[misterp266]

Originally Posted by Jim Robertson

If Jack says Go...I will start posting some pics as we capture them and work our way around these.

Jack,
Do you have any pics of the rockers you use on yours? The more pics the better...

Who made yours?

Jim,

Here's a pic of a stock 392 exhaust rocker (one of Jack's) beside a M/T aluminum Pontiac Hemi rocker. Jack uses Donovan exhaust rockers which are the same size as stock. Steve has the M/T rockers on his boat motor.

Rob...

[Pontirag]

rumour has it that somebody is doing an MT Hemi head? Is that what this is leading to?

[Steve Barcak]

Originally Posted by misterp266

Jim,

Here's a pic of a stock 392 exhaust rocker (one of Jack's) beside a M/T aluminum Pontiac Hemi rocker. Jack uses Donovan exhaust rockers which are the same size as stock. Steve has the M/T rockers on his boat motor.

Rob...

Correct. I am running the M/T forged alum rockers on my original HEMI Pontiac installed in a '72 HONDO flatbottom.

They work fine but, are too troublesome to service an engine between rounds and there are other limitations as well. Based on that, I am currently having a modern shaft system being manufactured for my other Pontiac HEMI stuff to be used on my 225" AA/FD.
Instead of a rocker shaft assembly as a whole, there will be a rocker base that bolts to the head. Then a separate custom shaft rocker will bolt to it individually on its own stand. This will make it much more adaptable and reliable. Plus easier and faster to tear down and put together between passes.

One of my heads is being used to do this and will be a vast improvement over the original design. As far as what they may flow, not overly concerned at this time. I am confident a 370-400" Pontiac with M/T HEMI heads can get a digger or funny well in the 5s at most any desired speed 250+. I've seen cars with iron 354 chysler heads, 6-71s, no trans and 12" nostalgia tires, old style point mag, 380-400 inches, etc already running 5.80s/ 240-50mph over 10 years back. It was very common and the M/T heads are far better in every way ( except availability ) than the iron 354s are. Exhaust ports need no work. This engine was designed ad built to be a Top Eliminator and other top class winner blown/injected engine- no compromises- The most power available.. No carbed intakes were made from the info I have gathered. Have not heard of injected intake as Jack mentioned, news to me.
It's really a neat engine. I'll be giving rides this summer and beyond to share!
I love and admire all the modern stuff out there in the Pontiac world but, it is really something to be able to do it with 50 year stuff that has yet to reach its real potential. Doing it 'Old School'.

[Jack Gifford]

Jim- post all the pictures you want. This whole effort is about sharing info.

As Rob said, my hemi V8 uses Donovan forged steel exhaust rockers meant for early Chrysler hemi, same basic configuration as the OEM cast-steel rockers. They work well to 9,000 RPM but are getting scarce and expensive. Stock Chrysler intake rockers worked fine for me.

If I use this head on a four-banger for the lakester, it won't use pushrods. I want to finish the details of a DOHC design I was working on, and employ it on the four (needs to be reliable at over 10,000 RPM to make my goal of 4 HP/c.i.).

[performerrpm]

Originally Posted by Ron H

Interesting. I am curious why you have not digitized a head and started widdling them out? Eventually casting and selling?

Having M/T designed Hemi head available I am sure would bring interest.

if there was ever to be a set of m/t heads reproduced, `id hawk the wife, kids and anything else to have a set!!!!

[misterp266]

This will give you an idea what Steve is talking about for rocker arms. This is a billet Alan Johnson 392 head.

[Don Chapman]

Guessing, As cast @.700 299int/265exh.

[misterp266]

Any updates Jim?

[Jim Robertson]

I can update you on Tom S's RAVs but that is another thread. :-) Besides Tom would string me up if I do not finish his first.

The Hemi's should have very good numbers for the valve size. You'll see the reason for asking about the rockers...

[Half-Inch Stud]

SHHHH!!!T, HOP'Solutely triple IPA & HEMI PMD heads don't mix. WOW.

[misterp266]

Nice job on the guides and seats Jack, not sure I'd trust the nearly 50 year old originals in my heads. Flow numbers should be interesting!
Rob...

[Jim Robertson]

Nice casting for early 1960s and excellent machine work in early 2011. Enjoy.

[Jack Gifford]

Originally Posted by Half-Inch Stud

... HOP'Solutely triple IPA & HEMI PMD heads don't mix. WOW.

Say what?

[Jim Robertson]

Some progress...we flowed the two different intake ports tonight
Had to mod a few things to get a fully operational set up to accept the Hemi. Will scan and post the flow sheet soon.

Fresh calibration tonight with the PAP plates.

Internal barometer read 28.08" Hg. Crazy low pressure and stupid hot temps.

Tall guides would allow .700" max lift

Flowed these on a 4.060" bore diameter at equivalent to 28" H2O pressure differential.

Noted a sound change at about .500" - .525" lift and it carried out to max lift on both ports.
Stock port - Some turbulence resulted in varied flow numbers at .700" lift anywhere from 276.1 - 290.6 scfm.

Modified port - also varied and flowed 282 - 295 at .700" lift.

[Jack Gifford]

Intake flows @ .300"/.400"/.500" lifts?

[Jim Robertson]

Flow sheet attached. Will be working on larger bore flow numbers and the exhaust. Exhaust should flow fairly good...but we shall see.

[Tom Vaught]

Would have guessed a LOT more flow there.

My "nothing" "2nd Run" Edelbrock boost heads will go 310 cfm at 28" at .600 lift and 255 cfm on the exhaust at the same lift.

Tom Vaught

[tom s]

2in intake a 4 in bore Tom!

[BruceWilkie]

Really not bad numbers for a 370-421 inch motor. SBC Brodix 11's have similar numbers with slightly bigger valve and smaller valve stem. Decent low and mid numbers too. Considering the era of these heads, thats pretty respectable. The exhaust numbers should be interesting. I'm thinking a much better in/ex ratio than a conventional Pontiac head. That would allow the intake to work more fully to its potential. Especially with a boosted motor.

[Jim Robertson]

I thought the numbers were good for a 2" valve up to .500" lift. After that both ports have a bit of turbulence that could in all likelihood be "tuned" with a bit of work around the seats.
More to follow.