Holley 670 avenger
 

I just got a 670 Avenger, and I plan on setting it up in a couple days. Does anyone know which jets sizes/sec.springs are recommended for a 351w. I've asked Holley.com but theyre unresponsive.

I have inherited quite a collection of jets...however, some of them have a wrench style head to them rather than a flathead screwdriver setup. When comparing the two, the numbers dont correlate with the diameters. Is there a known ratio between the two jets?

Best bet is to get a pair of calipers and measure the actual diameter of the inside of the jet. It is the only way to "really" know what size you have. Just because a holley jet sayes 093 does not mean that it is 93 thou in diameter.
As far as what size is best. Find a deserted road, (better yet a dynojet) go WOT, turn engine off after about a 6-10 sec run at WOT, coast to a stop and check the plugs, if they are black, lean it out 2 sizes and re-run. do this untill the plugs look clean or untill the car surges or lean misses then go back up one size. One size to big is way better than one size to small.

well, heres my real question....does anyone know the factory jet sizes for the primaries and sec? I just want to make sure I have it set up right.

avenger tuning
 

well, I finally got that 670 avenger set up on my 351w. Runs beautiful at idle and highway speeds but there is a large hesitation between. Mostly off idle. If I jab the pedal its almost flawless so I know I'm getting a good squirt. I do have some carb knowledge but I'm not sure if it's a jetting issue or I've heard mention of transition slots? The carb came with 65 and 68 jets and I swapped em out for 67 and 69. Havent checked the plugs yet,..I'll do that in a bit.

The hesitation could be from a power valve mismatch to the engine, this is the point that the fuel inrichment ocures. Try to get a power valve rated at 2-3" hg less than the vacume reading of the engine at idle. Also the "cam" that dictates the rate that the accelerator pump squirts could need adjustment. If you look closely at the actual linkage that causes the acelerator pump to move you will see a colored plasic cam that causes the lever to move which in turn thru another lever causes the accelerator pump to move. That plastic cam is adjustable by one position or you can replace it with a cam that has a faster ramp, or less agressive ramp as the case may be.

This might help... I threw it together for another guy in here a few months ago....

Accelerator Pump Cam Replacement/Adjustment

there's no way to tell you what jets to run really, altitude plays a big difference as well as intake choice and cam...

matt1190, have you adjusted the acc. pump? try tightening down the nut so that you give it more duration to the shot.. most holleys are set with the diaphragm partially depressed..

secondaries might be kicking in to quick too..

okay guys, just to put the topic at rest, I solved the issue!:D

Originally I had a stumble off idle but especially during light acceleration while coasting. My plugs were really clean first time I checked but I still had a stumble, so I advanced the timing to about 11 degrees and put in a jet that was two sizes larger, which made a little bit of difference but it was still laging. This time tho, the plugs were a perfect mixture of gray and brown. I changed the accelerator pump cam to the extreme, (a bright blue one, fast and early squirt, although I knew this wasn't the problem. Still had no effect. I checked the idle mixture screws and backed them out accordingly. Then I thought what the hell, and I backed them out an extra turn. Problem fixed! Thanx for your input!

Idle slot
 

The Holleys use a slot for the idle circuit. The slot is for "transition" or "tip in" from idle to main jets as well as for idle. It feeds from idle circuit, so I guess it has to be rich enough for it to work on the transition. I think I had the same problem in the distant past and the fix was the same as yours.

Rev