[J.C.you]

Since there are quite a few aftermarket cast and a few billet head choices out there to choose from, it would seem the next step would be a multi valve layout.
Anyone know if some work has been done on a 3 or 4valve layout? Just conversation.

[charlie66]

I agree, Would be the next step for all out performance.
I know alot of guys with less cubes and 4 valves per cyl making alot more power then the larger ci motors with 2 ..

I think theres a guy on FB that was doing something like that for a Pontiac..

[Matt Meaney]

there was something posted on here about a guy working on a three valve head, iirc. had pics too.

[mgarblik]

Mac McKellar knew the advantages of multi-valve heads in the early 60's. The couple of times I was fortunate enough to talk with him the conversation always moved toward 3 and 4 valve designs. He was also convinced the maximum benefit would come from OHC multi-valve designs as well. But it was a time of cheap fuel and low cost engines. Need more power, just make the engine larger, much less expensive than exotic camshaft drives and 24 or 32 valves. Some of the benefits are negated if a pushrod system is retained, but OHC, I would love to see.

[Aaron Quinton]

The value on the intake side is pretty big. The value in the exhaust side is significantly less with the right valve timing.

[john marcella]

Originally Posted by Aaron Quinton

The value on the intake side is pretty big. The value in the exhaust side is significantly less with the right valve timing.

Why?

[Stan Weiss]

Originally Posted by john marcella

Why?

At exhaust valve opening / low lift there is a huge difference in pressure differential as to what the intake valve will see.

If we look at a 535 ci, (bore = 4.35", stroke = 4.5", rod = 6.75") 14.5:1 cr that has a peak cylinder pressure of lets say 1600 psi @ 12.5 ATDC there will still be about a 10th of that @ EVO.

Stan

[Aaron Quinton]

Because it take energy to suck the ****e in. On the exhaust side only takes waste energy management which is free. The exhaust is not so important. You're trading off expansion vs. pumping work.

Originally Posted by john marcella

Why?

[Dragncar]

The 3 valve 428 car McKellar developed was given to him by GM as a retirement gift. Used to cruise it around town.
Oldsmobile made a 600HP 455 with a Q jet. 4 valve heads.
My Tundra has 4 valve DOHC Hemi heads. Its a very interesting engine. Smooth and powerful. The fly by wire throttle has some sort of lag. If it was a direct cable it would shred the tires. 14.56 in a 5700lb truck is impressive. Dead stock, just let the rear tires down to 20lbs and stab it in "drive".
I would love to get a engine and 6 speed trans out of a junkyard and shove it in a old Chevelle or something like that (no Pontiac's).
In conversations with high end head guys about 4 valve heads they say its nite and day better than any 2 valve head. Its where its at these days.
I always wondered why GM went with the 2 valve pushrod LS vs something like Toyota did with the 5.7 I Force. Toyota has to make special de tuned heads and blocks or they would run away from everything in NASSCAR.
I would like to see a takeoff of the 2 valve SOHC Hemi Pontiac tried in 1970. But in 4 valve. It would have real Pontiac roots. Even the purists would have to admit that. Its one way we could get around the bore space limits of our engines. Seems the old PMD engineers thought the same thing.

[steve25]

The factory in the early 60s had a 3 valve head 421 built it was duel overhead Camed ( one Intake , two Exh) that had a the Intake ports layed out like the RA5 head and this is what to this day pisses me off when people say that the RA5 head was patterned after the later Ford tunnel port head, when it was not!

The RA5 head was based off of the head from this 1963 motor.

[azbirds]

I forgot all about that three valve head. Somewhere I have some pictures of that thing.

[unruhjonny]

there was an SD-4 hemi head - strikingly similar to the Quad4 which came out at around the same time iirc...

I missed out on an auction for a nearly complete setup over a decade ago...

I don't know if it was ever officially released as a part of the SD-4 program - even though I seem to recall that around 1987 there was a hemi-head SD-4 "GTO" (Grand Am coupe) concept car in print...

I still think it would be pretty cool to find a nice solid 1985-1989 Grand Am SE coupe with the Iron Duke & 5 spd (I believe that 1989 was the last year you could setup an SE with that drivetrain) - and swap a complete SD-4 setup on it;
I get made fun of for liking those third gen Grand Am's (and Sunfires), but they are great little cars that can be alot of fun.
https://youtu.be/gIqRnfh-3k8

[Half-Inch Stud]

Valvetrain is truely the limit to my Fortitude, and surely other pay cubic dollars to get the Valvetrain to be on-par with the Bottom-End.

A blend of the OHC-6 with the Ford Modular Engine and YOU ARE HERE; a decent topology.

Roller followers being the most valuable player.
HP growth as seen in the Modular Engine APPLICATiONS as a guide.
Scale to the PMD Bore and I think there will be excitement.

[john marcella]

Originally Posted by J.C.you

Since there are quite a few aftermarket cast and a few billet head choices out there to choose from, it would seem the next step would be a multi valve layout.
Anyone know if some work has been done on a 3 or 4valve layout? Just conversation.

I have had a 4 valve design in my mind for about the last 3 1/2 years now. And the groundwork for this to become a reality was laid down last month ! However it is for a very specific market. And I have serious concerns whether it will be outlawed within its classes that it's intended for.
A 4 valve retro fit is not something that I'm intrested in pursuing. To do something really good is complicated And extremely expensive for Valve train parts. And on a retrofit it gets even more complicated and the design gets compromised.

[steve25]

I need to correct my post number 7 as Tom Vaught was kind enough to jar my mind in the right direction.

What I posted about the 3 valve head was wrong, as it still had paired Intake runners like a normal production head, the duel OHC 421 had the Intake port layout that was starting to look like a RA5 was in the works!

[J.C.you]

Just conversation again, but just observation, a v head could be used to make a "poor boy " pushrod version multi valve head. Already a split port so to speak. Pushrod going through the port activates both intake valves. Would have to relocate a single exhaust valve towards the existing exhaust port. Exhaust lifter bore would have to be rotated some for a single exhaust valve.

[Half-Inch Stud]

So, in my thoughts, an OHC multi-valve gets rid of The Ram AIR V Pushrod sleeve.

[steve25]

It would seem like the EDdy pro port head would be a good starting point for a multi valve head.

[Mr Anonymous]

In the mid 80s, a few gentlemen I knew built a four-valve-per-cylinder head for an IH pulling tractor. Two spark plugs per cylinder too. I sold them two buick V6 HEIs for it. They did all of the machining themselves except for the two camshafts and their timing sprockets. Front drive was visible thru the cover they built from plex/lex. Test runs N/A on alcohol and two 3-into-1 headers directly upward found that you could make it rain alcohol and it would still run. I was there for testing, it was out of this world and sounded absolutely beautiful. Made it to one pull and it was outlawed. NO FOUR VALVE HEADS. They then built a billet two valve head, with canted valves, still DOHC. Ran awesome. Outlawed. NO BILLET HEADS. Amazing craftsmen, and ran up those against advancing the technology. Rules states 6 cylinders, so they decided to build an engine using the jugs/etc from a R4360-35B Pratt and Whitney radial airplane engine. 180 cubic inches per cylinder. They got word of it, and it was outlawed while still being developed. Tractor pullers are an odd lot, but they go to great lengths to advance the technology.

[Aaron Quinton]

No doubt, when you're good you get outlawed. Have to put a plan in place to back off enough to make the rule makers happy for 10 years or so.

Originally Posted by Mr Anonymous

In the mid 80s, a few gentlemen I knew built a four-valve-per-cylinder head for an IH pulling tractor. Two spark plugs per cylinder too. I sold them two buick V6 HEIs for it. They did all of the machining themselves except for the two camshafts and their timing sprockets. Front drive was visible thru the cover they built from plex/lex. Test runs N/A on alcohol and two 3-into-1 headers directly upward found that you could make it rain alcohol and it would still run. I was there for testing, it was out of this world and sounded absolutely beautiful. Made it to one pull and it was outlawed. NO FOUR VALVE HEADS. They then built a billet two valve head, with canted valves, still DOHC. Ran awesome. Outlawed. NO BILLET HEADS. Amazing craftsmen, and ran up those against advancing the technology. Rules states 6 cylinders, so they decided to build an engine using the jugs/etc from a R4360-35B Pratt and Whitney radial airplane engine. 180 cubic inches per cylinder. They got word of it, and it was outlawed while still being developed. Tractor pullers are an odd lot, but they go to great lengths to advance the technology.