View Full Version : Timing affect on engine temp


sponge003
06-03-2009, 11:34:53 AM
What general affect does changing the timing have on your engines running temperature?

If you increase your timing (from 32 to 36 for example) will your temp increase or decrease?

Thanks

XxWickedz28xX
06-03-2009, 11:40:57 AM
I just went through this myself, and the fellas here set me straight, so im happy to pass along help.

My timing was off, it was about 8 at idle...car would run odd, and hot. Bumped the timing up to 14...car ran better, and cooler. So, for my setup, the more timing I gave it, the cooler it ran.

sponge003
06-03-2009, 11:52:13 AM
I just went through this myself, and the fellas here set me straight, so im happy to pass along help.

My timing was off, it was about 8 at idle...car would run odd, and hot. Bumped the timing up to 14...car ran better, and cooler. So, for my setup, the more timing I gave it, the cooler it ran.

Going to move timing @ idle from 11 to 15

COOL

TheStig
06-03-2009, 02:07:20 PM
Set initial at 12* shoot for a total of 34-36*. Limit the amount of vac advance to 8 crankshaft degrees and run it on manifold vac. This will give about 20* of timing at idle but will keep the total advance safe while under throttle. I have mine set up this way and I will never change back.

Todd80Z28
06-03-2009, 02:18:30 PM
The amount of vac advance is highly dependent on the engine config. 8* might be safe, but you may be leaving a bit of part-throttle response and fuel mileage on the table with so little.

I run almost 20* vac advance myself, on top of 10init, 34 total, but I have a fairly mild, 9:1 350 with aluminum heads and poor quench.

hhott71
06-03-2009, 02:59:20 PM
What general affect does changing the timing have on your engines running temperature?

If you increase your timing (from 32 to 36 for example) will your temp increase or decrease?

Thanks

it depends.

32 is usually way too retarded to get the proper burn in a typical SBC.
Too little timing and Too Much timing can have bad effects.

Depending on the Cam, Compression, Piston, Chamber, Fuel, Operating range, and a few more factors, 34-44 may work best, and of course light loads will want even MORE timing and that is where the vacuum advance is used, adding 10 or more.
The vacuum advance works best when connected to ported (or part-time) vacuum source, that is why the port is there. Having 10 extra vacuum advance timing at idle makes the engine idle faster, it also loses that advance and gets stumbly when that timing disappears, or can cause extra ping on light acceleration. ALSO too much timing ruins the sparkplugs, glazing and overheating etc.

Strive for 10-16 initial, 20-30 centrifugal and 10 or so vacuum advance.

sponge003
06-03-2009, 03:01:04 PM
I do not have vac advance, mechanical only.

This is strictly a track car right now.

I was running 32 total for the initial break in and first runs and am going to 36 total based on what we saw for times. might end up at 38 but we will wait and see.
The motor was getting a little warm ~210 running 2 classes and I was curious if changing the timing would help with this or add to the problem.

TheStig
06-03-2009, 03:12:15 PM
If its a track car only I would lock it at 36*

As far as the vac advance debate goes people will allways have thier opinions. I made the switch to manifold vac with great results and I will not change it back. My motor runs better, cooler, and way more responsive than it did on manifold vac.

Simon@London
06-04-2009, 09:15:58 AM
If its a track car only I would lock it at 36*

As far as the vac advance debate goes people will allways have thier opinions. I made the switch to manifold vac with great results and I will not change it back. My motor runs better, cooler, and way more responsive than it did on manifold vac.

???? so are you running port or manifold now. I have set my street up to 14/36 now and it runs fine.

hhott71 on this stock bottom end motor, Crane street Cam, flat tops, vortec heads is this a good timing range. You remember I don't run any Vac advance ( noise so that is dead issue )

idles at 14, all in at 36. Motor runs cool and exhaust seems to smell cleaner.

Todd80Z28
06-04-2009, 12:02:04 PM
I made the switch to manifold vac with great results and I will not change it back. My motor runs better, cooler, and way more responsive than it did on manifold vac.100% agreement on that.

If this is just a track car, then it's unnecessary, though. Vac advance does nothing at WOT.

TheStig
06-04-2009, 12:32:20 PM
100% agreement on that.

If this is just a track car, then it's unnecessary, though. Vac advance does nothing at WOT.

Thats exactly what I was trying to say when I said lock it at 36* I just figured everyone knew that.

hhott71
06-04-2009, 01:25:18 PM
My Racecar has the black bushing in the MSD 85551 which is supposed to be 18º advance, I use the Heavy silver spring and the blue spring so all the timing is in by 3200 rpm
The converter flashes to 3600 or so at launch.
Timing looks to be 36-38º at speed, Idle about 18-20º

My73LT
06-04-2009, 02:18:12 PM
I've run a couple of different motors, and each one was different. Some liked more, some less. Depended on cam, compression, gears, and tranny. 36 is a good start, tho. Certainly in the ball park. As far as timing versus temp, yeah, it could affect it a lot.

I'd take it to the track, and make small adjustments based on MPH. It's easy to get the WOT setting down, since most track runs are done with your foot to the floor and the motor rev'd. Then make your part throttle adjustments based on your known 'max advance' setting. IE: Say you know the car runs a best MPH with 39 degrees max, and your initial is 10, with 20 mechanical and 9 vac . Now, you want to adjust your initial to 15 to see if it runs better, you know you have to pull 5 from somewhere ( probably mechanical ), to keep your max at the stated 39. If you do it this way, you won't mask losses in WOT performance ( by over/under advancing ) with gains made in the low end ( by giving more timing earlier ).

I've seen other people use 60 foot times to adjust initial timing as well... So you mileage may vary, etc, etc.

TheStig
06-04-2009, 03:14:16 PM
You can also look at your spark plugs they can tell you a lot. I dont have the link anymore but there is a site that covers reading plugs that goes into depth on how timing leaves markings on your plugs and what they mean and how to adjust for perfect timing. Im a big believer in reading plugs, vac guage and using an infared temp gun.

sponge003
06-04-2009, 03:17:47 PM
My Racecar has the black bushing in the MSD 85551 which is supposed to be 18 advance, I use the Heavy silver spring and the blue spring so all the timing is in by 3200 rpm
The converter flashes to 3600 or so at launch.
Timing looks to be 36-38 at speed, Idle about 18-20

I have the same dist with the stock 21 degree advance bushing in it and whatever springs it5 comes setup with.