The 230 Headerfold project

[Jason Mills]

I just so happen to be taking a spare head to the machinist tomorrow if all works out well.. and I am thinking of milling .100 off the chambers.. I just measured it all out tonight, and there is .145 of room at the tightest --valve at full lift --to pocket clearance..(assuming the head gasket compresses to .050, gotta check on that)

Hopeful that there will be a compression boost with that much of a shave. I'll let you know what happens.. Stock was about 120PSI, with the first stroke producing 60 PSI with the B&B's throttle wide open.. With the B&B removed, the first stroke was 80 PSI.. So now I am trying to build a twin set up.. (I think) one carb is easier to play with.. But I have two B&B's to play with, so I might as well use them...

does anyone know what the copper head gaskets compress to?.. my used one gives me a reading of .065.. but i immagine that it will squish down a bit more than that when it is on the engine..

[chriscase]

I'm not sure whether either style of intake would be better. I'll find out next time it runs on the dyno, as compared to my 25 year old memory. I remember that my CC got 64 hp, with the collector style 'hi rise' intake, and long tube exhaust headers and duals , vs this one with tri-wye exhaust and a single 2 1/2" flowmaster.

Anybody got a spare late model head lying around? Higher compression might make a big improvement.

[Jason Mills]

[QUOTE=chriscase;60893]

My previous headerfold escapade was on a 1/2t command car, with plenty of head room to turn the runners upwaqrds into an exhaust header type collector. I believe there was some ramming of incoming air directly into all of the runners, and less of the suction form one runner pulling charge out of the other runners. If I don't see the gains from thei adaprtive system, I'll have to try and kink some more spagetti into a collector, rather than the 'plenum' that is really a four way tee.

QUOTE]

Nice work Chirs.

Inspiring to the point of wanting to give it a try myself.. Do you think there are advantages of the "plenum" style at lower RPM's... VS. the collector type higher up? or does it not work like that? My thinking was to try a dual 1BBL, like the cast alumnum ones that some people run.. But I am intrigued with the idea of a collector type, sort of a tunnel ram set up..

[chriscase]

I don't think "Middle rich" is a problem with my intake, since I looped the runner to make it nearly equal length as the ends.

Likewise I figure that the larger carb will eliminate that, since more inrushing air will charge all runners, whereas the restrictive carb made each cylinder suck charge out of the other runners.

[maineSS]

I think the 251 came in about 1961. I thought it interesting that the last 230 version developed 5 more Hp with about 21 fewer cu inches (120 vs 115). The 230 Tq was 201 lb/ft @ 1600, couldn't find a Tq listing for the early 251. Have you thought about making the middle intake manifold passage smaller in dia to avoid the "middle rich. ends lean" syndrome of carbureted inline engines? With a box plenum, you could modify the entrance of the center tube to take orfice plates of various dia, and keep going smaller until plug color looks similar on all cylinders. An infrared temp gun aimed at the exhaust header/head junction is a quick way to tell rich/lean cyl with the engine running.

[chriscase]

I think you are mixing metaphors here? The 251 is a different engine than the 230. I believe it was the 230 that got the higher compression, tighter valve pocket design in the late 50's. The 251 was not used in FFPWs until 60?

There were many different versions of the B&B, so maybe there were different venturi sizes? Were 251's square tops? Vacuum accelerator pumps?

[maineSS]

Better carburetion and exhaust is supposed to "really wake these engines up". However, in in the last two years of production, Hp went to 120- 5 Hp more than the early 251's. Since the intake/exhaust manifold stayed the same, something else had to change. I think the carb venturii size didn't change, but I could be wrong- maybe Clint could enlighten us on the late '58-1960 B&B venturii sizing. The compression went up 1/2 point to 8:1, and the valve pockets in the head were tightened up. There was a cam spec change in the mid 50's, but I doubt that had much to do with the increase. Tom Langdon at stovebolt 6 has a single 2 Bbl carb setup which will add about 10 Hp to the 230, so it'll be interesting to see where your dyno figures hit.

[chriscase]

I don't know whether I posted upthread about the possibility of using a billet aluminum plenum, with the tubes pressed in. Making a separate top would allow for different carbs, as well as machining the inside to smooth curves using a ball end mill. Starting with a largish billet, to allow water passages to be drilled. Doable, but I think I would also want to build new headers with largest radii to give a little extra room for the plenum.

ETA: And/or angling the center ex tubes outward, to give more space for the plenum....

Many options rise to the surface as problems are met...

[maineSS]

How about fabbing a small box at the junction of the 3 intake tubes large enough to accept the 2 1 1/2" dia pipes from the carb?

[chriscase]

I think the truck cam is the limitation at this point. There is just not much you can do with no duration, no overlap.

The filter housing is off of the same van 318 as the carb.

My adapter goes from the two 1 1/2 tubes to the one 1 3/4 that is the 'plenum'. The choke point is the two 1 1/8 venturis, as opposed to the old 1bbl, with 1 1/4". I can't make two 1 1/2 pipes fit into a 1 3/4 plenum, can you?

Flat/short adapter plates don't work in many apps. Too obstructive, even if they are just a flat plate over a large plenum. Entering a box like that can also be restrictive to air flow. I've learned some air dymnamics from autos, and some more from dust collection systems.

My previous headerfold escapade was on a 1/2t command car, with plenty of head room to turn the runners upwaqrds into an exhaust header type collector. I believe there was some ramming of incoming air directly into all of the runners, and less of the suction form one runner pulling charge out of the other runners. If I don't see the gains from thei adaprtive system, I'll have to try and kink some more spagetti into a collector, rather than the 'plenum' that is really a four way tee.

Anyway, when revved to full speed, in 3rd gear, the 2bbl barely makes manifold vacuum. Ought to be a big improvement over the restrictive 1bbl.

Oh, I had some idling probs that went away when I changed from the new slant 6 PCV valve to the junk yard 318 valve. Perhaps they have to match carb more than displacement?

[maineSS]

Chris- Nice aircleaner- always go with as large a dia and as tall that will fit. What did it originally come from? I've never been a fan of 2 into 1 carb adapters- they tend to cause a lot of fuel dropout, especially the short cast affairs. How about running 1 tube for each barrel straight down into your manifold plenum to get the height you need? You'd have to rework the top, but I'll bet the restriction reduction might be worth it. Siamesed intake ports tend to cancel out individual port pressure waves, so the traditional intake wave tuning is less effective- restriction reduction is the biggest bang for the buck. Hopefully your dyno gains will be impressive. The last version of the 230 supposedly got 120 hp with 8:1 compression and the 1959 head with better valve pocket shape.

[monkeymissile]

Re the horn, it is stock. But a short one was too. I like the low, classic sound. And it seems plenty vocal. Maybe because it is a 6v tuned to run on 12v?

would love to hear it, the stock horn on my M43 is loud, but too tinny for my tastes

[chriscase]

I'll try to get this iteration to the dyno next week. But I have recalled a possible major variation that I used back in '82, in case the dyno does not show my expected gain. It will necessitate a whole new intake that takes advantage of the lower profile of the 2bbl. We'll see.

Re the horn, it is stock. But a short one was too. I like the low, classic sound. And it seems plenty vocal. Maybe because it is a 6v tuned to run on 12v?

[monkeymissile]

Chris,
impressive engineering indeed! The color shift on your header paint is impressive, thought it would flake off rather than just turn black.
Is that the stock horn for a PW you have there? I plan to replace mine with an airhorn from a 50's era Mack truck, just in case people don't notice me on the road!

[chriscase]

Boy, did I overthink that one!

On the last 'heqaderfold' I made, back in '82, I simply welded an arm on the right end of the throttle shaft. LOooots less Rupe Goldberg engineering needed on that option.