[Verdoro 68]

I'm starting to plan out my winter engine refresh project around a set of Ram Air II heads and wondering how to optimize around them.

Current setup:
Original '68 400 .040, #16 heads non-ported
1.65 stamped rockers
Lunati Voodoo 702
-14cc dished Icon pistons
Stock iron intake w/ '68 Q-Jet
Ram Air Manifolds
2.5" Pypes exhaust
TH400 w/ 13" Continental Stall
3.55 Posi
A/C, PDB

With the RAII heads, I'll be using round port RARE manifolds, a Ram Air IV intake w/cross over (heads are ported on the intake side), and keeping the Q-Jet, but that's about all I have planned so far.

The easiest thing would be to swap heads and call it a day, but since I'll have the engine out to do a reseal I'm wondering if I should consider a cam swap as well. Plans could change depending on the condition of the bottom end. The engine was built about 10 years ago and has low milage, so it should be ok.

Would love to hear thoughts on how to build a stout streetable setup around these heads.

Also, given the rarity of these heads, is there anything I should avoid in terms of machining that might diminish the value? I assume hardened seats, new guides and seals are safe starting points.

[grandam1979]

Sounds like you have a sound shortblock personally I would get one of the Butler hydraulic roller ram air cams have the heads setup for the cam. I don’t know the cc of the heads but depending on what they check you will be able to keep compression under 10.1 with your dished pistons and different head gaskets available.If you don’t want the expense of a hydraulic roller a bigger hydraulic will work also. The other thing might be the converter what’s the stall? I do know a r/a IV cam with a stock 13” converter is like having a rev limiter on the engine till it hits 2600 rpm then it comes alive. One other thing to think about is the 3.55 gears of coarse a r/a II or IV could only be had with a 3.90. or 4.33 gear. So if you would go with a r/a IV spec cam cruising at under 2600 rpm the car will sound like it has a slight miss of course it doesn’t your just not into the cam rpm range yet. Back in the 80-90’s I had 3.55 gears in my GTO and had a r/a IV in it my buddy’s would say “can’t believe this car runs so good with that miss” I would just smile.

[steve25]

In terms of a Cam pick and then maybe the need/ use of the 1.65 rockers on the exh lobe’s I would get the heads flow tested and hopefully in 050” increments and with the intake bolted on if possible,and then average out those numbers to see if the motor will really need the exh lobe’s to have more duration and more lift than the intake side does.

In stock form those RAII heads have a high then needed exh to intake ratio.

[Verdoro 68]

I was looking through the Butler catalog - one of their Ram Air series rollers in the existing short block could be a good option to build off what I have.

Interesting thought with the 1.65 on the exhaust side. Related - the heads have the original tulipped valves in them. Is there any reason to keep them or am I better off replacing them with some new stainless Ferreas? Seems risky to keep 50+ year old valves.

I’m kind of gambling on the intake. I bought a repro RA IV anticipating that it will need a lot of work. If it needs too much, I have an iron ‘68 I can port match.

The stall in it now goes to about 2000 when you’re easy on it, higher when you flash it. I don’t want to go any higher on the rear gear, but a different stall is on the table. I always regretted not getting the 10” Jim Hand special instead of the more conservative 13”.

[grandam1979]

Something comparable to the 10” JHS would be great for a r/a profile cam. Stock 13” converters are very tight your 13” might not be. You could always change that later if you don’t like it. If you go hydraulic roller I personally would replace all the valves with something better like you said 50+ years old. They wouldn’t be a good choice for a roller setup if new.

[steve25]

Tulip valves are a disaster on the intake side of those D port heads, but on the exh side they will pick up exh velocity at low lift and help out with those heads too large exh throat size.

The main throat of the exh is 1.65”, the intake bowl throat is only 1.60”.
If anything it should be the other way around!
At any rate do not run 50 year old factory valves unless you like to gamble!

[johnta1]

RA II heads are round port I think?

[Verdoro 68]

Given the rarity of these heads, I wasn't sure if there was any hit to the value if I did a standard rebuild with of new guides, hardened seats, new valves and clearancing for 1.65 if necessary. However, it would all be a wash if I used old parts and I dropped a valve and destroyed everything. Better safe than sorry I suppose. Besides, they're already ported on the intake side so it's not like they're totally virgin.

This is going to be a long term project. Got in touch with my builder the other day and he has a 9 month backlog but said he could squeeze me in. I'll start stockpiling parts in the meantime.

[grandam1979]

Good aftermarket valves won’t hurt the value of the heads.

[Skip Fix]

Originally Posted by grandam1979

Good aftermarket valves won’t hurt the value of the heads.

And keep a head from popping off and grenading rare heads!

[Kenth]

I have never heard any racer anywhere complaining on too much flow in the exhaust. The bigger the better.
Also, i have found the main reason Pontiac made the exhaust ports round and boltholes further apart was for the racers to attach the tube headers easier with larger seal surface to prevent gasket leaks.

[Matt Meaney]

Originally Posted by Skip Fix

And keep a head from popping off and grenading rare heads!

until a hardened seat fall out, than all bets are off.

[steve25]

Kenth, then all I can say is that you’ve only been talking to uninformed racers with poor knowledge of why overall intake and exh ratios in conjunction with the motors cam spec’ s and compression are so important to max out a given combo’s power.

[66sprint6]

Good luck getting those round port RA exhaust manifolds if you are thinking Ram Air Specialties. But at least you'll have better luck finding some for a '68 and up chassis.

[Verdoro 68]

Originally Posted by 66sprint6

Good luck getting those round port RA exhaust manifolds if you are thinking Ram Air Specialties. But at least you'll have better luck finding some for a '68 and up chassis.

Ames had them in stock, which surprised me. Not sure who makes them, but I figured if Ames stocks them, they’re good quality. I know the d-ports have been very hard to find.

[roger1]

Originally Posted by Matt Meaney

until a hardened seat fall out, than all bets are off.

This is why I wouldn't have hardened seats installed.

[pastry_chef]

Originally Posted by Kenth

I have never heard any racer anywhere complaining on too much flow in the exhaust. The bigger the better.

https://www.speed-talk.com/forum/viewtopic.php?t=4214

Joe Sherman about I/E flow ratio.

by bigjoe1 » Sun Oct 15, 2006 6:07 pm
I have heard this ratio stuff for years and i NEVER have seen it to be important. THe only time it might be, is if you must use a stock, or near stock camshaft,for smoothness or economy.On serious race engines, I have seen fantastic results at ahything in the 60 percent range. I think this is some misunderstood magazine hype. JOE SHERMAN RACING

Exhaust comments from Darin Morgan

by Darin Morgan » Sun Oct 15, 2006 7:01 pm

The 75% intake to exhaust flow ratio is NOT correct and never was. I think some engineer pulled this out of thin air.
The engines RPM range, size and intended use as well as other design criteria will be the deciding factor as to valve size and placement but trying to hit some preconceived flow ratio with total disregard for other more important tuning variables is not an intelligent or well thought out approach. I will admit that the industry is full of these little snippets of pseudo wisdom but one should not believe everything they hear. When you try and optimize the valve area in an unlimited engine combination you always sacrifice exhaust valve size for intake valve size. Its much easier to cam and manipulate the exhaust system to evacuate the cylinder ( dynamic blow down and cam shaft events) than it is to manipulate the intake tract. Current Pro Stock and Comp Eliminator engines have intake to exhaust (size in diameter) ratios of 70% and flow ratios of only 58% to a maximum of 61%. These engines are producing 2.78HP/CID at over 5800fpm piston speed so the that kind of shatters the long held belief that the exhaust should flow 75%-80% of the intake. Could we make more power if the exhaust flowed more. No, we tried that. Could we make more power if we increased the exhaust size and kept the same discharge coefficient? Yes it does but there isn't any room left for a larger valve because we just stuck this big intake in there so its really a mute piont. I know thats a simplistic explanation of what is going on but I think it drives the piont home.

by Darin Morgan » Tue Aug 16, 2005 12:39 pm

My personal opinion and from what I have learned about exhaust ports I have to say that small super fast exhaust ports make more power over larger high flowing exhaust ports except in the case of full exhaust systems such as Nextel cup engines. For some reason they like a slightly larger exhaust port but no where even close to what I would call large. Large and Small are ambiguous. In my book anything over about 110% of the valve area is large and anything under 105% of the valve area is very small but the exit velocity seems to play a role here as well. I try to adhere to the 105-108% in our pro Stock engines and it seems that I am not alone in my theory because many of the top notch heads I have seen are about the same or within about 2%.

Another very big thing to consider in the tuning of exhaust ports is there sound or should I say the lack of sound. How smooth an exhaust port sounds and how quietly it can move the air are both very serious factors to consider. As the valve opens the sound of the ports should smooth up and get increasingly silent. The loudest portion of the exhaust flow on the bench is from .200 to .400 after that they should go increasingly silent with every lift increment. I have had exhaust ports that actually cracked and popped like fire crackers! With a little seat blending and chamber work I managed to smooth up the flow, gained a measly 2 cfm average and gained 26 horsepower and it still was not correct because the port was to big. The hardest thing I do is try and fix exhaust ports that are screwed up. Its much easier to fix intake ports!
Like an intake port, an exhaust port can be made to flow a great deal of air, Just make it big.

Some rules I live by.

(1) Exit area = 105-110 % of the valve.

(2) Exit air speed at a minimum of 300 and a max of 330 ft/sec mean.

(3) Smooth silent flow by at least .400 lift and absolutely by .500 lift.

[steve25]

There's no such thing as silent flow when doing a Exh flow test, especially once flow numbers of around 160 cfm are attained, its loud!
But that said, turbulent gurgling sounds and pop's are a sign of trouble and non smooth flow if you want to look at it that way.

Exh flow should sound non turbulent thru out the whole lift range, not just from around .400" and up, I I take real issue with Darin on that statement!

On the other side of this whole debate we have Smokey.

From his extensive testing long before many of these other people where around ( or even had Dyno's of there own to beat a motor up in 24/7)in terms of his 600 hp SBC paved oval motors he stated that 250 cfm on the Intake side and 200 cfm on the Exh side where the numbers he found to work with these combo's and there 12.5 to 1 compression ratios.
That's a 75% ratio.

While we are looking at info, let's look at all of it!

[pastry_chef]

Originally Posted by steve25

Exh flow should sound non turbulent thru out the whole lift range, not just from around .400" and up, I I take real issue with Darin on that statement!

If it performs it is a winner.

In 2006 Darin stated the only Pontiac heads he did were the 455SD heads on Don Kennedy's Super Stocker in 1989. Reportedly set the NHRA record.

Years later he did Kauffman high-port heads and intake for Mike Semchee that won Engine Masters contest.
https://www.motortrend.com/how-to/ho...ontiac-engine/

Darin did some work for Jim Robertson here.

Originally Posted by Jim Robertson

Yes the Darin Morgan at Reher-Morrison. He liked my roughed out intake port so he left it as is. He spent 2 hours on my exhaust port...so I guess I screwed that one up :-) He did the chamber complete. He is not concerned about the plug location.

Cool video by George Bryce, valve events and about intake/ exhaust flowbench numbers. https://www.youtube.com/watch?v=4E4HOpoyvsE

[Skip Fix]

Harold Brookshire Ultradyne cams and did work for Lunati, Comp would change cam splits depending on E/I ratio. John Angeles on his RAIV SS car he has run for decades has a single pattern cam also.