Thread: Thoughts on jetting.

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Does your carb have the idle eze adjuster?

Jerry

Jerry,

No, it doesn't. I bought it several years ago as I was stocking up on parts. In retrospect, I guess I should have waited until near the end of the project to buy a carb - but you know how we all like/need "presents" from the big brown truck.

I need some more work on the idle, but I think the main problem is solved.

Well, the sticky linkage was the problem. I put in clean plugs today, and drove 10-12 miles. No more carbon fouling. The plugs are pretty clean, the insulator is fairly white, and the electrode has a slight blue tinge.

Now I'm concerned that I may need to bump the jets back where they were. I don't hear any ping - but I can't hear much of anything except the exhaust.

Thanks, Denny. That's what I was seeing. I'm going to put the original jets back in tomorrow and see what happens. I know the plugs are the right heat range. It's a matter of mixture now.

Denny,

I went back to the original jets (2-steps up). It looks to me that I may need to go back down one step. The porcelain is tan about half-way down, especially on the piston side - then it gets a little black. The ground electrode is clean, and no sign of blueing from overheat.

They're a little darker tan than this photo shows, probably overlit somewhat by the camera flash.

What do you think?

What's all the black on the ribs of the procelan where the wire boot goes?
If your wires are dirty or greasy you could be shorting out down the side of the plug.
I also think you need a colder heat range plug and then work on the jetting

Originally Posted by DennyW

Jerry, did you see the other plugs in earlier postings ? Really lean, burning white, and ground electrode was blue, almost to the melt temp. The ground electrode is not the plug heat range ?

These are much better, but a little rich.

Looks like die-electric compound on the ribs.

Denny,don't even bother.
He does not even read all the posts.

The blue ground shows that there was a lot of heat that was carried off to the head that direction. I agree his earlier plugs were lean, but generally one or two jet sizes won't go from too lean to too rich.

Jerry

Denny,

Thanks for asking, but I haven't had a chance to try it yet. I didn't get to the shop early enough on Saturday to buy the jets, and on Monday we took off for Texas for about a week. All my kids and grandkids are meeting in Frisco for Thanksgiving and staying at my oldest son's house. (How did any of us get to be old enough to be the patriarch?)

I did check the plugs again though, after another 50 miles or so last weekend. I'm a bit concerned that some of the plugs are much darker than the ones I posted last time. It looks like unequal burning rates in the various cylinders. I'll have to deal with that when I get back.

I'm going to hook up the vacuum gauge again, and adjust the idle screws for max vacuum, because the idle seems a bit choppy - almost like a slight miss. If that doesn't get me there, I also might pull of the Crossfire distributor cap. I've heard that they are appropriately named. I'd have to buy new ignition wires, though. Have you heard anything about the reliability of the Crossfire caps?

The car still takes off like a turpentined cat, but I'm sure I'm not at max HP yet. So far, I'm not too thrilled with Barry Grant's setup - and their quality control.

All hotrodding is not lost though. Maybe I can convince my son to let me drive his Cayenne.

Denny,

It's the stock ZZ-motor dual plane vortec aluminum manifold. THe wires and the cap are brand new, so I'll concentrate on jetting and idle adjustment.

That reminds me. Before I left, I pulled the 1,7,2 and 8 plugs. The 1/7 were just a little rich, and the 2/8 were much richer. Since the the 1/7 and 2/8 cylinders fire from different plenums on a dual plane, that tells me something. Thanks for the reminder.

Jerry,

The black stuff was the result of my greasy fingers and a small amount of dielectric grease from the boots. They were clean when I put them in.

All you guys have a great holiday yourselves. I have an unusually long 11 days away from work, and I'm going to enjoy every minute of it.

Eleven days??? Good deal...enjoy the time off.

OK, I'm back. Texas was great . . . but cold. We didn't get a chance to use #1 son's new swimming pool.

Tonight I pulled all of the plugs from the last run. This is with the carb secondary linkage repaired and the original jets installed. I probably have 40 miles on this set. The plugs are in 1-8-4-3-6-5-7-2 order, left to right. The difference from plug-to-plug looks really odd to me - especially #5.

I installed new plugs, and I'm going to drop down one jet size for tomorrow. I'm also going to completely re-check the carb and set for max vacuum. Finally, I pulled the crossfire cap in put the stock one back on.

I'm also wondering if I have a vacuum leak. I get a whistle when I back off the throttle and the engine is compression braking.

I've NEVER had this much of a problem dialing in a carb.

This is the latest. Downsized one number on all four corners. Adjusted the idle screws for max vacuum, and got it up to 19" Hg from 15" Hg. Replaced the crossfire cap with the stock cap. I also reset the primary and secondary butterflies.

This is with about 15 miles on the plugs, and about 15 minutes of idling while I adjusted the floats, idle screws and idle speed.

Have you tried the combo I suggested?