Holley 950 Ultra HP Carb

[USMC_Spike]

A few issues still with this carb tryng to get it dialed in.
As many have noted here there was junk in the carb.

As for changes here is what I am right now, just pulled it and did a ultrasonic clean on it.

BACKGROUND
Carb came stock from Terry Walters and David Vixar speced 469 BBC engine.
The heads are a DV prototype for the AFR 300cc ovalport head poarted from
AFRs 290cc oval part units. Has big valves and moderate crank cam 248/256 with
with 108 LSA on a hydraulic roller set up. Holler Street Dominator intake port
matched. Chambers are 112cc. About 10.5 compression.
It should make max power at 31* and comes in at 700HP/700lbFt.

They claimed it idled well at 700 RPM. I've never had it idle well and the
valve train is noisey as all get up.

If we assume VE at 120% Then, (496 * 6500 * 1.2)/3456 = 1119 CFM flow for the carb.

I"ve barley used the carb and it drips fuel out of the throttle body shaft until it get hot.
Did Holley use a non hypereutictec alum alloy for the base plate?
Also, i was thining of useing Toyota rubber wtih teflon grease for the
throttle body shaft to help it seal better. Any ideas?

Currently it has the following (see attached):
e-hole #2 came plugged,
e-hole #4 I plugged.
IFR, relocated to the bottom.
I'll add jet extensions to the rear bowl.

NOTE: PVCR is 4.5 which is too close to idle vacuum at 5.0.
Thinking better to find a 3.5 or 2.5 PVCR. I"ve read that we want
2 inches of vacuum less than idle vacuum.

I'd be interested to find out if what y'all find works for you?
or
Any thoughts that you might have to get this running.

[HQM383]

Those things with 1.60” venturi and 1.75” throttle bore would flow well over 950cfm. I remember jmarkaudio saying he flow tested them when they first came out and the 1.56” venturi 850cfm had a better signal.

.029” will be too small for IFR on that size engine. Maybe .035”-.036”.

[Tobias Aldrete]

No way a 10.5:1 compression, pump gas 496 is making that kind of torque, dyno needs to be calibrated.

[Tom68]

A few issues still with this carb tryng to get it dialed in.
As many have noted here there was junk in the carb.

As for changes here is what I am right now, just pulled it and did a ultrasonic clean on it.

BACKGROUND
Carb came stock from Terry Walters and David Vixar speced 469 BBC engine.
The heads are a DV prototype for the AFR 300cc ovalport head poarted from
AFRs 290cc oval part units. Has big valves and moderate crank cam 248/256 with
with 108 LSA on a hydraulic roller set up. Holler Street Dominator intake port
matched. Chambers are 112cc. About 10.5 compression.
It should make max power at 31* and comes in at 700HP/700lbFt.

They claimed it idled well at 700 RPM. I've never had it idle well and the
valve train is noisey as all get up.

If we assume VE at 120% Then, (496 * 6500 * 1.2)/3456 = 1119 CFM flow for the carb.

I"ve barley used the carb and it drips fuel out of the throttle body shaft until it get hot.
Did Holley use a non hypereutictec alum alloy for the base plate?
Also, i was thining of useing Toyota rubber wtih teflon grease for the
throttle body shaft to help it seal better. Any ideas?

Currently it has the following (see attached):
e-hole #2 came plugged,
e-hole #4 I plugged.
IFR, relocated to the bottom.
I'll add jet extensions to the rear bowl.

NOTE: PVCR is 4.5 which is too close to idle vacuum at 5.0.
Thinking better to find a 3.5 or 2.5 PVCR. I"ve read that we want
2 inches of vacuum less than idle vacuum.

I'd be interested to find out if what y'all find works for you?
or
Any thoughts that you might have to get this running.

This post is a bit of a mess(hard to decipher) don't seal the throttle shaft, look down the carby and see where that fuel is coming from at cold idle.

What's the ignition timing at idle ?

What's with the 120% 1119 CFM thing ?

700 700 are you saying it makes peak torque and Hp of 700 at 5250, not that that matters either.

I probably can't give you answers but neither can anybody else without all the necessary information.

[USMC_Spike]

Sorry about that, didn't mean to make it hard to follow. I do have a few typos in there.

It has a moderate Crane cam 248/256 degrees on 108 LSA.

The CFM of the carb, follows the formula:

(CID * RPM * VE)/(2 * 1728)
where VE is the volumetric efficiency.
Vizard says for high end street/strip heads, professionally ported, etc, 125% is typical.
I used 120% (1.20).

So for the engine running properly at 6500 RPM the carb will flow 1119 CFM.
This BBC should be good to 7500. Its got many top shelf parts in her.

I haven't looked down the carb when it's running to see where the fuel
is coming from. it's dripping right out the side of the throttle shaft.

Maybe the sticky red synth grease would help? to keep it form leaking
the next install.

No, at different RPM points yes, so says the dyno sheet(s) received from TW.
I have 8 dyno sheets.

Note: It could be 11:1 compression but still alum heads he said will handle street gas.

Idle set varies, from a low of 10 before to 18 before. Depending on temperature,
Then engine sound changes, almost sounds like pre detonation condition happening.
Like the engine chokes (or stumbles) timing becomes irregular, then settles in, then the pre-det
seems to happen again. That is with 93 Octane.

Don't know how these carbs come from the factory, it appears to have the Booster undercut.
That is a step cut right above the fuel hole in the booster for fuel shear.
The booster tops appear to have been thinned out also, which should give 10 - 20 percent better
booster signal, per DV. Pretty simple job if machinist.

Hope that helps clarify.

[Tom68]

Others can help but that should be enough cam to run locked timing i.e 31 degrees locked, will need either start retard or separate ignition and cranking switches then.

[juuhanaa]

They claimed it idled well at 700 RPM. I've never had it idle well and the
valve train is noisey as all get up.

The fault may be somewhere other than the carb. As an outsider and without V8 experience, i would check the oil system.



-juhana

[USMC_Spike]

Sorry about that, didn't mean to make it hard to follow. I do have a few typos in there.

It has a moderate Crane cam 248/256 degrees on 108 LSA.

The CFM of the carb, follows the formula:

(CID * RPM * VE)/(2 * 1728)
where VE is the volumetric efficiency.
Vizard says for high end street/strip heads, professionally ported, etc, 125% is typical.
I used 120% (1.20).

So for the engine running properly at 6500 RPM the carb will flow 1119 CFM.
This BBC should be good to 7500. Its got many top shelf parts in her.

I haven't looked down the carb when it's running to see where the fuel
is coming from. it's dripping right out the side of the throttle shaft.

Maybe the sticky red synth grease would help? to keep it form leaking
the next install.

No, at different RPM points yes, so says the dyno sheet(s) received from TW.
I have 8 dyno sheets.

Note: It could be 11:1 compression but still alum heads he said will handle street gas.

Idle set varies, from a low of 10 before to 18 before. Depending on temperature,
Then engine sound changes, almost sounds like pre detonation condition happening.
Like the engine chokes (or stumbles) timing becomes irregular, then settles in, then the pre-det
seems to happen again. That is with 93 Octane.

Don't know how these carbs come from the factory, it appears to have the Booster undercut.
That is a step cut right above the fuel hole in the booster for fuel shear.
The booster tops appear to have been thinned out also, which should give 10 - 20 percent better
booster signal, per DV. Pretty simple job if machinist.

Hope that helps clarify.

Here is pics of the metering blocks cleaning in ultrasonic cleaner, 1:1 LA Awesome cleaner and water.
It took the anodozing off parts of the block. Maybe 45 minutes was too long.

[HQM383]

Carb wont be too hard to fix. I see one problem with the metering blocks above but I want to know more about this amazing engine.
Can you post some more specs and dyno sheets?

[Tom68]

Sorry about that

Never apologise, you did nothing wrong.

Just hoping to get you sorted.

[juuhanaa]

It doesnt matter if it has a new carburetor, EFI or what if the valve events are messing it up. Fix the idle and valve train noise prior to adjusting the fuel and/or ignition system! Hydraulic cam just does that

Drain the oils and go from there. You might find time to finish the carb..



-juhana

[rgalajda]

First of all , is this a street car ? Or a race car?

“469 BBC engine 700HP/700lbFT”
Do you mean it is a 496 ?

“moderate crank cam 248/256 with 108 LSA on a hydraulic roller set up.”
If you are quoting at .050 numbers then this is not a moderate cam , this is a race camshaft

“Also, i was thining of useing Toyota rubber wtih teflon grease for the 
throttle body shaft to help it seal better.”
What is Toyota rubber?

Currently it has the following (see attached):
e-hole #2 came plugged,
e-hole #4 I plugged.
IFR, relocated to the bottom.
I'll add jet extensions to the rear bowl.

Is this some picture you found and pasted or does this represent your actual jets , air bleeds sizing that are listed in the picture ?

PVRC stands for ( Power Valve Restriction Channel ) not power valve

“Idle set varies, from a low of 10 before to 18 before.”

Are you referring to base idle timing ?

You need to clarify things better , not just reposting the same jibber jabber

[ClassAct]

Don’t lock out the timing. You need a curve.
Your VE math doesn’t matter so forget that.
You should be running a vacuum advance.
You need to pin the carb and write down all the sizes of the holes.
Post ALL of the engine specs. You can’t guess at it. They should have given you a paper with all that.
Post the dyno sheets.

With all that you might start getting somewhere. Right now, we would be guessing.

[stealth]

Was likely just dirty... clean everything well and try again.. .

I wouldn't make any changes until you try it after cleaning.

[USMC_Spike]

@HQM 383 - What is issue with metering block?
Dyno Pull sheet Attached.

@juhana - If hydraulic rollers are noisy, then so be it.

@rjalajda - street/strip vehicle and engine. Yes, 496 cid.
.....Then yes, race cam shaft, as you say.
The picture of the metering block is from Holley, a 950 Ultra XR, and I updated
it with actual numbers from the carb, (i.e.: jet numbers, e-holes measured with minus pin gauge to .060".)
The larger holes, with back end of NOS, USA made drill bits.
Timing from 10* - 18* BTDC, at idle.

@ClassAct - thanks, I don't need more stuff to fool with, I won't lock out dizzy.
MSD has vacuum advance on it, but there are issues perhaps with fuel, I'm not sure.

BACKGROUND
Paperwork about engine, that is part of the issue, it seems they were unclear about
everything in the engine, carb, etc. They (Terry Walters, David Vizard) couldn't quite
recall everything about the engine and trying to gather information was difficult.

Then DV told me I couldn't post the Dyno Sheets, because even though I paid for dyno time,
it was DV proprietary information that he uses in publishing his books.

To find info about the heads, I contacted AFR with their S/N and they informed me
these were prototypes for their larger oval port heads based on the 290cc oval heads.
Perhaps DV was under non-disclosure?

I never got a real cam card as I have before. It appears like some internet made thing.

I'll post one internet cam cards. TWs information is different than DVs. I tried to get parts
numbers etc, and got the feeling they didn't want me posting the information online -- that
somehow everyone would just copy their proprietary builds.

I'll include some of the information that I received and post that here.
along with pics.



NOTE: if anyone has a set of minus pin gauges from .061 - .100, please PM me.