|
|
Vacuum advance can "?"
#1335129
11/14/12 10:30 AM
11/14/12 10:30 AM
|
Joined: Aug 2004
Posts: 8,087
Elk Grove, Calif.
bigblock340power
OP
master
|
OP
master
Joined: Aug 2004
Posts: 8,087
Elk Grove, Calif.
|
OK first, no I'm not sure it's adjustable. I really haven't looked. But I will.
I was tuning on my truck the other day, ('76 360/auto, 2BBL)'cause I noticed it pinging after heating up. Noticed my timing advance was a miss. I set the antical timing according to specs (with Vacuum advance blocked off, carb port plugged). When I put the v/a hose back on the timing went bonkers. Couldn't get it to settel down. Went way to advance. I tried sucking on the hose (keep it Moparts friendly) to see the v/a working in the distributor, it did. This has me baffeled. I left the v/a off and blocked off the vacuum port on the carb. Truck runs fine like this. I'm thinking new v/a canister, or just leave it off?
Thoughts?
|
|
|
Re: Vacuum advance can "?"
[Re: bigblock340power]
#1335130
11/14/12 11:12 AM
11/14/12 11:12 AM
|
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
|
Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
|
I'm assuming this is a stock eng with OE light and heavy springs in the dist. What is the initial and the total? (both checked with vac adv plugged). You would want the vac adv hooked to a ported port and have the idle speed low enough so there's little/no vacuum at idle & it sounds like you are getting vac at idle. Suck on the hose or use a vac pump if you have one then pinch the hose & see if it holds vacuum but I dont think that's the issue but I would check it. Yes when the curve starts would be adjustable with a 3/32" allen wrench in effect giving you more/less advance at any point along the slope at a given in hg till you reach the amount of vac needed to max the cans' advance and CCW requires more vacuum to get it started/& less adv at a given in hg. more info needed/holler back. EDIT when was it pinging: part or WOT. what rpm what gear
Last edited by RapidRobert; 11/14/12 11:31 AM.
live every 24 hour block of time like it's your last day on earth
|
|
|
Re: Vacuum advance can "?"
[Re: RapidRobert]
#1335132
11/14/12 01:38 PM
11/14/12 01:38 PM
|
Joined: Aug 2004
Posts: 8,087
Elk Grove, Calif.
bigblock340power
OP
master
|
OP
master
Joined: Aug 2004
Posts: 8,087
Elk Grove, Calif.
|
Quote:
I'm assuming this is a stock eng with OE light and heavy springs in the dist. What is the initial and the total? (both checked with vac adv plugged). You would want the vac adv hooked to a ported port and have the idle speed low enough so there's little/no vacuum at idle & it sounds like you are getting vac at idle. Suck on the hose or use a vac pump if you have one then pinch the hose & see if it holds vacuum but I dont think that's the issue but I would check it. Yes when the curve starts would be adjustable with a 3/32" allen wrench in effect giving you more/less advance at any point along the slope at a given in hg till you reach the amount of vac needed to max the cans' advance and CCW requires more vacuum to get it started/& less adv at a given in hg. more info needed/holler back. EDIT when was it pinging: part or WOT. what rpm what gear
Pinging starts right from the get go off a light/stop sign (when the truck is warmed up), at or just below WOT (so under power). The vacuum advance (ported) is in the same spot as it's been from the factory (factory carb. and manifold). I know that it's right. I can do the other tests you suggest in a while. Initial timing is 5 BTC, total is about 30/34.
|
|
|
Re: Vacuum advance can "?"
[Re: bigblock340power]
#1335133
11/14/12 01:49 PM
11/14/12 01:49 PM
|
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
|
Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
|
The initial and total are certainly conservative. With the allen wrench I'd crank it 4-6 turns CCW & retry. Are the stock (1 light 1 heavy) springs still in there? EDIT When you said the timing goes bonkers with it connected did you mean that you are getting vacuum at that port at idle or just that it's pinging as you described (or both)? With it disconnected/capped there is NO ping under the same conditions correct? EDIT Now I know what was bothering me that I was missing, you said that it was pinging at/near WOT & at and or very near WOT there would be no vac adv added & if it is pinging at that point either the timing is excessive (not the case here) or the DCR is too high (not likely on a stock 70's 360) or the fuel is real poor (maybe) or the springs are too light or are broken (I'm assuming they are not) or the eng is running real hot. I still feel like I've overlooked/missed something simple
Last edited by RapidRobert; 11/14/12 02:20 PM.
|
|
|
Re: Vacuum advance can "?"
[Re: RapidRobert]
#1335134
11/14/12 02:48 PM
11/14/12 02:48 PM
|
Joined: Aug 2004
Posts: 8,087
Elk Grove, Calif.
bigblock340power
OP
master
|
OP
master
Joined: Aug 2004
Posts: 8,087
Elk Grove, Calif.
|
OK, I think we got this thing figured out. My friend was helping me with this. When he told me the timing was going "bonkers" he ment at a higher RPM. At idle all looks good. I took the truck out and drove it with the VA disconnected, and the port plugged. No pinging, ran good. Came back, set the timing, and re-connected the VA. Took it out again, no pinging ran real good.
Thanks
|
|
|
Re: Vacuum advance can "?"
[Re: bigblock340power]
#1335135
11/14/12 04:32 PM
11/14/12 04:32 PM
|
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
|
Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
|
Where did you guys end up setting the initial at that took care of it
live every 24 hour block of time like it's your last day on earth
|
|
|
|
|
|
|
