If you look at Ebay 950HP's you will see some new ones and some with very little time on them.
Kinda makes you salivate.

I have found out why some are cheaper than others.

Wonder why your 950 isn't performing the way everyone said it would?
The following might be why.

In a video I purchased from Pro Systems called Professional Tuning,
Pro Systems owner Patric Hale describes how some companies save money by substituting the standard 4150 metering blocks for the HP models when they sell HP carbs.They don't inform you that the carb has 4150 blocks.
They sell many of these carbs on Ebay.

I happen to have two 950's.I found one of them did in fact have the standard 4150 blocks graemlins/angry.gif and yes I did get them from Ebay.

Patrick says that the substitution can create metering problems wich will create problems such as a lazy 60, and not pulling the big end.

I don't have a digital camera or I would post the pics and show the differences between the two.

One way to tell them apart on the outside is to look at where the spark ported vacuum source would be on the primary metering block.

On a standard 4150 block there will be a deep hole for the tube that screws into it so you can get the vacuum.This hole may not be drilled through, but there will be a small very deep and easy to spot hole.Stay away from these.

On the HP metering block the primary will have a SLIGHT round recessed spot where this vacuum hole would normally be on a 4150 block.
On the HP Block this round recessed spot will not look remotely close to being deep.

If you had the standard 4150 block in your hand you would see two locating pins that center the block to the main body.
Look to the one on the right.If your metering block has a passage shapped like a backwards L or a misshapped ^ of sorts...You have the stock 4150 block.Sorry.

The HP metering block doesn't have any passage that looks at all like that.

If you find that you have a regular old 4150 block you can always have it replaced from a shop like Pro Systems or another shop.
This is going to cost you some $$ :(

But hey look at it like this, they will ask you some questions about your ride and can modify the blocks for even better performance.

I,m sure there are shops out there that can modify the standard blocks to work well on an HP carb.
But why would you want to when there is more power to be had with the HP blocks?

The downside..Hp blocks do cost more to modify.

Wow, I never would have guess that kind of stuff was happenning. So I guess if I want a true 950HP, I have to buy a new one directly from Summit or Jegs or a trusted friend?

Jim

Interesting,

I had one from BIGS, I didn't get any improvements even after I put my own 50 cc secondary accel pump on. When I gave them the specs for my ride and the existing setup I had, I expected the same 50 cc pump as what I had on my 850 and I told them really helped my 60 ft.

SO, was a victim of this???? I wonder..

There was one on ebay for $499.Lost the bid.After reading this post I'm glad I did.Thanx for the info. graemlins/thumbsup.gif Buyer beware.....

Car Stats (http://www.prestage.com/Member+Pages/1201.aspx)
New Velle Pic (http://www.chevelles.com/showroom/onebadd66/DSCF0010.JPG)

so THAT is what was wrong with my 950hp... they were the metering blocks that you described... the blocks on my 1000hp are the right ones and even have HP cast into them in the recessed holes... that 950 was totaly un-tunable.. the fella was nice enough to offer my $ back and shipping too! so i sent it back.....

ahhhh ****. my 950hp from summit has the deep hole, now what? the 750hp has the slight indention. any ideas on recource? Dave

My 950 from Jegs has the deep hole. Just looked at a new HP950 that the owner of a shop got direct from his jobber, the metering blocks have those same deep holes you describe. This is not a ebay carb.

Just went over to Holley's site and clicked on an image of the 0-80496-1. Has the holes. http://www.holley.com/HiOctn/ProdLine/Products/FMS/Carb_pics/f0-80496-1.jpg

Now here's the 0-80528-1 HP750. Looks like this one does have the holes. http://www.holley.com/HiOctn/ProdLine/Products/FMS/FMSC/f0-80528-1.html

.. http://www.holley.com/HiOctn/ProdLine/Products/FMS/Carb_pics/f0-80528.jpg

I meant does NOT have the holes

Allright, I just went and looked at my 950 and it has the shallow holes so I guess it has the right metering blocks. It doesn't have the adjustable/removable air bleeds but from what I heard the first generation HP carbs didn't have them.

both my 950hp and 750hp look like the pics posted. i guess im in good shape then. Dave

I have an Ebay 80496-1 from the accused seller and it has the shallow hole HP metering blocks. Looks like maybe holley is using/used 2 different metering blocks on the 950. Carb has tuned fine for me.

If in doubt open it up and compare the metering blocks.

If you already have a standard 4150 carb (which I'm betting all of you do) this is what you do.

Remove the primary metering block from it.
Then remove the metering block from your HP carb.
Now lay them side by side.

Look at the locating stud on the right.
If they both look the same near that stud the HP carb you have recieved has the standard metering block.

I don't know what to tell you if you got the carb from Jeg's or Summit.
But that ain't the HP metering block if they look the same.

I'm sure someone on here has a digital camera that can take a pic of the passages in question, but that ain't me :(

Going from the pictures above I would say the first (upper) pic has the standard metering block since the hole where the spark ported vacuum would be looks deep.
The second (lower) picture is probably the correct HP metering block since it only has a SLIGHT recess in that same area.

Hello All.....this looks like a great site and have several Chevelle friends locally that I will recommend this site to......Thrasher, looks like you started a topic that needed some more honest input then what you and your video we able to detect....LOL!! many HP holleys even being bought today as we speak dont have HP blocks in.....new off the Jegs/Summit shelfs....all of the first generation HP's had the earlier cast block which works very well! We built MANY of our first addition carbs with the standard block.....We actually perfer the earlier block and it does require more work to modify the just installing the HP block.....but we like the way the fuel curve stays steady with our tried and true block, so we stayed with it.......By no means should anyone feel they got takin if the HP block is not used....Im sure your mainly talking about the "dyno time only" type used carbs on E-bay......I agree to try and stay away from them because we just dont know what they have been threw.....we sell only brand new components and have since switched to the current trend and have been using the BILLIT blocks for the last year or so......Holley has now released their BILLIT equipped carb and it will be a fine piece also......Talk to you guys later, Jesse

www.bigsperformance.com (http://www.bigsperformance.com)

Just to clarify...

You are saying that the early HP model carbs came right from the Holley factory with the standard metering block...

Right?

I knew that the early models came without removable high speed and idle air bleeds, but I had no clue that they also used the standard metering blocks.

If that's the case then it looks like they changed the HP's a couple of times, first they came with non removable air bleeds and standard metering blocks, then with removable air bleeds and standard metering blocks, and now with removable air bleeds and HP metering blocks.

I think their HP Ultra series is the one with the billet metering blocks.Does the Ultra series also have the billet base plate?

Thats correct Thrasher.......and yes the Ultra carb does come with a billit base as ours has for over 1 1/2 years now.......The ultra still uses the stock round throttle shafts.....ours uses teflon sealed milled shafts and the throttle pedal feel is much easier......our Billit base has vacume ports where Holleys dont....just a few differences..........Jesse

I've often wonderd why Holley didn't make thinner throttle shafts standard on their HP carbs.

I know the first 3310's came with a thinner shaft on the secondarys.
I think all of the aftermarket shops use this as a standard operation when adding flow.
Since Holley essentially coppied the aftermarket (Braswell) on the HP carbs why not use the slabed shafts too?
After all,they added thinner throttle plates, why stop there?

Makes no sense to me :confused:

I kinda like the thought of having a smoother throttle feel and the addition of slab milled shafts.Do you guys also use the stainless HP throttle plates?

Is is possible to purchase the base plate that way from Biggs, and for how much?

Are they also available for the 750HP like that and for how much?

So if the older HP carbs didn't have the removable airbleeds and the redesigned metering blocks, how do they run? I've got one sitting in the box waiting for my bigblock to go together. Maybe I should test it out on a friends ride first? I talked to a very sharp engine builder awhile back that said the 950HP is an excellent carb but do not mess with the airbleeds they are perfect and altering them makes it tough to get it back, so I figured the removable bleeds wouldn't be necessary on this one. I hope I've got a good carb.

Bob......it will run just fine.....this subject is a tad misleading.......You will have no problems! Jesse @ BIGS!!

To thrasher, I'm not trying to be a smart**s but the owner of Pro Systems is Patric James, Patric Hale owns Racing Systems Analysis, ( a racing simulations software company), in Arizona. Both are very nice people as i have dealt with both.

Harold, is your son going to MoKan this weekend,,looks like sunday now for the big bucks, if the rain holds off.