Timing changing itself...
Thread Starter
Advanced
Joined: Apr 2004
Posts: 69
Likes: 0
From: Lafayette LA
Timing changing itself...
Here we go: Set the timing with the weights undone and vacuum undone -- all pretty much according to Lars' write-ups. Engine was way advanced at
idle (50+). Get eveything back in line. Put the springs back on the weights
and put it all back together. Runs GREAT! Wheee! -- a few hours later bring my dad in to "show-off". Runs *bad*. Whip out the timing light and poof back
up to 50+ at idle! :confused:
If I use the finger in No. 1 to see when the compression stroke happens -- the
timing mark is close, so I don't think the balancer slipped (plus it was running
good - then bad and the timing light says the timing changed).
Ideas!?
idle (50+). Get eveything back in line. Put the springs back on the weights
and put it all back together. Runs GREAT! Wheee! -- a few hours later bring my dad in to "show-off". Runs *bad*. Whip out the timing light and poof back
up to 50+ at idle! :confused:
If I use the finger in No. 1 to see when the compression stroke happens -- the
timing mark is close, so I don't think the balancer slipped (plus it was running
good - then bad and the timing light says the timing changed).
Ideas!?
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
Re: Timing changing itself... (dfseidel)
Well, your idle vacuum will be relatively high with the advance connected, BUT that's not the problem.
I would think that you didn't tighten the distributor down enough. Try setting it back and tightening the holddown more.
-Steve
I would think that you didn't tighten the distributor down enough. Try setting it back and tightening the holddown more.
-Steve
Safety Car
Joined: Feb 2002
Posts: 4,286
Likes: 4
From: Guam
Re: Timing changing itself... (Pacin'California)
Do it again, but this time, mark the position of the distributor housing on a spot on the intake manifold. When it happens again, check the marks. If the marks remain the same, you have a more serious problem. I would safely bet too that the hold down clamp was not tightened properly.
Thread Starter
Advanced
Joined: Apr 2004
Posts: 69
Likes: 0
From: Lafayette LA
Re: Timing changing itself... (dfseidel)
The 50+ degrees was without vacuum advance.
I hope I didn't tighten it down enough, but I seem to remember having
to rotate the the distributor housing to a different location from what it
was the at first.
I'll try again - once I replace my tank. It seems to have sprung two holes
about the size of a dime and a pea. ARGH!
:mad :mad
Safety Car
Joined: Feb 2002
Posts: 4,286
Likes: 4
From: Guam
Re: Timing changing itself... (dfseidel)
It sounds like you are going to be busy....set the timing properly with the advance disconnected. Then tighten the hold down very firmly but don't overdo it. Mark the position of the housing. Start the motor and test for Vacuum at the booster twice, once at idle and once at about 2500 rpms. Test the brakes by stepping on the peddle while at idle and with the engine at 2500 rpm. Note any differences. If there is still problems, recheck the timing and post what your findings. We will go from there. Don't forget to pull the check valve and blow thru it to see if is working and if it was installed going in the proper direction. And lastly, good luck on the tank repair.
Pro
Joined: Jun 2003
Posts: 515
Likes: 0
From: patriot ohio
Re: Timing changing itself... (Sharky Guam)
check for sloppy play in the weights first before jumping to conclusions its the timing chain. if there is play that will allow some timing jumping also you didn't take the vaccum advance out did you? that will allow major changes in the timing if its not in there to hold the center in place. i'd run over my distributor or possibly try another before i'd say timing chain.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Thread Starter
Advanced
Joined: Apr 2004
Posts: 69
Likes: 0
From: Lafayette LA
Re: Timing changing itself... (dfseidel)
Didn't take out the v.advance but did pull its hose. Weights seem to
move okay, but I admit I didn't look too close. How well are they supposed
to move?
1974
Heh, while nothing is working I thought I'd check my compression
on the easy to reach cylinders (aka not the one under the A/C compressor)
basically 165-170 in most cylinders. Hmmm stock is 160 isn't it? So either
I have a hot one from the factory that aged 30 years and 98K miles
really well, or someone has been in the engine :smash:
[Modified by dfseidel, 1:28 AM 5/24/2004]
move okay, but I admit I didn't look too close. How well are they supposed
to move?
1974
Heh, while nothing is working I thought I'd check my compression
on the easy to reach cylinders (aka not the one under the A/C compressor)
basically 165-170 in most cylinders. Hmmm stock is 160 isn't it? So either
I have a hot one from the factory that aged 30 years and 98K miles
really well, or someone has been in the engine :smash:
[Modified by dfseidel, 1:28 AM 5/24/2004]