No Advance at all?

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jimmyray

jimmyray

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I recently had issues with the distributor that actually turned out to be a bad ecu. Got that fixed, car running, but no power at top end, kicks back, stalls, etc at WOT.

340 engine, Comp Magnum 280 cam, headers, Edel performer intake with 625 carter. Supposedly a Clyes timing chain. Mileage is unknown, suspect 75,000 +.

I mapped the timing and this is what I found:

idle - 850 - 10 degrees BTDC
1500 10 " "
2000 8 " "
3000 8 " "

Yes, it actually LOSES timing as the rpm's increase. That explains a lot regarding the poor high rpm performance, eh?

I swapped in another distributor, just to be sure it was not it, and checked the oild pump gear in the meantime, which looked fine, very tight fit against the cam drive.



I suspect the timing chain, but would like your thoughts before pulling it down.
 
This is a phyical impossibility, unless you have parts in your dist. wrong, like RB parts causing the advance to work the wrong direction

or something is so badly worn in the mechanism that it simply is not working

How are you determining this? You using a 'delay' or "dial back" timing light?

If so, throw that thing on the bench, degree your balancer, and use a standard old non-delay light
 
Vac advance on constant vac port on carb? Would explain more adv at idle, and retard as throttle opens, vac drops-timing retards, esp at wot. Try Capping all vac ports cept pcv on carb and run with no vac line on dist at all. See what happens. Unless you didnt have vac adv hooked up to begin with, in which case disregard post, you have other issues.
 
66V100 said:
Vac advance on constant vac port on carb? Would explain more adv at idle, and retard as throttle opens, vac drops-timing retards, esp at wot. Try Capping all vac ports cept pcv on carb and run with no vac line on dist at all. See what happens. Unless you didnt have vac adv hooked up to begin with, in which case disregard post, you have other issues.
Click to expand...

Good point. I assumed he had disconnected vac.
 
Well, if it happens, it must be possible. I tested 2 distributors, both with clowise rotation of the button to indicate mech. advance, as well as the pin in the CW direction.

I switched to my backup timing light, the trusty Sears metal version, with no features other than a trigger, LOL. Same results. timing basically does not move as engine is revved. Weird, never seen this before. I may try swapping out the distributor in my Duster, a known good one that works, but if the other 2 (a new reman one and the one in the car) gave these result, then something else is going on.

I snugged the timing chain by rotating the engine by hand CW to the 10 ATDC, and then rotated the engine CCW, and the rotor started moving at about TDC, so there is about 10 degrees slack in the chain. Is this excessive?
 
Funny, i try not to assume much, check the simple obvious first :)Make sure you have the proper year timing cover/damper combo as 70 was the change year and everything swapped sides.
Cam timing does retard as the chain bushings wear (stretch) which is why i set all mine *2 to *6 adv dep on grind. If i remember corectly the old book general spec is 3/16" of slop, measured at damper. 10 seems to be a bit much, would prolly have erratic timing with lite. Pop & snort under hard accel. Had an old wore out 318 do this to me long ago, put a new t set in and ran like a tired champ.
Sounds like you did all the obvious external poss. I'd throw a chain at it.
 
Im wondering if the 2 degrees are just the rubber ring in the middle of the damper stretched at higher rpm like the outside cant keep up with the center,rubbers worn out. Sure the mechanical weights arent locked out? or maybe no springs or broke springs and its retarded to where its reads 10 degrees with all advance in.
 
daredevil said:
Im wondering if the 2 degrees are just .
Click to expand...

I mis-read the OP If it's only changing 2* it must be the dist. mechanical advance is stuck, or he's got himself a "lean burn" distributor
 
I bet 2 degrees is just a sloppy damper. but either the dizzys all in and dialed back or the mechanicals stuck.
 
Jray: not being condescending but: do the dist you are using equiped with functional mechanical advance? Or welded, pinned, or lean burn?
 
66V100 said:
Jray: not being condescending but: do the dist you are using equiped with functional mechanical advance? Or welded, pinned, or lean burn?
Click to expand...

Nope, it's the correct distributor. I checked mechanical advance, it moves freely.
Bad news. Went to start it a bit ago, and it was spitting back and actin like I had way too much advance. Nothing changed since I ran it this am. I retarded the distributor about 40 degrees, and got it to fire off. Barely made it to the garage no power! Im thinking it has now jumped timing. Something is really weird, never dealt with this problem before. It was running fine until recently, where it has quickly degraded think I will put chain in it next, as this one does seem noisy.
U
 
Oh, and I did Mark th inner and outer ring of the damper, it has not moved.
 
Is what i figured. Anytime i've seen a damper move, it stayed moved and kept moving!
Weak springs rev and advance easy, but retard & die at low rpm in drive. (unless weights are drilled/lightened) which is the exact opposite of your symptom.
Double check your ign components, altho i've never seen faulty ign retard timing, unless you have a boost/retard box your keeping secret;)
Good luck, hope the tset cures it.
Cam calls for 106 icl?
 
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