Timing off - what next?
Hotshot
Joined: Apr 2009
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From: Stanley, VA
Wow! Only ~7"hg of vacuum at idle? That's way low, more evidence of a t/chain problem. Run a compression check, I think you're going to be showing uniform low compression also.
Keep us posted.
Keep us posted.
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Senior User
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From: Mad City
I'm researching how to go about degreeing-in my cam. First question would be whether I should expect "centerline degreeing" to work (are the valves "symmetric")? And/or does anyone know how I might find the "cam card" settings for my cam? (Don't know what cam's in there, haven't pulled the valve cover yet, etc.)
I'm willing to put in the time and effort to be 100% sure the timing's lined up, but want to be 100% sure I can be 100% sure that I can learn my way through this before tearing her all apart again.
Otherwise, she's off to the shop on a flatbed
I'm willing to put in the time and effort to be 100% sure the timing's lined up, but want to be 100% sure I can be 100% sure that I can learn my way through this before tearing her all apart again.
Otherwise, she's off to the shop on a flatbed
Postmaster
Joined: Jan 2009
Posts: 4,584
Likes: 3
From: Chesapeake, Va.
I'm researching how to go about degreeing-in my cam. First question would be whether I should expect "centerline degreeing" to work (are the valves "symmetric")? And/or does anyone know how I might find the "cam card" settings for my cam? (Don't know what cam's in there, haven't pulled the valve cover yet, etc.)
I'm willing to put in the time and effort to be 100% sure the timing's lined up, but want to be 100% sure I can be 100% sure that I can learn my way through this before tearing her all apart again.
Otherwise, she's off to the shop on a flatbed
I'm willing to put in the time and effort to be 100% sure the timing's lined up, but want to be 100% sure I can be 100% sure that I can learn my way through this before tearing her all apart again.
Otherwise, she's off to the shop on a flatbed
Thread Starter
|
Senior User
Joined: Jan 2010
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From: Mad City
Thanks! for the reminder - forgot about the mark on the cam gear.
I'm as sure as I can reasonably be about the carb - just rebuilt it to E-brock specs with tight tolerances. And the engine ran pretty good before I tore the front of it apart.
I'm as sure as I can reasonably be about the carb - just rebuilt it to E-brock specs with tight tolerances. And the engine ran pretty good before I tore the front of it apart.
Postmaster
Joined: Jan 2009
Posts: 4,584
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From: Chesapeake, Va.
Okay, I think we found the problem, I hope. Take the cover off and check the cam timing, get that right and then do a compression test, if that checks out you're in good shape. Pray for no bent valves.
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From: Mad City
I was just responding to your previous message...
I've taken a week off to recharge my ambition a bit. Evidence still seems to point to being off by a tooth. I did do my best to get the marks in alignment, turned the engine a bunch of times to verify, etc, etc, but must've been off. (Two messages back, I just forgot about the cam mark when worrying about "degreeing-in" the cam.) It's just consistently running best the same distance out from TDC which is more or less the amount you'd calculate from being off a single tooth.
I'm gonna install a grommet around the PCV valve and replace the old gasket between the carb and the manifold as a last ditch effort and then tear back into her when that don't work.
Will post as I proceed.
I've taken a week off to recharge my ambition a bit. Evidence still seems to point to being off by a tooth. I did do my best to get the marks in alignment, turned the engine a bunch of times to verify, etc, etc, but must've been off. (Two messages back, I just forgot about the cam mark when worrying about "degreeing-in" the cam.) It's just consistently running best the same distance out from TDC which is more or less the amount you'd calculate from being off a single tooth.
I'm gonna install a grommet around the PCV valve and replace the old gasket between the carb and the manifold as a last ditch effort and then tear back into her when that don't work.
Will post as I proceed.
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From: Mad City
The grommet trick didn't look like it was gonna improve the situation much, so I stopped pvssy-footing around and got after it: In under 2 hours, I made it down to the front cover. (Amazing how much easier something is the second time through.) Will get things set up right and post some pictures tomorrow afternoon.
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From: Mad City
A little confused at this point: The original timing marks line up where I thought I had left them the last time.
Here're the marks (may be a bit hard to pick out):
Here's the rotor position (where I thought it should be):
The only thing that surprised me a bit was that the paint marks I put on the gears and chain had moved relative to each other. I put marks on the chain and the gears so that after I'd lined things up "by gravity" off of the engine, I could verify the positions looked the same when I'd mounted the set. The chain must "walk around"? Also, there seems to be a lot less slack in the chain.
Here're the marks (may be a bit hard to pick out):
Here's the rotor position (where I thought it should be):
The only thing that surprised me a bit was that the paint marks I put on the gears and chain had moved relative to each other. I put marks on the chain and the gears so that after I'd lined things up "by gravity" off of the engine, I could verify the positions looked the same when I'd mounted the set. The chain must "walk around"? Also, there seems to be a lot less slack in the chain.
Hotshot
Joined: Apr 2009
Posts: 14,333
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From: Stanley, VA
Don't worry about the paint marks on the CHAIN not lining up, they will do that. They will line up every so often. How often depends on the length of the chain. It might take two or three rotations to line the same links up with the same teeth. The longer the chain the more rotations it will take to line the same teeth/links up again.
The important thing is that the marks on the gears line up.
The important thing is that the marks on the gears line up.
Postmaster
Joined: Jan 2009
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From: Chesapeake, Va.
Your timing chain appears to be correct. The chain should be tight om one sode and a bit loose on the other side. Look in the plug hole and verify that the piston is all the way up on #1. I'll get back with you on setting your static ignition timing in a short. Also look closely to see if the dowel pin in the cam end is straight, not bent.
Hotshot
Joined: Apr 2009
Posts: 14,333
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From: Stanley, VA
Glad you found it. Good luck.