Page 1 of 1

Zenith vn jetting for my mk1 1500 deluxe

Posted: Wed May 04, 2016 9:04 pm
by turbellion
Hey guys, need some input on this.
I had a pretty good lean spot on light acceleration so I rejetted my carb as follows.
100 main
112 comp (stock)
60 slow

My car now has no noticable flat spot and seems to run really well! The problems I'm seeing are my plugs are not coloring. They look as though I just installed them. I have put several hundred miles on the and have driven hard. Is this normal for these engines?
I'm Using autolites

The only weird running problem I'm getting is a kinda lumpy idle due to a fuel drip which I presume is too high of fuel pressure. You can watch tthe fuel drip from somewhere on the emulsion block followed by a misfire. Still drives fine.

What jetting have you guys used in the past to cope with today's gas.
I should add that my engine is 100% stock 1500 deluxe the only thing modified is a 2" exhaust with a pretty quiet muffler.

Here's my 65

Posted: Wed May 04, 2016 9:07 pm
by turbellion
Image

Posted: Thu May 05, 2016 9:34 am
by peteleo
1500 deluxe came with a Zenith. Book says: 92 main. idle jet: 55. air bleed: 70.
Fuel drip is obviously not right. It's either a bad needle valve ass'y or the fuel pump pressure is too high which should be between 1.25 - 2.5 lbs. A fuel pump regulator would cure that.
I have a few extra parts and kits for the Zenith if needed.

Pete

Posted: Thu May 05, 2016 8:32 pm
by Kiwi Cortina
In my 1600 X flow I use 91 octane plus Lucas octane booster 3X. Engine runs smooth through acceleration. A little lumpy when at idle but does not stall.

Posted: Thu May 05, 2016 9:14 pm
by turbellion
I ordered a Holley fuel pressure regulator today. Hopefully that will cure the fuel drip. As for my plugs, I may try a colder ngk plug and see if they color normally. I don't see it as a problem. It's just rather strange. I work on air cooled vw's for a living and I have never seen a plug come out if those looking as though it came out of the box. I don't hear any detonation and my car runs pretty darn good. Maybe I'm just nit picking. But I like to see tan plugs.

Posted: Mon May 09, 2016 7:43 am
by turbellion
It appears that the fuel pressure was the culprit. I installed the regulator and set it to about 2 psi. I was able to set the idle speed to a smooth 800 rpm. It now runs super crisp at all Rpms and no longer boils over after a hot shut off. Very happy!