CB Race Master Components On T4 Casting

[bugguy1967]

Sadly, STF is a ghost town. That's why I'm asking here. Has anyone ever heard of CB Race Master components being used on a T4 head. Doing some quick research, I found out that the valves are only .046" longer than factory T4 valves, and the Race Master springs are only ~.140" larger in diameter than the T4 springs.

I'm building an 82x103 engine. Anthony (Cub) from CB will be modifying and flow-testing the heads in-house (first time ever). It's hard to find a T4 guy that actually provides flow data and isn't scared to go way beyond conservative. We're using the Race Master components because that's what they have. I'll supply him the new AA 2.0 Porsche castings, which can handle over 50x40 valves without breaking-through.

[raygreenwood]

[bugguy1967]

Thanks for your input Ray. I work five miles away from European. It's the only shop I do business with, as far as machining goes.

AA does have a new 914 2.0 casting. Not AMC. It's a replica of the 914 head. Same chamber. Everything. It has angled plugs. It comes bare. The only change is it has an 8mm guide instead of the larger soduim valve sized guide. They're currently sold out, but will have some more in stock soon. I have pictures if you'd like to see them.

Also, while I realize they're T1 head guys, Anthony is well versed in varios types of cylinder head work. If you know CB, you also know they're not head hoggers. They've been progressively making more CFM with smaller and smaller ports.

We were planning on originally going the HAM route, but his info that he gave me was lackluster. He was against anything larger than 96 bore, his flow info that he gave me didn't sound right for the output they were seeing, which made me wonder if they're actually all flow tested. Also, they're outta stock for a year.

The flow data is so important to me. It doesn't seem like I can get that too many places in the U.S.

[bugguy1967]

Oh, and about European, Jorge has the heads there. He is responsible for engineering feedback on those heads. He is well versed when it comes to head machining, but not particularly head porting. I've used European for porting once. Jorge's machinist is not a head guy. He lacks basic understanding of what is condusive to good flow.

I had to bring my heads back twice because his machinist made a large D port, and did absolutely zero work after the guide. He removed, and replaced all the guides, then ported. So I had him remove the guides again, and at least port all the way to the seats. Huge, slow-flowing chambers. Looks like all the other hack stuff. In conclusion, not a porting shop. That's ok though. They do a ton of awesome machining work.

My plans are to take posession of the new heads, have Jorge direct me to someone who can fill-in the intake fins to allow for more porting, have Jorge bore for 103mm cylinders, and mail them to CB.

[modok]

I thought racemaster valves WERE type-4 size?
I guess there is a slight difference.

What goes in must come out. 1 bananna in, .75 banana comes out. Exhaust MCSA should be .75 of intake MCSA.
Intake port dia should be .75-.86 of valve, shoot for .80 Better the valve/chamber flows the higher that can get.
That's the shortest and sweetest info you'll overlook and spend a decade proving for yoruself

I too am a bit skeptical whenever I hear about 45mm+valves because the intake valve isn't where the bottleneck is.

[bugguy1967]

That's what I was thinking about valve size. HAM has a 48x38 head that flows 200 CFM, according to Mr. Hoffman. That's a HUGE valve for only 200 CFM. Seems like a 42 or 44 would be all that's needed. Lots of big T4 heads are using 48 and 50mm valves though. I doubt they're flowing 250+CFM. It seems like it's just easier to make good numbers with a huge valve.

I'm interested to know what Anthony will achieve.

Oh, Modok. I'm pretty sure they're a bit longer. CB states they're .250" longer than stock T1. T1 is 112mm, which is 4.409". T4 is 117mm, which is is 4.606". The Race Master should be 4.659" long. The actual difference between the Race Master and stock T4 is .053". I was a little off.

[bugguy1967]

Ray, about your B. statement: Wouldn't flow numbers tell you everything if they were plotted at each .050" or .100" increment? I understand that a max flow number wouldn't tell enough, but the way CB lists their numbers are at .100" increments for the intakes and exhausts.

[modok]

famous joke, which, strangely enough, seems to demonstrate the importance of the .75% banana ratio perfectly.

A guy walks into a bar with his pet monkey. He orders a drink, and while he's drinking, the monkey jumps all over the place, eating everything behind the bar. Then the monkey jumps on to the pool table and swallows a billiard ball.

The bartender screams at the guy, "Your monkey just ate the cue ball off my pool table -- whole!"

"Sorry," replied the guy. "He eats everything in sight, the little bastard. I'll pay for everything."

The man finishes his drink, pays and leaves.

Two weeks later, he's in the bar with his pet monkey, again. He orders a drink, and the monkey starts running around the bar. The monkey finds a maraschino cherry on the bar. He grabs it, sticks it up his ass, pulls it out and eats it.

The bartender is disgusted. "Did you see what your monkey did now?" he asks.

"Yeah," replies the guy. "He still eats everything in sight, but ever since he swallowed that cue ball, he measures stuff first."

[modok]

Sorry about that. Last week I was eating a banana, talking on speeedtalk.....the dots connected, now every time flow ratio comes up I think of that joke now, so NOW YOU can suffer with me.

[raygreenwood]

[Brian_e]

https://aapistons.com/collections/bare-casting/pro...round-port

Brian

[raygreenwood]

[bugguy1967]

I've held them in my hand. I have a bunch of pics in my phone. I'ma upload them.

That monkey joke is too funny btw!

[bugguy1967]

These are the castings. Jorge from European installed the seats and guides.

[raygreenwood]

Very nice!......not that its any problem at all.....but pretty sure those are welded snd CNC finished from the mill work done above the center stud between the ports and the port work on either side of the spark plug boss.

Also it has the same minor clean up required in the exhaust ports as the 1.8 castings.

Nice all the same!

One detail with reference ro your earlier question about flow numbers and this does eelate somewhat to Len Hoffmans numbers......because there is no it can't relate.

While in some ways the type 4 head....basic.....was improved over the basic type 1 dual port head (more fins, more material in the rocker box floors, better combustion chamber shapes for the factory applications at hand).......it has disadvantages as well.

The main failing of type 4 heads......all of them.....is NOT that you cannot do enough port work and valve work to get high flow numbers.......the problem is that you cannot EXHAUST IT.
The primary limiting factor of the type 4 heads.....is the way the exhaust port is laid out...and the way the exhaust header mounts.

Even if money is no object on your exhaust system....what you can do is limited by those two exhaust studs. If you make your own exhaust stubs.....you can port a little.....but the "meat" is not there....even in the new AMC castings to relocate those exhaust studs.....and....you still have to deal with the push rod tubes.

I saw long ago....albeit on a 1.7L head.....the result of working like mad to get killer flow numbers.....and we did.....about 30% better than stock with a 42mm intake valve....only to have it barely run at all. Putting the head on the bench and flowing the exhaust valve and port showed that there was no way to exhaust that intake flow increase.

You cannot do but a very small amount of port work in any of the round port type 4 heads without breaking through.

This is why almost all exotic type 4 high hp engines use carefully planned cams.....with overlap to increase exhaust velocity.....and excellent header systems like A1 made.....tuned for where you need to run.

Intake airflow is important.....but is not the sole decider of power output by any means. If you end up with killer flow numbers.....and you cannot exhaust it, or if it creates poor velocity through part of its intake range.....and actually reduces fuel atomization (common).....you can actually put out LESS hp.....or have great HP and tq numbers with worthless throttle response.

As both Raby and Hoffman have both said many times......its about the total "combo".....and not one item. Ultimate output is certainly not entirely dependent upon maximum intake flow numbers.....unless this is 10,000 hp top fuel with a roots blower on top .

Ray

[modok]

Right, just like the monkey and the cue ball.

No AMC logo? probably not an AMC casting.
I mean, they could have ground it off ect....

[bugguy1967]

There's this workaround that European does. You think it'll improve exhaust flow?

[raygreenwood]

[[email protected]]

ARAO engineering used to weld the exhaust ports up on the bottom, and the fins on the ends, and then make a Type 1 exhaust port onto the Type 4 head, to solve the exhaust port problem.

This was in the mid 80s.
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[raygreenwood]