I have gotten quite a few (alot more than one) email suggesting that my hp levels would skyrocket at the top end with a holley 950HP versus the carb I have, and I wanted to test the waters on what people thought.
What I have now is a 6300 rpm 462 making 565hp @ the flywheel (grumble) at 5900-6200rpm.
The carb I have is a holley 750DP matched to a holley 850DP baseplate, 72-78 jets.
I assumed by doing little CFM math programs that this was adequate, as I *estimated* the overall CFM capabilities of the carb I have to be 830cfm.

What do you think?
500 or 600 bucks is alot to give it a go, and to be honest you guys are my hot-roddin buddies since people around here are either into forced induction mustangs or ricer-type cars.

matt

Stick a vacuum gauge on it and see how much vacuum you have at WOT. I don't think you'd get a "ton" of HP.

Actually, a Holley 830 cfm is made the opposite of what you have done - Holley does it by mating an 850 cfm body paired with a 750 cfm baseplate.

You might be suprised how much vacumn you are pulling at WOT with your current carb. On my 640hp/602tq 496 I am using a 1050 Dominator - it still pulls 2" of vacumn at WOT.

I don't know how many engine builds like this that you have done, but there are PLENTY of potential areas that would cause low power.

I too would vote for trying out a larger flowing carb.

Things to watch beyond oil pressure and water temperature as you do your dyno pulls:
1) Verify your advance curve. After setting advance curve verify that you are not getting any unwanted high rpm advance creep.
2) Check fuel pressure AND volume. Often overlooked, you can think you are okay based on fuel pressure at WOT - but yet not have sufficient volume.
3) You really need to have O2 bungs at your collectors so that you can use a wideband sensor to measure a/f ratio accurately.

Good luck, Thomas

Isn't the Holley 950 just a 750DP with a 850 base plate??? I know it flows only 830CFM...so I dont thnik you will gain much if any,,I realize the 950HP has adjustable air bleeds and a few other goodies for tuning

Originally posted by bigjimzlll:
Isn't the Holley 950 just a 750DP with a 850 base plate??? I know it flows only 830CFM...so I dont thnik you will gain much if any,,I realize the 950HP has adjustable air bleeds and a few other goodies for tuning I agree.The 950 is based off the 750.
The 950's venturi has the same opening size of a 750.It tapers out from the top down to mate up with a baseplate that has 1 3/4 throttle bores.

If you want to go with more cfm try the 1000HP.
The 1000HP is based off the 850.
It is supposed to flow around 870 cfm.
Then you could add slabbel shafts and button head screws for a little more.

Don't know if you would need it though.
You could also add the slabbed throttle shafts with button headed screws on your current carb for a little more.We are only talking about a little though.

I went from a stock 750VS to the 950HP and have only used it for street duty so far. I like it a lot more than the 750. It was worth it just for the 4 corner idle system. I'm running way less of a 454 than you are, too.

EDIT: Interesting, I'm running the same size jets as you are on a stock bore 454 with a very mild cam. That must mean something...

I work weekends so if you want, I'd let you borrow the 950 to take to the track. I live near Lowell, not sure where you are but send me an email if you want to borrow it for a weekend.

Tim.

NOW THERE IS THE ULTIMATE ANSWER!!!

graemlins/hurray.gif

Buy a Demon, its cheaper, more durable, looks better and will run just as well. There is no reason on earth to spend the extra money on the HP holley, when you get a better version of it from Barry Grant

If you decide on a BG carb just keep it in mind that they flow more than advertised.

Just the opposite of Holleys HP line.

If you look on the Bracket Talk racing site
http://drr.infopop.cc/eve/ubb.x?a=frm&s=3476075&f=80760912
you will find a lot of people who have tried BG Demon carbs.They don't speak well of them.
These people are serious about racing and that says a lot to me.

I have not owned one so I can't say either way.

I dont agree that the BG is better.

the Holley HP is a well designed carb, and worth the money you pay for it.

just remember when you are ordering that the HP950 is 830cfm, and the HP1000 is 850cfm.

Ok dumb question

Can I check the WOT engine vacuum with the car just sitting in the driveway after its all warmed up (I usually just pull the power brakes vacuum and stuff my vacuum hose into it, perfect fit), or is running the engine with no load like that bad for it? (I'd need foam earplugs for gun shooting, the tone of the engine now really lives a ring in my ear).
My only other option would be to like tape my vacuum guage onto my windshield and hope the cops like my explanation. There are no wide, empty industrial parks around me that I know of that I can just go test stuff, you know, drive down, check for any activity, turn around, then test something.
The highway is too dangerous formyself and other people, never mind the cops, and I hate to figure out stuff is wrong at the dragstrip because its a PITA to get my car up there and then figure out it isn't working right.
I put my old rear springs back and picked up a little ride height, I am going to adjust the front coil overs up whatever the rear went up as soon as the springs in back settle, my ground clearance is so bad I can't drive on roads I don't know by heart.

Thanks,

matt

Matt,
Nope ;)
Gotta be full throttle, full load & close to max RPM.
Easy on a dyno but a bit of a problem on the Hwy :D

A WOT test needs to be done just like a drag strip run.Just run a line into your interior and have the gauge aimed so you can see it.
Maybe if you have a friend that is willing to have a quick ride :D you could ask him to look at it during the run.
And I know about the street testing thing.
I usually do freeway testing at about 3:30am :D
when traffic is about non existent.

The rule of thumb is that if you are pulling 2inches you need more cfm.

Ya just beat me to the enter button Wolf.

Originally posted by thrasher:
Ya just beat me to the enter button Wolf. =
about as close as I'll ever come to winnin somethin graemlins/beers.gif :D

Hey don't feeel to bad.

I once wone the choice between a piece of Pumice and a map.Of course I took the Pumice as it was more fun to play with.

I was in the first grade :D

OOp's forgot I also wone first place my first time out at the High School Drags :cool:

The next day at school they made an announcement over the loudspeaker and called me Mario :D

graemlins/sad.gif Freakin idiots.

I guess I really earned that :D

Damn that was a long time ago :(