Timing

jeremywatco · May 16, 2019

So I have my 302 with pertronix dizzy set at 10*. It starts fine, runs fine. Works fine. If you get on the gas it's sluggish. Up hill it struggles but makes it. All around runs ok.

So today I threw a vacuum gauge on for fun and adjusted the timing to peak vaccum and then subtracted about 2 degrees. Well that magic number was 30 degrees of timing at idle. That can't be right... Right? Engine sounded great right there too.

BUCKWILD · May 16, 2019

You could have a harmonic balancer that has spun on the rubber ring or the timing pointer is wrong. I would confirm top dead center on #1 and see what the pointer is reading it should say 0. If it runs well at 30 i would say one of the problems i listed.

jeremywatco · May 16, 2019

BUCKWILD said:
You could have a harmonic balancer that has spun on the rubber ring or the timing pointer is wrong. I would confirm top dead center on #1 and see what the pointer is reading it should say 0. If it runs well at 30 i would say one of the problems i listed.

Is there a danger to running at "30". I mean if vacuum and sound both say its running cleaner, better, stronger and not pinging do I even need to bother with what the light says?

triracer67 · May 17, 2019

My harmonic balancer lost it's marks years ago. I run a pertronix, and it's tuned with vacuum gauge with no issues. I have timing light, but, no marks and have no idea what the balancer would tell me. The biggest issue is predetonation. I'm unaware of any other issues, I'd be curious to hear others. My runs great, and pulls hard.

Slowleak · May 17, 2019

I had one that I tuned like that for years and it ran great. I would adjust it for peak vacuum and then drive it until it was hot, get on the gas and listen for pre-ignition. If it kicked-back when I tried to start it when hot, I would back the timing off until it would spin over at normal speed. I have no idea what the actual timing was and didn’t care. I just marked the balancer as a starting point...

jeremywatco · May 17, 2019

Slowleak said:
I had one that I tuned like that for years and it ran great. I would adjust it for peak vacuum and then drive it until it was hot, get on the gas and listen for pre-ignition. If it kicked-back when I tried to start it when hot, I would back the timing off until it would spin over at normal speed. I have no idea what the actual timing was and didn’t care. I just marked the balancer as a starting point...

Thank you. I think I am going to go this route and see what happens. Like I said.. the motor runs "OK" but it has no punch whatsoever. It gets up to 65mph.. but it takes its time. Going up hill on normal grades it stuggles to go 45... could just be a tired motor.. BUT.... when I turned the dizzy the RPM's & Vacuum went way up. I kept turning until the motor started to stumble and then backed off 2-3 degrees.... I never drove it like that as I was worried. However now that I see its possible for the balancer to be off I think I will test it out.

DirtDonk · May 17, 2019

jeremywatco said:
Is there a danger to running at "30". I mean if vacuum and sound both say its running cleaner, better, stronger and not pinging do I even need to bother with what the light says?

His point was that the marks might be off, so you're not actually running at 30 degrees of advance.

Another question might be where is the vacuum advance connected to the carburetor? And are you pulling the hose off for timing checks, or leaving it connected?

If it's on a timed, or ported vacuum source, you don't really need to disconnect the hose. But it still doesn't hurt to do it as a way of verifying no vacuum signal.
If it's on a full manifold vacuum source though, and the hose is connected while you're setting the timing, this would skew the reading a lot. In that case as soon as you start to accelerate the timing retards a lot, which would be one explanation for the lack of power.

Otherwise it could still be the wrong timing marks.

Let us know how you're set up.

Paul

jeremywatco · May 17, 2019

Paul,

Thanks for the info.

See the picture below. You can follow the vac line i have from the dizzy to the carb to see where i have it plugged in.

Yes when I was setting the timing I pulled that line.

I hooked my vacuum gauge to the vac line on that same side of the carb that comes out of the manifold and goes to the tranny.

Would poor timing also be a reason I get crappy gas mileage (like 5mpg or less it seems). PS.. this is an older photo.. so disregard the choke and mismatched plug wires. This isnt current just shows my vac advance

y4mAH_T7NhkNJtB3DipbSIVIS4vydnxOBVY8qKcamVgDp46wK7tzQ39h-NjzNLPElXNHPBvGWOQOEaPoQ80EhIeImxc5sve7vkfMKhpCXyO3bhpH1UtK_TM5c3dQSeRw66Fa59KGOwy2g2CqWEsPpN3S4CHuAZkOjYTyjxxzPth488sKCm9ENOE7TNxVWM6mWeCIEpBKIXz-vGFltcG1LXtZg

rmk57 · May 17, 2019

With 30 degrees initial timing it should be hard to start. Like slow cranking until it finally catches.

chrlsful · May 17, 2019

total v initial & mechanical?
Could in B in the dizzy weights'n springs rather than just the initial?

jeremywatco · May 17, 2019

rmk57 said:
With 30 degrees initial timing it should be hard to start. Like slow cranking until it finally catches.

Yeah.. let me go set it and see. If its really 30 degrees it should be pretty easy to spot. I'll set it. Stop it.. Start it. Drive it. I have a feeling my timing marks no longer are accurate....

I guess the other thing I could do is pull the plug on #1 and find TDC.. but whats the fun in that!

DirtDonk · May 17, 2019

Hah! Yep, that's the attitude!

And yes for sure, to the poor gas mileage issue. More advance is good up to a point, and part of that is throttle response (as I think you said you felt an improvement with?) and fuel economy.

Paul

rmk57 · May 17, 2019

The piston stop method for finding true tdc is the route I'd go. Easy to see if the balancer has slipped.

jeremywatco · May 17, 2019

So.. maybe my timing marks were correct.. twisted the dizzy until I got highest vacuum before stumbling.. then backed it off about 4 degrees, then drove it. Noticed NO difference in power except hot starting was a chore. SO put it back at 10 degrees.. idle and vacuum dropped however the cruising power seemed the same and it hot/cold starts like a champ. Maybe my expectations of this 302 are a little high.

DirtDonk · May 17, 2019

You can try something in-between. I've run up to 15° easily with my '71 and no starting issues. Overall I ended up at 12 or so, but it ran fine at that 15.

But have we talked about what tire size and gear ratio and transmission you have? Maybe it's not the engine that's causing most of the sluggish behavior, but the wrong gearing for the tire size.

Let us know.

Paul

m_m70 · May 17, 2019

16* is the sweet spot for mine with aluminum heads and headers...…..
Have you tried changing to a lighter spring for the mech advance? I went with the lightest spring and made a tone of difference.
Also, was the dizzy the only change you made? How did it run before or has it always had this issue??

jckkys · May 17, 2019

It seems to me you're shooting in the dark. You don't know where you are OR where you want to go. Here;https://www.fordmuscle.com/archives/2000/03/timing/index.php is a good tutorial on timing stock small block Ford engines. None of stock EB engines were high compression. Your 302 looks like a '71 or 8.6 to 1 compression. 15 degrees initial should be OK. How many degrees are in the mechanical advance? How many in the vacuum advance? I don't have the specs for Pertronics. At least the vacuum advance is plumbed to the timed or ported vacuum source. That helps in light accelerations. Once you find where TDC is, you'll know if the harmonic damper has slipped, creating a need for a timing tape, or not. The Ford Muscle article will tell where you need to get to, but first you need to know where you are.

latrucker · May 18, 2019

You might be reading vac advance and initial timing together. If your using manifold vac (vac source under the throttle plates in the carb). If you have 15 initial and 15 on the vac advance that would give you 30 total at idle which isn't uncommon. Pinch or disconnect the vac hose and plug it so you dont have a vac leak and the check timing. That should be your true initial timing.

jckkys · May 18, 2019

The photo in post #8 shows his vacuum advance hose is attached to the correct timed or ported vacuum source, on the 2100 carburetor. At idle there would be no vacuum.

jsfrv6 · May 18, 2019

Here's a good article on timing...
http://www.superchevy.com/how-to/ad...now-about-vacuum-advance-and-ignition-timing/

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