1000cfm of carb on a mild 302?

DarkoStoj · Aug 20, 2005

I just bought another mustang and It has a rebuilt motor in it. I got it from some kid who didn't know much about this stuff and he built the motor with Eagle rods, 9:1 TRW forged flat tops, New GT40 heads, and a edelbrock intake that has dual 500 cfm carbs. Out of all the reciepts I can't find the cam specs for the life of me

I'm guessing this is WAYYYYY too much carb for the motor, but is there anyway I can make it work? I'm leaning towards buying a weiand stealth intake and putting on the 150hp shot of nitrous I have sitting on my shelf with a holley 750 vac secondary carb (3310)

Pics are soon to come. Dual carbs look coool

2nd Mustang · Aug 20, 2005

They have that cool look. Probably run on the back four barrel most of the time.

bnickel · Aug 20, 2005

they are a vacuum secondary carb so the secondaries will open only when there is sufficient vacuum drop across the venturies. they will run on the primaries on both carbs, if it has a sufficent cam it shouldn't be too much carb for the motor, however a single four barrel is more efficient. but there is no denying the look of dual carbs.

ddonaca351 · Aug 20, 2005

A single would probably make more power, but you would loose the visual affect of the duals. You might be able to trade someone strait accross for a decent single set-up and not be out any cash...

DD

10secgoal · Aug 21, 2005

Keep the intake, convert it to 2 x 2, and runs 390's.

DarkoStoj · Aug 21, 2005

I just got done putting the headers on (PO had new stock exaust manifolds?) and I was just drooling over these things

So would I really be losing performance with the dual carb setup over the single carb? How would this intake compare to other intakes? Is it more for low end torque or high rpm or what?

I wanna keep it

rbohm · Aug 21, 2005

this settup has the progressive throttle linkage, thus it runs on the rear carb primaries untill you really start opening the throttles, then the front primaries open, then the secondaries together. you dont really lose power so much as throttle response, mostly because people use too much throttle opening at the wrong engine speed and load. that said, dual quads are more for show than go these days, and a good single 4bbl intake with a properly sized carb is hard to beat. if you like the look i say keep it, just be careful when you run hard that you dont use too much throttle opening untill the engine is ready for it. these carbs do have air valves that wont open untill the engine is ready, but you still have what is essentially a double pumper carb, even though the second set of primaries doesnt open untill the throttle is pushed past a certain point.

D.Hearne · Aug 21, 2005

Yea, dual fours look impressive, but on a small block, my three two's will run rings around it.

race-rodz · Aug 21, 2005

looks great... but when it comes to drivability and performance...a single 4bbl is really hard to beat.

i had a similar set up, flat top, gt-40 heads, comp 270 cam, with a single very well tuned 600 holley, a T5 and 3.50 gears i could cruise @ 75, getting 20+mpg. on one trip i guess the planets were aligned and everything was perfect.... i knocked down 23.4 mpg. around town mileage was about 14-15

pm sent if your interested in the single 4 intake off that motor.

JB66 · Aug 21, 2005

Put limiters on the secondaries so they don't open more than 1/4 (about 20 degrees)

coolblue65 · Aug 21, 2005

2bav8 ran dual quads for a long time, and if I remember correctly he really enjoyed them even though he did end up going with single 4bbl later on.

does look nice, i would keep it for awhile and see how you like driving it.

DarkoStoj · Aug 21, 2005

quick question about the vacuum.

Should I be running the timed vacuum port or the regular vacuum port for the vacum advance, and should I have both carbs go to a tee then go to the dist instead of just plugging one?

Also same question with the PCV. Should I just run both of them to a tee then to the PCV? Could I just plug one or both of them? Never really knew what the purpouse of the PCV was anyway

race-rodz · Aug 21, 2005

ported vacuum, just one is fine, pcv just one if fine also... pcv is there to keep negative pressure inside the engine(vacuum)... positive pressure could among other things cause oil to seep past seals.... thats just the short and simple version.

zookeeper · Aug 21, 2005

That is one great-looking motor! I for one love the looks of two-fours and will be installing them on my motor soon. A friend loaned (wouldn't sell, but loaned as long as I keep the car) me a nearly new, original Shelby two-fours intake. To try to make it as driveable as possible, I'll use two 390cfm, four bbl Holley carbs and progressive linkage. I wouldn't take the words of the single-four barrel only crowd too seriously. After all, if driveablity is your only concern, why not buy a Toyota? We build and drive early Mustangs and the like because we like the way they look, right? Since nothing looks as cool as mulitple carbs, I say keep it, if for no other reason than to baffle those who have trouble with one carb, let alone two!

zookeeper · Aug 21, 2005

D.Hearne said:
Yea, dual fours look impressive, but on a small block, my three two's will run rings around it.

Ever hear the old saying, "when the green flag drops, the bullsh1t stops"? Three dueces went out in the fifties, Fonzie...

Max Power · Aug 21, 2005

Looks Purdy!

Unfortunately, way too much. Stroke the motor and put smaller holleys and you would be getting closer, but even a single 750 is a LOT of carb for a 302.

DarkoStoj · Aug 21, 2005

Max Power said:
Looks Purdy!

Unfortunately, way too much. Stroke the motor and put smaller holleys and you would be getting closer, but even a single 750 is a LOT of carb for a 302.

From what I understand the carb acts like a 500cfm double pumper(primaries from both carbs) until the vacuum from the motor opens up the secondaries.

WELL..........

so sorry to say, but I was getting the motor together and realized the stupid bastard put on GT-40P heads instead of the normal GT40's like I thought he did. So instead of going out and buying new headers I'm pulling the heads off and replacing them with some world windsor sr heads I have.

Now while I was pulling the motor apart between the carb and carb gaskets he had these metal tabs that basically would have gave me the worst vacuum leak.... have absolutely no idea why they were even there. He also forgot to put in the plugs for the brake boosters in the back of the carbs

When I went to remove the intake manifold 1/2 of the bolts were loose

SOOOOOOOOOoo since the kid was 18 when he put this thing together I pulled out the hoist and the motor is coming out tonight so I can go through and double check everything(I think the main reason was that not knowing what the stupid cam was, is going to drive me bezerk )

It just sucks that he bought forged TRW pistons that are only 8.78:1 with a 63cc head........oh but he did buy $130 rings. I figure that if I take my heads(milled them to 62 already) I could get the compression to just under 9:1 (blah)

It looks like this stupid motor was more of a headache then I thought it would be. Lets hope he had the head decked to bump up the compression some more

cross your fingers!

10secgoal · Aug 21, 2005

You could keep the heads, and try this...???
http://insaneindustry.com/showthread.php?t=4861

DarkoStoj · Aug 21, 2005

too late, motor is pulled and the heads are off.

It seems like the head was decked so the piston was flush with the block.

SO glad I pulled this thing, The upper bellhousing bolts were finger tight, there was a missing plug for the crankcase on the pass side of the block, mis matching motor mount bolts..........complete mess

rbohm · Aug 22, 2005

would you be willing to sell the gt-40p's? and if so how much? pm me.

1000cfm of carb on a mild 302?

DarkoStoj

2nd Mustang

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