this motor never idled right since ive gotten the car about 40K ago. Runs fine off idle and doenst burn any oil. I think the motor maybe a parts store reman engine because of the bar-code sticker i found stuck to the side

It has a random miss at idle. Clack-clack-clack-clack-thump-clack-clack-thump-thump-thump-clack-clack-clack-clack. The "thump" sound sounds just like if the miss you get if you unplug a plug wire. The whole car shimmies when it misses.

Ive given in a tune up. Autolite plugs. Brass cap /rotor. 8mm wires checked out.
I ran the valves about 30K miles ago and no change
ive swapped the intake/exst manifold and have had it off to dbl check the seal. Checked it with brake clean and cant find a leak. Ive swapped 1920's and got no change. compression checked out when i got the car.
PVC/breather are fine.

It has a MP dist and orange box but some JC whittney looking crome coil. My next step is to swap that.
It also has a condenser hooked up to the coil. Did stock electronic ignition cars have one or just points cars?

It runs strong and the miss goes away as soon as you bring up the RPMs.

Any ideas?

Sounds like a vacuum leak due the intake manifold gasket not sealing on one of the cylinders. Mine does the same thing, It is number 5 intake that leaks and number 1 exhaust on mine, but not enough to really hurt anything. I have been on a quest to find something better than a Fel-Pro gasket. I had my manifolds resurfaced and a new gasket, but after awhile the vacuum leak will develop again when the gasket shrinks. My leak seems to also go away with a little rpm. Most of the gaskets listed on the SL6 manifold article are no longer made.

Maybe slant Six Dan can advise on where better gaskets can be found.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Sounds like a vacuum leak due the intake manifold gasket not sealing on one of the cylinders. Mine does the same thing, It is number 5 intake that leaks and number 1 exhaust on mine, but not enough to really hurt anything. I have been on a quest to find something better than a Fel-Pro gasket. I had my manifolds resurfaced and a new gasket, but after awhile the vacuum leak will develop again when the gasket shrinks. My leak seems to also go away with a little rpm. Most of the gaskets listed on the SL6 manifold article are no longer made.

Maybe slant Six Dan can advise on where better gaskets can be found.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Look under slanted network(on the main page) for "the good gaskets", they are in Australia. I dont know which U.S. made gaskets work well. Someone should let you know.

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Excuse me, does this smell like chloroform to you?

Are you using the vacuum port in intake runner number 6? (power brakes, AC controls...) plug & test. Also plug and test the PCV valve.

The next area to check is under the distributor cap. Rotor type and "phasing" can cause a large gap between the rotor tip and the cap's contact / tower. I have a "cut-away" distributor cap that I use to check the alignment and the amount of gap between the rotor tip and cap's contact point.
DD

Huh? Which ones have you found to be discontinued? Just curious; none of them is as good as the newly-available good gaskets for the manifolds-to-head and the intake-to-exhaust (heat riser/hotbox) junctions.

I'm suspicious of the generic chrome coil, the orange box (they're mostly junk these last five years or so) and what might well be the race-curve distributor that was part of the MP electronic ignition conversion package. That distributor has only one mechanical advance spring, and it's a super-lightweight item, so the timing can really flop around at idle.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Dan,

I tried ordering both Mr. Gasket #320 and NAPA's #MS-16030 and the parts man at several stores told me they were no longer available as of this year. Both are suppose to be better than the FelPro which I have been using.

Are there other gasket options?

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

1) Perhaps Mr. Gasket's #320 is gone, but MS16030 is very much still alive and available. Your parts guy was being lazy.

2) It doesn't matter, because the good gaskets come from clicking the "good gasket" link I supplied above.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

What is the part number for the intake to head gasket?
I am not so concerned about the intake to exhaust heat riser gasket.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Uh...dude, just go to the link I gave you!!!

And you should be concerned about the heat riser gasket. If you use anything other than the one at the provided link, it almost certainly will leak.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

That port is plugged and i plugged the PVC port for testing.

I was thinking today at work how I could rule out the ignition system and I think Im gona try and ghetto rig the inductive pickup for my timming light to an oscilloscope and see what it looks like. Duno what ill learn from that :shrug:

Ill also window a cap and see whats up. Did you drill holes in yours so you could see if there is sparking wile its running?

The timming is staying put at idle. Its not jumping around.

Ill have to triple check the intake to head sealing.