DK4A distributors

[Malcolm Parker]

Howard, I always try to put Tesco Momentum E5 in my seven.   During the petrol shortage last September I had to use some Tesco E10 and it didn't like it at all.  There are forumists who use E10 and are happy with it but not me.  My engine is probably a similar spec to yours except I use a 1 1/8" SU.
Regarding distributors, I have tried Lucas DK4A and various Bosch equivalents.  My experience is that the engine runs sweeter on a good Lucas distributor than on the Bosch.  It is easier to find a poor Bosch distributor than a good Lucas one!

[Howard Wright]

Thanks Malcolm

I did wonder about E10 after so many had said they had no problems.

Cheers

Howard

[Speedex750]

Hi all,

I have wondered if those who have changed away from the DK4 and declare a great improvement are just reflecting on what poor shape their distributor was in rather than how good the replacement actually is. I tried a strobe light with what I thought was a decent DK4 and could visibly see the timing scatter of a varying number of degrees at tick over. A NOS Reliant distributor was much better with almost no scatter.

I am curious about folks' experiences with unleaded petrol. The change from original unleaded to E5 seems to have resulted in both my A7 and AH3000 running very hot. E10 doesn't seem to make any difference in this. I've tried adjusting the timing but found both to be insensitive to changes. Previously I used to advance the static timing of the AH3000 until pinking occurred and then retard slightly but I can't get it to pink any more! What are the burning characteristics of the E grade petrols, how do you time in with E5 or E10 - more or less static advance?

Thank you for your advice.

Dave

[Bob Culver]

Cars with excessive advance run hot, contrary to the tales from days of Model Ts  run retarded with glowing manifolds. Adjusted for max power scatter may not make much performance difference but the crank will wince at the early shots, with avoidable roughness.
For anyone retaining manual advance, if only as an override, a light spring can eliminate lost motion.
Old lawnmower controls offer scope fro an override.

[Marcus Ling]

Hi Howard,

It may be a bit late to answer but my Lucas Equipment catalogue for 1939 list the distributors for 7HP starting with 1932 as;

1932 400801 DJ4/7
1933 Same
1934 400801 but just DJ4
1935 400289 DK4A
1936 404440 DK4A
1937 405508 DK4A
1938 Same for 7HP but  Big 7 is 400206 DK4A
1939 Same for 7  and Big 7

Marcus

[Howard Wright]

Thanks all

Dave, the DK4 I have removed from the car was in good condition when checked with a strobe and I will retain it in the car as a spare. I haven’t checked the replacement DK4A yet but it definitely seems to improve things and the car runs more smoothly.

My research of E10 and it’s propensity to cause knocking is restricted to Google! Several web pages seem to confirm that higher grades of ethanol do cause knocking. Perhaps others will comment on the chemistry.

Marcus. It seems the only one of my three DK4A distributors that are definitely for the A7 is the one I’ve put on the car (top right in my earlier photo). Thanks for the info.

Once again many thanks

Howard