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Well okay guys, something just isnt right with my chevy 350, It just dosnt have the power it needs, and it randomly backfires but very randomly and not often. i have a 570 cfm carb on it and it dosnt even want to accept the secondaries opening even though it should be too small of a carb (it wants the stiff black secondary spring) and at wot it dosnt want to accelerate after 40 mph. Ive tried to diagnose the problem today by putting the engine on tdc, i pulled the dist. Cap and the rotor was a tooth after it being exactly lined up with the #1 spark plug pick up so i retarded it by 1 tooth taking it back to point at the #1 cylinder and went to go fire up the engine and it didnt want to start! So we advanced it aton to even get it running and it wouldnt even take any gas with out stalling. Why would it run with the dist. A tooth retarted but not with the rotor pointing right at #1? is it possible that in the past when i changed the timing set i have the cam a tooth off? Or do i have a cam that requires a degree timing set? At idle it ran good at 15 degree advance, and if i remember correctly it got to 36 degrees total advance. Thanks for the help and im more then willing to answer any questions!
 

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Discussion Starter #5
That is correct, it is 15 degress with or with out the vac advance on, i had a stock timing cover on my 350 but i took it off and replaced it, and i put on an aftermarket timing pointer that matches the same point the stock one did, i didnt replace the damper, i put the motor on exact tdc with a thread in tdc finder and the line still matched up so it didnt move either and i will give that page a look!
 

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So what i got from that article that i need to do is make some timing tape, then get the compression stroke on tdc and stop at 10 degress before tdc, and put the rotor pointing at the #1 cylinder
 

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Discussion Starter #7
because before i had the engine at tdc and had the distributor pointing at the number 1 cylinder, that explains why it needed so much advance to even start that way
 

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because before i had the engine at tdc and had the distributor pointing at the number 1 cylinder, that explains why it needed so much advance to even start that way
Have your rotor pointing to the 'distributor cap's' post that you plan to start #1 wire at, not the cylinder. typically if the motor is on TDC compression stroke, the rotor will be pointing at about 5:30 and should be pointing to the post..:D
 

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Discussion Starter #9
Have your rotor pointing to the 'distributor cap's' post that you plan to start #1 wire at, not the cylinder. typically if the motor is on TDC compression stroke, the rotor will be pointing at about 5:30 and should be pointing to the post..:D
Right, i was just referring to how the wiki article said how to do it that was shared above, and just kind of simplifying it to make sure i understood it correctly
 

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When was this motor running correctly? What has happened since then?

X2 with finding correct TDC. Piston stops are cheap or easy to make if you have some fabricating skills.

Questions : how do the plugs look?
How does the cap and rotor look, especially on the contacts?
What color is the spark?
Have you checked the wires?

A manual compression or leak down test wouldn't be a bad thing. Your issue prior to pulling the distributor is a classic sign of cam going flat.

And I'd say don't worry about the tooth off thing. If the timing set is off, then it would've never ran correctly. And being a tooth off on the distributor has no bearing - the rotor can point anywhere - what's important is getting the plug wires on the correct post depending where the rotor is pointing when at #1 TDC.
 

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Discussion Starter #11
When was this motor running correctly? What has happened since then?

X2 with finding correct TDC. Piston stops are cheap or easy to make if you have some fabricating skills.

Questions : how do the plugs look?
How does the cap and rotor look, especially on the contacts?
What color is the spark?
Have you checked the wires?

A manual compression or leak down test wouldn't be a bad thing. Your issue prior to pulling the distributor is a classic sign of cam going flat.

And I'd say don't worry about the tooth off thing. If the timing set is off, then it would've never ran correctly. And being a tooth off on the distributor has no bearing - the rotor can point anywhere - what's important is getting the plug wires on the correct post depending where the rotor is pointing when at #1 TDC.
Right now im going to test a theory i have that article the guy above posted to put the crank at 10 degrees before top dead center and put in the distributor pointing to #1 ive never done that before but i see it being very promising, but if that dosnt work ill post the results and start doing more of the tests you suggested
 

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hi. while you are testing things, check the carb floats, fuel pressure and fuel flow. the fact that was running OK and now seems to die out around 4k rpm, to me seems like it might be running out of fuel. you may be looking at a low float level or plugged fuel filter. your looking for 5-6 psi of fuel pressure and you should get about a cup of fuel in 10-15 seconds. ALSO inspect your balancer very very closely. if you see any bulges or irregularities in the rubber band between the outer ring and the hub, replace the balancer, it has shifted or "spun" and is not in proper position any more. this is a very common problem on sbc engines. good luck and good hunting,
 

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Discussion Starter #13
Okay guys, i have an update, I think i got the timing situation delt with, The question is i just put in mr gasket mechanical advance springs and weights but now the timing is really advanced like 40 to 45 degress at like 5000 rpm, how do i limit the advance? The timing kicks in at 35 degress at 2500 rpm like i wanted but how do i limit it so my engine dosnt detonate, thanks!
 

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http://www.crankshaftcoalition.com/wiki/Hot_rodding_the_HEI_distributor

Reading all of this would be helpful to you. But if skip to the section titled ignition advacne, then what you're experiencing will be explained - and it is normal if you're seeing this much timing sitting in the driveway free revving the motor to 5K and holding it there if the vac can is hooked up.

When revving the motor to 5k with no engine load allows the vacuum advance to be applied. Meaning that you will have your initial, mechanical (centrifugal) and vacuum advance all at once. If you were to check this with the vacuum advance line unhooked and plugged, then you would be able to determine the amount of vacuum advance your vac cannister is applying.

I mention all of this assuming that you measured it with the vacuum cannister hooked up. If it was not then let us know where the initial advance is and at what rpm the mechanical is 'all in', and lastly how much mechanical advance you have.
 

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please read the articles having to do with "total timing". this the total of the initial or base timing and the centrifugal timing. what you are looking for is 32-36 degrees total with NO vacuum advance. and it should be "all in " by 2800-3000 rpm. when you hook up the vacuum advance you should be looking for 48-50 degrees at 3000 rpm with no load on the engine. spinning it to 5000 is not the proper way to set timing and is hard on the motor. by the way- if the total advance with the vacuum is higher then 52 degrees back down the vacuum advance by getting an adjustable advance can for your distributor. if you are running a gm HEI unit there is a provision built into the distributor to limit the amount of centrifugal advance it puts out. this web site has a great article on timing in the WIKI TECH section on the home page. i followed the info in this article with my own car and gm HEI unit and it has never run better! BEST OF LUCK AND START READING MY FRIEND!:thumbup:
 
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