Distributor Identification

[John Smith]

I did not want to hijack the other dizzy thread so...
Is this an advancer or retarder? I have it hooked up as an advancer but if it is actually a retarder it would explain a few things. I believe it is the original 79 distributor that came with my truck and I am desmogged.

 

[71/monarch]

I don't have personal experience with that dizzy but here's some fact's:
http://www.ih8mud.com/tech/dist.php

check it out!!!

 

[John Smith]

Thank You! Not sure how I missed that one, but the addition of pictures to JimC's information on that page would rule.

 

[FJ40Jim]

79-80

Thank You! Not sure how I missed that one, but the addition of pictures to JimC's information on that page would rule.

You could put the picture of your 1979-1980 dual advancer dissy into that tech link.

 

[John Smith]

Jim, I don't see any way to post in that link. I don't think it is a tread anymore or it is locked.

 

[65swb45]

John, beyond the ID issue is the more practical issue of what to do with the second stage advancer. Starting with the caveat that RESULTS MAY VARY based on condition of engine, operating temps, gearing, tire size and weight, you can:

1. hook them together with a single T into the advancer port on your carb, and adjust timing for best result.

2. Hook them in series to sequential vacuum ports on a multi-ported carb [like a 79], thus somewhat delaying the initial application of additional vacuum, and hastening it's release under higher loads [lower vacuum]

Most people go for plan 1 because of its simplicity, and because unless the engine is in a very good state of tune, it's hard to get any significant effect from plan 2.

Hth

Mark A.

 

[FJ40Jim]

Some quick facts to help with actual timing settings:

The 79-80 dissy has total mech advance of 20-24*. This number varies depending upon the degradation of the stop pin bushing.
Primary vac advance of appx 18*.
Sec vac advance 6*.

If all 3 advances are available, there could be 48* of advance added to the base of 7*, yielding total crankshaft advance of 55*.

The generally optimal timing for the open chamber cylinder head is 36-38*

This brings up vacuum setup option #3.

Connect distributor sec vac advance to carb ported vac. Giving max advance of 6+(20 to 24), total available 26-30*.
Set base timing at 7*, total crankshaft advance is 33-37.