Testing New Carb-Not Happy

[stroker1]

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I have my 1,000HP Holley installed and went to test tonight. 383 SBC w/Track1 heads, Hurricane intake, 2" Hussler headers, 4.56 w/29.5x10.5 tires, 14:1 compression, 180ish shot, foot braking. Damn truck slowed down. Even the top end was lazy feeling. I sprayed the same shot, same fuel pressure, difference is the carb and jetting in the carb. Probably too much jet in the carb, but I was still disappointed. Jetting was 84P/92S with rear PV blocked. Also seemed to spin a little when the nose came down, but still not as much nuts on the top end. And I shifted at 6500 instead of 7000. It didn't seem up to the RPMs tonight. What ya'll say? Any suggestions?

1st pass.
1.4368 60ft.
4.0735 330ft.
6.3413 660ft.
107.55 mph

2nd pass.
1.4888 60ft.
4.1337 330ft.
6.4066 660ft.
107.37 mph

Previous best, right before changing to this carb. 750DP with Proform main body and base plate.
1.4029 60ft.
3.9765 330ft.
6.2021 660ft.
109.25 mph

[wikd69]

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I have my 1,000HP Holley installed and went to test tonight. 383 SBC w/Track1 heads, Hurricane intake, 2" Hussler headers, 4.56 w/29.5x10.5 tires, 14:1 compression, 180ish shot, foot braking. Damn truck slowed down. Even the top end was lazy feeling. I sprayed the same shot, same fuel pressure, difference is the carb and jetting in the carb. Probably too much jet in the carb, but I was still disappointed. Jetting was 84P/92S with rear PV blocked. Also seemed to spin a little when the nose came down, but still not as much nuts on the top end. And I shifted at 6500 instead of 7000. It didn't seem up to the RPMs tonight. What ya'll say? Any suggestions?

[Craig W.]

The HP1000 is what I use and its been a great carb. Picked me up quite a bit on my old 12:1 383 as compared to a 850 double pumper. I played with jetting a lot, but ended up with 84/92 with the rear PV blocked.

[supernova]

The cam will have a lot to do with the vacuum signal on the carb. I have the same carb and if it doesn't match the cams duration it won't run right. In other words the crab you have likes lots of duration, over 260 at .050.
Check the specs of the cam and know for sure what you have.

[jmarkaudio]

A couple of things, tune the carb to run best without NOS, and try your old and new back to back to ensure what the difference is. Make sure you have no vacuum leaks. Make sure the throttle is opening all the way. That one gets a few. What cam, what timing? Do you have a distributor with advance in it, if so what initial and total timing? And spinning will usually kill ET.

[sc racing]

If I remember correctly the hp's have a hole all the way though where the air cleaner stud goes. Did you block it off ?

[Bob West]

How did weather conditions compare in both outings? I love my 1000HP.

[stroker1]

OK, thanks allot guys. Lets see if I can adress each of these responses.

Weather was not favorable for the 1000HP test. Humidity was higher. The carb has a stud installed in the center. I will double check the full throttle. I was running identical timing with both carbs. I did have to drill and tap the intake for a vaccum fitting for the HP carb. Used grease on the inside of the intake plenum to hold cuttings. I have the timing with the mechanical advance still working. I previously had it locked out but was tearing up flexplates and starters, but also had a 106LSA cam before. So it had alot more cranking pressure with the other cam. I am NOW running a solid roller identical to my old cam except for the 110lsa. It is a 256/268 @.050 .604/.604 but with 1.6 rockers it's .640/.640, and 110 lsa installed on a 106 icl. I know the cam is a little small, but I had it already, so I used it.

I was using a 180ish?? shot with 73N/71F jetting and 31-32 deg timing. I have also been running 1 fuel system for awhile, but I think I should change back to a dedicated fuel system for the nitrous.