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Discussion Starter · #1 · (Edited)
Will be setting timing tomorrow (hopefully) on my gm performance 350 HO. The included specs calls for 32* BTDC @ 4000 rpm.
That's well and good, but is there any way to convert that to * at idle or 1000 rpm or something less than 4000 rpm? I'm not sure I could even see 32* BTDC behind the serpentine belt system... That would be about an inch or so before the timing tab!!! The tab doesn't even read 32* BTDC.
I did read one supplier spec that said 10* base BTDC 32*total. Are they saying 10* at idle will be 32* total?
Just read another supplier spec. 10* BTDC @ 700 RPM. Is that my answer? Add anything for 5000' altitude? We used to ad a couple degrees in the old days?
Am I missing something here?
Thanks again...
 

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Depends on the octane rating of the gas you use. You can advance it till you get detonation then back it off a scoch. 10 degrees is a good place to start.
 

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Discussion Starter · #5 ·
2800 rpms would be good enough, what * is it at idle right now?
I haven't checked it yet, turned it until it turned over easily and started, advanced it until it reached the highest rpm and that's where I'm at. I'll put a timing light and tach on it today and see.
 

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I lived in Colo Spgs

while in the Army and found that I could advance the timing quite a bit,
I'd start with 10 degrees at idle, but would try more , alittle at a time,
I doubt you will want more than 5 degrees past that,
the 32 degrees at 4000, is IF your dist curve has been set up, (most are not!)
to limit total advance,
as stated, try until it pings and back off some,
 

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Discussion Starter · #7 ·
while in the Army and found that I could advance the timing quite a bit,
I'd start with 10 degrees at idle, but would try more , alittle at a time,
I doubt you will want more than 5 degrees past that,
the 32 degrees at 4000, is IF your dist curve has been set up, (most are not!)
to limit total advance,
as stated, try until it pings and back off some,


Set at 12* right now. Starts great and seems to be pretty good. Guess I'll stay here for a while a tweak it if needed.
 

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You can do some simple math and convert degrees to inches on your balancer.

Let’s say you have an 8 inch balancer:

8 X 3.14159 = 25.13272
25.13272 ÷ 360 = .0698131 inches which is 1°
.0698131 X 32° = 2.234 inches

Make a mark on the balancer 2.232 inches (2¼ inches) to the right of the factory mark. When this mark is in line with the 0 mark on the tab at 4000 RPM you will have 32° of total advance.
 

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You have two ways to check total timing.

1. Use a "dial back" electronic timing light. With it, when the dial is set at zero, you are reading the true timing on the timing tab. With say 10 degrees on the dial, your timing is what you read on the timing tab + the dial reading.

Note that most dial back lights don't work with MSD and other high output ignitions.

2. Get a degreed balancer or a "timing tape" so that you can extend what you can see with a standard timing light. Mr. Gasket sells the timing tapes very reasonably. Or you can make marks with a tape measure as Farm Boy suggests.

Total timing is not the whole answer. And 32 degrees is more of a "safe" setting than a good performance setting. For starters what grade of fuel you use is a big factor.

There's lot's more than this, but that's for other posts.
 

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I feel your pain on trying to read the timing with all the stuff in the way. I ended up taking the belt off to be able to get the timing light close to the tab. Worked for me.
 

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Discussion Starter · #11 ·
I feel your pain on trying to read the timing with all the stuff in the way. I ended up taking the belt off to be able to get the timing light close to the tab. Worked for me.
Got it set at 12* at idle. Seems to be good, starts easy and idles good, although the rpm is much slower than when I had it around 16* and it still started fine at 16*.
I'll leave it at 12* and see how that works for awhile. Need to run up to the auto parts store an get some 1/4" tubing so I can hook up the vac adv. see what that does...
 

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I'm not sure of the hp and compression you have, but most sbc engines like 8-12* of initial timing. They also like about 36* of total timing (32* for vortec engines). I agree with the others, to do this right, you need to get a dial-back timing light. Also, does your distributor have vacuum advance? That will change your part-throttle timing, and if it is too aggressive, you will ping.

If you have a relatively stock engine, I would start with 10* at idle and with a dial-back timing light, set 26*. As you rev up the engine, you will see the timing mark get closer to the timing tab on the block. If you can't "zero" out the light, aka put the timing mark back on your idle amount (in this case 10*), then you don't have enough total timing.

If you have a pertronix, msd or mallory distributor, you can recurve the timing advance with a combination of springs and weights. This is how you really dial in your advance for your car.
 

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Good read HERE...just did this myself. Get yourself a good dial-back timing light as others have said.
 
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