# 70 vert skipping engine



## jzegowitz (Jun 12, 2009)

after going the summer w/ trying to unsuccessfully diagnose and/or ignore the engine skip, had another mechanic look at it, put it on the 'scope' (?). says valves sticking, effectively killing two cylinders. 

last guy said definitely carb issues, rebuilt the carb, no change - except what was left in my pocket. 

this guy says it needs a valve job, 1250 without any new guides. yea, it has some ticks when starting/cold, and does blow a little smoke pass side at cold start. 

what might cause sticking valves and is there any possible additive or other attempt prior to pulling the heads? losing (lost) faith in mechanics around here fast. mass/nh border. 

thanks


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## jetstang (Nov 5, 2008)

Get out the manual, read up, pull the heads, have them redone, reinstall and you are good. Pretty basic stuff, only a few bolts to take off. Well, more than that, but you have all winter..


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## Instg8ter (Sep 28, 2010)

:agree....valve job with seats and guides and a few valves with no porting should be a few hundred, Your paying mostly labor not a hard job to remove and re-install just time consuming especially if you have AC.


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## freethinker (Nov 14, 2009)

jzegowitz said:


> after going the summer w/ trying to unsuccessfully diagnose and/or ignore the engine skip, had another mechanic look at it, put it on the 'scope' (?). says valves sticking, effectively killing two cylinders.
> 
> 
> 
> thanks


no way. its possible that it could have leaking valves which could be tested with a leakdown test but they are not "sticking".
define skipping.


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## Rukee (Feb 8, 2007)

Could also be a bad cam not opening the valves.


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## jzegowitz (Jun 12, 2009)

first, thanks all.
car idles reasonably while parked, although definitely not the rhythm i remember before (trying to have all leaks fixed, engine was leaking everywhere, but ran great). while driving at steady pace feels like running over squirrels every second or so, not at constant intervals. much less noticeable under accelleration, definitely no power like 'the old days' when it's punched. it definitely feels like it's only running on 6 or 7. 

the says he checked compression (not running) said he was getting over 200 (thought he said 230, can't remember now) but 190 at bad cylinder - #4. said he put on scope and says he found spark but no combustion at 4, and it was running lean. said he found plenty of lift, didn't think was a cam issue.


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## Rukee (Feb 8, 2007)

190 is plenty for combustion, if the valves are opening and it has spark and compression, the only thing missing is fuel. #4 intake runner restricted somehow? Or vacuum leak at #4 and the head? Open vacuum port on that runner?


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## freethinker (Nov 14, 2009)

jzegowitz said:


> first, thanks all.
> car idles reasonably while parked, although definitely not the rhythm i remember before (trying to have all leaks fixed, engine was leaking everywhere, but ran great). while driving at steady pace feels like running over squirrels every second or so, not at constant intervals. much less noticeable under accelleration, definitely no power like 'the old days' when it's punched. it definitely feels like it's only running on 6 or 7.
> 
> the says he checked compression (not running) said he was getting over 200 (thought he said 230, can't remember now) but 190 at bad cylinder - #4. said he put on scope and says he found spark but no combustion at 4, and it was running lean. said he found plenty of lift, didn't think was a cam issue.


so what exactly did they do to fix leaks? you said it was running fine before so it seems logical it is related to what they did.


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## BearGFR (Aug 25, 2008)

Back to basics...

First thing, absolutely SCOUR the intake and carb looking at every connection, every vacuum line. See if you've got any cracks or leaks in any of the lines. From your description "running over a squirrel" - I get a visual image of a perceptible 'bump' (skip like you said) that happens every few seconds while you're driving at a steady speed down the road --- as if one or more cylinders aren't firing _now and then_, not failing to fire at all. Is that correct? If so, then I've very doubtful that any of the suggestions you got from the shops you've been to are correct. Something that intermittent is most likely in the ignition system --- a plug wire that's marginal perhaps, or maybe a dirty spark plug -- something that's on the verge of failing completely but hasn' t yet. Also you said it seems 'worse' at cruise than it does under acceleration - right? That sort of points to a mixture that's borderline lean -- accelerating will begin to activate the carb's power circuits which richen up the mixture. So far nothing you're describing sounds like a major problem that would require opening up the motor and replacing parts. Not to me at least.

Bear


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