Finally got the stumble out of my car

[Sixt8Chrgr]

I had a stumble off idle which led me to rebuilding the carb, setting the air/fuel mixture several times and then finally I believe I have it sorted out. I checked the timing, and static was at about 18* at 1000 rpms. Oh yea someone had put a BB in the vacuum advance hose so I was getting no vacuum advance signal. Anyway I removed the BB, set the timing at 15* at 900 rpms in park, and the car seems to run much better. I was unable to drive it far because of domestic duties but around the block she seemed to run much better. Someone has installed an after market lopey camshaft in the car so to get a steady idle at 900 was hard but I got it as close as possible.

[PlainfieldCharger]

I would be looking for detonation if you hook up that vacuum hose. You might have to re-curve your distributor

[Sixt8Chrgr]

No detonation that I have found. Car runs well.

[myk]

BB as in ball bearing?  Why wouldn't they just cap the damn thing off?

[BSB67]

BB as in ball bearing?  Why wouldn't they just cap the damn thing off?

People have done it to retain the stock look, but that does not sound like the case here.

[myk]

 

[Sixt8Chrgr]

Yes a ball bearing in the vacuum advance rubber hose. I guess trying to keep the stock look?

[Dino]

Only 18 degrees with a lopey cam?  Damn, I think my base timing is 24...

[myk]

Shoot I should probably try 24* of initial...

[Sixt8Chrgr]

Only 18 degrees with a lopey cam?  Damn, I think my base timing is 24...

I have all vacuum disconnected to the distributor when setting the timing.

[Dino]

Only 18 degrees with a lopey cam?  Damn, I think my base timing is 24...

I have all vacuum disconnected to the distributor when setting the timing.

Same here

[Back N Black]

Only 18 degrees with a lopey cam?  Damn, I think my base timing is 24...

I have all vacuum disconnected to the distributor when setting the timing.

Same here

Dino, are you at 24 and using your Vac Advance?

[Dino]

Only 18 degrees with a lopey cam?  Damn, I think my base timing is 24...

I have all vacuum disconnected to the distributor when setting the timing.

Same here

Dino, are you at 24 and using your Vac Advance?

Yep.  Disconnect vac advance and the car becomes temperamental.  Crazy stuff.

It's the cam, it is so mismatched to the rest of the engine it's not even funny.  But my driving season is over, except for driving it to the a/c shop and back next week.  So the next time she fires up the cam will have been replaced.  I'm starting at 12-14 degrees this time.   

[Sixt8Chrgr]

I was really surprised the difference in the drivability of the car from 18* to 15* static timing. My car is not perfect because the cam is not matched right for the torque converter and when I plug in the vacuum advance it does not have enough vacuum to instantly advance the timing. But when I give it a little gas the ported vacuum will pull the advance which then runs the idle up to high. If I let is sit there for a minute or so it will idle back down.
I had good luck with the Comp Cam XE268 in my 68 with a non original 440. This car has the OEM drive train so may just put the stock grind back in it? Not sure right now what I will do. It is hard to argue with technology and the old profile is just so ancient. So undecided.

[BSB67]

But when I give it a little gas the ported vacuum will pull the advance which then runs the idle up to high. If I let is sit there for a minute or so it will idle back down.

This is usually a sign of a vacuum leak.

In fact, your other symptoms also sound like a vacuum leak

[Sixt8Chrgr]

But when I give it a little gas the ported vacuum will pull the advance which then runs the idle up to high. If I let is sit there for a minute or so it will idle back down.

This is usually a sign of a vacuum leak.

In fact, your other symptoms also sound like a vacuum leak

I will check that out. Where would you suggest I start to look?

[BSB67]

I place my hand over the carb when it is idling and positioning my hand to restrict the air flow to choke out the engine.  When your hand is in the right position the engine will die.  Pay very close attention and listen for an engine rpm change during the process.  If the engine goes from a constant normal rpm to dying out instantly, no vacuum leak.  If just before the engine dies, the rpm goes up slightly for one second, then dies, there is a vacuum leak.  I have found this method to be very reliable.  It takes a little practice and a good ear, but anyone can do it.

You can spray soapy bubbles, or a light hydrocarbon aerosol (WD40, carb cleaner...) to pin point the leak.  Some people like this the best, but I find that sometimes it is unreliable.  For all but an intake-head mating surface leak, you can usually find them by simply looking once you know you have a leak.  Check all hoses, fitting and devices that see engine vacuum (head light door system (if so equipped), power brakes, PCV ...)

[Sixt8Chrgr]

ok thanks I will check it out

[500Jon]

No old school cams for us Limeys!
Lunatti dual pattern from now on.
1/2 inch of lift and 20 inches of vacuum.
Try getting anything over 10 with PURPLE shafter .
Its all about the VACUUM...
Very handy when you wanna stop lol...
5J

[Sixt8Chrgr]

I place my hand over the carb when it is idling and positioning my hand to restrict the air flow to choke out the engine.  When your hand is in the right position the engine will die.  Pay very close attention and listen for an engine rpm change during the process.  If the engine goes from a constant normal rpm to dying out instantly, no vacuum leak.  If just before the engine dies, the rpm goes up slightly for one second, then dies, there is a vacuum leak.  I have found this method to be very reliable.  It takes a little practice and a good ear, but anyone can do it.

You can spray soapy bubbles, or a light hydrocarbon aerosol (WD40, carb cleaner...) to pin point the leak.  Some people like this the best, but I find that sometimes it is unreliable.  For all but an intake-head mating surface leak, you can usually find them by simply looking once you know you have a leak.  Check all hoses, fitting and devices that see engine vacuum (head light door system (if so equipped), power brakes, PCV ...)

Could not find any vacuum leaks.

The cam in the car is just not the right one for the car. Very lopey idle, torque down low is not good, stock torque convertor does not match cam, car pulls hard at higher rpms. I think I need to put in another cam...either a Comp cams XE 268 or some other. Need suggestions.