304 rebuilt-need timing help! RESOLVED! Look

[79cj5]

I have just finished the rebuild and start-up of my 79 304 in my cj5.

I rebuilt with the original distributor, msd6/tfi ignition upgrade, edelbrock 600, edelbrock performer cam, and performer intake. I can set my base idle timing at 10 btdc and run it fine without the vac advance connected. If I connect it to ported vac, it back fires through the carb when accelerating. If I run it without vac advance, I am at about 22 btdc at 1800rpm...don't know what timing is at higher rpm. The engine feels solid but lacking power when accelerating. :-|

My vac advance can is at full advance at 12-13" Hg...it begins advancing at about 2-3" Hg. Does anyone know if this is within specs??? I cannot find a replacement vac advance can to fit. Does anyone know of a matching unit for a different application? Ford maybe???

My carb is brand new and I have verified closed butterflies at idle.

Can anyone help? I need some advice to get timing right with vacuum advance.

Greg
79 cj5 304/t-150 full restore

[pyagid]

On initial start with my dads 304, with the advance disconnected and pluged we ended up at 14 BTDC I believe with the advance hooked up it was at about 34 I will have to talk to him to verify, or maybe i could get him to actually post here, since he is stuck in the house for 7 days due to knee surgery.

-Paul

[dimension4]

How does your manifold vac. look?

[79cj5]

Manifold vacuum is steady at 19".

[BRAD ARTHUR]

i am running close to the same set up with the hei inmstead of the tfi /msd. and can only pull around 15" hg @ idle , and i am @ 10* btdc. what rods and jets /springs are you using in the 600 cfm carb?

[79cj5]

Brad

I don't have a good carb setup yet...I can't get timing to a happy location with decent throttle response... and if I add my vacuum advance everything goes bulls**t. Back fires and shuts down.

My last bit of tuning included going to pink springs for the 19" of vacuum and rods for the "#23" position in the book. It improved the response but it is still running like sh*t. I also am having trouble getting my idle screws to adjust much...I seem to have the throttle advance (idle) screw in too far just to make it idle well. I suspect that I have the mid circuit opening too soon.

I am about to tear the front down, verify proper oil passages at the cam and timing gears (to put myself at ease), and verify proper timing chain/gear position. Sort of "Start Over"!

I also had a 3-angle valve job done on the heads which may? improve vacuum.

What timing set are you using?

What is your carb set-up? How does it run?

Greg
Florida

[ol' school power]

On initial start with my dads 304, with the advance disconnected and pluged we ended up at 14 BTDC I believe with the advance hooked up it was at about 34 I will have to talk to him to verify, or maybe i could get him to actually post here, since he is stuck in the house for 7 days due to knee surgery.

-Paul

34 @ idle?
What did you connect the advance to?

[79cj5]

I just posted this on the MSD tech board.

MC-We spoke about this yesterday...read the solution it may make you sick.

""""
I recently rebuilt my '79 Jeep 304 v-8 with new edelbrock cam, edelbrock intake, edelbrock carb, msd6 ignition, msd tfi coil and original distributor. I purchased and installed the msd 8869 wiring adapter to connect the msd6 magnetic pick-up wires to the oem motorcraft(ford) distributor. When I fired the motor it ran poorly. Rough idle, timing was impossible to set, vacuum advance caused timing to become totally erratic, slight misses that seemed to move around the engine, etc. I managed to run-in my new cam at 2000 rpm, but it otherwise would not run.

I have chased all possible sources of the poor running conditions for three weeks. Thank god this isn't my daily driver!I have posted questions on four different forums trying to get a little help. I was about to tear my front end apart to inspect my timing set to make sure that I installed it correctly. There must be a mistake somewhere. Yesterday I thought I would look here again to find any clues. Someone had recently posted about his similar installation (and problems) on his ford motor with the same 8869 wiring adapter. He had found the wires to be reversed in the adapter. He switched them and it ran well. The msd tech appologized for poor quality control.

I went home last night, studied the wires from the msd6 through the adapter and into the distributor and couldn't find any obvious wiring reversals. I could not verify, however, the proper location of the adapter wires at the distributor end since they disappear into the waterproof (motorcraft) plug. I decided to try reversing the wires at the msd6 end of the adapter. I plugged it in, started the engine, twisted the distributor, and it settled right into a smooth proud idle. Wow! I fixed it; but by "fixing" the manufacturer's mistake...this really agrivated me! So either the polarity is reversed in the msd6 unit, or the adapter was built wrong.

I am glad it is now running properly...thanks MSD???

Greg
Florida
"""

[Penguin]

Not to be jerk, but I am so glad you had this problem. I am going to be going with this setup and you saved me from commiting murder. I would have killed someone on that problem.
So now I just have to rememeber this problem if I have the same symtoms.

[pyagid]

Excellent discovery, unfortunatly it happend. But your MAJOR headache will save lots of other people from headaches.

Thank you very much for sharing this with us

-Paul

[jeepsr4ever]

:? I knew it was something stupid simple..thats great man

[BRAD ARTHUR]

hey glad you fixed it ! :t: i also had the 3 angle valve job done @ rebuild. i am back at the stock settings for the 1405 carb , went al the way rich and plug reading was good but sucked mpg. the timing set is an edelbrock. keep me updated on that carb if you adjust her. i'll play with mine!

[79cj5]

For Brad and others...

The engine now has 15" of steady vacuum...I am currently running the orange springs with the standard rods and jets. My idle smells rich so I suspect that my idle circuit needs to be adjusted. I'll post final set-up notes after I finish.

Greg
Florida

[ol' school power]

That's why I initially posted ( on the other forum) to hack up a distributor cap and watch the rotor with a timing light.
You would have seen it plain as day.
Either way, it's resolved.