they are oppossed along the head with the pushrods not vertical,but on an angle to the head.i'll see iff i can get some photo's.check out the mopar market(australia)site.there is a wealth of info and photo's there

hello $UM FUN,
there are some pictures on this guys site that will help you.
http://www.drhemi265.com/

regards,Rod

Hi Walpolla, Thanks for the link, thats what I was looking for.

The inclination of those valves is very slight, with the inlet being more inclined than the exhaust. The chamber isn't a hemi chamber as you'd expect it. But they must be a reasonably efficient head as they got a bundle of power out of them when they stuck triple Webers on them. 302hp in fact, with people today wringing many more ponies out without supercharging.

The main thing you should be looking for here is cylinder spacing. This sort of thing is an exercise not for the light of heart. A guy here named Laurie Seidl once cut the centre two cylinders out of a Jag twin cam head, welded it all back together and put it onto a Peugeot 403 block. That was fitted with Standard Vanguard sleeves and crankshaft to enlarge it from 1460cc to about 2 litres. It ran in speedway.

Depends on how keen you are on welding cast iron, I suppose, but I think head bolt locations are going to be one of your main concerns.

Somewhere, the ghost of Zora Arkus-Duntov is chuckling about this. Remember the ARDUN ohv conversion heads for flathead Fords? Seems to me like that's what you need for your Mopar flattie. Unfotunately, I have no idea where you'd get something like that, or if anyone ever made them.

How about the relative ease in which the hybred SBC heads bolt to our sixes? He probably giggles about that, as does whoever found it out.