I have a 1955 Mercury Montclair, with the stock 292. The engine has been completely overhauled. I have replaced the harmonic balance, which had some play in, along with the distributor. The distributor has been converted to electronic. the car has also been converted to a 12 volt system My problem is that with the timing set at the correct setting, timing advances 40 degrees. The timing has been set by vacuum, but the problem persists. I have tried everything I could think of to try and solve the problem, and have reached the end of my rope. At lower speeds, she is surging and bucking. At higher speeds, it better, but still runs poorly, and performance is very poor. If anyone has any solutions, or ideas that could help me it would be greatly appreciated. Thanks...Billy

Are you using the original teapot carb with the original distributor?  If either has been changed to something else, the compatability may no longer exist.  When you replaced the damper, did you get a used original?  If so, the damper ring may have slipped and you are getting a wrong timing reading.  Your symptoms do indicate excessive timing advance.

John - "The Hoosier Hurricane"

John, Thanks for reply. No I don't have the original teapot carb, nor the distributor. I got the damper from John Mummert, and the distributor from Carquest part # REB 30-2808. When I purchased the car, it had a Edelbrock carb 4V. I had to replace it. I now have a Holley 4V. Do you what I need too do to make it compatible...Thanks, Billy

We are going to have to know, what is the "correct timing" as you understand it? - This would be the intial timing you have used with the distributor vacuum line opened and plugged at the carb, engine running at idle.

What sort of idle speed setting do you wish to have, and the vacuum reading at idle? Have you had any problem with vacuum leaks?

Is the 40° advance something you got with the vacuum advance connected - or disconnected? At what engine speed?

Which Holley carb have you installed to replace the old one? We'll need to know the model number or CFM rating? 

There is a lot to sort out - we need some info in order to help you....

 
 Steve Metzger       Tucson, Arizona

Have you used a vacuum gauge? Should be 18-21 in.,,,,taken from the manifold.

Hi Steve, thanks for your assistance. Here is the info you need. The correct timing is 6 degrees BTDC, This is with the vacuum disconnected, With the vacuum connected, the reading is 40 degrees at idle. The idle is set 700 rpms, there are no vacuum leaks, and the holley carb is 600 cfm. Again thanks for your assistance. If you need to talk too me call me collect at 352-854-8142..Billy

I can't figure out how to use the Carquest website. Is that distributor, REB 30-2808, the correct one for your '55 or is it for '57 and up?


Lawrenceville, GA

Billy, are you sure you are using the timed vacuum port. If you are using the full vacuum port full vacuum advance would be applied as soon as you hooked up the vacuum line. 34 degrees is still a lot of vacuum advance though. Mike

1956 Fairlane Victoria (ORREO)

 

Overlooking Beautiful Rimrock AZ

Hi Billy - Thanks for the aditional info, clears things up a bit. It sounds to me like the vacuum advance pot on the distributor is set "wide open". In that situation - at idle where vacuum is maximum - its going to kick things up quite a bit when operating on live manifold vacuum - more than you would want it to be. Is this a stick shift car - or an auto? The 6° initial is typically factory recommended for an auto I believe.

These graphs are in the mid-seventies Ford training information for distributor service techs....they are typical values for Ford distributors - not exactly what every last one is set up at. As you can see on the upper chart, at vacuum reading of 10 to 15 In.Hg. (inches of mercury) - the added advance in distributor degrees could be as high as 10°. That would equate to 20° at the crank. So when you add the vacuum advance to your initial - you could get (for instance) 6° plus the 20° - making the advance go to 26° - if the engine did not increase in idle speed (which I'm reasonably sure it does).

On the second (lower) graph - at 500 distributor rpm (1000 engine rpm) the mechanical advance of the distributor is shown as 3-1/4° to 4-1/2° - which is doubled at the crank, so now its up to a range of 6-1/2° to 9°. This - added to the inital and vacuum numbers seen above - gets you up to 32-1/2°/35°. So its very possible to be creeping near to the 40° you are speaking of.

The Holley carb most likely has two small vacuum control ports - one of them should only provide a vacuum source when the engine is revved up off idle - ported vacuum - have you tried using that one? It might help this situation out without having to get too deep into retuning the car. 

 
 Steve Metzger       Tucson, Arizona

Hi Steve,the trans is auto. I have been using the vacuum port that increases above idle. I tried changing ports, and the idle increased. What would correct the vacuum advance being wide open? Thanks again...Billy