DM6 distributor on the an early production BJ-7

[gonzo]

Hello All - I've been away and have not enjoyed the forum in a long while.

DM6 distributor on the an early production BJ-7 was removed for refurbishing, upon installation the engine cranks but only produces sporadic backfires through exhaust and carburetors. It refuses to fire suggesting incorrect installation to some original position or orientation. However, the distributor was slotted into correct position (2 o’clock) with pulley notch timing marks aligned and piston TDC confirmed. Distributor HT / LT wires were checked and correct for firing order. Static timing was set which confirmed an electrical connection but the spark between points appears to be weak.

The engine was running fine before the dist was removed. Another working DM6 (from a claimed 40k mile car) is on the shelf as a spare and could be used for troubleshooting. It was also used for visual comparison to the refurbished distributor – with the exception of the distributor drive spindle (where rotor installs) being 180 degrees from the refurbished everything is the same. Recall that the drive-dog allows for only one position for dist installation. Sometime this could be 180 degress from TDC. Is it correct to remove the distributor drive spindle, easily done on a DM6, turn 180 degrees and install, or does removal somehow effect timing?

The points, condenser, rotor and perhaps coil will be replaced today for another round, but I’m running out of options for troubleshooting. What are the chances that that the timing gear skipped a tooth and now affecting timing? I’m posting in hopes that as fresh set of ideas will help.

Thanks in advance (no pun intended). GONZO

 

[Keoke]

Hi Gonzo, Yes it is possible to install the "driving dog" on the bottom of the distributor shaft 180 Degrees out. If the spare unit you have verifies this error, by all means drive out the retainer pin and reposition the "driving dog" to agree with that of the spare unit.---Fwiw--Keoke

 

[gonzo]

Keoke thanks for your reply. On a DM6 repositioning the lobed spindle (where the rotor attaches) is easier than drifting the pin out of the distributor’s drive dog shaft and repositioning the gear. Does simply repositioning the lobed spindle 180 degrees affect any of the distributor's functions? Currently the engine produces sporadic backfire with the rebuilt dist installed. Advance Distributor, the re-builder, strobes the distributor to recurve. If the spare distributor fires the engine, then I’ll work from there. This is frustrating. GONZO

 

[Keoke]

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Please note: The distributor should be slotted in at: 20 Min-to-2 is that the position you used or was it "2 O'clock"---Keoke--? ?

 

[gonzo]

Keoke, thanks for the clarification: 20 min to 2. And the engine fired to a perfectly smooth idle. Can't wait to take it out for a spin this weekend. Jeff, at Advance Distributor, said that there will be noticable difference in power delivery as the advance curve and other slight modifications were made during rebuild.

Checking other items now like engine ground- starter is turning too slowly and may be the next thing to be rebuilt.

Thanks again for responding to such an elementry question.
GONZO.

 

[Randy Forbes]

Keoke, thanks for the clarification: 20 min to 2. And the engine fired to a perfectly smooth idle. Can't wait to take it out for a spin this weekend. Jeff, at Advance Distributor, said that there will be noticable difference in power delivery as the advance curve and other slight modifications were made during rebuild.

Checking other items now like engine ground- starter is turning too slowly and may be the next thing to be rebuilt.
Thanks again for responding to such an elementry question.
GONZO.

Just a plug for the gear reduction starters on the market: it'll spin the engine over so fast that it scares you until you get used to it.

My old starter would barely draw the Weber's shot of fuel into the inlet tract; it was like "... I think I can, I think I can..." every time I went to start it.

Several years ago, I put a gear reduction starter on one of my old MGBs too; sounded like a 1960s Chrysler Product cranking over, but it sure lit off fast!

 

[Johnny]

If the starter is cranking too slow you might want to check the battery cable as well as the grounding cable as they tend to corrode from the inside out.

 

[terp83]

Hi Gonzo:

Back in March of this year, I removed the DM6 distributor from my 1962 BT7 and sent it out for rebuild and recurve. The vehicle was not moved or otherwise disturbed while the distributor was removed. Upon its return, my son and I reinstalled the refreshed DM6, and when we attempted to start the car, the symptoms were as you described above. We aligned the notch on the crankshaft pulley with the pointer, allowing for advance. Standing on the right side of the Healey, I removed the distributor cap. Instead of the rotor pointing at the 3 o'clock position and the #1 plug lead, it was pointing at the 9 o'clock position and the #6 plug lead. After number-tagging the plug wires so we could always go back, we moved each plug wire to the plug 3 plugs away. With the firing order of 1 5 3 6 2 4, we put the #1 wire on the #6 plug, the #5 wire on the #2 plug, the #3 wire on the #4 plug, the #6 wire on the #1 plug, the #2 wire on the #5 plug, and the #4 wire on the #3 plug. Simply stated, we switched #1 and #6, #2 and 5, and #3 and #4. The car started right up and idled smoothly. We took it for a test drive, and it ran as well as either of us could remember. That was roughly 1,500 miles and several great drives ago, and it has started and ran fine ever since.

I hope this may help.

Jerry