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MG TD TF 1500 - Timing

Hello,

Is the adjustment of the distributor the only thing needed for adjustment to the timing, or does it also require adjustment to the timing chain?

Steve
SD Denham

Hard question to answer Steve without knowing what, if anything, has been done to the engine. What engine is it? Was it rebuilt, was the timing chain/ timing gear/ cam replaced, was the distributor replaced? PJ
Paul161

Steve,

Normally, yes. As PJ notes above, if the engine has been recently rebuilt and/or torn apart then you may need to check the timing chain to make sure it was installed correctly.

Gene
Gene Gillam

If your car runs, the timing chain needs nothing - it self-adjusts. Timing is checked after points are gapped; 32 degrees at full advance is best, with a timing light that shows advance.

Tom Lange
MGT Repair
t lange

Tom, what is the approximate engine RPM when full advance occurs? (XPAG engine).

Tim
TD12524
TW Burchfield

Sorry, Tim, I don't know the answer to that - Jeff Schlemmer will, of course. I don't think it is in Woody Wood's useful manual (a rare omission...). I would guess that it varies between all the different T-series distributors, also.

I use 3,200RPM as the point where full advance is assured, just to be positive - others say 2500-3,000, 3,000 or 3,500. I usually end up driving around 3200 RPM, so that's what I use.

I am not even sure when the advance begins to kick in - I have heard 300rpm, 500rpm and 700rpm. I believe Woody uses 700.

Tom Lange
t lange

See http://ttalk.info/Tech/Advance_curves.htm for a look at the advance curves. Bud
Bud Krueger

Looks like the advance reaches 30 degrees and stops at about 5K rpms for a late model TD. That doesn't seem correct. But I'm not that familiar with early British engines to be sure. According to the chart, if I set the timing to 32 degrees at 3k rpm the distributor will continue to advace until 5k rpms. Am I reading that correctly?

Tim
TD12524
TW Burchfield

IF those advance curves are to be believed, the TC/early TD and late TD do not reach full advance until 4500 and 5000 RPM respectively. According to that information, only the Mark II and TF reach full advance at 3,000. This seems unlikely to me, as TC's and TD's run great when timed at 32 degrees at 3,000 RPM.

I will call Jeff Schlemmer next week and see if he agrees with these curves for stock distributors.

Tom Lange
MGT Repair
t lange

In my experience the original advance curves are no longer appropriate for the fuel you buy today.

Do yourself a favour and have the distributor re-graphed to suit modern fuel - it will be the best value for money you can spend on your XPAG !.

Octagonally

Tony
A L SLATTERY

I have looked over that chart several times in the past and have always wondered about the source of the information.

In other words, where did "fellow TD owner named Don" obtain the information? I am not disparaging his information, I would just feel more confident about it if it included references to factory documentation.
DLD

Jeff Schlemmer can probably answer that question for you. He is owner of Advanced Distributors in MN.
Contact him at:
jschlemmer1@comcast.net
Jim Merz

It is hard to imagine that a set of centrifugal weights would not move in a linear fashion. According to the diagrams above, the weights move outward at a steady rate and then at about 2000 rpm start moving outward at a slower rate (Late TD). I also would like to know the methods used to determine the advance curves shown in the above chart.

Tim
TD12524
TW Burchfield

Hi Tim - the primary and secondary springs control that degree of advance - and differing spring tensions control the amount of advance, This difference in spring tensions/spring rates causes the change in arc on the graph.

I am thinking that the source of the information for the graph must have been simple observation of the different distributors. I have never seen factory references - though Lucas would certainly have had to document these curves for the purpose of manufacture and service.

Does anyone have one of those nice Lucas Service/Spares reference books?

Also - it would be good to hear back from Steve Denham on his issues.
DLD

Quote
"Does anyone have one of those nice Lucas Service/Spares reference books"
End Quote

Some additional data.
The statement, on the left, is from a Lucas publication detailing the Lucas components in the MG-T.

The plots are from the publication by Woods.
Those plots a copyrite and should not be published.

Jim B.

JA Benjamin

Thanks Jim, glad to know those come from Mr. Wood's text. Would still like to know where he obtained them though. His entire booklet has been scanned and is available on the web - I think I even saw it on one of the TD websites. I am not versed in copyright law, so I will leave that issue to others!

DLD

This thread was discussed between 28/12/2015 and 02/01/2016

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