timing problems
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Joined: Dec 2004
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timing problems
Just rebuilt a 302, new Comp cam (252h-10), Performer intake manifold, Eldenbroc 600 carb, 289 heads have adjustable rockers, and running 165-170 compression all cyl.
Problem: When set to recomended timing (8 deg. BTDC) Spark nock. Sounds like the whole valve timing is out. No power, low vacume. Idles great.
Things that I have tryed: Reset lash Hydl. lifters, center line of cam 106, pulled intake thought maybe a leak under one of the runners, checked vacume advance on Dist. Points set right, leaned out carb (jets and rods). The only other thing I can think of is maybe the valcume advance is advancing to much, it is the only thing on the motor that is not new.
Need some professional input, from what I have ben reading I would say This is the right place to ask.
Thanks
Problem: When set to recomended timing (8 deg. BTDC) Spark nock. Sounds like the whole valve timing is out. No power, low vacume. Idles great.
Things that I have tryed: Reset lash Hydl. lifters, center line of cam 106, pulled intake thought maybe a leak under one of the runners, checked vacume advance on Dist. Points set right, leaned out carb (jets and rods). The only other thing I can think of is maybe the valcume advance is advancing to much, it is the only thing on the motor that is not new.
Need some professional input, from what I have ben reading I would say This is the right place to ask.
Thanks
Postmaster
Joined: Nov 2002
Posts: 3,447
Likes: 1
From: Littleton, CO
I would double check the wiring on the cap, then back down the timing to 6 degrees, then double check the dwell on the points (assuming you are still running them). Don't forget to pull the vacuum line off the distributor and plug it while setting the timing.
The experts will jump in shortly...
--Mike
The experts will jump in shortly...
--Mike
Elder User
Joined: Sep 2004
Posts: 500
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From: midwest
do you have your advance hooked to manifold or ported vac? try ported, if you have manifold you are problably advancing to much off idle. also with the high compression you may need to richen up your carb or run a better fuel.
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Timming
First thanks for infor.
I am on ported vac. I have ben all over the chart on mix. I have the weakest springs in carb now because when rods come up in mid thotal it goes to rich. I have no mid thotal at all. Vacume to low, and it should not be with the mild cam that is in it. vacume is at 10 on 820 RPM. There is no vacume leaks.
Wires OK that was first check I did. Timming is at 6 now, wish I could get more to kick up vacume, but here comes the spark knock. Seems like cam is out of time but is not acording to degree wheel.
Thanks again.
I am on ported vac. I have ben all over the chart on mix. I have the weakest springs in carb now because when rods come up in mid thotal it goes to rich. I have no mid thotal at all. Vacume to low, and it should not be with the mild cam that is in it. vacume is at 10 on 820 RPM. There is no vacume leaks.
Wires OK that was first check I did. Timming is at 6 now, wish I could get more to kick up vacume, but here comes the spark knock. Seems like cam is out of time but is not acording to degree wheel.
Thanks again.
Last edited by carusdr; Dec 14, 2004 at 12:54 PM.
Senior User
Joined: Jul 2002
Posts: 313
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From: Orlando
What is your static compression?
If your in the 10+ range you need to be running premium fuel. If your already doing that you may need to lower compression some (thicker head gasket, etc.). Have you calculated the compression ratio of your engine?
Senior User
Joined: Jul 2002
Posts: 313
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From: Orlando
Link to compression calculator
http://www.bgsoflex.com/cr.html
There are other sites with calculators. I think SpeedPro has a good one too.
There are other sites with calculators. I think SpeedPro has a good one too.
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Postmaster
Joined: Mar 2003
Posts: 4,038
Likes: 2
From: Spokane WA
Wow, great calculator, shocked me to see how changing head gaskets thickness changes compression so drastically for so small of a change.....
Changing a head gasket from .020 to .040 (doubling thickness by using two is what I was thinking) would drop a 10.4:1 to a 9.9:1 in my scenario, can you use two head gaskets sandwiched like that? would it even work, or does someone make them that thick?
Changing a head gasket from .020 to .040 (doubling thickness by using two is what I was thinking) would drop a 10.4:1 to a 9.9:1 in my scenario, can you use two head gaskets sandwiched like that? would it even work, or does someone make them that thick?
Last edited by Icicle; Dec 17, 2004 at 01:32 AM.
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Senior User
Joined: Jul 2002
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From: Orlando
Don't try and sandwich gaskets they com ein various thichnesses
I have seen head gaskets from about .020 (compressed) to .050" for the same engine. Changing cams can also lower dynamic compression - as another option.
Note, static compression is what you get on a compression gage while dynamic compression is what the engine sees while running. It is the later that causes problems.
Note, static compression is what you get on a compression gage while dynamic compression is what the engine sees while running. It is the later that causes problems.
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