The 230 Headerfold project

[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]

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 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]

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 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.

[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'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]

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]

First stroke is meaningless. It will depend on the pistons location- all the way down= your 80 psi. All the way up would = zero. And that variation means that it takes several strokes to get it all evened out. So ignore all readings except the final, after it has had plenty of cranks to max out. No preconceived number, just crank until the gauge stops rising. And don't get me started on wet tests, or I'll tell you what I think of them. And mechanics who charge money to do them.

I think a rule of thumb was every .005 = 1/10? so .100 could raise it from 6.7 to 8.7?

120 seems high, but that depends on your gauge. I seem to recall that my CC had 95 on a good Snap-On gauge.

What is the casting # on your head? Seven digits, plus maybe a -x. They did use 6-8 different castings, with some of the 218 heads having the smallest chambers. Apparently the latest heads had small temp sender holes for the electric gauge.

[maineSS]

Jason- If you're going to run dual carbs, make sure they are have identical internals (jet size/acc pumps, etc), or you'll have a tuning nightmare. The 1 Bbl B&B was used on a wide variety of cars & trucks, so it helps to know what your carb's history is. You have to be careful building compression (heat) in these engines because the cooling system isn't as efficient as modern designs. The system is not pressurized, it has an upflow radiator, and the 2-vane water pump impeller looks very prone to cavitation. A tractor-pull contestant in Tennessee noticed after a pull lasting 20-50 sec that every metal surface including the oil pan of the 230 was "blistering, spit frying hot", yet the coolant temp hardly changed- sounds like poor circulation to me. Chris- I was wondering why you looped the center tube down- you may have fuel droput at the bottom, as fuel will tend to separate from the air stream on the outside of a bend. It would be interesting to weld in a bung for a drain plug and see. The fuel/air stream in a flathead has a long and winding road compared to an OHV engine, so the key is to keep flow velocity up and manifold lengths short (triple sidedraft carbs would be best). Your comment about the PCV valve got me thinking about a device sold in the 80's called a "Condensator"- basically a separator in the PCV line that allowed oil mist, water vapor, and exhaust blowby to condense in a removable jar that could be removed and drained. In theory, crankcase fumes are supposed to be burned in the engine, but things like oil mist promote detonation, so a separator is likely better. Maybe the crankcase fumes in your situation were upsetting your fuel/air burning? I managed to locate one of the 1959 230 heads with the better valve pockets and 8:1 compression- should have it in sometime this week. Going on vacation to Seattle Fri for a week- hopefully I can post pics before then.

[chriscase]

I tried to lengthen my center runner to that of the end runners. The loop downward is right between two exhaust runners, so ought to be hot enough to prevent droplets settling out. No heat riser, but all those header pipes ought to give off lots of heat to radiate towards the thin intake runners. I hope. It seldom gets cold enough to ice up carbs here in San Diego.

So far as condensation in the PCV system goes, an engine in good condition hardly makes any blowby. And most would be made under full throttle, when the blowby goes through the vent pipe to the aircleaner, where condensation will fall out into the air cleaner. So no condensationerator required.

I checked my compression this morning, about 117. That's about 7.8:1. So maybe my head has been milled already? Jason has 120, makes me think his has been milled too. Beware that the latest heads had the smaller temp sender port, and may need to be drilled and tapped bigger.

Anybody know how think an OE head is? Check with your machinists?

One problem with milling heads is that it cuts down on the size of the transfer port, between the valves and the cylinder. It's another built in restriction of flatheads. Perhaps, since you can mill .100 of the head in general, some die grinder work to open up that transfer area would be advantageous? Just in the 'roof' of that ramp area where the edge of the cylinder would be? I know that the highest compression heads had a port only an inch wide, and 1/4" deep. Darn archaic engine designs...

Can you CC your heads? Directions ought to be on the net somewhere.

(ETA: Here is a link <http://www.jrbranson.com/HondaRacer/honda/How-to-CC-a-head.htm>
end edit.

I think all it takes is a piece of Plexiglas big enough for one chamber, with two holes in it. Grease it to the head and fill with a syringe . The second hole allows air out. The range of dodge heads is 65 to 85 cc, erso. I calculate that mine at 7.8 would be about 80cc, but I have not had it off. I've got lots of time to find my horse syringe...

[maineSS]

Carburetor icing is more a function of humidity than temp- lots of early pilots bought the farm at air temps of 40-50 deg and high humidity (clouds) before carburetor heaters became common equipment. Same thing happens on the ground, which is why OEM's went with manifold stoves for air cleaners. Before grinding on any flathead casting, it would really help to have it sonic checked- core shift was a common thing, and can really ruin your plans. A small transfer slot is not necessarily a bad thing- look at the of the Hudson car and Indian motorcycle flatheads- they were the best performers. From what I've heard, shrouding the backside of the valve, making the underside of the valve head as flat as possible, while biasing intake port flow towards the cylinder side of the valve helps quite a bit. The Hudson valves were smaller, closer and canted towards the cylinder. The Dodge has much more distance to cover, along with a wider slot that lets the mixture spread out and lose velocity, along with bigger valves. Don't know if a lot can be done about that.

[Jason Mills]

Chris, how does one figure out the compression ratio from a PSI reading?


I got the head back from the machinist thursday, and got to play with it this afternoon. Some work with a die grinder is necessary to give the valves plenty of room, after taking .100" off the head.. But was rewarded with a 16 PSI bump in compression.. so it is up to about 136PSI.. a little short of what i was hoping for (150) but I think the headers and intake manifold actually may offer more potential anyway..



Both my heads were milled previously and had valve relief's in the .420-.435 inch range.. course the valve relief is not flat, so the farther in you measure, the deeper it gets. both heads had been milled, and were about at the same place. I believe that is about as far as you want to mill the head, unless you are willing to run a die grinder.. As the valves (on this engine) sit up about .070", and the valve lift on this cam is .374.. so that is .440 above the deck at full valve lift. Thus it is only the head gasket that is preventing interface between the valves and the head chamber.. After taking .100" off, (I had a low reading of head chamber depth of .321,) clearance is now back to about .400

[chriscase]

Taking your 136 and dividing by the 14.7 ambient air pressure gives us 9.25 static compression ratio.

That's a good modern CR. You may need to lessen the centrifugal advance to prevent pinging/detonation. On the stock distributor this is done by bending the spring tangs under the breaker plate outward- more tension = less advance. Or take the dist and your 136 reading to a good tune up shop that has a distributor machine and knows what to do with it. Net result ought to be an initial of 5-10 btdc with easy starting and no pinging ever. But some pinging if initial bumped up two more degrees, so bump it back down. It's an art.

[chriscase]

Jason, how about a head 'floor' thickness guesstimate?

There is a small plug in the middle of the head. It's basically a 3/8" bolt with a sealing washer on it. You could measure the overall thickness of a head, and then using the depth gauge on a dial caliper, the depth of that hole. The difference will be how thick the head is in that location.

That hole also acts as an air bleed when refilling the cooling system.