My apologies in advance to those who have been over this stuff a hundred times already but we'll go down the same track for those with a little patience. I just cleaned and reset the points on my '47 with crab distributor. Set them both as best I could to 16thou. One was at a little under 12 on cam lobe and the other was at about 8 on cam lobe! She seems to run better now, but I,ve also noticed that the timing seems to be set hard over to one side. Not sure whether it is advanced or retarded but it is hard over. Would it be a good idea to experiment with that while I'm at it and maybe try setting it mid-way somewhere then take her for a run. Just seems strange how someone would've cranked the timing right over like that. What is the correct initial timing BTDC?, and do we time these things with a light as on a late V8? Anyone's thoughts?
Crab Distributor points gap and timing.
- Thread starter 66miles
- Start date
Thanks Ken. That's kind of what I thought. Thanks also for the tip on the vacuum brake. To be honest I haven't looked at the thing! Just seems like every time I come up with what I think is a good idea for my flattie I get completely defied by the unique nature of these beautiful machines. Thank god there are a few who know how this stuff works!
FlatheadTed
Well-known member
Ian NZ
Well-known member
FlatheadTed
Well-known member
Nice one Ian good to see you have the unit up and running .We check all points spring tension particuly with unknown origins of points suppliers ,its has been over looked its something we have been doing for several years now along with a few tricks to compensate for after market coils .
Pete
BANNED
If you made it through grade school, you are more than qualified to get that distributor running acceptably. Setting the points with a feeler gauge may not be the ultimate way but they have been done that way since they first came out and got by ok. After you do that, drive the car and see if it pings. If not advance the timing (move clockwise) a couple notches and drive again. When it pings screw the vacuum brake in a turn or so.. Drive again. etc etc etc.
A distributor set up on a machine will not always be dead on when bolted on a car. Some need tweeking because of engine variations, fuel differences, altitude, driving style and several other parameters.
Ian NZ
Well-known member
Here in N.Z it is very hard to get a flathead V8 engine to ping on account of the fuel we have here, so the only other way to finally tune these engines is by using a vacuum gauge. 'Ted' - I am pleased you check the contact points tension, a lot do not when they fit new contact points, and I find I have to adjust every new set of points too Fords specifications to the performance of the engine.
Bassman/NZ
Well-known member
Ian, to keep this all in the one thread, do you want to elaborate on the vacuum method of tuning a dissy?
Pete
BANNED
Spring tension is extremely important if you want the points to last.
Many of the Chinese junk ones available now won't last too long if just installed as is.
I forget who made them years ago but the best points were the ones that had a pure silver button on the contact face. They could have even been OEM.
Always keep your eye out for OEM parts like this at swap meets.
These old distributors worked great for racing also and could be made to be reliable to 6000 rpm if touched up every week.
Ian NZ
Well-known member
The Ford distributor was well designed originally and the later crab type is one of the best models of them all. I read it some where who designed it for Henry Ford,
Testing the vacuum brake on the Ford stroboscope I found out the crab type with the aluminium housings that the vacuum brake piston chamber wore out quicker than the cast iron housings therefor they would leak more vacuum so the adjusting screw would have to be altered to correct this, therefor the cast iron crab type of distributor housings are the better models to use, in fact I have seen cast iron housings with a bronze bush in that chamber, they give a real good reading. Of course all the earlier model helmet type are cast aluminium too.
Using a Vacuum gauge, what I have done was to run the engine up to about 1000rpm adjust the timing to the highest reading standing still, which should be 17 to 21 inches, it can also be set by placing the vacuum gauge in the car and going for a drive and adjust the timing to the highest reading at your cruising speed, Other people might have different ideas.
Testing the vacuum brake on the Ford stroboscope I found out the crab type with the aluminium housings that the vacuum brake piston chamber wore out quicker than the cast iron housings therefor they would leak more vacuum so the adjusting screw would have to be altered to correct this, therefor the cast iron crab type of distributor housings are the better models to use, in fact I have seen cast iron housings with a bronze bush in that chamber, they give a real good reading. Of course all the earlier model helmet type are cast aluminium too.
Using a Vacuum gauge, what I have done was to run the engine up to about 1000rpm adjust the timing to the highest reading standing still, which should be 17 to 21 inches, it can also be set by placing the vacuum gauge in the car and going for a drive and adjust the timing to the highest reading at your cruising speed, Other people might have different ideas.