Total timing question

[81GrandPrix383]

Have you verified were TDC is? do you have the right balancer and pointer? some have tdc at 12:00 and others at 2:00 and it could be throwing off your reading. Just throwing some ideas out there

Thanks,

I'm at work not at home where my car is.
Trying to figure out what balancer I have on the car.
It looks the exact same as the 8" summit racing one with the pro street sticker on it.

When I put everything together top dead center was at the zero on the pointer and balancer.
I cant confirm that they still line up now.
Interesting.

 

[81GrandPrix383]

Do you have a stock harmonic balancer on your engine? If so it sounds like the outer ring is slipping and your 42 degrees could very well be 36 degrees.

Stock or not, I'm starting to think this is the problem because a few months ago we set the timing to 38* and it ran okay.
Now 38* doesn't cut it. Spun damper sounds like the explanation without even checking....but I will still check.
Thanks.

 

[DoubleV]

If I set the total timing to 34 to 38 degrees the car does not run in gear unless I have the idle set to 1300rpms and it keeps running after I shut it off.

Total timing has nothing to do with how much timing you have at idle( aka intial or 'base' timing ). Your timing you get at idle is just your base timing. If you're running the vac advance off manifold vacuum, then it would be even higher. The total timing ( base + mechanical ) has to do with making the most power at higher rpm's, not getting a good idle.

Note adjustable timing lights CAN be very inaccurate. Might want to try another non-adjustable light.

If you know for a FACT your MSD is giving you 22 mechanical, then set your adjustable timing light to 0 ( or use a good non-adjustable one ) and set your base timing to 14. If you do that then you know you have 36 total timing. If your engine refuses to idle like this and/or not make good power up top, then there are most likely issues elsewhere like spun balancer ( giving you false timing numbers ), distributor off a tooth or carb issues.

 

[565bbchevy]

The MSD Streetfire is 21 degrees of built in advance and apparently not adjustable. I would try setting your timing as DoubleV suggested and try to use a timing light without the dial back feature because MSD's can get fluctuations in readings sometimes but more so with the separate ignitions box versus HEI.
If your balancer is similar to the Summit pro street unit then it is a 2 piece (basically a stock design) and if it is the one that is around $60 then quality could be questionable so I wouldn't rule it out as a possible issue.
Also since you have a 383 is it internal or externally balanced?

 

[81GrandPrix383]

If I set the total timing to 34 to 38 degrees the car does not run in gear unless I have the idle set to 1300rpms and it keeps running after I shut it off.

Total timing has nothing to do with how much timing you have at idle( aka intial or 'base' timing ). Your timing you get at idle is just your base timing. If you're running the vac advance off manifold vacuum, then it would be even higher. The total timing ( base + mechanical ) has to do with making the most power at higher rpm's, not getting a good idle.

Note adjustable timing lights CAN be very inaccurate. Might want to try another non-adjustable light.

If you know for a FACT your MSD is giving you 22 mechanical, then set your adjustable timing light to 0 ( or use a good non-adjustable one ) and set your base timing to 14. If you do that then you know you have 36 total timing. If your engine refuses to idle like this and/or not make good power up top, then there are most likely issues elsewhere like spun balancer ( giving you false timing numbers ), distributor off a tooth or carb issues.

Friend, we are having a communication problem.
I set the timing at 3200 rpms. I was just mentioning the idle. 2 different things.

 

[81GrandPrix383]

The MSD Streetfire is 21 degrees of built in advance and apparently not adjustable. I would try setting your timing as DoubleV suggested and try to use a timing light without the dial back feature because MSD's can get fluctuations in readings sometimes but more so with the separate ignitions box versus HEI.
If your balancer is similar to the Summit pro street unit then it is a 2 piece (basically a stock design) and if it is the one that is around $60 then quality could be questionable so I wouldn't rule it out as a possible issue.
Also since you have a 383 is it internal or externally balanced?

I just checked TDC. just did it quick with a pencil in the #1 plug hole. Showed 9* advance at TDC.

Winner Winner Chicken Dinner.
Time to shop for a better quality balancer.

I don't want to spend more than I need to so I will ask. What damper is recommended for my setup.

Thanks again.

 

[online170]

To answer your original question, I dont think the engine will like 43*, its way too much. I think even 38 is too high, but im sure someone somewhere has a radical SBC that likes it.

Ive always found an SBC to be happy around 34-36.

If I set the total timing to 34 to 38 degrees the car does not run in gear unless I have the idle set to 1300rpms and it keeps running after I shut it off.
Vacuum is plugged into manifold vacuum, not ported but I have tried both and both were plugged off when I was setting the timing.

Sounds like an unrelated issue. 1300rpms will cause your car to run on because the idle is so high. It sounds like the other tuning issues are being brought to light as youre playing with the timing.



A big cam like yours, (assuming the XE274 like in your sig.) will like about 20ish degrees at idle. It will be lopey sound at 10-14*, but it should still run just fine. All DoubleV is saying is, youre setting your timing to total, but youre symptoms are all at idle (initial timing). Its kind of important to know what youre base is at in this case, since thats where your issues are.



Another thing to keep in mind, if you advance your timing, leaving all things the same at idle, you'll notice the idle starts to get faster. If you back off the timing, your engine might slow down again. Lets say your carb tuning, is WAAAAAAAAAAAAAAAAY off, and the engine doesnt like it when youre in gear, or idling, etc... If you advance the timing enough, the idle may speed up, and make it seem like its running OK.


I think you have all sorts of issues in your tune, but its hard to say without being there. Curious to see what you find. Keep at it, you'll get there.

 

[81GrandPrix383]

To answer your original question, I dont think the engine will like 43*, its way too much. I think even 38 is too high, but im sure someone somewhere has a radical SBC that likes it.

Ive always found an SBC to be happy around 34-36.

If I set the total timing to 34 to 38 degrees the car does not run in gear unless I have the idle set to 1300rpms and it keeps running after I shut it off.
Vacuum is plugged into manifold vacuum, not ported but I have tried both and both were plugged off when I was setting the timing.

Sounds like an unrelated issue. 1300rpms will cause your car to run on because the idle is so high. It sounds like the other tuning issues are being brought to light as youre playing with the timing.



A big cam like yours, (assuming the XE274 like in your sig.) will like about 20ish degrees at idle. It will be lopey sound at 10-14*, but it should still run just fine. All DoubleV is saying is, youre setting your timing to total, but youre symptoms are all at idle (initial timing). Its kind of important to know what youre base is at in this case, since thats where your issues are.



Another thing to keep in mind, if you advance your timing, leaving all things the same at idle, you'll notice the idle starts to get faster. If you back off the timing, your engine might slow down again. Lets say your carb tuning, is WAAAAAAAAAAAAAAAAY off, and the engine doesnt like it when youre in gear, or idling, etc... If you advance the timing enough, the idle may speed up, and make it seem like its running OK.


I think you have all sorts of issues in your tune, but its hard to say without being there. Curious to see what you find. Keep at it, you'll get there.

Thanks.

I never had my car at 1300rpms. that was just an example of what it would need to be at so it would not stall when I put it in gear.
Everything will fall into place once a new damper is installed.

 

[81GrandPrix383]

The MSD Streetfire is 21 degrees of built in advance and apparently not adjustable. I would try setting your timing as DoubleV suggested and try to use a timing light without the dial back feature because MSD's can get fluctuations in readings sometimes but more so with the separate ignitions box versus HEI.
If your balancer is similar to the Summit pro street unit then it is a 2 piece (basically a stock design) and if it is the one that is around $60 then quality could be questionable so I wouldn't rule it out as a possible issue.
Also since you have a 383 is it internal or externally balanced?

I'm having a bit of a memory issue. I bought all this stuff over 1.5 years ago.
I am 90% sure it is internally balanced.
Wow, that hurt. I haven't thought it once in a year.

Thanks again.

 

[565bbchevy]

As far as harmonic balancers you can't go wrong with the big name brands. I have personally used Fluidampr,TCI Rattler and ATI Super Damper and all have worked well. I currently have the TCI on which I like because if I don't get one of my spark plug boots on all the way it will rattle on that cylinder.
You appear to have a good amount of money in your set up so I wouldn't skimp on the one thing that keeps your engine balanced and if you go to the track you would want an SFI approved balancer anyways.