So i just got an original 4x2 intake...i want to make it streetable...i have a 48 flathead thats bored .030...what cam & carb jets do you think would be good...im running the new Stromberg 97s
First thing you need is .042 mains in all four with #69 powervalves on the ends & #67's in the two centers. Straight linkage.
OK, so tell us a little more about what you want the motor to do, and what kind of heads you are thinking about running, pistons, are you going to have headers..................my guess would be L-100, Isky 400jr, or even a Schneider 270F-1. The one thing nice about the Schneider is that you can bet a brand new cam and the base circle is not cut down like most other cams.................means you can run stock length valves without going to .050 or .100 greater length. IMHO
Which 4x2 intake do you have? Does it have a common plenum or does each carb barrel feed only one cylinder? For a mild engine, hard to beat the Isky Max-1 - what car is it in?
Alright the intake has the common plenum. The engine I have now was a completely stock rebuild its just bored .030 over. Its the stock crank and connecting rods...stock style pistons...the engine was run on a test stand but nothing after that...As far as the motor its either getting edelbrock block letter heads or Harrell heads I havent decided as of yet. I also have a Harman Collind Dual coil dist. that is going on it...I just want it to be a driver...its going in a 36 3-window that im planning on driving cross country from PA to Bonneville
L-100 cam. That intake has alot of carburators for that motor. Progressive linkage I am guessing. I have a motor very similar to your with two 97's, L-100 cam, headers; runs good. Do a search on the cam and you will find out more info on it. Neal
When I was running a 4x2 Edlebrock intake, the 97's were to much, so I ran 4 81's jetted to the smallest jets I could find ( back in the 70's that was easy) & it ran great pulling 3:08 gears at 18 mpg.You can't run progressive, so it's all 4 or nothing.Your problem now is finding 4 81's without getting a bank loan.
If your intake had individual runners to each port, I'd say go for it. Otherwise, I think you're probably not going to like trying to drive it. Has been covered several times - here's one good one: http://www.jalopyjournal.com/forum/showthread.php?t=164109 Do a search for "flathead 4x2" and there's lots of discussions...
Iv never understood how 600 cfm is to much. I would think (manifold allowing) running progressive would keep the velocity up. Wouldnt the big vacuum drop of them all opening at once be more of a problem than total cfm? yes no?
Most of the 4 carb manifolds put the carb directly over ports, which means the air has to take a detour to half the motor when it is at low rpm
i realize that its a lot of carb. but im still planning on running it. If im going to do it i want to do it right no matter what it costs. If i have to remachine the block Ill do it to get more cubes...Im just looking for the best advice from people running them on street engines
Could you run the common plemum intake with the two outer carbs blocked off but there for show? Just running the two inside carbs? I wonder if you could do a setup where it looks just like all four are running but really only have a two carb setup? If this would work it might be a whole lot less expensive than everything needed to make the car run on 4 carbs.
What brand is this manifold?? 600CFM on an open plenum is way different than the same on a 180 and very different again from a normal 4X2 semi-independent runner. Stop and think. Cam is nearly irrelevant here. If manifold is something weird, you can sell it to a collector and get a normal 4X2...
Your question was about which cam to use. With 4 carbs you are going to need alot of vacume from the engine. No matter which intake is used. Try and get a cam with little duration and a higher lift than stock. The more duration means less time between the intake and exhaust valves open;thus less vacume into the manifold. This means poor performace at lower rpm. Usually street use is around 2800 rpms. I suggest somthing like a WINDFIELD SU4. It will plant you in the seat up to 5000 rpms. What Im trying to say is don't over cam, especially for street use. Another thing to keep in mind is: part of the cooling success with flatheads come from the volume of air passing thru the engine. BLUARDUN
Isky 433 - but I would not call it street-able Yes, it get's the plugs a little black; but it runs strong! We tried to run (4) 48's on alcohol - but the cam has way too much duration to pull in enough volume; we would really have to switch to injection to run methanol. Also, the big lift on the cam, along with larger valves required us to take a lot of material out of the heads - so it does run hot.
Literio L 100. Have one in my '28 8BA AV8 with 2 97's. Pulls lots of vacume and sounds good. Cam Dynamics in Florida will regrind your old cam
It's a Vertex (small bock chevy) that we shortened and reversed the direction; runs directly off the front of the cam - works awesome!
here is where im at...im using this intake...I was just looking for some cam advice and seeing what other people have run when using 4x2s on the street...I have decided to just strip the block down and start from the bottom up...stroker crankshaft, big bore and just build the shit out of it...i found a flathead camgrinder that has done a ton of 4x2 set ups on the street and has guided me in picking engine internals...so i got the problem solved here is pictures of the intake...
yeah youre right it is dual-plane...i guess i just didnt pay any attention...basically it came in the mail and went straight to the garage...but yeah it is dual plane
well we were talking different bore sizes and crank combos...still not fully decided on that...but he can do a custom grind to give me good power range with the intake...said with the right grind should run just like any other flathead probably better
Dual plane 2x4 won't work well on the street, IMO. Not that I've ever run one, but each cylinder still sees too many barrels. The only way I'd attempt a 2x4 on the street (and I intend to do so) is with an individual runner intake.
That Edelbrock is the normal one, and perfectly usable for this. It has small connecting passages on a 180 type basis, but looks like flow would be much like an IR and reposrts seem to indicate that it does work that way. Note that with IR type flow, an engine needs FAR more CFM of total carb than with a 360 or 180, since each valve sees only one throat. Flatdog's experiments seem to bear this out. I have a dyno article showing a low-RPM truck 350 running happily with 1500 CFM of carbs. Read the old HAMB discussions on this. And pay attention to Pete...he never says very much, but probably has more miles on 4 carb flatheads than the rest of us have on the grocery getter.
Guys: This may be treading on unchartered waters for some, but there are many 4X2's running happily on the street. One car of note is Vern's '34 Coupe from the Choppers. It may take some thought but can certain be made to happen.
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