Gradually running rougher, And tailpipe popping |
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Gradually running rougher, And tailpipe popping |
jeffdon |
Feb 12 2012, 10:27 AM
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#1
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Senior Member Group: Members Posts: 1,094 Joined: 24-October 06 From: oakland, ca Member No.: 7,087 Region Association: None |
So, My carbed, cammed, malloried 2056 has been steller for about 6k miles. Then on a run up to Santa Rosa it started feeling less "crisp" on acceleration, and is popping out the tailpipe when cruising along. Not loud bangs, kinda softly doing it. Getting also a bit of snorting out the carbs on start up. Going to crawl under today and check for exhaust leaks (SS exchangers).
What else should I check? Valves? Timing? Ignition circuit? Also, as an engine wears in and you start putting some miles on it, can it change in such a way that would require re-evaluating your jetting? |
jmill |
Feb 12 2012, 10:49 AM
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#2
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Green Hornet Group: Members Posts: 2,449 Joined: 9-May 08 From: Racine, Wisconsin Member No.: 9,038 Region Association: Upper MidWest |
Valves
Timing Sync/tune carbs Check for exhaust leaks Did you not check/adjust any of those in the first 6k miles of a fresh rebuild? |
jeffdon |
Feb 12 2012, 10:58 AM
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#3
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Senior Member Group: Members Posts: 1,094 Joined: 24-October 06 From: oakland, ca Member No.: 7,087 Region Association: None |
Valves Timing Sync/tune carbs Check for exhaust leaks Did you not check/adjust any of those in the first 6k miles of a fresh rebuild? Been into the valves three times at regular intevals. Timing a couple, its been solid. Carbs have been synched and I have felt pretty dialed in on the jetting. Leaks, I think I have been good, at least I have not seen or felt any when under the car. That being said, I suppose something could have been knocked out of whack at some point. The car rides rough on poor roads, and thats a lot of jarring about. |
jmill |
Feb 12 2012, 11:15 AM
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#4
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Green Hornet Group: Members Posts: 2,449 Joined: 9-May 08 From: Racine, Wisconsin Member No.: 9,038 Region Association: Upper MidWest |
What type of linkage do you have? I gave up on the cheap ones due to movement. At a minimum you want the hex bar with cast arms and carb plates for the ends.
On a side note, carbs are putzy. I played with them at every oil change. |
jeffdon |
Feb 12 2012, 11:22 AM
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#5
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Senior Member Group: Members Posts: 1,094 Joined: 24-October 06 From: oakland, ca Member No.: 7,087 Region Association: None |
What type of linkage do you have? I gave up on the cheap ones due to movement. At a minimum you want the hex bar with cast arms and carb plates for the ends. On a side note, carbs are putzy. I played with them at every oil change. Its a home brew bell crank my dad fabbed up around '85. Its actually been dependable over the years, and on a couple different engines. This is the closest i have now for a pic, but I think it gives the general idea (NOT attached to the carbs in this pic) |
914.SBC |
Feb 12 2012, 11:33 AM
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#6
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Member Group: Members Posts: 248 Joined: 12-December 10 From: CORONA, CA Member No.: 12,479 Region Association: None |
Mine did exactly what you are describing (keep in mind I have a v8) but it turned out to be an exhuast leak.
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jeffdon |
Feb 12 2012, 11:34 AM
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#7
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Senior Member Group: Members Posts: 1,094 Joined: 24-October 06 From: oakland, ca Member No.: 7,087 Region Association: None |
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mrholland2 |
Feb 12 2012, 11:54 AM
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#8
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Senior Member Group: Members Posts: 753 Joined: 7-September 11 From: Santa Maria,CA Member No.: 13,531 Region Association: Central California |
Mine did exactly what you are describing (keep in mind I have a v8) but it turned out to be an exhuast leak. Interesting that a V8 would behave the same way. Not sure this is even germane, but a coworker of mine had this happen in a late 70's/early 80's Cadillac. Turned out it was because of low oil pressure not pumping up the lifters. Is your 2.0 hydraulic lifters? Low oil pressure? Unlikely, but every idea might lead to another. (IMG:style_emoticons/default/idea.gif) |
jeffdon |
Feb 12 2012, 11:56 AM
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#9
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Senior Member Group: Members Posts: 1,094 Joined: 24-October 06 From: oakland, ca Member No.: 7,087 Region Association: None |
Mine did exactly what you are describing (keep in mind I have a v8) but it turned out to be an exhuast leak. Interesting that a V8 would behave the same way. Not sure this is even germane, but a coworker of mine had this happen in a late 70's/early 80's Cadillac. Turned out it was because of low oil pressure not pumping up the lifters. Is your 2.0 hydraulic lifters? Low oil pressure? Unlikely, but every idea might lead to another. (IMG:style_emoticons/default/idea.gif) Mechanical, and my OP is right where it should be. |
TheCabinetmaker |
Feb 12 2012, 12:06 PM
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#10
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I drive my car everyday Group: Members Posts: 8,304 Joined: 8-May 03 From: Tulsa, Ok. Member No.: 666 |
gradual deterioration of power would point me towards a dirty carb, decreasing fuel pressure (maybe due to a dirty filter), weakening spark, or worse, losing compression. did you do a compression check when fresh? If so, do another one and compare.
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jeffdon |
Feb 12 2012, 12:14 PM
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#11
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Senior Member Group: Members Posts: 1,094 Joined: 24-October 06 From: oakland, ca Member No.: 7,087 Region Association: None |
gradual deterioration of power would point me towards a dirty carb, decreasing fuel pressure (maybe due to a dirty filter), weakening spark, or worse, losing compression. did you do a compression check when fresh? If so, do another one and compare. You know, I was having hot start problems (cranking, no firing) and found that moving my coil (bosch blue) to the firewall solved it. Perhaps its breaking down. As a complete aside, yesteday morning, I had a belt squeeling, and found I had lost the Alt. adjuster bolt. No gen light warning. I fixed that, and was hoping that maybe i was running rough due to voltage dropping gradually. After running for half an hour, it made no difference. |
TheCabinetmaker |
Feb 12 2012, 12:29 PM
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#12
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I drive my car everyday Group: Members Posts: 8,304 Joined: 8-May 03 From: Tulsa, Ok. Member No.: 666 |
Ha! that would definitely cause a weak spark
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jeffdon |
Feb 12 2012, 12:46 PM
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#13
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Senior Member Group: Members Posts: 1,094 Joined: 24-October 06 From: oakland, ca Member No.: 7,087 Region Association: None |
Turned in the idle mixture screws, and it seems to have its old crispness back.
Plugs at idle look like this....what say all yee ole plug reading pros? |
TheCabinetmaker |
Feb 12 2012, 12:50 PM
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#14
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I drive my car everyday Group: Members Posts: 8,304 Joined: 8-May 03 From: Tulsa, Ok. Member No.: 666 |
Electrode is kinda hard to see, but doesn't look rich. Is that oil on the threads?
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struckn |
Feb 12 2012, 12:53 PM
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#15
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Senior Member Group: Members Posts: 1,069 Joined: 9-November 11 From: South Central York Pennsyvania Member No.: 13,764 Region Association: MidAtlantic Region |
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jeffdon |
Feb 12 2012, 12:58 PM
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#16
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Senior Member Group: Members Posts: 1,094 Joined: 24-October 06 From: oakland, ca Member No.: 7,087 Region Association: None |
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jmill |
Feb 12 2012, 01:01 PM
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#17
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Green Hornet Group: Members Posts: 2,449 Joined: 9-May 08 From: Racine, Wisconsin Member No.: 9,038 Region Association: Upper MidWest |
I'd be happy with that plug. Looks to be #9.
Attached image(s) |
Porschef |
Feb 12 2012, 01:02 PM
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#18
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How you doin' Group: Members Posts: 2,165 Joined: 7-September 10 From: LawnGuyland Member No.: 12,152 Region Association: North East States |
[/quote]
Look for arcing from the plug wires and the connection from Coil to Dizzy and plugs also. If you have electronic ignition (i.e. pertronix) Gap your plugs .040 - .050. [/quote] I swapped out to Pertronix, but didn't read any mention of changing the gap. Is this your experience to find it to run better with the .040-.050 setting? Thanks |
jeffdon |
Feb 12 2012, 01:07 PM
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#19
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Senior Member Group: Members Posts: 1,094 Joined: 24-October 06 From: oakland, ca Member No.: 7,087 Region Association: None |
[quote name='Porschef' date='Feb 12 2012, 11:02 AM' post='1623529']
[/quote] Look for arcing from the plug wires and the connection from Coil to Dizzy and plugs also. If you have electronic ignition (i.e. pertronix) Gap your plugs .040 - .050. [/quote] I swapped out to Pertronix, but didn't read any mention of changing the gap. Is this your experience to find it to run better with the .040-.050 setting? Thanks [/quote] (IMG:style_emoticons/default/agree.gif) |
jeffdon |
Feb 12 2012, 01:08 PM
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#20
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Senior Member Group: Members Posts: 1,094 Joined: 24-October 06 From: oakland, ca Member No.: 7,087 Region Association: None |
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