New distributor - timing?

[James W]

Hi all

 

I've just recently bought a new lucas distributor from Moss (part number 40795). Perhaps foolishly, I'd assumed it would be pretty much identical to the one previously fitted but, critically, it appears to have no mechanism for setting the advance. Not that I've done it before, but reading the handbook the original way of setting the timing looked so straightforward (i.e. adjust the gap, set the points to open at TDC and then use the thumbscrew to set the advance). What an earth am I to do with no thumbscrew?! I'm sorely tempted to send the old unit in for reconditioning, and then remove this new unit to keep as a spare. Advice please? Keep it simple, my mechanical knowledge is pretty basic!

 

Cheers. James

[MikeF]

Here's what I do, others may know better

 

Warm the engine, set the idling to about 1200- 1500 rpm.

Loosen dizzy clamp

Rotate the dizzy for max engine speed

Back off slightly so the engine drops about 100rpm

Tighten clamp, reset idle.

 

Mike

 

 

[stuart]

Personally I would send that unit back and get your old unit rebuilt correctly to suit your engine by Martin Jay (Distributor Doctor 01398361678) It will make a lot of difference to the running. Then reset as Mike has just described then road test and advance on the thumb wheel until it will just pink slightly under load uphill in a high gear then back off one click.

Stuart.

[Richard V]

Hi,

 

I had my Distributer overhauled by Martin (Distributer Doctor) last year. He offers a fantastic service, a nice guy, and very professional, he knows the product inside out and back to front. He even sorted out a special shipment to get the dizzy back to France so I could drive the car over to Malvern last year.

 

You will not recognise your distributer when you get it back, really stunning. Mine is still in perfect nick after 2000 miles (and will be for many more I suspect).

 

No link to the doctor, just a very impressed customer.

 

Cheers,

 

Richard.

[Badfrog]

Hi,

 

There is a mistake, obviously. 40795A is a regular 25D4 with depression cup. Either yours is an incomplete unit or it is a modified dizzy for improved camshafts with more initial advance, shorter curve and no depression. Just like the 45D4 "TR4race" made by Cambridge motorsports (ask me how long it took me to know).

 

I would complain to Moss for a new, correct 25D4.

 

Cheers,

 

Badfrog

[StevedTR4A]

Hi all

While we are on timing, can anyone please clarify how much rotation of the thumbwheel = 4 deg.

One scource states one division on the vernier scale = 4deg. Another states One full rotation of the wheel = 8deg thus 1/2 rotation = 4deg. On my vernier, 1/2 rotation is nowhere near a full division.

What is the answer here.

Thanks

Steve

[James W]

Just a note to say thank you so much to everyone for helping. Replies much appreciated. James

[James W]

Badfrog, how sure are you about this before I take it up with Moss? The box just says 40795 REP - at the time of purchasing, they were insistent it was the correct distributor for an unmodified TR4. I'm blowed if I could get it to work, even with the advice from this forum. It's now come back off the car and will be going on eBay if I cannot get any joy out of the suppliers. You sound like an expert in such matters? Cheers. James

 

 

Hi,

 

There is a mistake, obviously. 40795A is a regular 25D4 with depression cup. Either yours is an incomplete unit or it is a modified dizzy for improved camshafts with more initial advance, shorter curve and no depression. Just like the 45D4 "TR4race" made by Cambridge motorsports (ask me how long it took me to know).

 

I would complain to Moss for a new, correct 25D4.

 

Cheers,

 

Badfrog