Is there a Holley-Doctor in the house?
Post by bluesman2a on Sept 24, 2006, 11:47pm

I've been doing a lot of reading on general Holley tuning here lately and have learned a lot. I now have some specific questions for the Holley guys here. Looks like SpicerGear and Elwenil had some good input over on Pirate... I'm close, but I could really use a hand here folks... Any assistance appreciated.


Specs:
Vehicle: Heavy ASS M-715
Engine: 383 stroker with vortec heads and air-gap intake 9.5 to 1 compression
Cam:LIFT 486intake, 508 exhaust, DURATION @ .050 234 intake 244 exhaust
Carb base specs: Holley Truck Avenger 670CFM (Gen#2, so that's taken care of)
Ignition: MSD HEI distributor, with AC Delco plugs 41-932 gapped at
.045

Where we started (stock):
Stock Jetting: primary 68 secondary 89
pump: nozzle .028 30cc diaphragm orange cam
Power valve 2.5
Secondary spring: black

INITIAL PERFORMANCE:
The carb ran super rich right outta the box. Also had the flat spot everybody talks about at around 2500 RPM's. Per Spicergear's post, I checked the linkage on the accelerator pump and it was WAY off. Essentially it was running partially depressed all the time and probably responsible for fouling at least one set of plugs.

Adjusted linkage and flat spot cleared up, but coming off-idle, it'd still fall on its face, then pick up. If I blip the throttle sitting still it would sputter and die.

CHANGES:
Moved up to .035 squirter
Performance improved, again, but coming off-idle is still not great. Almost acceptable except pulling off from a dead stop.

CHANGES:
Moved up to 50cc diaphragm and .040 squirter.
Haven't had a chance to test this yet, ran outta time.

QUESTIONS:

1) I am seeing noticable improvements here, does it sound like I'm on the right track?

2) The orange cam seems to have the best engagement aside from the yellowish or brown ones. Should I have to step up to something that radical?

3) Any advice on cam/pump diaphragm/nozzle selection to at least get me started would be greatly appreciated.

4) Should I change over to the hollow screws for the .040 nozzles?

5) I haven't gotten into re-jetting yet, but at this point I'm thinking I'm about to the point where I need to run it and get some time on it to read the plugs before I jump into that, am I correct in this assumption?

Any other general thoughts or input? Am I missing something here?

Tomorrow I'll give Holley a call as well to see if they can give me any recommendations, if I get anything useful, I'll post back.