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MG TD TF 1500 - Spark Plugs - 1/2inch reach in TF1500 ??

Is there any reason to use 1/2 inch reach spark plugs in my TF 1500?

I bought the car a month ago and am doing basic maintenance to bring it back to specs. I removed the plugs today and found that they are 1/2 inch reach instead of 3/4 inch that is specified in the manual.

Don't want to replace with 3/4 inch reach if there is a chance of damaging a piston. I measured the depth of the hole in the head for the spark plugs. It's 3/4 inch at the bottom.

HEAD
The head casting number is 22952. Don't know if it is original,

COIL
The coil is a gold Lucas Sport coil. "BYS" "45341" "10 87" or "10 57" Does it have an internal ballast resistor?

PLUG RECOMMENDATION?
What do you recommend as a replacement for the Champion NA8 plugs that were originally specified? Are non-resistor plugs available? Any problem running resistor plugs? What gap? I use 90 octane non-ethanol gas.

The plugs that are now in the car:
three - Autolite u25
one - Champion L86C

The car runs poorly. I hope that it's ignition and carburation.

Thanks for your help,

Lonnie
TF7211
LM Cook

Lonnie, using a 1/2 inch plug in a 3/4 inch hole will eventually clog the remaining 1/4 inch threads. If you want to go back to the proper plug for the 1500 head, (3/4 inch), you should chase the threads to clean them so the 3/4 inch plug won't bind at the bottom. I always use high heat anti seize on the plug threads also to prevent any galling when they need to be removed. The performance issue should be addressed on your individual engine. PJ
Paul S Jennings

22952 is definitely an early TD/TC head that uses 1/2" reach plugs. I think the correct 1500 head has the numbers ground off and something like AEF177 stamped in (not sure about the number). Either the L86Cs or NGK B6HS plugs work fine in my 1/2" reach TD. George
George Butz

Lonnie, I hate to tell you this, but 22952 is the casting number for an early banana port head. Yes, the 1/2" reach plug is the correct one for that head. You might want to start looking into acquiring a later head to take advantage of the better breathing. Bud
Bud Krueger

PS- what is the number on the block brass plate and stamped into the block itself above the plate?
George Butz

Thanks for the infomation, guys. I'm bummed about the head, but at least I know what I have. I'll start looking for a TF1500 head. Any suggestions? Maybe I can sell / trade the TC-TD head.

George - the number on the octagonal brass plate on the block is 977 type XPEG, which is the same as on the identification plate. I didn't see a number stamped into the block above the plate. The chassis build date was 23-Sep-1954

I just researched and found that the casting code on my '55 TF1500 block should be AEF117. And the head casting code should be 168422, instead of the 22952 that is on my 1500. Where is the casting number on the block?

Thanks for your help,

Lonnie
TF7211

LM Cook

I think that I made a mistake on the TF1500 cylinder head casting number that I quoted above. It should be AEF118. 168422 was the TD head that was updated in 1952.

- Lonnie
LM Cook

Not sure about the 1500 block, but the 1250's have the number under the tappet cover and behind the dynamo. It may be a good idea to take a rag with some carb cleaner or something and rub off some of the gunk/paint just above the brass plate on your block. There will be a number stamped in there, which should be 977.
George Butz

Cylinder head numbers:
1. 22952 TC or early TD banana water hole
2. 168422 Later TD round water holes
3. 168425 TF 1250 the last digit(5) is stamped in the head.
4. AEF118 TF1500

In addition the XPEG will have AEF117 cast in the the left side of the block under where the generator sits.
Cheers, Hugh Pite
H.D. Pite

I'm confused, my 1951 TD has a head with 22952 cast in next to the valve cover on the carb side. Recently I measured the depth of the plug hole threads and the best I could tell they were 3/4 inch deep. How can that be? Is is absolutely certain that all heads with 22952 cast in are short reach plug heads? The car was made July 1951 and has engine number XPAG/TD/LHX 9342
John Quilter (TD8986)

Lonnie, I have a TC head on my TF that has been ported and polished and has the larger TF valves fitted. You may find that yours has had similar treatment and shouldn't effect the performance.
Don Sth. Oz TF 4887 (1310cc)
DJ Walker

There is another fact that may throw confusion or light into this issue. Where do the XPAW head casting numbers fit into the number sequences. Plenty of Wolseley heads have migrated onto MGTs after valve size conversions.

I know because my TF1250 has a XPAW head, XPAG heads are a scarce resource here in Aus unless you have a big wallet. Long reach plugs however are not a problem.

Graeme
G Evans

Lonnie,
Don't waste your time searching for an TF 1500 head. The TF and Mark II heads were rare and were snatched up for TD upgrades way back when. Knowledgeable sellers will want a bundle. If your really want to add 1 whole horsepower, you can look for the TF head, or better yet, just get a valve job with the larger valves. The best thing you can do concerning your head is have inserts installed under the exhaust valves.

The TD had 45cc combustion chambers and the TF 1500 had 44.4cc, so there's no significant difference.

Other than the larger valves & heavier springs, the TF head cores were reshaped for a bit better cooling. Not a big deal.

You sure you got the 1466 XPEG? ...1 1/2" carbs?

Take the money you would've sunk into the TF head and throw it towards a roller lifter cam. No comparison in improvement and long term insurance.

The BEST 1/2" reach plug for the dollar is the Autolite Platinum AP425 (not the copper 425!). O'Rielly still sells them for $2.99 for 1970 vintage VW Beetles. Cheapest price on ebay is $4.47. They're out of productions, so order them while you can. Workshop Manaul calls for .014-.016in point gap and only .020-.022in plug gap, but you'll probably run .030" or more (I gap .035" with no missing) with the platinum plug. They also run colder which is a benefit.

Car runs poorly? Start with a compression test (and report readings here for interpretations), it'll give the best forecast right from the gitgo.

Post photos!

JIM
JRN JIM

Thanks again for the info. You guys helped lower my blood pressure after I learned that the engine has the wrong head.

I'll look for a TF1500 head. I'd like to return the engine and car to original condition. Or at least within reason. But it's good to know that the TC head can be made to work - if it hasn't already been modified.

I hope to coerce my wife into pulling the starter button while I check compression this weekend. I'll report any problems in a new thread and ask for more advice. I'll also check points, cap, wires, etc.

The only block casting number that I could find is "320" low on the block between the distributor and the oil dip stick. It is a casting number, not a stamped number. I haven't removed the push rod cover nor the generator to look for more numbers.

I wiped the area above the brass octagon with carb cleaner. I can see a "7" stamped into the block. I couldn't remove the paint covering the other numbers. The "7" seems to be a little forward of where I would expect it to be if the entire number were "977" like on the octagon in my photo. Could the number on the octagon be bogus so that it matches the data plate?

The body of both carbs is numbered AUG 6020. Are they the correct carbs for a 1500? I don't know if the inlets in the manifold match the carburetors, or if it is an older manifold with smaller inlets. I haven't pulled off the manifold or carburetors. Don't know if you can tell anything by the air opening to the air cleaners -- it is 1-3/8" diam.

I attended the Mecum auction in Kissimmee with my neighbor today to look at a '55 TF 1500. A real nice car. Thanks to you, I looked like an expert when I announced that the car had the correct head. And yes, he bought it.

Lonnie
TF7211
LM Cook

Lonnie,

That's another kewl thing about a T-series. You can push the starter switch on the back side and crank it without help.
Rich (TD 3983) Taylor

Lonnie,

Hugh Pite has the correct listings for the Head
and Block numbers.I guess with smaller production numbers,1500 designations often can get confused.

You really need at this stage to carefully examine
the cast letters/numbers located under the lower edge of the side engine cover and adjacent to the lower edge
of the generator body.If it is a genuine 1500,it will read AEF117.

Be aware that one side of a genuine TF1500 Cylinder Head,(stamped AEF118)has the castings for the water holes slightly offset compared to a TF1250 etc.

The 1500 Head Gasket therefore had a different Factory part no.

Unfortunately around the world,many TF1500s are knowinglybeing sold as a genuine TF1500,when closeexamination often reveals otherwise!

The 1500s carbs are the same as the TF1250,AUC 6020,one and a half inches.

Graeme E,the Wolseley 4/44 was produced from 1952-1954.
The Cylinder Head cast nos.were 168422.When the TF1250
came out,the Factory ground off the last cast number(2),and stamped in('5') to indicate the larger valve head size.The Wolseley Heads are very useful these days,as the stock was thicker ie. there is plenty of metal to be able to planed off compared to a 1250 Head.Enlarge the valves,and you have an excellent Head set up for a 1250 motor.

Cheers
Rob Grantham
TF3719("Aramis"),TF9177("Athos").



R GRANTHAM

Rob Grantham

Thanks for the insight into the XPAW head history. My head was modified to take the original XPAG head valves which was cracked and unrepairable.

The issue I encountered was being able to adjust the valve clearances without fitting longer adjustment screws. I made numerous posts on this subject.

Graeme
G Evans

AS Rob says, the block casting number would be more under the generator, maybe remove the inspection plate under the wing to see better. The octagonal brass plate is likely original, but could have been put on another block. Where are you in Florida? George
George Butz

Lonnie,
We were scratching our heads for a while on our 1250 TF. Turns out we have a 1500 block and a 1250 head. (I want to make hood plates that says "1375".) On ours the water passages didn't quite line up but we dremmeled them to be as close as we could. The important thing was making sure that we used a 1500 head gasket as the pistons were slapping the underside of the 1250 gaskets we had been using.
Good Luck,
Safety? Fast?
Scott Ashworth - '54 TF 1375
S. R. Ashworth

Here are some answers to your questions and an update on my engine.

> George - I'm in downtown Orlando.

> The block has the casting numbers AEF117, so it is a TF block. I used my iPhone to shoot a video of the block behind the generator. By moving the phone along behind the generator, the video captured the entire casting number. Easier than removing the inspection plate.

> It may be a pipe dream, but I'll look for a TF head to revert the car closer to original specs.

> I talked to two previous owners about the 22952 head. An owner from 1963-1968 told me that he had ported and polished the head, but didn't know if it was a TF head or the TC head that is on my engine. The last owner told me that she had the head repaired, but not replaced - so she believes that the 22952 head was on the engine for the entire 41 years that she owned it.

> I ran a compression test with my 40-yr old push-in compression tester. Even though I pushed the rubber plug hard into the spark plug holes (burning my hand on the exhaust) some of the compression leaked past it. I read 145 - 148 psi on all four cylinders. Weird numbers, but they were consistant.

> I worked on some ignition problems and the engine is running a LOT better.
++ Soldiered the wires at the end of the plug wires so that set screws on the spark plug connectors will hold the wires more securely. One fell off when I touched it, which prompted the action.
++ Cleaned the corroded high tension wire at the distributor cap from the coil.
++ Installed new NGK B6HS spark plugs at .025" gap. Jim: Advance Auto Parts has Autolite Platinum AP425 plugs available for ordering from their warehouse for ~$2.50 each.
++ And the most important improvement - I gapped the points to .016". They were almost completely closed. I'm suprised that the engine even ran with the tight point gap.
++ I didn't adjust the timing after I set the points. No spark knock during road test. It was about 30-deg advance (BTC) at 2000 RPM before I set the points.

> I still don't know if the Lucas Sport coil. "BYS" "45341" "10 87" (or "10 57") has an internal ballast resistor. I don't see an external ballast resistor in the engine bay.

> The elec system was recently changed to negative ground. I haven't traced the wires to see if the polarity of the low tension ignition is correct.

> I cleaned the filters into each carb. Tried to adjust the carburators, but found that the retainer on the return spring on the front carb is broken. So I roughtly balanced them until I can make a repair. The return spring for the rear carb closes both carbs for now. Got a lot to learn about SU carbs. Vastly different from the Rochester single barrel on my '54 Chevy pickup!

> I'll adjust the valves when I learn more about the head, or when I find a TF head.

I still have a lot of inspection, cleaning, and maintenance to do.

I sincerely thank each of you for the information that you gave to me. I'm sure that you saved me a world of problems and confusion. I'm really glad I posted the question about spark plugs.

Have a great day,

Lonnie TF7211
LM Cook

Lonnie,

<<I still don't know if the Lucas Sport coil. "BYS" "45341" "10 87" (or "10 57") has an internal ballast resistor>>
I don't think Lucas coils have internal ballast resistors, at all.
If you measure the resistance between the (low tension) + and - of the coil it should read 3 Ohms for a car without ballast resistor (like the TF) and 1,5 Ohms for cars with ballast resistor (like later MGB's).
The resistance between one of the LT connections and the HT outlet should read approx. 5.000 for a normal coil and up to 10,000 Ohms for a Sports coil.

<<The elec system was recently changed to negative ground. I haven't traced the wires to see if the polarity of the low tension ignition is correct>>
For a neg.ground cars the wires to the points has to be connected to the - connection.

<< I'll adjust the valves when I learn more about the head, or when I find a TF head.>>
Why wait? adjust to 0,015" just for peace of mind; you don't want burnt valves, do you?

Just out of curiosity; how did you manage to burn your hand on the exhaust whilst measuring the compression? On my XPAG the sparkplugs are on the other side of the engine than the exhaust? Maybe you have a super-duper-special cross-flow cylinder head! If so, please post some pictures! ;-)
Willem van der Veer

Willem -

Thanks for the information. I'll follow your recommendations.

> I assumed that all 12-volt vehicles use a ballast resistor. I'm still learning! I'll measure the resistance so that I know for sure what I have.

> Thanks for the polarity of the wire to the points. I'll correct if necessary.

> You're right. I'll adjust the valves.

> I goofed. I was looking at the tender spot on my knuckle when I wrote about checking the compression, so "exhaust manifold" was the thing that popped into my mind. I burned it on the head surrounding the spark plug hole -- not the exhaust manifold. The only cross-flow is the cross-flow in my feable brain. And you don't want to see a pic of that!!

Thanks again,

Lonnie
TF7211
LM Cook

This thread was discussed between 22/01/2014 and 26/01/2014

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