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L-Head Mercer Rods

Guest T-Head

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Ivan and All....These were the L-Head Mercer rods that I mentioned before in the post about Bosch mags. They were Morris Burrow's and he said that they came out of a racing car that ran at a track near Atlantic City.

They have been excessively lightened (the beams are maybe half of their original size) and in fact one of them broke just below the eye and has been welded back together. I have a full set of them.

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Guest Silverghost


I have never seen any long stroke racing conneting rods so thinned-out and lightened by the hole drilling "Swiss Cheese" method in my life~~

They sure took this rod lightening to a severe extreme !

There is not very much metal left in the rod's web areas.

It's a wonder they survived for any time racing at all !

Were these rods made of bronze or steel ?

The photo's color tint seems to indicate bronze~~~ But that could possibly only be because of photo lighting or my viewing screen ?

Did Mercer make any attempt to balance their rotating assmblys ie: Crankshaft, Pistons, Rods ?

What did the crank-case and engine blocks look like on the Mercer L-Head engine that these rods were removed from ?

Were they welded & patched from prior rods punching through them after throwing rods ?

What was the stroke & bore of these Mercer engines; and what was the typical top maximum racing engine RPM ?

I suspect that these rods only survived at all because of the engine's rather low RPM operating range.~~~

These racing rods pctured are unbelieveable !

A real accident waiting to happen in my opinion.

Edited by Silverghost (see edit history)
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Morris never showed me those ones, David. He did show me a good set of long rods, as distinct from thr shorter rods for higher compression height pistons used in later L-heads like his '22 Raceabout. I never presume or intrude, and only look at and discuss what people show me. Because I am Asperger's syndrome I am very literal, and need people to be literal with me. In retrospect I think he was hinting that he may have been offering certian things for sale to me. That 1916 Locomobile was the main one, but I didn't take the bait because I did not aspire to something that would have been so greedy for fuel. Morris had to have comprehensive spares for his cars if possible, and I suspect he may have had most of a dismantled Locomobile 48 chassis as well. What I would really like to have now are that good crankshaft to fix the 1918 engine, and the spare Series 5 back axle. I have enough for another series 6 to build from parts from disparate sources. I have chassis crossmembers which were incorporated when a Series 6 engine and gearbox et cetera were used to hot-up a CO2 Delage , and the chassis fittings from Don Pedersen's rusted-out frame, which was replaced by one that Morris had saved and offered to me. Ralph gave me chassis blueprints, so I can make a short chassis for a Series 6 Raceabout. Mercer used a Series 5 rear axle assembly for the very few Series 6 Raceabouts built, probably for the higher gearing. I am not surprised that one of those drilled L-head rods broke at the top. Just like the drilled Series 6 rods, they are really only safe and sensible as an exhibit. (Others had the same inspirational ideas, too. I have a 1913 12/16hp Sunbeam, which is a 3 litre engine similar in most essentials to the L-head Mercer with identical bore/stroke ratio. This engine from outback Queensland ,and has drilled rods like that. I will use others. It also has a very "lumpy" camshaft, so the factory obviously played around and let some of the modified cars go to customers. ) Anyway, Morris had Caleb Cressman take parts to swap meets for a while. Do you know him?

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Brad ...... The rods are steel with a bronze backed babbitt insert and the wrist pin bushings are the typical bronze. Without looking it up the L-Head bore and stroke is I believe 3.750" X 6.750".

Other than that I know nothing more about them or the engine that they were in....

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  • 4 weeks later...

Not to change the subject - but - any advice as to who to go to for repair/parts for a Waltham air driven rev counter (Double driven drum spins aluminum drum to drive needle?)?? Grasping at straws here, no one sems to have seen one of these (Fitted to my 1921 Bentley, of all things!!! Thanks, Koke T-S

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I have never seen a Waltham air-drag rev counter. Main users of their speedometers were Packard, Lincoln, and Pierce-Arrow. Late mercers used them also, very much universally in the Rochester-engined Series Six; but as at the end they were building cars to order from parts inventory, it is probably enievitable that some late Series Fives had Waltham speedos too. Someone among owners of those makes may know an instrument technician with experience in those, but do not readily allow someone without successful record to touch yours. That indicator drum is far more fragile than an egg-shell. I visited Jack Nelson very briefly the other day to deliver some A4 prints of a few of his early photos. I'll possibly see him again shortly, so I'll ask him what he knows. He only has a 3 litre Bentley left, but he is best to know what is about.

Reference to Brad's question about rpm of an L-head Mercer, I made notes of things Ralph Buckley told me in 1980. They used the new engines to generate power for the factory, and then up-ended them to check that all was well inside before fitting them to their chassis for extensive road testing loaded with concrete block. Ralph said that someone's error failed to notice that one engine ran unintended for 18 hours at 3800rpm without ill effects, which is really getting towards the risk zone with 6 3/4"stroke. (However, I am told that there is a relationship involving that very long conrod length which moderates piston acceleration. If anyone can explain this I will be grateful.) Anyone who has run an L-head to around 60mph in 3rd gear is probably taking the revs near that too.

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Thanks for the reply Ivan. I guess this is a unique instrument in a Bentley, but records support it being the original as fitted in 1921. When I got the car in 1995 or so it was in it, but not operating. I did get the cables and all hooked up, and it worked fine for quite a while, but than self destructed. Looks like the round nut seen inside the double brass drums came loose, and the brass drums wobbled to the point that they destroyed the very thin aluminum driven drum, and aalso broke the needle shaft near the tip, and the needle itself broke off the tip. What a mess! If anyone knows of an instrument repairer that can tackle this thing (would have to spin a new driven drum, repair needle, etc.) I'd love to hear from you!

I'll try to attach some pics, note that I have reassembled the shaft onto the doubl;e bras driving drums in the case. When it went blooie, the shaft actually fell out the back of the case, along with a mess of little tiny bearing balls.

Heres a thought, anyone make an elctronic tachometer for a 4 banger that I can adapt the face too?

Anyway,hope these pics load! Cheers, KTS

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  • 4 weeks later...

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