NC-car-guy

How buttercup got her groove back

Recommended Posts

3 minutes ago, JohnD1956 said:

Do you have a spare coil to test it with?

I don't see how a coil would affect only two cylinders and even on those two I can pull the wire almost an inch away and get the spark to jump

Share this post


Link to post
Share on other sites


Benefits of AACA Membership.

8 minutes ago, NC-car-guy said:

I don't see how a coil would affect only two cylinders and even on those two I can pull the wire almost an inch away and get the spark to jump

Spark plugs wire resistance.  How old are the wires.  If you switch to a good known wire is there any change to the affected cylinder?

Share this post


Link to post
Share on other sites

Let's go back to vacuum leaks:  check the lines and fittings at the fuel pump...or just turn on the wipers to see if they still work.

Share this post


Link to post
Share on other sites
3 hours ago, old-tank said:

Let's go back to vacuum leaks:  check the lines and fittings at the fuel pump...or just turn on the wipers to see if they still work.

All vacuum lines are plugged just in case.  And yes the wipers work

Share this post


Link to post
Share on other sites
5 hours ago, avgwarhawk said:

Check for vacuum leaks at the intake manifold at those cylinders. 

 

4 hours ago, old-tank said:

Let's go back to vacuum leaks:  check the lines and fittings at the fuel pump...or just turn on the wipers to see if they still work.

 

Considering you have spark, compression, tried a different plug, etc. this is most likely the answer. Vacuum wipers are disconnected and plugged? Right at the manifold? Good. Got power brakes? Do the same.

 

Does this nailhead have the exhaust passages that run up through the manifold and contact the baseplate of the carb directly? The exhaust has been known to eat the gasket and throttle body up. If you have that setup it is possible for exhaust to be leaking into an intake passage. Technically its called a "dilution misfire", but the result is the same as an ordinary vacuum leak, a horrible miss.

 

 

5 hours ago, avgwarhawk said:

After taking a break and deep breath, pull the valve covers.  Check to see the rockers for the cylinders are working as designed. 

 

This probably isn't it since you have good compression, but I wouldn't rule it out, and if you can't find a intake leak this probably comes next.

 

 

Edited by Bloo (see edit history)

Share this post


Link to post
Share on other sites

I wish I was closer.  It's always good to walk away for a day if you find yourself frustrated.

Share this post


Link to post
Share on other sites

Had to pull forward into the garage.  With no verse and a muddy yard its going to be a while before I can take it back out 

Share this post


Link to post
Share on other sites

After checking again for vacuum leaks, check continuity of the wires and change the plugs.  I have had long dormant engines with new appearing plugs fail to run well.  And if some misguided person installed platinum or other exotic plugs, throw them away.  Autolite 85 or 75 will serve you well.

Share this post


Link to post
Share on other sites
9 minutes ago, old-tank said:

After checking again for vacuum leaks, check continuity of the wires and change the plugs.  I have had long dormant engines with new appearing plugs fail to run well.  And if some misguided person installed platinum or other exotic plugs, throw them away.  Autolite 85 or 75 will serve you well.

Shes got all new auto lite 85s in it but I suppose I can scrap two and replace. But I have tried switching the plugs around and that didnt seem to change anything.  The wires are whatever was on it when I got it. Again I tried switching them around and it had no effect but suppose I can replace them too. I will try for more vacuum leaks, maybe just go ahead and reseat the intake.

Share this post


Link to post
Share on other sites
1 minute ago, NC-car-guy said:

Shes got all new auto lite 85s in it but I suppose I can scrap two and replace. But I have tried switching the plugs around and that didnt seem to change anything.  The wires are whatever was on it when I got it. Again I tried switching them around and it had no effect but suppose I can replace them too. I will try for more vacuum leaks, maybe just go ahead and reseat the intake.

 

 

If you have have verified all ignition components are good then look again for a vacuum leak.  I would replace the spark plug wires.  These are unknown.    

  • Like 1

Share this post


Link to post
Share on other sites

Also it has a pertronix in it from previous, previous owner... Could that affect only 2 cylinders?

Share this post


Link to post
Share on other sites
3 minutes ago, NC-car-guy said:

Also it has a pertronix in it from previous, previous owner... Could that affect only 2 cylinders?

 

One way to find out....put in the points!  Then leave them in there!       

  • Like 1
  • Thanks 1

Share this post


Link to post
Share on other sites

isolate the spark plug wires to eliminate crossfire. New or old, insulate them till you know they are not part of the problem.  

Share this post


Link to post
Share on other sites
19 hours ago, NC-car-guy said:

I don't see how a coil would affect only two cylinders and even on those two I can pull the wire almost an inch away and get the spark to jump

 

19 hours ago, JohnD1956 said:

Do you have a spare coil to test it with?

 

23 minutes ago, NC-car-guy said:

Also it has a pertronix in it from previous, previous owner... Could that affect only 2 cylinders?

 

First, what JD said with a sort of qualifier. Try a KNOWN GOOD coil. I once went through most everything you've done on an engine that would run fine at idle and until it got at operating temperature but would skip and die when ran for awhile.I finally put on a new coil, still to no avail. Ran the problem by an old mechanic friend and he said it's got to be the coil. Swapped it with one from another good runner and problem solved. Couple that with the fact it has the Petronix (news to me) and the original coil and I'm thinking you've found the gremlin.

Share this post


Link to post
Share on other sites
2 hours ago, NC-car-guy said:

Also it has a pertronix in it from previous, previous owner... Could that affect only 2 cylinders?

I think you just nailed the problem.  I have heard of Petronix units failing and having this affect.  

Share this post


Link to post
Share on other sites
16 minutes ago, dmfconsult said:

I think you just nailed the problem.  I have heard of Petronix units failing and having this affect.  

Oh really?  Well I'll swap some points in tonight.  I have 6 distributors hanging up, one's gotta have a serviceable set of points to it...lol

  • Like 1

Share this post


Link to post
Share on other sites
7 minutes ago, NC-car-guy said:

Oh really?  Well I'll swap some points in tonight.  I have 6 distributors hanging up, one's gotta have a serviceable set of points to it...lol

 

 I would have dumped the Pertronix from day one.  Ain't no question....

Share this post


Link to post
Share on other sites

I am very curious to see if this fixes it.  I can't imagine how it would have this effect.  I love my Pertronix but keep a set of points in the glovebox just in case!

Share this post


Link to post
Share on other sites
5 minutes ago, lancemb said:

I am very curious to see if this fixes it.  I can't imagine how it would have this effect.  I love my Pertronix but keep a set of points in the glovebox just in case!

 

You keep the old engineered points in the glove box just in case the newly upgraded Pertronix fails?  Why not just another set of points?   Just curious.     

Share this post


Link to post
Share on other sites

Pertronix?:o

Check or replace the rotor too.  If the Pertronix was wired to bypass the ballast resistor the central carbon core in the rotor will arc and may even catch fire (happened to me in at a Little Rock hot truck stop)...especially if it is the original rotor!

  • Like 1

Share this post


Link to post
Share on other sites
2 hours ago, avgwarhawk said:

 

You keep the old engineered points in the glove box just in case the newly upgraded Pertronix fails?  Why not just another set of points?   Just curious.     

Pertronix won't fail due to moisture, corrosion, etc. after sitting a few winter months as points used to do on me.  They won't experience slowly degrading performance like points do.  They will, however, eventually fail; nothing lasts forever.  When they do, it's often sudden.

 

I've been running Pertronix for about 10 years and 5k miles and have had no issues.  But, if one day it suddenly fails I have a backup until I can order another.

  • Thanks 1

Share this post


Link to post
Share on other sites
1 hour ago, lancemb said:

Pertronix won't fail due to moisture, corrosion, etc. after sitting a few winter months as points used to do on me.  They won't experience slowly degrading performance like points do.  They will, however, eventually fail; nothing lasts forever.  When they do, it's often sudden.

 

I've been running Pertronix for about 10 years and 5k miles and have had no issues.  But, if one day it suddenly fails I have a backup until I can order another.

 

 I am with you. Only I went the next step to HEI. 

 

  Ben

Share this post


Link to post
Share on other sites

Well...buttercup's groove is gone.  Pulling the heads this week. 

I replaced the entire ignition system, going back to points. Plugged every vacuum port. Retourqed the intake and checked for leaks with propane...all brought no joy. I took the valve covers of and watched the rockers for signs of an issue. Nothing

I decided to redo the compression test....

Ah cr@p!  I was sure I'd checked every cylinder but I guess I missed one in my initial moment while stressing out. #8 cylinder has no compression. Pulled the rocker assembly and there it was. One valve sitting lower than the rest. It still travels up and down, just not all the way up.  I sure hope is just the valve and I've not busted a piston too. 😭😭😭😭😭😭

Share this post


Link to post
Share on other sites

Barring any damage to the head or piston, can I just lap in a new valve? Should I replace head gaskets again? Should I replace the head bolts?

Share this post


Link to post
Share on other sites

Before tearing it down  have you considered pulling the valve up and charging the cylinder with pressurized air? Might just be a broken spring on that valve. If the seats were addressed when you had the heads off previously I don't think a seat could be ruined with what little use it has had since then.if the air holds that valve in position, changing that spring might be enough to get her back in the groove.

  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now