Holley/Proform main bodies

[88502]

I was going to buy either a Holley or a Proform main body but after doing a few searches there was alot of negative feedback on the Proform body and from what I can gather the Holley main body will change my 650 cfm to a 750 cfm, is this correct? I was trying to avoid cutting up a good carb and also think a 750cfm is too big for a mild 350 motor at low boost.All opinions welcome

   Thank you
   Bill (88502) 

[slow67]

I was going to buy either a Holley or a Proform main body but after doing a few searches there was alot of negative feedback on the Proform body and from what I can gather the Holley main body will change my 650 cfm to a 750 cfm, is this correct? I was trying to avoid cutting up a good carb and also think a 750cfm is too big for a mild 350 motor at low boost.All opinions welcome

   Thank you
   Bill (88502) 

Yes it will convert your carb to a 750. The only difference between a 650,700,750, and 800 is the main body.

[10secgoal]

They will change the 650 to a 750. Only draw back I ever had with them is the poor signal, which you just get with down legs. Probably fine with your 350, but with smaller motors just don't work well. Just tried one on a 302 and it WOULD not enrich through the PVCR's. Chagned back to the straight legged 650 and didn't touch the PVCR's and had to start pulling jet from the same setting I used with the proform that wouldn't work.

[gt40_5.0]

They will change the 650 to a 750. Only draw back I ever had with them is the poor signal, which you just get with down legs. Probably fine with your 350, but with smaller motors just don't work well. Just tried one on a 302 and it WOULD not enrich through the PVCR's. Chagned back to the straight legged 650 and didn't touch the PVCR's and had to start pulling jet from the same setting I used with the proform that wouldn't work.

thats not what i wanted to hear. i just switched out my holley main body to a proform main body so i could have adjustable air bleeds. havnet tried out either one yet tho

[slow67]

thats not what i wanted to hear. i just switched out my holley main body to a proform main body so i could have adjustable air bleeds. havnet tried out either one yet tho

Air bleeds are easy. Drill out the bleeds on top and tap 8-32 where it comes out into the metering block, and drill out brass 8-32 set screws.

[chris406]

Mine works good.  I have had it since I went blowthrough.  I have a CSU carb, that is now built for E85.

[gt40_5.0]

Mine works good.  I have had it since I went blowthrough.  I have a CSU carb, that is now built for E85.

you still have the downlegs on it?

[chris406]

you still have the downlegs on it?

CSU put their annular boosters in it.

[darkostoj]

if you want adjustable air bleeds just drill and tap them for brass set screws and get yourself a small drill set

[poboyracin]

if you want adjustable air bleeds just drill and tap them for brass set screws and get yourself a small drill set

Add to this....  The brass set screws are like $6.00 per box of 100 while the jets for the Proform/Holley bodies are $20.00 for 10.

[darkostoj]

Add to this....  The brass set screws are like $6.00 per box of 100 while the jets for the Proform/Holley bodies are $20.00 for 10.

Yea the holley jets are way too much, i prefer to make my own for much cheaper

[N2Otorious]

if you want adjustable air bleeds just drill and tap them for brass set screws and get yourself a small drill set

Do you have pictures to help me wrap my head around this, I read and understand you, just not sure how to implement it.

[darkostoj]

Do you have pictures to help me wrap my head around this, I read and understand you, just not sure how to implement it.

basically you buy a bunch of set screws (6/32, 8/32, 10/32) depending on what you want adjustable bleeds for.  You then tap either the air bleeds, ifr's, pvcr's, ccrs, whatever it may be for that size screw.  Then you drill out the inside of the brass set screw for whatever size you want the jet to be and screw it in.

[N2Otorious]

basically you buy a bunch of set screws (6/32, 8/32, 10/32) depending on what you want adjustable bleeds for.  You then tap either the air bleeds, ifr's, pvcr's, ccrs, whatever it may be for that size screw.  Then you drill out the inside of the brass set screw for whatever size you want the jet to be and screw it in.

Excellent...  I can tell I need to buy the BG drill bit set, where do you get the set screws from?

[darkostoj]

Excellent...  I can tell I need to buy the BG drill bit set, where do you get the set screws from?

http://www.mcmaster.com/ they are not expensive if I remember right. 

I ordered a pack of 6/32, 8/32, and 10/32 bits, and a 6/32 tap, 8/32 top, 10/32 tap.  I dont remember the depth of the set screws off the top of my head.

If you want to do a little reading and learn some there is a lot of good info over on this thread.

http://www.chevelles.com/forums/showthread.php?t=228153

[N2Otorious]

http://www.mcmaster.com/ they are not expensive if I remember right. 

I ordered a pack of 6/32, 8/32, and 10/32 bits, and a 6/32 tap, 8/32 top, 10/32 tap.  I dont remember the depth of the set screws off the top of my head.

If you want to do a little reading and learn some there is a lot of good info over on this thread.

http://www.chevelles.com/forums/showthread.php?t=228153

Thanks..  I will read that when I get a moment. 

[wwnf]

Had a Proform and the casting was off enough to create at least a 1/16th lip on all the bores.  Had all sorts of problems with tuning until I swapped it for a Holley.  Now I use the Proform to hold my air bleeds for drilling.