30 replies to this topic

[bikewiz]

 

 

What you elect to install for a distributor depends on what your expectations are for the car and your budget.  What are your plans?

Doug I'd like it more "driveable" it runs fine but I think it advances too much causing it to knock (over here) pink (over there) obviously on part throttle put your foot down and it goes fine. I've got the timing set at 4 degrees at idle.

 

Agree with Kernow Cooper, for a modified 1275 with MD276 would expect to be more like 14 - 18 degrees at idle.

 

What octane fuel are you running on? And how much mechanical advance does your 65D give.

 

I don't know what the advance is. I run a mix of 100 octane VP race gas with 93 octane pump so I probably run somewhere around 97 octane our octane rating is (R+M)/2 I believe your fuel is RON which is 4 points or so higher.

[carbon]

So in UK terms you're likely running 100+ octane petrol, good quality. Any idea what compression ratio you have?

 

I am not familiar with the later 65D distributors. With the earlier 25D and 45D types there is a 5 digit number stamped on the side of the distributor.

 

This should also be stamped on the 65D, something like 41975B. This number can let you know what it came off, and the likely advance and vacuum settings (unless it has been modified...)

[dklawson]

Doug it appears an Aldon Yellow costs around $200 + shipping Jeff charges anywhere from $130-200 for rebuild/recurve  the only thing with a rebuild is I'll be without the distributor for 4-5 weeks. I may buy an Aldon and see how it works I can then send out the original to see if it can better.

 

I know that Jeff's web site said 4-5 weeks.  However, when I looked at the site, the information about lead time appeared to be from August so things might be faster now.  It also is worth asking Jeff if he has a distributor that he can supply already re-curved and take yours in on exchange as a rebuildable core.  If he doesn't you still might be able to buy a good used core for Jeff to rebuild (eBay, Craigslist, local club, etc.) so you can drive your car while Jeff carries out a rebuild.

[KernowCooper]

If you look in the FAQs electrical I posted the curve for the Aldon Yellow there, this is the info direct from Aldon.

[bikewiz]

So in UK terms you're likely running 100+ octane petrol, good quality. Any idea what compression ratio you have?

 

I am not familiar with the later 65D distributors. With the earlier 25D and 45D types there is a 5 digit number stamped on the side of the distributor.

 

This should also be stamped on the 65D, something like 41975B. This number can let you know what it came off, and the likely advance and vacuum settings (unless it has been modified...)

And the race gas is expensive......

 

Numbers on the existing distributor

65DM4

NJC10038       2026

42535A           4892

 

I found this with a Google search for the 65DM4 42535A  15º-17ºat6250rpm 13º15ºat5340rpm 7º-9,5ºat2840rpm  4º-6ºat 1870rpm  -1º-1ºat 1000rpm

http://members.home....distributor.htm

 

Not that it really means much to me, I'm assuming the advance is plus your idle vacuum disconnect start.  So with 4 degrees at idle I should have some where around 11-13 degrees advance at 2840 rpm?

Edited by bikewiz, 20 October 2014 - 09:29 PM.

[carbon]

That looks right. And with 4 degrees static that spec would give you a maximum of 4+16 = 20 degrees total advance at max rpm.

 

I'm probably running close to 18 degrees at idle...

 

Are you running a very high compression ratio on this motor?

[bikewiz]

That looks right. And with 4 degrees static that spec would give you a maximum of 4+16 = 20 degrees total advance at max rpm.

 

I'm probably running close to 18 degrees at idle...

 

Are you running a very high compression ratio on this motor?

CR is unknown but I would suspect pretty high, a guess would be high 10's only because when I run 93 octane pump gas it pinks like crazy. Others I've spoken to say their high 9's low 10's cars run fine on it. Using higher octane also stopped the run-on at shut down.

I don't fancy taking off the head just to figure the CR. I think the Aldon curve is similar to the 65DM4.

[KernowCooper]

The A series though needs more than 20deg of maximum advance to produce its maxium power, remove the base plate in the distributor and see whats stamped on the weights, rembering that distributor advance is half crankshaft advance, so weights stamped 12degs would give 24degs of maximum advance 8degs od static is 32degs. Depending on the engine spec and fuel used and CR you need approx 30/34degs +/- for best bhp and torque.

 

The Aldon yellow curve is nothing like a 65D4M

Edited by KernowCooper, 20 October 2014 - 10:24 PM.

[Dusky]

The A series though needs more than 20deg of maximum advance to produce its maxium power, remove the base plate in the distributor and see whats stamped on the weights, rembering that distributor advance is half crankshaft advance, so weights stamped 12degs would give 24degs of maximum advance 8degs od static is 32degs. Depending on the engine spec and fuel used and CR you need approx 30/34degs +/- for best bhp and torque.
 
The Aldon yellow curve is nothing like a 65D4M

Depending on wich 65dm4 unit you have I think.
There is one with 12° at 2800 7°@1880 5°@ 1440 dizzyrpm . thats close to the aldon yellow imo

[ACDodd]

The biggest issue you are all making here is that dizzies don't wear. They do, a lot!

Therefore they bear little resemblance to there initial factory specs. The best option is to measure what you have using a strobe. Then sensible choices can be made. There are many different advance curves for the 65dm4 dizzy. From little advance to truly huge!

Ac

[Dusky]

http://www.starchak..../pdfs/lucas.pdf

 

 

Quite handy PDF file when comparing stock dizzy's :)

[Steve G]

I actually disconnected the vac advance on my 1380 engine as it improved the idle a lot. Before I did it wasn't really possible to get it to idle much lower than 900-100rpm well enough to get the emissons checked for the MOT.

I've got a 286 cam fitted and the timing after it was set up on a rolling road is set at 14 degrees. 

 

I'm considering getting a programmable ignition of some sort when the engine gets put in my Scamp, these weren't available when I built it originally.

[carbon]

 

That looks right. And with 4 degrees static that spec would give you a maximum of 4+16 = 20 degrees total advance at max rpm.

 

I'm probably running close to 18 degrees at idle...

 

Are you running a very high compression ratio on this motor?

CR is unknown but I would suspect pretty high, a guess would be high 10's only because when I run 93 octane pump gas it pinks like crazy. Others I've spoken to say their high 9's low 10's cars run fine on it. Using higher octane also stopped the run-on at shut down.

I don't fancy taking off the head just to figure the CR. I think the Aldon curve is similar to the 65DM4.

 

If you have (or have access to) a compression tester then this will give an indication of the CR.

[Dusky]

by the way, a comparisson of the 'ideal' 54DM4 and a aldon yelllow curve.

Seems quite similar to me.

 

Black is 65DM4

Green is aldon yellow  Aldon Yellow Advance Curves.png   42.03K   20 downloads

[KernowCooper]

But which 65D4M ? as AC pointed out they vary so much in advance