CarburetorsCarb discussion and questions. Upgrading a Third Gen carburetor, swapping TBI to carburetor, or TPI to carburetor? Need LG4 or H.O. info? Post it here.
Welcome to ThirdGen.org!
Welcome to ThirdGen.org.
You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join the ThirdGen.org community today!
To any of you thinking of buying a ProForm mainbody instead of a Holley Hp main body....my advice is DON'T!!! Spend the extra $25 to $30 and get the Holley HP mainbody.
My finding have been that the ProForm bodies look nice...but are dimensionally inaccurate.
Here's what I found:
1) Acclerator pump shooter gaskets were cracked and shriveled. Not a big deal....but just the tip of the iceburg.
2: Throttle bores did not line up with throttle plate. Off by nearly 1\16". Original Holley main body was dead nuts accurate. Proform piece either had core shift or was machined incorrectly. Had to remove locating dowels in throttle base to " fudge" alignment of throttle bores. This of course, could now cause a misalignment in some of the fuel transfer holes between the Mainbody and the throttle body. Not good at all.
3: Secondary metering block is positioned 1\16" lower than Holley specification. This causes the Secondary fuel bowl to hit the PCV boss. I had to file down the PCV boss and file down some casting " flash" on a brand new Holley Quick change bowl to even get it to fit. Getting the PCV hose on is a case of lots of silicone spray and cursing. A common problem according to Internet searchs. Again...inaccurate dimensions.
4: Metering block holes on main body face are not accurate. Pacing a brand new Holley metering gasket against ProForm body, showed some of the metering holes did not line up accurately. Likely a cause of many problems of " Cross Feeding" with ProForm bodies which people " think" is due to a warped body.
5: Primary Vacuum Chamber shape different to Holley. This caused a major issue with my Weber Power Plate. There is a screw boss in the Power Valve Chamber in the main body. On the Proform piece, this boss is not the same shape as the Holley design....but most important....this boss is 1\16" closer to the metering face than the Holley design. If you use a thick gasket under the Power valve ( some gaskets are thicker than others ) the Power valve can hits this boss when things are tightened down. This results in the metering block gasket not crushing enough and you get cross feeding.
6: Main booster channel id is smaller than Holley specification. Reduces fuel flow. Not good.
So...IMHO...the ProForm bodies are a PIECE OF CRAPPOLA. Just far, far too many variations from stock Holley dimensions to be just one bad casting. Doing a search on the Internet showed a LOT of people having similar problems with the ProForm pieces.
Fortunately for me, Summit had their usual excellant service policy. Full refund after explaining the situation. They have also passed an advisory to their Sales and Tech people based on my situation.
BTW, this part sat in my tool box for 4 months before I got around to installing it. Not a problem with Summit. Kudos to them
This ad is not displayed to registered members. Register your free account today and become a member on ThirdGen!
__________________ Hunter Motorsport Team Member.
New 2005 Knox Mountain Hill record.
1.58.636
Ioco hill record holder.
Lap Record SP3 Rivers Edge Raceway
2000 BC Autocross ESP Champion
1986 BC AutoCross ESP Champion
Car is SOLD
Last edited by Chickenman35; 05-23-2006 at 01:21 PM.
Sponsored Links
Registered users do not see this ad. Click here to register for free!
intrestingly enough, i have a 750 4150 dp with the original main body and currently a proform main body - so far so good for me...
How was the alignement on the main body bores to the throttle plate? Did you check closely when assembled?
Have talked to two other racing buddies since posting and they both found mis aligned venturi bores. Could be core shift...but I've never seen it this bad on any Holley. As I mentioned.....YMMV ( Your milage may vary ).
Hopefully you got a good one...but I've since researched, and read about too many issues with the ProForm body, for it to be on my "Recommended List".
"Best bang for the buck"? That's a rather absolute statement on a very subjective topic.
At the time it was introduced, the $100 Proform mainbody was the cheapest way to go from a street-like carb to a race-like carb. Of course, if you didn't already have a street-like Holley, it didn't make any sense to go buy a new one and then buy the Proform mainbody when you could just start with a race-like carb. But, if you already have the street Holley, or can get a used one cheap, $100 is a lot less than $700, even if the $700 would give you a better carb in the end.
When I got the Proform mainbody, it went into a $200 used Holley. $300 is still a lot less than $700, even if the $700 carb is a better carb in the end.
The only "issues" I had with the Proform were: 1) The secondary idle bleeds were the 4-corner idle size, and I had 2-corner idle - apparently sometime along the way they started including the 2-corner idle air bleeds, but didn't with mine. Simple $7 fix. And, 2) One of the secondary idle/transition slots was not well machined in the throttle body, which led to a shaky idle, but was easily handled by picking at the slot until it matched the other one. That, by the way, was a Holley problem, not a Proform problem, and would have existed even if I had gotten the HP mainbody.
Wow, I lost a full tenth of a second and a mile pr. hr. after installing a proform main body, I had removed an HP which was on the car prior. I have been scratching my head all summer and had this thing apart a dozen times and found exactly the same problems you mentioned. I will also be returning this piece of s____ to my local speed shop for a refund towards a new HP.
Doc
Quote: "Best bang for the buck"? That's a rather absolute statement on a very subjective topic.
My opinion is based on doing Carburetors for over 40 years, my associate has being doing carburetors for 43 years, we have sold no less than 3000 Mighty Demons over the last 10-12 years. We both concur that for the money the Mighty Demon is the best bang for the buck, yes a few modifications need to be done to them to make them this way but I would guess there's at least 200 "Holley Modifiers" in the USA and at least 10 Offshore companies trying to build components for Holley's.....Why do you think that is? I haven't see any of these companies trying to build "Improvement" parts for Mighty Demons.
To my knowledge we are one of about 3-4 carburetor companies in the U.S. that acturally make these subtle modifications to make them more engine specific.
Quote: "Wow, I lost a full tenth of a second and a mile pr. hr. after installing a proform main body, I had removed an HP which was on the car prior."
Quote: "Have talked to two other racing buddies since posting and they both found mis aligned venturi bores. Could be core shift...but I've never seen it this bad on any Holley."
Your Honor, at this time I would like to rest my case and pass the witness.
I'm not arguing that the Proform is as good as the HP. I also don't know why anyone would remove an HP mainbody and install a Proform. The competing-brand good Doctor did not include that tidbit of information in relating his experience.
Relating only my experience with the Proform DP mainbody, I didn't have any manufacturing issues with it. I am also not trying to get the last nth out of the carb or car. And, the HP wasn't available when I got the Proform (which I already said). If I was in the same market today, I'd get the HP.
There have been a few people relating issues with Proform mainbodies, but there have been a bunch of people reporting problems with Street and Race Demon carbs (not the Mighty Demons). While there isn't any reason to condemn all Demons based on the Street and Race Demon issues, one also shouldn't conclude from your experiences with the Mighty Demons that you should buy a Street or Race Demon instead of a Holley HP main body for your current Holley.
As for "bang-for-the-buck", I gained a tenth going from the stock Holley to the Proform mainbody. Perhaps I would have gained 2 tenths going to a Mighty Demon, but $100/tenth beats $300/tenth if calculating bang-for-the-buck that way. If, on the other hand, one needed three dyno sessions to sort out a Proform MB install, that would make a Mighty Demon that could be installed out-of-the-box look very attractive (even though you admitted MD's still need modification). There are other possible BFTB measurements, such as consistency or throttle response, but they are arguably more subjective.
There are some very good reasons there are more Holley modifiers than Demon modifiers. Holley has been around for a long time, and wasn't facing significant competition from other carb manufacturers. Barry Grant changed that, and the entire market is better off for it. However, comparing a 4150 Holley to a Mighty Demon is an unlevel playing field - compare the Holley HP to the Mighty Demon, different story.
Since you brought up "why do you think that is", why doesn't Summit carry Barry Grant products, but Jegs does?
But, that wasn't the topic of this thread. And, staying on topic, I agree with the OP - if considering an upgrade main body for your 4150 Holley, go with the Holley HP rather than the Proform.
I'm not arguing that the Proform is as good as the HP. I also don't know why anyone would remove an HP mainbody and install a Proform. The competing-brand good Doctor did not include that tidbit of information in relating his experience.
Relating only my experience with the Proform DP mainbody, I didn't have any manufacturing issues with it. I am also not trying to get the last nth out of the carb or car. And, the HP wasn't available when I got the Proform (which I already said). If I was in the same market today, I'd get the HP.
There have been a few people relating issues with Proform mainbodies, but there have been a bunch of people reporting problems with Street and Race Demon carbs (not the Mighty Demons). While there isn't any reason to condemn all Demons based on the Street and Race Demon issues, one also shouldn't conclude from your experiences with the Mighty Demons that you should buy a Street or Race Demon instead of a Holley HP main body for your current Holley.
As for "bang-for-the-buck", I gained a tenth going from the stock Holley to the Proform mainbody. Perhaps I would have gained 2 tenths going to a Mighty Demon, but $100/tenth beats $300/tenth if calculating bang-for-the-buck that way. If, on the other hand, one needed three dyno sessions to sort out a Proform MB install, that would make a Mighty Demon that could be installed out-of-the-box look very attractive (even though you admitted MD's still need modification). There are other possible BFTB measurements, such as consistency or throttle response, but they are arguably more subjective.
There are some very good reasons there are more Holley modifiers than Demon modifiers. Holley has been around for a long time, and wasn't facing significant competition from other carb manufacturers. Barry Grant changed that, and the entire market is better off for it. However, comparing a 4150 Holley to a Mighty Demon is an unlevel playing field - compare the Holley HP to the Mighty Demon, different story.
Since you brought up "why do you think that is", why doesn't Summit carry Barry Grant products, but Jegs does?
But, that wasn't the topic of this thread. And, staying on topic, I agree with the OP - if considering an upgrade main body for your 4150 Holley, go with the Holley HP rather than the Proform.
Sorry I was unclear, I managed to pull the threads out of one of the shooter holes on the HP when I was tuning. No repair available at the time and I was going racing that day. I shot down to the local speed shop and picked up the only thing they had, a Pro-form main body. Wished I never had, I was being kind when I said a tenth. It is closer to 2 tenths difference and I will be replacing the PF piece of junk over the winter now that racing season is over.
Probably with another HP or the possible repair I have discovered recently on the net. WWW.BLP.com is the sight for this repair if anyone else has a thread problem with the shooter holes of their holley products. I would imagine this repair will also work on any other brand as well since they all use the same screw.
Doc
