Helper in need of some help!!!!!! 35 - 3cyl

DavidP, South Wales

Well-known Member
Have a customer's 35 3-cyl in. Absolute pig
to start from stone cold. Once started and
warmed a little will start immediately and
sounds great. New thermostart fitted and
all compressions are spot-on. Have adjusted
tappets which were all just about tight.
The problem that I have is with the pump
timing. Have set flywheel to 'Spill 18'
mark in centre of inspection hole on number
1 on compression. Have removed pump
inspection plate. Initially pump appeared
to be way too far advanced. Have retarded
to try and align circlip scribe mark an 'E'
line on rotor. Have removed timing cover
and all gear marks are spot-on. Appears
that someone has filed the pump slots to
retard the pump further but at max rotation
(present slots)the marks are still nearly
2mm 1/16" apart. Have even measured spill
mark in inspection hole to ensure that it
is central. Have not stripped a DPA before.
Is it possible for the circlip to turn in
it's groove and to lose the timing point?
Really struggling to find an answer to this
one. Thanks in advance for any help.
DavidP, South Wales
 
The circlip MAY not be in the correct location, it's set during the final timing after pump is bench tested. Post the pump complete 323 number and I'll see which outlet and what degree the hub/flange mark should be. DPA drive plate bolts inside are offset, pump can't be assembled wrong IF the correct splined drive plate is used, there are more than one. Just curious, what is the cranking compression PSI as tested?
 
Hello, thanks for your detailed reply. Comp test figures taken over 3 tests were;
Build-up 1/ 180 2/ 200 3/ 235
Cranking 1/ 390 2/ 400 3/ 385

Assuming that the circlip was in the wrong position I made chalk marks on the crank pulley for 1 TDC and 18 degrees BTDC. The engine was turned past the 18 mark and the point of spit noted from number 1 port on the pump. Initially the 'spit' was too far advanced. The pump was retarded in the slots. Next check was close. I have made a jig which clamps to the triangular flange of the pump and locates on the two outer pump studs. By means of a 5/16 with a knob on the end and by slackening the third nut I have fine control to be able to adjust the pump whilst the engine is running.
It was made for a previous 35 and 175 that were giving problems. Difficult to judge cold start performance yesterday with fuel system interupted but indications were promising. Going back to the farm this morning to start from stone-cold. Will let you know the result.
DavidP
 
List the complete DPA 323 number so I can see what pump you have. Some are fixed phase timing, some are light load advance, and some have speed advance. If I recall yours is fixed phase, but the pump number and spec sheet will show for sure. Some late DPA spec sheets also no longer give the correct letter/ snap ring setting, which used to be done after bench testing.
 
Hi, went back to the farm this morning and started the tractor easily at half throttle and no heat. It was an embarassment to the owner before as " three cylinders don't have those sort of problems". Not able to get the number of the pump. Owner now very happy. I have attached a photo of the pump setting jig that I made. Yes, you can turn the pump by hand but it's hit and miss when you only want to move it a fraction. I'm not aware of any commercially made jigs to do this job. Thanks for your help.
Cheers
DavidP
mvphoto14669.jpg
 

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