Ok I have a question for anyone who has used the Proform main body swap. Have you seen a worthwhile gain after the swap? I can see where you would gain some power over a standard double pumper since you would have no choke horn anymore to restrict airflow but they are claiming a 25-50hp increase! Just curious if there is anyone that can attest to this causing a substantial increase?

I have performed a search and found several good tips and what not but I would just like to know about power gains and I didn't find that in the search.

 

My personal experience: I gained 2 tenths going from a 750 VS Holley to a 650 DP Holley. It picked up slightly more when I went to the Proform mainbody, perhaps another tenth, but I only had it in one week before I put in a higher stall torque converter, and the list of mods goes on from there.

The replaceable air bleeds has been a very nice feature for me this year with the bigger cam and conversion to E85. Shall we say it supports performance mods very well.

The Holley HP mainbody wasn't available when I got the Proform. It might be the better choice.

 

Well I guess their not to far off in their claims then for HP gains. Hmm well I have a 750 DP on their now and it works well although has a slight bog if you stab it to hard from the get go so im thinking about a 50cc pump kit and the HP main body. Maybe that would drop a tenth and get rid of the bog problem.

 

You really shouldn't need the 50cc pump kit. I'd look into other areas first, such as squirter size, check ball, pump cam, pump adjustment, etc.

 

So you dont think I would see any sort of a gain by installing a 50 cc kit in the carb?

 

You need to tune out the bog. I just doubt you'll need the 50cc pump to do it.

 

What would you recommend as a good upgrade then after the HP body? Right now that carb is completly "out of the box" should I step up the jet sizes on both front and rear a size or two? Also I was reading and they claimed that if you block off the power valves that this will produce more power....? This car gets driven on the street occationally but only a couple of miles at a time and is MAINLY a track car. So coughing and snorting on the street once in a while doesn;t bother me as long as it performs best under WOT

 

i wouldn't block out the power valves unless it was track only completely. You don't gain "more power" but what you "might" gain is a little consistency out of the launch due to eliminating the variable of the PV opening, now will this really matter if you're not a bracket racer though?

 

So how about one of those adjust-a-jet kits for the front and rear? Do those work well or are they junk?

 

i'd just use the old fashioned jets, never seen anyone at the track use anything else.

 

You can buy a lot of jets for what those adjust-a-jet blocks cost. In fact, you can buy a 66-99 jet kit for less than one would cost.

I assumed you had the jetting right and still have a bog. Start with the basics: Float level, timing, jetting, PV - then work on any remaining bog.

 

I have the float level set, timing is great, plugs are burning clean but still have a bog if I just stab the throttle right away. It doesn't bother me now since I went to a transbrake and 4k stall but I still figure I could gain some more performance if I fixed it.

 

off topic, but what is your trap RPM and tire size being that you show 123 mph and 4.56 rear gears.

 

I run a 30" tire. The 123 11.51 time was with my 700-r4 I had built up. I was in 4th pulling but I dont remeber what kind of rpms I was pulling I figure with this new th-350 I have in now will definitly lose some mph but thats why im changing to 4.10 gearing. Now my biggest thing has been getting traction off the line. 4k stall, with transbrake and 4.56's makes for some fun stoplight's lol Im changing to the the 4.10's cause i can already tell the car is going to tachout before I want it to.

 

We have NEVER seen any gains by using a Chinese main body over the original one unless the carb main body was junk to start with or the tune up was so far off that anything would help. Every instance we've encountered with the the tune up correct and the carb in good condition the insertion of a ProJunk main body slowed the ET an MPH. I'd go ***** racin' before I'd put Chinese plagerized parts in my American Iron Muscle Car.

 

What are your motor specs Cuda?

 

cuda has been posting on almost every thread downplaying proform parts. I've had a proform 750, demon 750&850, holley 850, and quick fuel 750 on my motor at the track. They all ran within .1 or .2 of each other just bolting them off my buddies cars, but the proform and the quick fuel both gave me the most adjustability with removeable air bleeds, idle fuel circuit adjustability, etc. For me they were the best bang for the buck. I have a proform 750 on my camaro and i'm much happier with it than the holley 850 I had before which wouldn't let my motor idle for some reason. Tried every trick in the book and still no luck, even drilled out the throttle plates as a last resort and that didn't help either.

 

I see..... I just dont understand when he was saying about the proform not outflowing a holley standard main body beings that the original holley is going to have choke provisions on all. I found the acually HP main body and I was going to try that out.

 

if you are having problems with off idle (tip in) stumble, double check that pump arm adjustment!
have a friend open the throttle all the way (engine off!) and press down hard on the pump arm with a flat blade screwdriver. this will keep your hands free to set the gap between the pump arm and adjusting screw to .015.
i have had no problems with my proform vac sec main body. in fact i recently bought their base plate, race type primary metering block, and secondary metering block conversion. jegs now offers individual air bleeds so you don't have to buy the entire $170 air bleed kit!
i will be posting a full review when the motor is done.
Eric B

 

If I roll into the throttle it will go fine and full throttle it has no problems but if I stab it quick and hard it would stumble (it doesn;t do it anymore) since I changed torque converters it stopped this problem cause it lets the rpm's go up very quickly.

I decided to go the high tech route since my LT's have provisions for O2 sensors I am going to install them to monitor air/fuel ratio and make my carb adjustments based on that. Maybe it will help me a lil.

 

.I can't b*tch too much about the proform main body. for Cuda the proform body was developed by Marty Brown and Marvin Benoit at Quick Fuel which were both employed at Holley before they started QFT so they still know their stuff. I like QFT metering blocks and baseplate better than Proform's though but then again who knows Proform might make them but they seem a littl emore on spec. The main body is the same deal I have seen a few people buy just the main body to convert a holly and it looked like crap because of casting inconsistencies but I know my Q750 everything looks perfect but they go through everything when they build them there and they also dyno everyone before it is boxed.