tune up ???s
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tune up ???s
I have a 72 350/190 hp but was rebuilt before I got it. What is the Dwell angle setting? Also, the mechanical advance works fine but when I disconnect the vacuum advance hose, the timing marks move away from zero instead of toward it and when reconected it increases the advance. Looks like I need a new vacuum advance? Thanks, Paul
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by Paul72
and when reconected it increases the advance. Looks like I need a new vacuum advance? Thanks, Paul
this sounds right to me? if you have vacuum the vac cannister should advance the timing, why do you think this wrong?
the timing tab has numbers on both sides of the 0 could you be reading it wrong?
Le Mans Master
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From: Little Rock AR
Originally Posted by Paul72
I have a 72 350/190 hp but was rebuilt before I got it. What is the Dwell angle setting? Also, the mechanical advance works fine but when I disconnect the vacuum advance hose, the timing marks move away from zero instead of toward it and when reconected it increases the advance. Looks like I need a new vacuum advance? Thanks, Paul
The vacuum advance is probably set up to use manifold vacuum based on what you have described. This is probably not the way it was from the factory but this is not always a bad thing. If this was done right, it works great. I have it that way on my cars.
The thing that sounds strange is the way it behaves when you disconnect the hose...
"when I disconnect the vacuum advance hose, the timing marks move away from zero instead of toward it and when reconected it increases the advance."
This is confusing from what we would expect. The timing should go closer to zero with the hose removed and it should advance with the hose installed. If the timing advances with the hose connected and backs off with the hose removed you are doing fine.
This assumes that the correctly selected replacement vacuum advance canister was installed in the first place. You can not just hook up the hose from the ported connection and slap it on the manifold vaccum using the factory vacuum advance canister and expect it to work properly.
Hope this helps in some way.
-Mark.
Last edited by stingr69; Apr 26, 2005 at 08:18 AM.
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by stingr69
The thing that sounds strange is the way it behaves when you disconnect the hose...
"when I disconnect the vacuum advance hose, the timing marks move away from zero instead of toward it and when reconected it increases the advance."
-Mark.
"when I disconnect the vacuum advance hose, the timing marks move away from zero instead of toward it and when reconected it increases the advance."
-Mark.
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Thanks for the info, the orginal dwell was at 20 so I'll set it to 30 tonight and recheck the timing and the vacuum issue. I know the replacement edelbrock carb has 2 places for the vacuum and maybe it is in the wrong one. The engine does run well and has good power so that is why the vacuum results seemed off to me.
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From: Little Rock AR
Originally Posted by bobs77vet
you know could this be happening.....lets say the initial timing is at 8* BTDC with direct vacuum.....he disconnects the vacuum and it moves away from 0 to say 4* ATDC....then when he connects the vacuum it advances the timing to the BTDC range....however can a car effectively run at timing ATDC?
-Mark.
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From: Des Allemands LA
Originally Posted by Paul72
I have a 72 350/190 hp but was rebuilt before I got it. What is the Dwell angle setting? Also, the mechanical advance works fine but when I disconnect the vacuum advance hose, the timing marks move away from zero instead of toward it and when reconected it increases the advance. Looks like I need a new vacuum advance? Thanks, Paul
ltlevil
