Your thoughts?
Thread Starter
Le Mans Master
Joined: Nov 2004
Posts: 6,128
Likes: 21
From: North Alabama
Your thoughts?
Troubleshooting a small block with a miss. Some popping out the pipes. Idles fine but put it in drive and she dies. #2 and #3 are running 120 degrees cooler on the header pipes relative to that cylinder than the other 6. They run 140+ degrees while the other 6 run 260+ degrees. Pulled the plugs for those 2 cylinders and did a compression check. Got a reading of about 90 psi in each. Next step I should take for troubleshooting purposes?
Motor is a mid 60's 327 cui
Motor is a mid 60's 327 cui
Melting Slicks
Joined: May 2007
Posts: 2,171
Likes: 1
From: Warwick RI
Troubleshooting a small block with a miss. Some popping out the pipes. Idles fine but put it in drive and she dies. #2 and #3 are running 120 degrees cooler on the header pipes relative to that cylinder than the other 6. They run 140+ degrees while the other 6 run 260+ degrees. Pulled the plugs for those 2 cylinders and did a compression check. Got a reading of about 90 psi in each. Next step I should take for troubleshooting purposes?
Motor is a mid 60's 327 cui
Motor is a mid 60's 327 cui
).I may have come in late but did this just start missing out of the blue?
Thread Starter
Le Mans Master
Joined: Nov 2004
Posts: 6,128
Likes: 21
From: North Alabama
This is just old school backyard experience talking but did you check compression on the other cylinders? That would be the first thing after ignition system that I check( I assume that you have already ).
I may have come in late but did this just start missing out of the blue?
).I may have come in late but did this just start missing out of the blue?
Melting Slicks
Joined: May 2007
Posts: 2,171
Likes: 1
From: Warwick RI
It gives you a reference, if the others are the same then chase ignition issues/firing order. If memory serves 90# might be low but a plug should still fire at that.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
I'm surprized it still runs.
Buy a cheap Chiltons manual at Pep Boys. I recall min ing press is something like 150 psi with no cyl more than 20 psi (or maybe its 20%) different than the others. Regardless of the ignition/plug wires you have cylinder leakage. Unless of course u have a huge duration camshshaft. You need to test the other cylinders to see if you are measuring compression correctly or have a bad gauge.
cardo0
cardo0
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Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
you know when cars idle fine then die when put in drive always make me think that the timing is changing due to low vacuum.....i would like to know the timing....so for a test i would see where the timing is at both idle and in gear.....you could also put vacuum on your vacuum advance cannister and see if its holding vacuum and more importantly if its pulling in the vacuum advance and at what " of mercury....then compare this to the vacuum at idle and in gear...so thats three more trouble shooting tests that are not too painfull and will eliminate a lot
Thread Starter
Le Mans Master
Joined: Nov 2004
Posts: 6,128
Likes: 21
From: North Alabama
#1 105
#2 105
#3 65
#4 85
#5 100
#6 105
#7 100
#8 100
Squirting oil in #3 and #4 only boosted their numbers by a few pounds.
Distributor is tight. I did loosen it to play with the timing but could not get rid of the miss. When I found the best spot for idle I tightened it back down. Now it, with the first revolution of cranking, cranks slow...then fires. Checked rocker arms and checked for bent pushrods. No abnormalities. Any other ideas?
Race Director
Joined: Feb 1999
Posts: 16,978
Likes: 7
From: In Dreams There Is Truth Ohio
#3 is way off..could be a burned or slightly bent valve. At most, cyl should not vary more than 10lbs. The slow cranking means you are really advanced, back the distributor counter clock wise, just a hair, the cranking will be easier.
Damn...I can't type for crap...I meant the distributor plate, the points sit on the plate...sometimes through age, the plate wears and is loose.
Damn...I can't type for crap...I meant the distributor plate, the points sit on the plate...sometimes through age, the plate wears and is loose.
Last edited by GDaina; Sep 30, 2009 at 11:36 PM.
Thread Starter
Le Mans Master
Joined: Nov 2004
Posts: 6,128
Likes: 21
From: North Alabama
#3 is way off..could be a burned or slightly bent valve. At most, cyl should not vary more than 10lbs. The slow cranking means you are really advanced, back the distributor counter clock wise, just a hair, the cranking will be easier.
Damn...I can't type for crap...I meant the distributor plate, the points sit on the plate...sometimes through age, the plate wears and is loose.
Damn...I can't type for crap...I meant the distributor plate, the points sit on the plate...sometimes through age, the plate wears and is loose.
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 39
From: Fremont CA
Swap plugs with another cylinder that's running hot and see if temp picks up (maybe you dropped and cracked a sparkplug?), swap plug wires with another cylinder (keeping firing order correct of course) to see if secondary wiring is bad. Spray some carb cleaner around carb and intake manifold to look for vacuum leaks (RPM will pick-up if there is a leak.) Then I would look under valve covers for valvetrain/rocker arm/push rod problems (collapsed lifter is a possibility or rocker arm adjustment.) Then do a leak down test rather than a compression guage test as they are a better indicator of cylinder condition. Then if all else failed, I would order a new motor
Race Director
Joined: Feb 1999
Posts: 16,978
Likes: 7
From: In Dreams There Is Truth Ohio
Racer
Joined: Mar 2008
Posts: 428
Likes: 0
Ok...here's the numbers
#1 105
#2 105
#3 65
#4 85
#5 100
#6 105
#7 100
#8 100
Squirting oil in #3 and #4 only boosted their numbers by a few pounds.
Distributor is tight. I did loosen it to play with the timing but could not get rid of the miss. When I found the best spot for idle I tightened it back down. Now it, with the first revolution of cranking, cranks slow...then fires. Checked rocker arms and checked for bent pushrods. No abnormalities. Any other ideas?
#1 105
#2 105
#3 65
#4 85
#5 100
#6 105
#7 100
#8 100
Squirting oil in #3 and #4 only boosted their numbers by a few pounds.
Distributor is tight. I did loosen it to play with the timing but could not get rid of the miss. When I found the best spot for idle I tightened it back down. Now it, with the first revolution of cranking, cranks slow...then fires. Checked rocker arms and checked for bent pushrods. No abnormalities. Any other ideas?
Just checking about the compression test, you mentioned that it was turning over slowly on the first turn. Was the engine turning at normal cranking speed when you did the compression test?
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
ok those numbers are definitely low.......have you adjusted the valves on those two cylinders? maybe somebody screwed up the adjustment and have them tighten down too much so they are slightly open.....maybe the lifters were bad and bubba cranked down on them to quiet them up?????
Last edited by bobs77vet; Oct 1, 2009 at 07:03 PM.
Racer
Joined: Mar 2006
Posts: 264
Likes: 1
From: west central INDIANA
All cyl.s seem low. Leak down all 8 holes. Just blow air in the holes and you will hear your leak. Listen closely for air coming out of opposite cyl.
as in head gasket between 2 weak ones. Mid 60s 327s were hi compression 160- 180 psig. just my thoughts
as in head gasket between 2 weak ones. Mid 60s 327s were hi compression 160- 180 psig. just my thoughts