XRV8 Gremlin

and...

Stock RV8 heads are limited to about .420" lift by valve spring coil bind with 1.85" install height. These are set up using AMC 360/401 valves cut down to 1.95" intake/1.60" diameter exhaust sizes with +.050" custom cut dual spring retainers to get .500" lift with 1.9" spring install height (about 125 lbs. closed/285 lbs. open spring pressures with Melling VS-500 outer & Sealed Power VS-527 inner springs)

Fully detailed and ported with oversize valves, all cylinder head work done exclusively by XRV8 Race Parts.










Edited by amcenthusiast - Apr/16/2017 at 7:48am

A longer explanation to describe and explain the ideas behind siamesed exhaust ports would be appropriate here but I can't seem to make time & effort in order to write it...

But check this out:

My plan for the valvetrain set up and the cam worked out 'just right'; I don't need custom pushrods (my calculations were correct)








Edited by amcenthusiast - Sep/11/2018 at 8:47am

With 285# pressure closed you should be able to run regular oil (after break-in) with no issues. Over 300 lbs and cams start to wipe on flat tappet motors. 

scott wrote: I see that on both of your intake manifolds you keep the exhaust crossover passage, even though it no longer provides heat for your intake as originally intended. Knowing that you are a thinking man, nothing done without research & planning behind it.  I am sure there is a reason why you have kept it, when it would be easier (less fabrication) to eliminate it. What is the reason for keeping it?? If I had to guess, I'd say it acts in a similar fashion to an H pipe further down the exhaust. Am I close??? Have you considered running pipes from the crossover ports in the heads under the intake manifold to the rear of the engine & connecting them to the headers?? Could that be a way to crutch the siamesed center exhaust ports?? I really enjoy what you are doing, keep the updates coming!!

Scott, thank you for your observation with good question.

Because, like 304dude's comment, there will be people who are instantly turned off by the sight of siamesed center exhaust ports used by AM's '56-'67 Rambler V8.

This question branches off into engineering topics which are not normally studied by the average auto enthusiast.

I plan to make a few drawings and post them here so I'll reserve this space for that, to be done in the future.

(Thanks AMC Forum for the space)

For now, we can look at several other early US V8s that used siamesed center exhaust ports also;

We should remember also that Nash and Hudson top of the line models were rival to Cadillac, Packard and Studebaker top of the line cars. (can't find a good pic of a Stude' head right now)

'62 Cadillac 390 V8 head:


'55 Packard V8 head:


'56 Pontiac V8 head:



Edited by amcenthusiast - Apr/23/2017 at 8:13am

With all the engineering skills you have I'm sure you're capable of making a divider plate like the one made for the 3rd gen 6 cylinder engines (199,232,258). If they're well made they will last a long time. Neat project.