[Tom Vaught]

Agree the head intake ports positions are like a Square Port RA-V head would look like.
Not likely that the Tunnel Ram Tri-Power intake would fit that configuration.

Same deal with the belt drive "belt wrap" as shown in the picture of the "Adjuster" wheel
on the rear of the engine. Belt wrap is all wrong.

Tom V.

ps I personally worked on the "F" 3 valve cylinder head design and the small dual ports are typically for the INTAKE
side of the heads. That means that the Pontiac 3 valve heads would be an abortion as far as the flow thru the heads
if mounted as shown. As Tom S said Intake manifold is all wrong. .

The larger exhaust valve in the "F" heads (See Pictures) is there as a second exhaust valve is not needed.
The time sequence for the "F" heads was 4 Valve heads first, then the 3 Valve design, then the 2 valve design used on the V-8 and the V-10 Modular engines.

Tom V.

My direct Boss, Jim Clarke, loved the Pontiac engine 2 valve/3 valve design. He would not have COPIED a flawed design. The Pontiac Heads are not like the "F" heads at all. A Screw-up by Pontiac in my mind.

[PontiacJim1959]

Originally Posted by tom s

Jim,take a close look at that middle pic of the 3 valve engine.The intake was on there for a mag pic.No way the ports line up with the intake valves.That had been pointed out before.Tom

Tom, not quite seeing what you are seeing. The single intake valve is 2.280" and the pair of exhaust valves are 1.420".

Appears to me the large intake valve is in alignment with the intake port at the top of the head/photo. At the top/end of the heads on the intake side you can see the round holes used for the water inlets. This head is in a side comparison of a stock head and all head bolt/steam holes all line up, so the view is intake runners on top, exhaust ports on bottom.

"By using a double chamfer in the throat of the port, a venturi shape was created to phase in the incoming gasses with less turbulence. The single intake valve could be placed directly on the centerline of the cylinder bore and at a relatively good inclination angle of 20 degrees. A consideration which prompted our 'engineering exercise' on the single intake/two-exhaust setup was the fact that the intake port did not require 'splitting' of the port, with a resultant increase of surface area and possible inefficiency of the port.

Now it certainly could be a clay model concept for the magazines.

[tom s]

The head has 4 individual intake ports,the intake has 2 paired intake tracks like a regular Dport bathtub except for the injector ports and a diff top for 3 throttle bodies and a stack of spacers for the top.Pretty much like the intake im going to reproduce.Tom

[tom s]

Again NOTHING to do with the original thread.Tom

[Tom Vaught]

Originally Posted by tom s

Again NOTHING to do with the original thread.Tom

Maybe in your mind Tom S, but I am trying to visualize the airflow path from the Intake openings in the plenum thru the runner (or two runners), to the
given Intake ports in the heads.

A Pontiac member removed the dividing wall on his Offy intake and removed a portion of the intake runner prior to the intake valve of his pontiac heads.

So in your Bathtub repops are you going to have a common runner to two
short intake runners or 8 intake runners. Is there a dividing wall at the gasket surface of the Head mounting surface?

I have a right to ask questions Tom S.

Tom V.

[tom s]

Tom,there are many pics of the intake in the bathtub thread.It will be just like the one Randy made for Bill Blair.W plenum with very straight runners.Bills tempest ran in the 9s with it and my 62 421 drives great with it.Tom

[PontiacJim1959]

Originally Posted by tom s

The head has 4 individual intake ports,the intake has 2 paired intake tracks like a regular Dport bathtub except for the injector ports and a diff top for 3 throttle bodies and a stack of spacers for the top.Pretty much like the intake im going to reproduce.Tom

OK, got it. You were referring to the misalignment of the bathtub intake ports and the intake ports on the 3-valve head. It came across as the large intake valve did not line up with the head's intake port.

The 3-valve head may have only been used for flow test purposes and never had an intake to match, thus the one installed for the photo shoot. The intake ports do appear more in line with the RA V.

[Tom Vaught]

Originally Posted by PontiacJim1959

OK, got it. You were referring to the misalignment of the bathtub intake ports and the intake ports on the 3-valve head. It came across as the large intake valve did not line up with the head's intake port.

Agree.

PontiacJim1959, Pontiac Engineering never had a flow bench in their organization in the 1960s. Ken Sperry, who did flow bench testing at the GM Tech Center did eventually build a basic Flow Bench using a Roots supercharger (as a suction device) to move the air thru the cylinder heads and intake systems. The 3 Valve heads or any Pontiac Heads/ Intakes were never tested on a flow bench.

So the intake systems people are copying are based on assumptions vs actual testing in the early 60s.
Malcolm still hit a home run in most cases.

Tom V.

[Island Boy]

Tom-I had one of the 428 splayed bolt RAV blocks. Our buddy in Chicago has it now. It came with all the RAV parts I got in Atlanta. This one is only the second one I have seen.

[johnta1]

Does it have the boss this thread started with?






Have any pics of yours?

[74SDformula]

Originally Posted by Island Boy

Tom-I had one of the 428 splayed bolt RAV blocks. Our buddy in Chicago has it now. It came with all the RAV parts I got in Atlanta. This one is only the second one I have seen.

Was that stash of parts from Don Moore?