2 bbl. Motorcraft & a dwell cam

[Dave Noll]

Forgot to mention that, It's already blocked (with a plug from a holley) & I have .066" jets in it.

[Billy Nees]

What is your duration @ .050? Lobe sep? Cam grinders tend to want you to put WAY too big a cam in 2V motors. No sense in putting a 7500 RPM cam in a 6000 RPM motor.

[Dave Noll]

Billy,
250 @ .050", 299@ .006", 105 lobe separation installed @ 103. Lift right now is .375" with the stock rockers but should be .407". They told me the cam wouldn't be the problem, the carb would. I protested a little cause it sounded big to me but they assured me this was a good one. (it's a Cleveland, run it like one).

[G Anderson]

Rochester 2G totally different but I would expose those trans slots play with the float level-need full timing at idle(On mine 39*) my cam is 260@.050 on the intake 107 c/l (installed to 106ic)runs good to about 71-7200 rpm ??? oh and would close these holes to about 5/32"

[Ed Wright]

If your spark plugs are dark, I'm guessing it idles best with the idle mixture screws all the way in?

[Billy Nees]

First rule of any engine combo, find the restriction, build to the restriction. You've got way too much cylinder head and valve area, lots of valve lift and as I recall way too little compression so you can't be giving up cylinder pressure with a big cam. You've got a 350 CFM carb that's not going to make power at any kind of RPM so why spin it up there? It sounds to me like that big cam isn't making any vacuum.

[jmarkaudio]

You need to figure out how to generate more idle vacuum so you can close the throttle blades up. The t-slots need to be covered or you will have a tough time getting it to idle without closing the mixture screws all the way, and even then it won't be enough. More initial timing might help, if you run a distributor with a vacuum advance using the vacuum to add timing under no load can help. If you find that you have all the timing it will stand, I would look at advancing the cam.

As a last resort, make the idle feed restriction smaller, drop it to the point where it's tolerable at idle and doesn't cause a stumble coming up on the throttle. Being a race car you should be able to find the happy medium. You can try to solder the restriction after measuring it, it's the small tube in the middle of the larger one in the booster cluster. You might want to get a spare to play with to do this. The other place looking at what I can find is there may be an idle down channel restriction, making this smaller
will help as well. Again these are last resorts, making more idle vacuum to allow the blades to close is your best bet. Here is a picture to give you an idea on what is going on.

[Bobby DiDomenico]

Originally Posted by Dave Noll

Forgot to mention that, It's already blocked (with a plug from a holley) & I have .066" jets in it.

Dave,
My Ford 2bbl stuff is away from here, is it possible the plug gasket is leaking some? Have 1/8" holes in blades, 1/4" seems plenty big to just about close the blades all the way. Did I read right it idles with the mixture screws turned all the way in? My current cam seems to require near full ign. timing, plan to change it to wider sep. Great info here

[Dave Noll]

Bobby, Yes you read it right. Idle mixture screws are shut. There's fuel coming out of the boosters @ idle , but with the 1/4" holes in the plates & the idle turned all the way up, that's a lot of air going thru there. I don't THINK I have a leak but I'll re-check.

Sean, This carb is 350 cfm. I know round track 2bbl. Clevelands regularly go over 7k, with a 4412 Holley. A while back I ran this combo on a simulation program & no matter what I tried, power fell above 6K but I figured we don't race computer's & blew it off.

Bill C., About all I can say on reversion control is the cam has 40 degrees overlap @ .050 & a 3 angle valve job.

JMark, I found an article that has the same illustration & saved the file, thanks. I may just weld the advance in the dist. & set it @ 40. Anybody have starting issue's there ?

Thanks for all the input guys.