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Le Mans Modification Kit Trivia

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John Morrison

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This probably falls into the "For What It's Worth" category, but the recent thread on "Value Premium for a Le Mans Kit-Equipped 100" jogged my memory a little.

Sometime during the mid '70s I was told about a 4 cylinder 100 engine with "really big" carburetors on it at a local junk yard in central Pa. I bought it immediately when I saw the cold air box with the brass plaque.
After ensuring that it was in good shape and rebuilding carbs, changing oil etc. I dropped it into my 100, envisioning great performance improvements.
I was very disappointed with the results, seemingly minor (if any) improvements.
After working on it to get more power for some time, I then contacted British Leyland to see if I could find out exactly what I had.
Some kind person in Leonia, NJ xeroxed a copy of the <span style="font-weight: bold">"AUSTIN-HEALEY HUNDRED (MODEL B.N.1.) SPECIAL EQUIPMENT AND TUNING INSTRUCTIONS"</span> and mailed it to me.
This was somewhat confusing, because I had always heard that the "Le Mans" cars had flat-top pistons and those were not listed in the document.
I also checked the cam lift and discovered that it was NOT a high lift cam, but an even <span style="font-weight: bold">LOWER</span> lift than stock.
Even more confusing.

All was explained at Encounter 1979 in Harrisburg,PA. Geoff Healey and family were our guests that year, and they all participated graciously and unstintingly in our event.
At some point during the car show on Saturday, Geoff and I were walking around looking at the cars until we came to mine. I began to whine about my thwarted expectations about the engine swap.
He filled me in on the history of the Kit and the Factory "Le Mans" cars.
In the ensuing conversation, I mentioned the "Low-Lift" cam, to which he replied "Oh Yes. Well, a number to those kits were dispatched to the States with defective camshafts." (i.e. wrong spec).

Apparently my transplanted motor had one of the defective kits fitted to it.

One wonders whether any of the bad cams found their way into the "Factory" cars.
 
John Morrison said:
This probably falls into the "For What It's Worth" category, but the recent thread on "Value Premium for a Le Mans Kit-Equipped 100" jogged my memory a little.

Sometime during the mid '70s I was told about a 4 cylinder 100 engine with "really big" carburetors on it at a local junk yard in central Pa. I bought it immediately when I saw the cold air box with the brass plaque.
After ensuring that it was in good shape and rebuilding carbs, changing oil etc. I dropped it into my 100, envisioning great performance improvements.
I was very disappointed with the results, seemingly minor (if any) improvements.
After working on it to get more power for some time, I then contacted British Leyland to see if I could find out exactly what I had.
Some kind person in Leonia, NJ xeroxed a copy of the <span style="font-weight: bold">"AUSTIN-HEALEY HUNDRED (MODEL B.N.1.) SPECIAL EQUIPMENT AND TUNING INSTRUCTIONS"</span> and mailed it to me.
This was somewhat confusing, because I had always heard that the "Le Mans" cars had flat-top pistons and those were not listed in the document.
I also checked the cam lift and discovered that it was NOT a high lift cam, but an even <span style="font-weight: bold">LOWER</span> lift than stock.
Even more confusing.

All was explained at Encounter 1979 in Harrisburg,PA. Geoff Healey and family were our guests that year, and they all participated graciously and unstintingly in our event.
At some point during the car show on Saturday, Geoff and I were walking around looking at the cars until we came to mine. I began to whine about my thwarted expectations about the engine swap.
He filled me in on the history of the Kit and the Factory "Le Mans" cars.
In the ensuing conversation, I mentioned the "Low-Lift" cam, to which he replied "Oh Yes. Well, a number to those kits were dispatched to the States with defective camshafts." (i.e. wrong spec).

Apparently my transplanted motor had one of the defective kits fitted to it.

One wonders whether any of the bad cams found their way into the "Factory" cars.
Click to expand...
IMHO, it appears that beauty is only skin deep on some of the LeMans cars that left the factory. I had a 100 that was fitted with a complete LeMans mods, but I never checked the cam so who knows for sure how much of it was a LeMans.
 
Just for fun, I went back to an article that appeared in the March 1956 issue of Road & Track in which the 100M that was raced in the Nassau races was tested. The 100M cost a whopping $290 more than the standard 100. This was 10% of the purchase price of a new 100. Included as options were:

1. 8.0:1 compression ration, obtained by a steel head gasket
2. A high-lift camshaft
3. Special valve springs, cups and seats
4. Two 1 3/4" S.U. carburetors and necessary attaching parts
5. A cold-air box for the carburetors
6. A special advance-curve distributor
7. A new 4-speed gearbox (overdrive is also standard equipment)

The engine mods were said to increase the 100's 90bhp to 110bhp as compared to the 100S's 132 bhp

Performance figures were as follows:

Model 100 100M 100S

top speed ... 102 109 119
0-60mph ..... 11.7 9.6 7.8
SS 1/4 mi.... 18.1 17.4 16.1

So the M offered substantial performance gains over the 100. Nearly 2 seconds were knocked off the 0-60 time and 3/4 of a second in the quarter mile. Don't forget though, that this was a Healey race entrant and may have had some laying on of hands by Roger Menadue and might not be representative of what the average Healey buyer would get under the bonnet.

Interesting that R&T indicated the higher compression ratio was obtained through use of a different head gasket, rather than different pistons.

And about that camshaft. R&T said: "However the valve timing of the 100M is still extremely conservative at only 10 degrees overlap, and for those who are not interested in production car competition a reground camshaft can be used to good advantage."
 
Hello,

Does anyone know if the steel head gasket is still available somewhere?

Thanks,
Walt
 
I just got off the phone with John at British Car Specialists, sounds like the one they sell is the Denis Welch piece. It says in the description "Being the same thickness as original it does not change the compression ratio".

Therefore, it really doesn't get you to the desired result of the increased compression ratio of the "Le Mans Kit" steel head gasket. Oh well.
 
From what I've heard/read, there were actually two 'versions' of the 100M shipped (as if the story wasn't complicated enough). Some shipped with an 8.0:1 compression ratio, which may be more than a 'stock' BN1/2, and which may have been achieved with a thinner head gasket. Some of the 100Ms shipped with an 8.5:1 compression ratio; this was achieved with different pistons which, while still dished, had a 'thicker' flat area at the periphery of the top of the piston.

The steel gasket is necessary to contain the greater BMEP, and also helps eliminate the common coolant leak between the #2 and #3 cylinders.
 
I have Mordy Dunst at Gasket Works in Duarte, CA make my custom copper single piece head gaskets for my 100-SIX race motor. He can make them in a variety of sizes to meet you compression target. I think he has the template for the 100-4 motor now. Good quality, he's a racer so he cares about performance.

https://www.headgasket.com/index.html
 
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