[X72GPX]

New combo, 295cfm eheads 10.3 compression
Butler sp8030 roller on a 112, torker 2, auto trans, msd 6al and billet distributor, heavy Grand Prix,

On a Holley hp950 Is this a good starting point for initial startup?

3/4 turn out on all 4 corners, transition slot window seems ok, 6.5 power valve, 78 primary and 94 secondary jets

Thank you!

[steve25]

My crystal ball is out on lone right now , so what CID motor are we discussing here ? :-)

I would leave the carb as is for now until you drive it and or take it to track, or better yet if you can strap it onto a chassis Dyno.

I have heard that the 950 HP ultra models need nothing but some jetting tweaks to produce the best HP and torque, but even without that they run very well drivability wise right out of the box.

I would assume from looking at your posted set up that yours , even though not an Ultra model would be the same.

The only uncertainty I have which also hinges on your cars rear gearing is if that primary power valve might open too soon.

At any rate your secondary side jetting sounds rich enough to keep you from burning the pistons up and sending rods out of the motor at WOT and high rev’s.

Speaking of getting things out of the motor , should we assume your running headers on this build?

Also I hope since this seems like mainly a fun street car that your Distributor has vacuum advance?

To me and many others on this forum who have tried running street motors with and without, having Vacuum advance or using an electronic ignition system that can be programmed to act as such is a flat out necessity and only does real good things when limited to 8 to 10 degrees of added timing.

PS

It would also help if you posted your Cam specs / details and not left it up to us to go track them down.

PS
I know this is a heavy car.
I had a 71 and looking out over the steering wheel to the nose of the hood was like looking out over the deck of a Aircraft Carrier from my Navy service days!

[X72GPX]

236/242 521/540 on cam specs an RA manifolds.
Very similar to the combo in this thread (using their jets)
https://forums.maxperformanceinc.com...ight=236%2F242

[PAUL K]

Yes, that is a good starting point. Fire it up and start tuning as you break it in..... Seems like a nice combo. Good luck

[X72GPX]

Thank you!

[PunchT37]

Last 2 carbs I had ran best at 1 1/8 turns out. T2 intake with a 246/253 cam though. 463 cubes.

[ta man]

76 to 78 front 88 to 90 rear is what I run in my 80496 950hp

[Formulas]

Fire that puppy up yet ??

[X72GPX]

Yea, it started right up, ( I was almost in disbelief since it was my first roller cam and ehead swap) but it came to life right away. Got ignition timing and it seems to like @16 degrees, got idle with 15hg vacuum, at around 13:1 AFR, got 13hg in drive.
Kept tuning, was rich at cruise, but ran great (felt so much more powerful that flat tappet iron heads) came down in main jets twice with no real improvement in AFR then realized air bleeds were all clogged, then different power valves 6.5, a few heli coils later for the fuel bowls and still tuning.

Then all of a sudden the carb was all over the place so took it apart, sprayed carb cleaner in every orifice I could find, there was no needle under the discharge nozzle, ordered that…. Hopefully when I get it back on the car it will behave. If not, maybe I have a vacuum leak, (been using a vice grip to clamp of pcv hose, maybe I gouged it? I’ll let know when I’m happy with it where I end up.

[Formulas]

Working the kinks out, Its definitely a process....

What symptoms were you investigating by eliminating PCV input? That hose should bounce back if its healthy.

[X72GPX]

I pulled the pcv hose from the intake and vice gripped it shut to hook up a vacuum gauge to that intake port.
Yea tuning can definitely be a “process” lol with a lot of cursing in between. Also forgot to mention that my rally temp gauge was showing hotter than pre head/cam install so I added an auto meter guage, fortunately the stock rally gauge was faulty and temps are fine..
At some point will get that dash off and have the gauges reworked and rebuilt.

[X72GPX]

Took it to the track today, only did 1 run and it did 12.79 @106mph and a 1.78 60 ft, pretty happy with that this car has never been in the 12's
Eheads and roller cam are great, tons of work but worth it! Drove it @50 miles each way to Island Dragway and it was great.

Ended up with 74s/94s but cruise is still rich, it's at 11.xx AFR at 3K rpm at 65mph, going to try 70s in the front at some point. Idle is fine @12-13 and full throttle is fine, in the 12's.

What's strange is a few times, I got into and when I got off, it leaned out- usually gets rich, why would it lean out right after I let off from flooring it?

Thx!

[chiphead]

What are HSAB and emulsion stack in the metering blocks? That rich at 3K, I'd expect the HSAB is on the large side or the emulsion setup is wrong.

Is this the classic (2) at .028 or something else? And yes, a large (.031 and up) main air bleed can start the main circuit flow earlier and richer.

At least on my 750 downleg, the flattest fuel curve is with .027 in the HSAB and (2) .028 emulsion bleeds in the classic holley locations. Fuel level just covering the upper emulsion. You want the HSAB to be right around the size of the kill bleed. The new-fangled holley-clone setup usually has too large a HSAB and too many emulsion jets. That tends to send it pig rich when the mains start, but it leans out to 12.5 at WOT.

[X72GPX]

Had a 120 needle in the primary fuel bowl, dropped it down to 100, much better now.
Thx