Timing advance, funny story
August 6th, 2014, 10:57 AM
#1
Registered User
Thread Starter
Join Date: Jul 2012
Posts: 368
Timing advance, funny story
When my guy built my engine, I gave him my carb and distributor so he could run the engine on the stand. When I got the engine from him he told me to run the total timing at 35. Since I have 20* of mechanical advance that means I'd be running 15* base timing. My vacuum advance puts out 14* too and I run manifold vacuum so I should have plenty of advance at idle.
Well dispite that I've been plagued with tuning issues. Idle rougher than what it should be, power doesn't seem to be where I think it should be ( though I've only had a couple of short wot runs ), popping through the carb at wot, forced to tune the carb rich or it would run even worse when in gear, lack luster milage etc.
So just for the hell of it, I checked the timing. Perhaps it got bumped when I installed the engine? I'm out of ideas so what the hell. So I checked it with the vac advance still connected. 14* advance at idle. Uh what? Unplugged the advance and checked again. 0* timing at idle. D'oh! I think I found my problem! I assumed when the guy ran the engine on the stand he set the timing at 35 ( he even put a mark on the balancer at 35 ). He did not in fact do this and just installed the distributor at exactly TDC.
So I'm pretty happy I found the issue. This things going to be a monster now! Having more than 20* total timing at WOT is going to make things a liitle more fun I believe.
Moral of the story; don't assume your timing is set correctly. Takes just a couple of minutes to check.
Well dispite that I've been plagued with tuning issues. Idle rougher than what it should be, power doesn't seem to be where I think it should be ( though I've only had a couple of short wot runs ), popping through the carb at wot, forced to tune the carb rich or it would run even worse when in gear, lack luster milage etc.
So just for the hell of it, I checked the timing. Perhaps it got bumped when I installed the engine? I'm out of ideas so what the hell. So I checked it with the vac advance still connected. 14* advance at idle. Uh what? Unplugged the advance and checked again. 0* timing at idle. D'oh! I think I found my problem! I assumed when the guy ran the engine on the stand he set the timing at 35 ( he even put a mark on the balancer at 35 ). He did not in fact do this and just installed the distributor at exactly TDC.
So I'm pretty happy I found the issue. This things going to be a monster now! Having more than 20* total timing at WOT is going to make things a liitle more fun I believe.
Moral of the story; don't assume your timing is set correctly. Takes just a couple of minutes to check.
August 6th, 2014, 01:55 PM
#2
Registered User
Join Date: May 2014
Location: Washburn, Illinois
Posts: 25
It's always nice when the issue is as simple as that! Glad she's running better for you now.
I had a similar issue with my 425. The PO had retarded the timing to give it more of a "lobe" at idle (with a stock cam no less) as well as installed a carb that they apparently didn't even bother to tune at all as one idle screw was about 1/4 turn out and the other was around 3 - 3 1/2... A timing light, screwdriver, and about 15 minutes later I have smoke coming from my rear tires at WOT from a stop instead of it wanting to fall on it's face.
And best of all, our fixes were FREE
I had a similar issue with my 425. The PO had retarded the timing to give it more of a "lobe" at idle (with a stock cam no less) as well as installed a carb that they apparently didn't even bother to tune at all as one idle screw was about 1/4 turn out and the other was around 3 - 3 1/2... A timing light, screwdriver, and about 15 minutes later I have smoke coming from my rear tires at WOT from a stop instead of it wanting to fall on it's face.
And best of all, our fixes were FREE
Last edited by Jeff K.; August 6th, 2014 at 02:01 PM.
August 6th, 2014, 03:32 PM
#4
Registered User
Join Date: Oct 2010
Location: Boise ID
Posts: 1,275
The butt cheese that did mine did the same thing. I took it in for there free little dyno tune they offer and when I picked it up it ran like crap. Checked timing when I go home it was set at 0 and they say they know Oldsmobiles!
August 7th, 2014, 01:37 AM
#5
Registered User
Thread Starter
Join Date: Jul 2012
Posts: 368
Yeah you can't beat free fixes.
Though I only had time for a quicky tune, I was able to better pretty much every aspect of the engine. I got more vacuum at idle in park ( about 15.5 ), more vacuum at idle in gear ( almost 14 ), a smaller drop when going from park into gear ( drops about 125 rpm if I recall correctly ), and overall has a stronger idle ( no more wanting to stall when I turn the steering wheel hard at idle ).
I'm sure milage will improve too.
The biggest difference of course is the much improved power. Couldn't really get on it too much but heavy throttle ( still not wot ) at 40 mph accelerated the car like a rocket along with some tire spin.
Still have some playing around to do, but things are at least pretty good as is.
Though I only had time for a quicky tune, I was able to better pretty much every aspect of the engine. I got more vacuum at idle in park ( about 15.5 ), more vacuum at idle in gear ( almost 14 ), a smaller drop when going from park into gear ( drops about 125 rpm if I recall correctly ), and overall has a stronger idle ( no more wanting to stall when I turn the steering wheel hard at idle ).
I'm sure milage will improve too.
The biggest difference of course is the much improved power. Couldn't really get on it too much but heavy throttle ( still not wot ) at 40 mph accelerated the car like a rocket along with some tire spin.
Still have some playing around to do, but things are at least pretty good as is.
Thread
Thread Starter
Forum
Replies
Last Post
