carb size

[lskarritt]

347 stoker. ford x heads gt40 allum, ford x cam .224 .224 @.050{roller}
rpm air gap intake. msd ing, 9.5 to 1 comp, c4 trans, tci 1000 over stock stall converter. 355 auburn possi 8' rear end on my 66 coupe.{street car}
Now running a 650 speed demon vac, sec. In cold weather 40 deg, it seams to bog out of the hole untill rpms reach 2500 rpm.
hot days 80 to 90 its fine
Should i have gone to a 750 or switch brands?holly.

[gofastmercury]

I think the carb you have is fine. sounds like the accel pumps need to tuned. Get a holly kit for that and start playing. It takes a bit of work, but its worth it.

[Ron1]

I run an 825 CFM Race Demon on my 347, but selected that size based on the engine Dyno results. Refresh my memory, does the Speed Demon come with jet extensions and what size shooters are in there? For your after market components the size seems about right.

Ron

[lskarritt]

I have no idea, stock 650 speed demon carb. vacuum secondaries. I did have an over richness on the idle circuit, demon fixed that. I was wondering that on a cold day the mixture is not rich enough, yet on a hot day the air is thinner making a better mixture?

[gofastmercury]

Originally posted by lskarritt
I have no idea, stock 650 speed demon carb. vacuum secondaries. I did have an over richness on the idle circuit, demon fixed that. I was wondering that on a cold day the mixture is not rich enough, yet on a hot day the air is thinner making a better mixture?

And thats why God gave us EFI.....

[Ron1]

"And thats why God gave us EFI".....

And chip burners so we could burn custom chips every time we made a change...

Ron

[crewzin]

Ive seen guys run the demon on a setup like yours with a 750 baseplate and extensions. They loved it and it run 10 teens no prob.

[Ron1]

10.teens? On a 9.5/1 Compression motor with 3.55 gears? Without even knowing the lift on the cam, or if its a hydraulic or solid roller? It takes 575 to 600 rwhp to run that quick. I think you may be overlooking something.
Anyway..the only way to fix your problem is by trial and error. A bog is normally caused by too small a shooter, or the secondary jets coming uncovered when you launch. You might also drop the secondary jets down a couple of sizes and see if it improves.

Ron

[lskarritt]

Remember this is a Saturday night, nice weather, street car not a strip car. cam size like I said was a Ford x cam 303 duration@.050 224/224 with a .542 lift.(roller) I have never had it to the strip. My p235/60r-14 t/a radial tires do not hook at all.
I need to go with a larger 15 ''. Alot of my friends told me that do go to the strip. This car should run on 12's with stickier tires. But I am afraid my 8" rear end won't hold up (355 Auburn posi unit)? Car also has hooker ceramic headers, MSD, RPM air gap, and Ford GT 40 X heads. Can anyone give me an idea on tire size? I still want to keep this a street car.

[Ron1]

Do it like I did years ago. I bought an extra set of steel rims and mounted some MT 26 x 8.5 on them. I bought the rims for about $12.00 each at a local tire outlet. I also got one of those mini jacks. One tire in the back seat, one in the trunk with the mini jack. Drive to the track, swap tires and race. And reverse the process at the end of the day. It was pretty much a daily driver..here is a picture of how it looked back then.


I had to sell the car to start my next project.

Ron