I spoke to an interesting fellow on the weekend who is experimenting with 235chevy heads. he has done some neat things with a 3-d cnc mill as far as porting is concerned. What was really interesting is he showed me some literature about a 235 that the intake runners were filled and above the intake valves was milled and threaded for a pipe to go directly into the bowl area. Doing this would enable 3 carbs to be run without the 90 turns. I was thinking it could be adapted to any inline, I was wondering if anyone has tried it and what kind of results they got. Cheaper than a crossflow head and my thoughts are its more efficient seeing as the AF mixture drops straight into the cylinder.
That would be great on a 235. I have a very similar set-up for a Ford 200-250 six. Its an Aussie 2V head (12 port, but not crossflow) with a Linx intake for 3 Webers, each port gets a straight shot of fuel/air. Later, Kinky6
What the guy showed me would need a custom valve cover made because he milled it right above and beside the valves and insert a piece of pipe with the carb pad welded to it. I would really like to see if it works
Don't know why it wouldn't work. It is going to be a balancers nightmare. Not worse than any other multi carb set up with separate plenums but still a balancers nightmare.
He doesn't happen to have a 1954 Car Craft lying on his bench, does he? They ran a two part article on Chevy/GMC sixes in late '54, and I remember seeing a picture of a Chevy with the modification you described.
Isn't that basically what the Rajo head did? http://www.museumofamericanspeed.com/Collections/Engines/600pix/IMG6654.JPG
That head was for sale on e bay some months ago advertised as a 1950's home made racing head and was discussed on Inliners where the general consensus was that the guy was way ahead of his time. Out of curiosity I drilled/threadmilled an inlet thru the top of a sectioned pc. to see what I would end up with. Maybe some type of injectors could be placed there to spray down at the valves and still bring in the air from the side? More research is definetly required and here's a few pic's:
HEY! Curt I believe you are the guy I am talking about! I was thinking Enderle injection could be used in this application. If you put an injector here and brought air in from the side my worry would be causing turbulent air flow slowing the AF mixture.
quiet and interesting design. Would be worth to look into. Maybe a new 235 chevy head after what 50 years?
Maybe not a new head design but an interesting speed mod that could easily be done. A person would have to be one heck of a knowledgable welder to weld the original intake ports shut then machine theM back from the top with a smooth transition into the bowl area.
If someone decides to build one of these into a runner, I'd be careful posting pictures of your progress. Seems as though we have a few floating around here that are looking for something to copy, and get rich off your hard work. Just a friendly warning.
Yep, what ooltewahspeedshop said; They'll even bait you by sayin' if you don't post pictures the validity of your post is suspect!
That's too bad that there are guys like that. I just want to learn something here and have a nice open discussion and share information with others having the same interests who could perhaps offer suggestions or improvements to the projects. This project is more of a homegrown idea that could be done by any machinist. I think that if somebody did design a head like this they are putting more work to form the casting. Essentially they are taking the basic idea I am talking about and taking it to a new level
Does anyone have access to an engine dyno? I'd be extremely interested to see the differences between a stock motor with a single carb, an intake with 3 carbs, and then this modified head with 3 carbs.
Just a little info. This has been done before with out much if any real gains. A few guys tried this years ago for roundy round racing but did not see any real improvement. The best gains come from a redesigned chamber. Some thing that did show positive results was to move the head so the chamber was more over the cylinder. This allowed for a larger "lump" on the piston, hence more compression. While your at it, take a look at the intake valve angle, and how a head is milled. How good is welding. Just a few things to test your gray matter.
I would like to do some research, but do not have the resources to find a modern piston with the same pin to piston top measurement and better rods, does anyone have this sort of information? Milling the chamber and increasing valve size and angles would be a huge benefit.
There are those that might think you are plowing old ground. Personally, I've reconciled that the later design of L6, Chivvy 250/292, with the 'already done' upgrades that I can simply copy are my choice. That said, experimenting with the 235 could be rewarding. You will need to invest a bit to proceed. I would suggest that you enlist two different specialties; Machining and welding. No need to share with either what your plan is. Point out to the machine guy where you want the pipe threads cut. Point out to the other guy where you want the welding done. Do the routing yourself with a carbide die-grinder. A good supply of heads, two or three, maybe more?, with plans (in advance) to recycle the first one to scrap when you hit water will be in order. But, of course, then, you'll know where the water jacket boundaries are after that!! Eh?
It appears to me that moving the chamber over is not possible as the intake valve will overlap the deck (see pic) unless I'm missing something. As for chamber work I have learned facing .075" is enough to completly remove the quench trench and leave the intake valve sticking up about 1/32" and that changes to the "waterfall" and tight corners may be beneficial. On the exhaust side I have tried removing the bulge both manually with a piloted tool as well as with a lollipop cutter on the CNC mill but don't have results of that yet. Are there any other proven alterations I am missing? P.S. Thanks Kevin and Mr Nash for the heads up.
That straight port theory was done several decades ago by some Chrysler engineers on a slant six. I don't remember how it ran, but it didn't survive the onslaught of our crossflow 300 Fords.
I have heard about this, I havent been able to find anything on it though. Anyone have a link or info?
Reread what I said in the second paragraph, then put them together, it will come to you. Yes, it will work because it has. You gust have to figure out how they go together.
Crazy idea , I love this Straight 8 buick are bad on the intake side . Maybe this should help .. Suscribed ..
playin devils advocate here...would it not be easier to design a cross flow head? I mean if you inject in the top and come out the side with your gasses there would be a 90 degree angle right? I am a noob to this so bear with me, I am facinated by the conversation...
Down porting [ as we call it down under ] was done on early pre-crossflow 1500cc Cortina "kent" engines. Known as a poor mans Cosworth, it was also used to circumvent the rules about stock camshaft location [ in Racing 105E Anglia's ] A huge amount of labour was required, and the ports were bored and brazed [ through the water jacket ] Was it worth it? You bet. In a bored out 1500cc Anglia [ 85mm bore 120E Block ] with a 1600cc X-flow crank = 1830cc These engines would pull about 180hp @ 9000 rpm [ that's a BMEP of about 140 @ 9000 ] which is pretty good. Nowadays you would just buy a Zetec Conversion if the rules allowed them On a chevy 235 you would need a good bottom end to justify down porting.
. Lotta things here on this post ive thought doing to a buick head . I had read about drilling a new port, and it seems to be reasonable. Having a flow thru head is good but the Buick exhaust ports arent that bad, its the corkscrew maze of 90 degree intake manifold tunnels and crowded ports that are bad. Just getting a straight shot into the port is good enough and they wouldnt need to be very big for flow. I was thinking long the lines of filling the existng port, by plugging, and then boring down at an angle into the siamesed port area, they used to do this baknthday. The rajo chevy 235 head was similar of this type of porting. ♠ http://www.museumofamericanspeed.com/Collections/Engines/RajoE033.shtml On a chevy 235 you would need a good bottom end to justify down porting.[/QUOTE]♠♠ the 235 bottom end isnt that bad, as long as it has full flow oiling, and an after market harmonic balancer
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