What Manifold Vacuum and Timing w/ these mods?

[FullSizeJeeper]

Alright, now I'm getting somewhere, finally got a guy over to help out today. It helps having someone more knowledge than yourself sometimes!

Anyway, had/have a couple of issues. First had the EGR hooked to maniflod vacuum and was pulling my vacuum down by staying open at idle. Teed that off the ported vacuum from to the dizzy and cut out the EGR TBI switch altogether. That helped alot.

Next we richened up the carb. I was running a little lean on that.

Next we timed with an advance light were it was running best and it was at 29* with 55* total. Took it down to 10* degrees, and it would back fire, worked it up in increments and it likes it at 23*-24* - no pinging or backfire. With a total of about 50*

Pretty sure I need to degree that cam. Summit said the intake should open TDC, close 34* ATDC
exhaust open 49* BBDC, close 5 BTDC . I had this cam in this same motor for a couple of thousand miles and didn't degree it had ran fine

It also had a stumble on WOT before the vacuum advance kicked in so we lighten the springs to kick that advance up a little quick. She runs much smoother now and will put you back in your seat. But it should not be at 24* BTDC. So I will be researching this site and the AMC Forum (which is back up) to make sure I know what I'm doing and take the cover off and make it scream.

Thanks everyone for all the input. I feel alot better openning the cover when I have a clear objective, not just looking for what could be the problem. I'm starting to get excited this baby is going to rip when the valves are openning on time! She has more power at this moment than she ever has.

One last question for this post. My mechanic friend does not seem to think running it softly with the timing at 24* will hurt in the next week. I plan to do this next weekend, but may need to some run errands next week. Will running it a low RPMs during the break in period with late valve timing be bad? I'm so close I don't want to screw up now!

[FullSizeJeeper]

One last piece of the puzzle. We did a compression test and the values are still very close al at the 165 to 170 range. So I feel like my valves are adjusted pretty well. Its just the retarded cam thats missing stuff up. Not the retarded home mechanic.

[1980_Cj7]

Is it still pinging? Don't run it if it is.

[AMX69PHATTY]

If the lifters are pumped up from running the engine then they will not bleed off immediately when adjusting the valves. That's why when adjusting them, they would open the valve when going 3/4 turn past zero lash. After a while under spring pressure the lifter should bleed off and allow the valve to close.
The .020 to .045 lifter preload is just to get the lifters inner plunger from off of the intenal snap ring that holds the plunger in the lifter body when they are loose and in the box, and to keep the plunger from "bottoming out" on the snap ring when they pump up. If you have 3/8-24 Rocker Studs, then 1 turn turn equals .042", if 7/16-20 Rocker Studs, then 1 full turn equals .050", so in both cases 1/2 to 3/4 turns should be good. I know when I did mine with the intake manifold off, there was very little resistance from the plunger when zero lash was reached. I could look and see exactly when the plunger started to move off of the internal snap ring. Would be hard to judge from just feel with the intake mounted, but the lifters were not pumped up since the motor had not been ran. Might be easier to go by feel once they're pumped up I guess.

A stumble right off of idle is usually the accelerator pump out of adjustment,
or too little of an accelerator pump shot.

Man that's way too much timimg advance, can't be good for it.

Have you checked the distributor Phasing ?
The Distrib Cap is keyed to the housing and does not move.
I used an old dist cap and hacksawed a big strip out off the side of it si I could see what was going on inside.
When the mech advance is all the way in, the rotor button should be pointed directly at a spark plug wire post. It's tricky cause when sitting initial the whole dizzy is turned, which moves the "switch" (points) relative to the dist shaft "bumps" or "triggers" relative to the crank, mech advance moves the "Bumps" or trigger or reluctor relative to the "switch", and vacuum advance moves the "switch". Three different things moving there. When Phasing the distributor, when full mech advance is in, when the "trigger" trips the "switch" the rotor button should be pointed directly at the post in the cap. On my '69 Delco dizzy it wasn't very close to being properly phased stock unless there was full vacuum and mechanical advance, and total advance of both was basically never achieved because the weights were light and the springs heavy and engine vacuum was low due to the big cam. I removed the vacuum advance altogether, installed heavy weights and light springs, phased it, and locked down the "switch" plate in that postion. The Vacuum advance normally hold the "swith" plate in position, so with it removed it was free and had to be tied down with a little metal strip and a screw in a vacuum canister mounting hole.

I know what you mean about 6 marks on the crank sprocket and 3 settings. Each setting has a mark by the keyway, and another corresponding mark by the tooth that goes with that keyway.

[FullSizeJeeper]

Yes 24 is way to much, but no ping. My understanding is by not degreeing the cam, I'm openning my valves are late and the engine is not running very efficently. We are adjusting for the late valves by advancing the timing. Thus it is firing closer to the valve timing. It seems this would cause potential probelms because it is firing way before the cylinder reaches TDC. This could stress the lower end and cause excess heat correct?

AMXPhatty
I will reread you phasing post when I'm fresher. I think I understand but it been a long day (several months) dealing with the engine). I'm going to try and grasp the cam dailing procedure first and take care of that and go from there.