ProForm carb main bodies!

[Just 6T9 CHGR]

Heres a great product alert.

Was dealing with some fine tuning issues on my 440 with a 750 vac secondary Holley carb.  Had a small tip in hesitation at a cruise rpm (slight stumble with light a throttle apply when fully off the throttle)

My intial best vac reading I could obtain with the mixture screws was a shaky 14" in neutral with about 10.5-11.5 in gear.

Upon the recommendation of my friends and Ron (firefighter3931 who was helping me through PM's) I initiially raised my PV up to a 9.5 from a 6.5 and was playing with squirters & cams.  This greatly improved my problem but not totally.  I also upped my main jets from 72's to 74's

Ron had suggested looking into the ProForm main body for the carb for better air flow as well (since I dropped my aircleaner base closer to the carb, my airhorn could have been restricting flow a bit)

Anyhoo, I ordered up the main body as well as a 3/8" phenolic spacer from Summit Racing ( I got the ported 4 hole spacer for better low end response....3/8" was all I felt comfortable with since dropping my aircleaner to gain hood clearance.....worked out great.  Still no rubbing od the hood pad   )

Followed the easy instructions.  While I was in there I swapped in a 10.5 power valve just to try.

Bolted on the carb and did a tuning session with my friend Ronnie (coincedence!)

Picked up 2 full inches of vacuum at idle (16" rock solid) with a soild 12.5" in gear!!
The idle mixture screws actually "work" now.....before, turning the screws all the way in made a small change in idle.....now turning them in practically stalls the engine....the idle circuit is working nicely now.  Cleaned up the "raw fuel" smell as well....still stinks a bit but is much better.

I was able to drop my idle rpm down from 950 to 850 as well.  Car runs much smoother in gear now as well....still has a nice cam lope but not as "harsh"

As for my hesitation, I can honestly say it is 99.1% gone.  Im sure with a little more fine tuning  I can totally remove it.

I havent tried to up my timing yet back up to the prescribed 18º initial after the swap.  I still have it set at 16º

Overall well worth the $99 for the body.  My friend was actually impressed that an aftermarket product actually worked!

Some pics....

[BrianShaughnessy]

Sweet! 

[dodge freak]

I have had good luck with them too. Holley makes a hp metering block that has a different idle feed hole, its on top instead of the bottom. It helps on the idle. Summit racing can order it, I use the ones for the hp 950 carb. I think you could lower that power valve back to 6.5" You don't want it opening until you step hard on the gas, millage will go up a bit and power will stay the same. That body does not have a choke but so what you don't really need one.

[Just 6T9 CHGR]

I have had good luck with them too. Holley makes a hp metering block that has a different idle feed hole, its on top instead of the bottom. It helps on the idle. Summit racing can order it, I use the ones for the hp 950 carb. I think you could lower that power valve back to 6.5" You don't want it opening until you step hard on the gas, millage will go up a bit and power will stay the same. That body does not have a choke but so what you don't really need one.

I originally had the 6.5" using the old method of halving the max vac reading in gear....even tried lower but still had the hesitation.
If you go on Holley's tech site, they recommend chosing a PV that is 2" lower than your max vacuum in gear....
10.5 worked for me...
gas mileage?  whats that?

[firefighter3931]

Nice work !  That Proform center sure looks sharp on there 

Your comments on improved vacuum, decreased smell and idle mixture pretty much confirms what i suspected ; The previous setup was idleing on the main circuit which accounted for the rich smell and higher idle speed. This often happens with longer duration cams and carbs that aren't tuned for that application. The transfer slots are completely exposed in order to get it to idle so it is no longer idleing on the "idle" circuit. Those proform bodies are dialed in with a more agressive fuel curve which makes tuning a warmed up combo that much easier. Sounds like a win/win situation for a small investment....can't beat that. 

Maybe try bumping the timing back up to 18* and see if it's still predetonating.


Ron

[Just 6T9 CHGR]

I will try that Ron in the days coming up...

[greenrt_se]

hmmm.I have a old 750 Holley 3310 in the garage,maybe I order that proform too...just in case

[BrianShaughnessy]

They need to make one of these for a 2300 2 barrell   

I wonder if their billet metering block with the adjustable idle air bleeds would help any   

[dodge freak]

Those adjustable metering blocks I have not tryed, yet. I have had good resualts with going down to a .064 air bleed for the idle circuit and making sure the mains are about .035. One thing I have found is what bleeds come with it are not always right. They are to be .036 main and .072 for idle but if you have wire drills and cheak them you find they are off sometimes. I went and got wire drills and a pin vise for the drills. I would have just got a air bleed set from holley expect they cost $150.00 , thats a rip off I think. The power vavle hole sometimes is at .040 and is to small alot of times. I have found .055 - .060 works good but be carefull it can get to big and the block is junk. I like to run the smallest jet I can without no leanest noticeable when cool then open the power valve hole up until it has the most power. You can increase the main jet if you think it needs more gas and drive it and see what happens, if it does has more power and you don't need the mains that rich go back doen on the jet size and open up the power vavle hole. Just go up .002 -.003 at a time, like I said you go to big and then you are stuck. better to have the main jet to big for a few days, you can always change that. Good luck guys, I think its worth it if you what to get the most out of your engine.

[Chryco Psycho]

I installed a Proform carb onto Daves Cuda , man it responds like EFI now , definatly worth the $$