I have an engine problem that has stumped me and I also brought the car to a local "oldtimer" mechanic who also cannot figure out the problem.  I have a 1961 292 in my '54 Mercury.  I am still running a 6 volt system.  I put a "B" intake manifold on the engine and a new Holley Model 4160 465 CFM carburetor.  The exhaust manifolds are '54 Ford Police/Mercury accessory duals.  The distributor is the stock original.  The compression is 140-150 lbs in all cylinders.  The points, wires and plugs are new.  The point gap and valve lash has been set per specs.  The timing is advanced a few degrees beyond the factory 3 degrees.  The engine sounds good and has lots of power while driving.  There is no noticeable engine miss.  The intake tested negative for vacuum leaks.  

I'm wondering if the exhaust manifolds have something to do with it. The Ford and Merc engines in 1954 were only 239's and 256's and the manifolds might be too restrictive for a 292 with a Holley 4 bbl on a B manifold.


~DJ~ AKA "Bleach"
1956 Ford Fairlane Town Sedan 30K original miles

You say the distributor is stock original.  It is a stock '61 or a stock '54?  The '54 distributor would be incompatible with the later carb.  Do you know for sure what camshaft is in it?

John - "The Hoosier Hurricane"

Check Hoosier's comment first, but if the engine "has lots of power while driving" then I would imagine that your distributor is from 1961. That being said, I would look to that carburetor and the idle screw adjustments. What happens (happened) when you adjusted those after initial warmup? Are you sure that the timing pointer/crank dampener is correct? You know how people talk about the sleeve in the dampener that gets loose and the outer ring spins and all. Why not time by ear just to satisfy your curiosity?

Daniel Jessup

Lancaster, California

aka "The Hot Rod Reverend"
check out the 1955 Ford Fairlane build at www.hotrodreverend.com

The distributor is the '61 which came with the engine.  The mechanic checked the carburetor idle mixture adjustment and told me that it is o.k.  On exhaust restriction theory, this is interesting.  However,  I would think that the early dual exhaust that I have on the engine has to still be less restrictive than the single exhaust/crossover exhaust that Ford used on 292 truck engines until 1962.  Could I test this theory by removing both exhaust manifolds and running the engine without exhaust to see if it runs smoother at idle?  Alan

If the engine has good power as you drive and put it under more load (thereby increasing exhaust flow and pressure) then I would be unsure how the exhaust manifolds could be so restrictive at idle (when there is very little need for good flow, etc) but then give you good power as you drive...?

Daniel Jessup

Lancaster, California

aka "The Hot Rod Reverend"
check out the 1955 Ford Fairlane build at www.hotrodreverend.com

From reading your post I get it that the car is still 6 volt positive ground. What coil are you using and is there a ballast resistor in you system? Do some more trouble shooting by checking you engine manifold vacuum reading at idle. If the vacuum is low ( camshaft) that can cause the power valve in the carb to spill fuel into the intake. Try to get some more information if you can. It is nothing to do with the exhaust manifolds, forget that. Pete

Pete, that does make more sense than my far fetched idea. I was just thinking in that direction because of the description of the strange combustion sounds.

~DJ~ AKA "Bleach"
1956 Ford Fairlane Town Sedan 30K original miles

I am using a new standard 6 volt coil.  I thought that all 6 volt coils were basically the same.  Am I incorrect?  I thought that ballast resisters are only used on 12 volt and not 6 volt systems.   On the manifold vacuum, what is an acceptable reading at idle?  I would like to check it but I have no idea of the readings I should have.  Thanks, Alan

At the top of my list of things to look at would be low voltage to the ignition system at idle. This could be verified with a volt meter connected across the posts at the battery.  Beyond that, then a steady vacuum gauge reading at idle without any irregular blips taking place would at least point to an engine that is in good mechanical condition.  Any irregularities in the vacuum reading can point to electrical or mechanical problems.

Lorena, Texas (South of Waco)