Safe jetting for my street combo?

Posted By: ProSport

Safe jetting for my street combo? - 08/07/14 03:33 AM

I have a 500" low deck pump gas motor with cnc ported Eddy RPM heads. I have a bone stock #4779-2 Holley 750 Double pumper to throw on it just to get the car up and running, I will buy the 950 Proform main body for it soon. This car is 100% street.

For now, I want to make sure the stock setup won't hurt my motor. It comes with 70-80 jets, 6.5 power valve up front, blocked in the back permanently I believe, and 28-31 squirter nozzles.

Let me know if I need to jet it up or anything to make it safe. The only reason it's 500 inches is because of the smokin deal I got on the short block and the fact that I'm running 3.55 gears and a tight converter for street use. Money has run dry so don't tell me to just run out and buy a 950HP carb.

I gotta get to bed for work so I'll check this thread in the morning. Thanks!

Posted By: Dragula

Re: Safe jetting for my street combo? - 08/07/14 03:53 AM

That is way under carbed. Even a 950 is a little light. When I was running a 950, I had a 4.5 PV, 86 front, 94 rear, and 45 squiter front and I do not recall the rear. HS bleeds I will have to look up, but would be around 31 ish....Car ran good enough to win the championship, but switching to a custom built 1000cfm with 50cc pumps and 95 jetting square, and it picked up a tenth and 3mph...

I am testing an 1100cfm SV1 currently, it still needs work yet.

Posted By: hemi-itis

Re: Safe jetting for my street combo? - 08/07/14 03:58 AM

Quote:

That is way under carbed. Even a 950 is a little light. When I was running a 950, I had a 4.5 PV, 86 front, 94 rear, and 45 squiter front and I do not recall the rear. HS bleeds I will have to look up, but would be around 31 ish....Car ran good enough to win the championship, but switching to a custom built 1000cfm with 50cc pumps and 95 jetting square, and it picked up a tenth and 3mph...

I am testing an 1100cfm SV1 currently, it still needs work yet.

What you said

You know what's involved tuning an SV1, try 2

Posted By: justinp61

Re: Safe jetting for my street combo? - 08/07/14 03:58 AM

ProSport I'd go up to 76/84 to start and add squirters as needed to get rid of any hesitation at the hit.

Posted By: hemi-itis

Re: Safe jetting for my street combo? - 08/07/14 04:00 AM

IMOP,start fatter and lean it as needed

Posted By: MR_P_BODY

Re: Safe jetting for my street combo? - 08/07/14 04:07 AM

Quote:

That is way under carbed. Even a 950 is a little light. When I was running a 950, I had a 4.5 PV, 86 front, 94 rear, and 45 squiter front and I do not recall the rear. HS bleeds I will have to look up, but would be around 31 ish....Car ran good enough to win the championship, but switching to a custom built 1000cfm with 50cc pumps and 95 jetting square, and it picked up a tenth and 3mph...

I am testing an 1100cfm SV1 currently, it still needs work yet.

You guys arent reading what he said... 100% street
and a 950 LATER will be fine for a STREET car... on
the 750 I would jet it up 4 sizes all the way around
to be on the safe side but check the plugs if you
start getting on it... you'll most likely need to
change the PV to a 4.5... with the 750 its gonna respond
very quickly from idle

Posted By: 383man

Re: Safe jetting for my street combo? - 08/07/14 06:22 AM

I run a 850 DP on my 493 and I had to jet up alot from what my old 440 needed. I believe I have 86's and 92's in it to have no breaking up at full throttle at about 5200 when at the track. I know its a street car but I agree with some others as I would rather be a tad fat then lean. I use a 3.5 power valve up front and none in the rear and it drives and works very good on the street and strip with that jetting. I drilled my squirters as I think I have about 32 & 34 but its been a bit ago and my memory is not what it used to be. Ron

Posted By: ProSport

Re: Safe jetting for my street combo? - 08/07/14 12:11 PM

Believe me I know it's way under carbed.

I just want to get this thing running, it will have a bigger carb before I go playing with the loud pedal.

I will jet it up and install bigger squirters, my main concern is the air bleeds(non-adjustable), I hope they are not super restrictive.

Posted By: Bad340fish

Re: Safe jetting for my street combo? - 08/07/14 02:38 PM

To make it real happy on the street you might need to either leave the jets or go down in the front, then increase the power valve channel to add fuel under load.

Posted By: ProSport

Re: Safe jetting for my street combo? - 08/07/14 07:38 PM

Quote:

To make it real happy on the street you might need to either leave the jets or go down in the front, then increase the power valve channel to add fuel under load.

How do you increase the power valve channel?

Thanks for all the ideas so far guys.

Posted By: Mr.Yuck

Re: Safe jetting for my street combo? - 08/07/14 08:43 PM

If all you have is 31's use those. You might need more. Also I'd probably start at 78-84 and go from there. PV 4.5

Posted By: justinp61

Re: Safe jetting for my street combo? - 08/07/14 09:22 PM

Quote:

Quote:

To make it real happy on the street you might need to either leave the jets or go down in the front, then increase the power valve channel to add fuel under load.

How do you increase the power valve channel?

Thanks for all the ideas so far guys.

If this a temporary deal I wouldn't start opening up the power valve restrictor channel. If this was the carb you were going to leave on and the jet spread was huge then I'd consider it. Get the primaries right then work on the secondaries. I just went down this road, be careful it's a slippery slope.

Posted By: Chris2581

Re: Safe jetting for my street combo? - 08/07/14 09:58 PM

I had mine at 80/84 with 6.5PV squirters are 31's F/R,other than that,it's a stock Holley carb.Never messed with PVCR's or anything else on it and it ran great.That is on my old 440 with the same cam you have.

Posted By: Sport440

Re: Safe jetting for my street combo? - 08/08/14 12:30 AM

With my old 750 ProForm combo. My jetting was 72/84 with 35 squirters F/B and the blue pump cams on the front set position 2.

This is with the DP RPM, with a single plane and MW ports, you may need more, but you do have 500 CI with a 110 LS that could offset that. But I do think you need a little more jet and squirters. Dont forget about the pump cams, as they can make a world of difference too on bog elimination.

Posted By: Dragula

Re: Safe jetting for my street combo? - 08/08/14 03:11 AM

Quote:

Quote:

That is way under carbed. Even a 950 is a little light. When I was running a 950, I had a 4.5 PV, 86 front, 94 rear, and 45 squiter front and I do not recall the rear. HS bleeds I will have to look up, but would be around 31 ish....Car ran good enough to win the championship, but switching to a custom built 1000cfm with 50cc pumps and 95 jetting square, and it picked up a tenth and 3mph...

I am testing an 1100cfm SV1 currently, it still needs work yet.

What you said

You know what's involved tuning an SV1, try 2

Ha, you get to deal with Patrick twice as much....I am learning a little with it. I got to the car show and back tonight and didn't totally kill the plugs....

Posted By: ProSport

Re: Safe jetting for my street combo? - 08/08/14 02:14 PM

Quote:

With my old 750 ProForm combo. My jetting was 72/84 with 35 squirters F/B and the blue pump cams on the front set position 2.

This is with the DP RPM, with a single plane and MW ports, you may need more, but you do have 500 CI with a 110 LS that could offset that. But I do think you need a little more jet and squirters. Dont forget about the pump cams, as they can make a world of difference too on bog elimination.

Thanks Mike!

Posted By: Thumperdart

Re: Safe jetting for my street combo? - 08/11/14 06:41 PM

Quote:

ProSport I'd go up to 76/84 to start and add squirters as needed to get rid of any hesitation at the hit.

AND get a wide band............