Points/dwell

I have a 73 455 engine and it just doesn't seem to be hitting right. Can someone lead me through the steps of:
Setting the gap for the points
Setting the dwell..........Most important here is the order in which to do all this from start to finish and a detailed explanation from start to finish. And what about adjusting the carb. also.......vacuum? If there is a place to look this up on this site I have not seen it so I apologize if I am rehashing something but I think this would help alot of people if a qualified person posted this info. I feel as though I am doing something wrong when tuning this engine.

Info greatly appreciated.

Dennis

 

Dennis

You can't really set the dwell without a dwell meter, setting the point gap is how the dwell is changed so a specific point gap means an approximate dwell angle. If you can find a dwell meter you adjust the dwell using an allen wrench through the little door in the distributor cap.

Dave Berry

 

A surprisingly accurate way to do it is to turn the point adjusting screw in while the engine is running until the engine almost dies. Then back it out 1/2 of a turn.

I just might have the procedure backwards, but am 80% sure that is the way you do it. sorry but its been 10 years since I've fiddled with points.

Point gap and dwell are different ways of measuring the same thing. So if you adjust one, then you shouldn't worry about the other. Dwell is the preferred method.

 

Once you set the dwell, the timing changes. You'll then have to reset your timing. Dwell changes timing, but timing does not change dwell. FYI.

 

Timing/Dwell

You know,

I used to know all this stuff when I was eighteen, 48 now though. Thank you all so much for all the help. I have a dwell meter and used it. The engine did not run right,,,,,,,,,,timing changes? hmmmmmmmmm no wonder. I will repost when I am done to let you know how I made out. Thanx again,

Dennis

 

I recommend sending it to the ignitionman

To have your points converted to HEI for $175 & another $30 for a new accel coil. That way you never have to screw with it again and improve performance & reliability.:TU:

I never had a problem before my conversion. I just plugged the vac advance, started the car, then adjusted the screw until the dwell was 30 degrees (from what I recall). I haven't done that since 1990, it's been a while....:bglasses:

 

30 degrees

All V8 motors are 28-32 degrees of dwell. Yeah, I'm that old!

 

Dwell/Timing/Hei

I have an hei in my 70 455 gs clone. Runs ok, but it always felt like it is lacking some, especially with the cam and 800 cfm carb. Or, maybe the carb needs some tuning. Anyway, on this 73 455 Riv, i set the dwell at 30 deg. and then put the timing on 4 deg.btdc. I pulled the vacuum off the dis. before doing so,,,,,,,,,,,,correct? Took it for a ride and it ran a little worse than before. In nuetral the engine comes up to rpm very quickly and smooth. When in gear, and you go to take off it wants to hesitate, and if you jump into it and hold it there, you can feel the torque, but it feels like it doesn't want to come up to rpm fast enough. Feels kind of dead. Idols like a dream, sounds very even like there is no mechanicl problems. If I have done everything ok, then it must be the carb. Any other ideas?

Dennis

 

Try not to cut your fingers off when you adjust the dwell. That's the only bad thing I see from having a distributor up front.:gt:

 

Bump the initial timing up to 10* advanced. 4* is pretty low. The 69 Riv calls for an absurdly low 0* initial timing! We run ours anywhere from 4* to 20*+ initial. As long as it doesn't ping under WOT.

Be sure to adjust your carb, and look for vacuum leaks. A good place to start is to plug every vacuum line with golf tees. Then add them back one at a time and see if you get the stalling you mention.

Also, if you never replaced (or if it has been years since you replaced) the vacuum lines, then replace them.

 

Find a good distributor man with a distributor machine. Have your distributor set (curved) on a machine. You will be amazed at the performance difference.

Most distributors are WAY off. Especially if they are old with lots of miles. This is true for point distributors or HEI.

 

Misc ramblings blahblahblah...

Set dwell first, THEN timing as mentioned

Vac adv working?

Secondary lockout on the carb getting in the way? LOL.

Check the mechanical advance for missing springs, bad bushing, or ? I had a bad stop bushing once that caused me some grief.

Set timing with the advance all "in". Read that years ago and really liked the results. You can tune the advance on the car or do it in a machine as mjs mentioned. Every once in a while you even see these machines for sale. For who might have one, check with tech schools - schools never throw anything away it seems like.

You can adj the carb for highest vac reading to get started.

How about the rest of the ign? Not "hitting right" implies something other than what you mean I think so its likely not related.

Shawn

 

Vacuum -

Facing the carb from the front, upper left 1/4" port is manifold vacuum, lower right 1/8" port is "ported" vacuum - this gets vacuum applied as the throttle blades open.

I'm running points in my '68, they have been less trouble than when I messed with a Pertronics a few years ago.

I'm set up with 28 degrees dwell, 16 degrees initial advance, 15 or so mechanical in the distributor which comes in by about 2200 rpm, and vacuum advance is limited to 6 degrees. Vacuum runs from the "ported" source with the thermo switch to add advance when the motor gets hot.

My car has the 230-245 "Popular Mechanics" cam and about 9.8:1 compression, it idles at 750 rpm and holds 15" of vacuum. The additional advance really helps with idle stability.