Miss and Solution

Karl

Karl

Well-known member
A quiet day at work today so I thought I would share with you a new to me miss and cause in my 34 Fordor .


Recently I attended an Art Deco festival about 2 hours drive north of were I live We took the 34 and driving up everything was great apart from the odd stumble . Coming home the car was missing quite a bit . Seemed to be ok below 50 mph but much worse when I pushed it a bit.


My initial thoughts were condenser or coil or perhaps fuel
I replaced the condenser and coil with no real improvement. I did notice a little bit of sediment in the glass filter of the (later than 34) fuel pump and wondered if there was gunk in the carb- I changed out the carb for my spare one. No Improvement so I started form scratch.


What I found was that the cap on the vacuum plunger on the distributor had worked loose by vibration. Hence the vacuum brake was not working -Tightened up and the problem is gone !


I've often wondered if the vacuum brake was needed with modern fuels -I now know it is!


Karl
 
Good to know, I’ll keep that one in the “ what to check” column of flathead repairs.
 
RalphM said:
Good to know, I’ll keep that one in the “ what to check” column of flathead repairs.
Click to expand...

Not yet Ralph its started doing it again.
This afternoon I pulled the distributor (1934 Helmet) and installed my spare.
I think the problem is that there appears to be a quite a bit of forward and reverse movement (end float ) in the distributor shaft . I'm not sure how much is acceptable but certainly much more in the distributor than the spare I installed . Haven't measured it but it would be pushing 1/8 of an inch

So far running ok with no problems

Karl
 
Karl, more than likely the problem was the distributer points, burnt or out of adjustment or too weak spring tension. The shaft end play should be about .010 thou and no more. You can adjust this with a fibre washer in the front end. Set points to .014 thou each if you don't have a timing fixture to set your distributer up on. Regards, Kevin.
 
FlatheadTed said:
Karl it may be developing a short through the rotor to the shaft ,?
Click to expand...

Yes I think that is a possibility but from memory I put some shrink wrap on the shaft -I'll have a good look when I pull it apart. You've had a look at it previously and found the rear end to be quite dry. I have unplugged the holes in the timing cover so hopefully that problem should be fixed -Karl
 
koates said:
Karl, more than likely the problem was the distributer points, burnt or out of adjustment or too weak spring tension. The shaft end play should be about .010 thou and no more. You can adjust this with a fibre washer in the front end. Set points to .014 thou each if you don't have a timing fixture to set your distributer up on. Regards, Kevin.
Click to expand...


Thanks Kevin I do have a timing fixture ( A Bear Brand ) which seems to work quite well . It was set up by me and checked by Flathead Ted about 12 months ago -But I do a lot of miles so possible the points are suspect or out of whack . I will pull it apart to install the fibre washer(s) so will check it all out then -Karl
 
FlatheadTed said:
Karl it may be developing a short through the rotor to the shaft ,?
Click to expand...
Ted, you know back in the days (1960s) I repaired/rebuilt hundreds of ford V8 distributers and we never ever insulated the shafts. It did not seem to be a problem. However these days I put a couple of layers of shrink sleeving on them just for luck. Regards, Kevin.
 
Koates I have only struck it once with this good original 34 stuck out 25 miles from the shop ,all we I had was a screwdriver and pliers and a roll of tape to get the dizy of. With some skinned knuckles we got it on and driving ,till then it just would not negotiate a hill..
Karl
I thought it was set up good ,I might be responsible for the loose vacuum nut I usually remove them to save the Radiator on 34s ,
 

Attachments

  • P1010791_4236.jpg
    P1010791_4236.jpg
    87.9 KB · Views: 17
Karl ,I find that most of the miss fire problems on our 33 are self inflicted,like too much grease on the points cam,spins out when hot and gets on the rotor, too much oil on the bushes when resembling,same result,oil on the rotor.
the end float may be a problem with the rotor,I got a pile of helmet dist and found some have a non ford rotor that is shorter than a ford one,hence having too much end float. like Kevin said a fiber washer fixes it,
Also check the gap between the rotor tips and the terminal plate contacts, they also vary with aftermarket pieces.
Lawrie
 
Lawrie said:
Karl ,I find that most of the miss fire problems on our 33 are self inflicted,like too much grease on the points cam,spins out when hot and gets on the rotor, too much oil on the bushes when resembling,same result,oil on the rotor.
the end float may be a problem with the rotor,I got a pile of helmet dist and found some have a non ford rotor that is shorter than a ford one,hence having too much end float. like Kevin said a fiber washer fixes it,
Also check the gap between the rotor tips and the terminal plate contacts, they also vary with aftermarket pieces.
Lawrie
Click to expand...


Thanks Lawrie
If this week ever finishes I'll tackle it this weekend. I have about 3000 patients in my practice and today it seems like every one of them is sick. My poor brain is struggling to cope -Karl
 
FlatheadTed said:
let us know ! if you cant find the problem ,I will give you a free run up on the Vane strobe,
Click to expand...

Thanks Ted . My son made an observation yesterday -He is building a 1930 Austin 7 Special with ( lots of ! ) help from my vintage car friends . He asked me how come guys who own old cars are such good guys . This forum just confirms the fact .

My response to Tom (after agreeing with him ) was that the most important thing is to play it forward. In the future he needs to help out other guys who are interested in old cars

Some say our hobby is dying but by the simple giving of time and support my son is signed into the hobby

Karl
 
You must log in or register to reply here.
Back
Top