japjohnpeterson

I have an 87' 4x4 Yota. Brand new rebuild. 32/36 DGEV weber carb. No other engine mods whatsoever. All emissions controls disconnected. Running a single vacuum line to the outer pod on the vacuum advance. Inner plugged. At idle, engine purrs like a kitten, runs beautiful. Once we throttle up, the timing is retarding instead of advancing. Any ideas?!?

abecedarian

you have the distributor vacuum lines hooked up wrong maybe?
the dizzy has two vacuum connections, right?
the outer one should be to a manifold vacuum port and the other one should be ported off the carb... if I remember correctly, or could be reversed. I have efi and haven't dealt with carbs in years.

japjohnpeterson

From what I understand, with the new carb I have, only the carb vacuum line is needed. All of the other 22r engines I have searched on the forums that have a weber 32/36 are running with just the one vacuum line. From the pictures I've seen and the people I've talked to, I'm pretty sure my vacuum lines are hooked up correctly for my setup. Though we have tried reverse, to no avail...

alltracman78

Vacuum diaphragm in your dist damaged?
Pull the cap, hook up a vacuum pump to the diaphragm and see if the advance moves when you apply vacuum to it.

japjohnpeterson

Checked that alltracman. Diaphragm is good. Checked and tested distributor. That's good. I am getting a small amount of advance, just not enough to overcome the retarding.

alltracman78

It may be related to your emissions controls, they have an ECU controlling them [your OE carb was electronically controlled IIRC].
If that ECU has anything to do with ignition timing [I'm not positive that it does, just making an educated guess] and it doesn't see what it wants from the emissions stuff it may retard timing.

japjohnpeterson

Gonna have to have a look at that. I'm not sure that it does, cause I've seen other guys on here with the same setup I've got, but maybe they haven't got ALL their emissions controls removed. Thanks!

abecedarian

1) the timing should be at your initial setting at idle
2) the timing should advance with your rpm's
3) the timing should advance or retard based on throttle opening

#1 is pretty self explanitory: is checked with vacuum port(s) disconnected and vacuum lines plugged.

a single port vacuum distributor takes care of #2 through weights and springs in the distributor and #3 through the vacuum port- high vacuum advances and low vacuum retards the timing.

the dual-port vacuum distributors don't have weights and springs to mechanically move the pickup coil, thus rely on vacuum porting to accomplish moving the pick-up plate. Full manifold vacuum pulls on one side of the diaphragm and ported vacuum from near the throttle plate pulls on the other side of the diapragm to change vacuum according to throttle position. At any particular throttle position, held constant, manifold vacuum will be at a stable value, as will throttle ported vacuum, and this should give you the (somewhat) correct advance for your engine speed and load.

now, I could be wrong, so don't take me to the bank on this, but that's my understanding of how the dual-diaphragm distributors work.

japjohnpeterson

I believe you are 100% correct. Some weber carbs I have seen, have that second diaphragm hooked up to manifold vacuum, some have it capped. I have tried both. So far it's not solving my problem.

Also, I checked through all my emissions controls today, looking for an electronic command, signal, or whatever that might be affecting my ignition timing. Can't find anything...

superex87

Might be a silly question but, How do you know the timing is retarding or advancing when not at idle?
Is it not running right/well?
idk if it matters or not but to accurately measure the timing, the engine may need to be under load.

japjohnpeterson

Timing light show me it's retarding. At about 2000rpm it starts to sputter, and backfire. Same issue if driving, so I assume it's doing the same as when it sits still and is revved.

superex87

That is quiet odd...
I would take the distributor cap/rotor off and confirm that when applying vacuum (sucking on the hose...) that the advance is actually working and moving in the correct direction.

Also, stuttering/backfire/afterburn could also be the carb running too lean!
Did the engine run ok before the rebuild?
What are the settings on the carb? Number of turns out from base of the idle mixture screw and jet sizes?
It is also common for the weber adapter plates to not seal well and cause a vacuum leak, aka running lean...

japjohnpeterson

Sorry... On vacation, so I haven't checked messages for a couple of days. We have checked the distributor though. I even went and got 4 more used ones just to be sure.

The engine ran fine til I blew it up. It is a complete rebuild with a new short block, as I snapped a rod, and blew a 2" hole through the block.

We have checked the carb for leaks, especially through those adapter plates as I've heard that thought from others. No leaks to be found. Will be checking the carb again as soon as I get back home.

abecedarian

Good luck.

drew303

sounds like a jetting issue... ive never seen a 22r retard, weber/or stock after throttling up, but sputtering sounds like a jet issue, cutting out, loss of power under load etc, atleast in my weber experience. Backfiring however, never had that, so this is tricky.

if you've gone thru 4 dizzies... my monies on something not working right in that weber.

japjohnpeterson

WAHOO!!! Carbs good... Dizzies good... Jets good... Turns out there's a bit of electronic retard in the ignition module under the ignition coil... That was malfunctioning enough to cause an extreme retard in timing... New ignition coil assembly, and purring like a kitten at all RPM!

abecedarian

Yay!

Glad to hear it's running.