Truck Avenger tuning tips?

[funwheeling]

This is some real good information. Currently getting the same issue:
Holley TA 670
Compcam 260H
Edlebrock shorties
Performer intake
msd offroad
billet dizzy and blaster coil.

Went down to a 64 primary. Did not change secondaries. Didn't know about the secondary blocks (need to check my choke). Change the power valve to 6.5. I am at about 7 degrees on the timing will up that a little tomorrow.

Will be following this thread intently.

[my 2j20's]

Truck Averngertuning tips?

What it has #1 on the choke horn

[BLiP]

Ok earlyier you said it runs better but after awhile it seems to run more sluggish I would check the fuel pressure while running I had a holley blue on my 1985 Rx7 when I did a holley 600cfm carb conversion and the fuel pump gave me all kinds of problems I hated it I wanted to toss the pump in the trash it would start off with 6psi and after like 20-30 mins it would drop down to 3 psi at idle and at wide open throttle the float bowls would go dry I hated that pump and swore I would never go back to holley pumps

[bluesman2a]

OK, I've been running into some of the same stuff on my M-715, GREAT tech here, I have a little more to add to the pot...

After a bit of reasearch I was able to determine that there is problem with the Truck Avenger Gen-1 carbs. The issue is an off-idle stumble and other assorted tuning problems.

The Gen-1 Truck Avengers (part number 90670-1) had a couple of design problems. While Holley did not have a general recall on them, if you call and talk to them, tell them you are having problems, they will swap you the updated 90670-2 free of charge.

You can reach Holley's tech support Monday through Friday, 8AM to 5PM CST @ 270 781-9741.
==========================

So I did that, and they sent me a newer model carb no questions asked (Gen-2, Identifiable by part number 90670-2).

My setup:
Specs:
Vehicle: Heavy *** 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.

I tested the 0.040 nozzle with the 50cc diaphragm. It was good, again a seat of the pants improvement, but had no acceleration on the top end, and a VERY slight stumble coming off-idle. I put in a lighter secondary spring so they kick in around 2.5-3 grand, and that smoothed out quite a bit.

Based on what I learned from Holley Tech support (not much help, but I was persistent): above 0.037 requires a 50cc diaphragm. You are also supposed to use the hollow screws with the larger nozzles.

Next steps: I didn't use the hollow screws (didn't know when I set it up) so I'll change those out. At this point I have at least addressed the symptoms. I'm not sure I've solved the problem. I'll put some more miles on it tomorrow and read the plugs. If it looks like they are running lean, I'll go up to a set of 70 main jets.

[funwheeling]

Dumb questions. What's the choke horn? I don't see that called out on any of the illustrations.

[Lindel]

The Choke Horn is the part that sticks up out of the carb, and the choke plate lives in.

[J10-401]

Bluesman,

Some people have OK results with them out of the box. But many don't! I was one of the "don't" guys. I have 35 years of Holley experience and I just gave up on that POS. Holley swapped it for a Street avenger that's still in the box until my next smog test is over.

I tinkered with a MC 4300 and it runs great now.

I suspect Holley has nagging quality control issues and the product is not consistent. Mine came with that stupid 2.5 power valve too. What bonehead made that standard?

[Lindel]

It's easier to take a universal Holley 600 and mod it, probably cheaper in the long run too.

You get a better selection of parts to start with, and all you have to do is the "high angle" mods.

[Gawdzilla.]

sounds to me like lean pop- increase the squirter size and put the accel arm on position #2, if that doesn't work change the cam up a size or two.
Dunno where you're at with this b/c I just skimmed thru it, but it sounded like you were almost there.

[funwheeling]

Just got off the phone with Holley on mine which is a -2.

He said that there was an issue with the -1 that caused the off idle issue with an occasional back fire. Unfortunately they have the same issue with the innitial -2's.
With the lifetime warranty on the holley they want me to send it in for them to test out the carb and they will fix it or replace it then.

I told him that with the lifetime warranty I'll wait till after hunting season.

The issue is that something in the metering block was drilled in the wrong direction.

[my 2j20's]

Truck Avenger tuning tips?

That's good news! i'll pull it off right now and ship to em....

Thanks for the info.

[funwheeling]

Here's another one that I forgot to mention.

When I first received my holley, I took it apart to learn about it. Inside the holes in the metering block I noticed a buch of filings from the drilling process.

I highly recommend that anyone how has not take apart your holley and checkout all your channels in the carb.

Take it for what it's worth.

[funwheeling]

Update from my tweaking.

Well my hesitation is almost gone and almost doesn't backfire.

What I did:
Took off air cleaner
Got up on engine to be able to look inside of carb
With the choke held open slowly activated the throttle linkage.
Took note that mine took about 5 to 10 degrees before gas came out the jets
Adjusted the ny-lock nut over the spring to make sure the power valve cam was touching the throttle linkage cam.
Jumped up on engine and activated cam
Notices this time that gas cam out between 5 and 8 degrees.
Took ny-lock nut and placed washer under power valve cam and replace nut till there was some tension on spring bu not pushing on power valve
Gas cam out a lot faster
Took for a test drive.

A lot less hesitation and only 1 back fire.
May add another washer
Need to wait till tomorrow to get another timing light. Fan ate mine.

Over all this was a huge improvement. I really had issues in reverse and that is almost gone as well. Will update after I finish tomorrow.