detonation and timing

[38plymouth]

Ever since I added a fenton head to my engine it has been detonating once in a while. I tried checking the timing and I can't locate the mark on the pulley no matter how hard I try so I really have no idea where my timing is. I did loosen the clamp and backed the timing down a bit for now. Last night I drove the car with 4 people in it and it was detonating really bad going up hills. I may just try higher octane gas but I would still like to make sure everything works in the distributer. The pictures in my manual are tough to see and I have no experience with a points style distributer. I want to check the vacuum advance and I have a vacuum pump, should I hook the pump up to the line that runs to the carb and then start the engione to see if it works or do you just watch it to see if it's working with the engine off?

[greg g]

of the line from the carb. With the cap off when you pump the pump you should see the breaker plate move. Remember to retard the timing turn the diz clockwise. There is another bolt with a sloted screw on the base of the distributor body which allows for more adjustment, than the hold down screw. Fell under the body and loosen this one if you have too. most of the Aluminum heads gave a mx of about 9 to one compression ratio. you shuld be a bit lower as CR is effected by piston bore. So you should be able to run regular with spark knock. what ever it takes get it taken car of as Pistons and rings are damaged by excessive ping/knock per ignition. Might retard the timing and try a bit of mid rade fuel.

Speaking of fuel, how much ethanol is in you local blend????

[38plymouth]

I don't really know about the ethanol I never paid attention to it, does it say on the pump?

[Young Ed]

It should. Pretty sure no place in the country has more then 10% in the normal gas. Also around here unless you seek out the special collector car stuff you get 10% no matter what level you buy.

[grey beard]

If this is a serious vehicle to you and you plan to keep and enjoy it, I would suggest you do whatever is required to find that timing mark and KNOW where your timing is set.

This is critical for two reasons. First, it's the only way you can be certain where your initial timing is set, and secondly, this allowsyou to check both your vacuum and centrifugal advance mechanisms with an advance style timing light. If you are concerned enough about performance to run a "go faster" cylinder head, you will want to be certain that both of these advance units are functioning and within specs. Alternately, you could pull the distributor and have it tested by someone with a test bench, but you would still be faced with resetting the intial timing.

I'll bet if you crawl underneath with a good light and a wire brush on your cordless drill you can polish up that crank pulley and find that elusive timing mark. When you do, I'd refresh it with a blunt chisel and then paint it white, so it stands out nicely when you use the timing light to get it right. I painted the 10 degree BTDC mark on mine and just set it there. Easier. JMHO

Lots of luck. L:)

[greg g]

Or you can static time it with a circuit testing light and make a mark on the pully that alignes with the pointer for your version of TDC.

Schroll down the tech tips for the static timing procedure.

http://www40.addr.com/~merc583/mopar/framesets/techtipframeset.html