Lotus Elan

Trash or treasure: Ancient TwinCam race engine

PostPost by: benymazz » Mon Aug 27, 2018 5:23 pm

Hello all,

Much of the back story here is nonessential, so I'll just give the important details: I have in my possession a TwinCam engine that was used by my father for racing in the late 60s, 70s, and possibly the early 80s. I don't believe the engine has run since the car(s) it powered were retired from racing (one of them was my Elan, which now has just a standard road engine). Unfortunately my father passed in 2014, so I have very limited information about how this engine was modified over its time in service.

Anyways, enough of the boring sad stuff. Here are some pictures with my comments on what I've found so far. I'd also appreciate input on whether or not this engine is able to be restored. Warning: Pictures are large.

Image
This is the engine, as I found it. It was sitting on a wooden dolley, which was lucky for me as there was no help in sight to assist in moving it!

Image
I was somewhat pleasantly surprised when I pulled the cam cover. I expected worse.

Image
Upon closer inspection however, the exhaust cam is pretty tired. This was the lobe for cylinder #2. The lobe for cyl 3 was pitted and had one small chip near the edge also. So, this camshaft is now suitable for use as a paperweight (or a trophy to put on my desk?)

Image
This is the block exactly as I found it when I pulled the head. The bad news is that all four bores have rust in them. The good news it that this block has never been bored out. Pistons 1 and 2 are also in rough shape, as you can see. The cooling channels are very badly corroded indeed, and the surface of the block isn't in great shape.

I don't have any pictures of the bottom end, and I didn't get to pulling the pistons and crank yet, but my only comments there were that 1) the sump was converted to a dry sump system and 2) the bottom end was free of rust and nothing stuck out to me as a red flag, similarly the jackshaft was free of pitting or rust and showed very little wear.

I suspect that the dust in the cylinders (especially #2) was unfortunately corroded aluminum dust from the head, as that exhaust valve was left open when it was stored. The rust dust in cyl 1 was also due to a similar problem, but was due to rust in the exhaust headers going back into the head when I tipped the engine over on its other side. I don't have any pictures of the head, and I haven't assessed its condition yet but the entire valvetrain would need to be redone at minimum. I just started this a few days ago and had to go out of town yesterday, so apologies for making this post before I finished cataloging everything. I'll update within the next week or so as I make more progress.

Edited 10/11 to fix some statements I made previously that I now know were incorrect
Last edited by benymazz on Thu Oct 11, 2018 5:00 pm, edited 1 time in total.
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PostPost by: trw99 » Mon Aug 27, 2018 6:03 pm

Is there an engine number on the intake side engine mount? I might be able to identify which Elan it came out of and date.

Tim
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PostPost by: StressCraxx » Mon Aug 27, 2018 9:08 pm

Hello Beny,

By the exhaust, it looks like it was used in a formula B car or a sports racer such as a Lotus 23, Genie, or Bobsy.

As far as rebuid, an old gas turbine engineer once told me, "there isn't anything that your time or money can't fix."

I'm sure it can be rebuilt and returned to service. Right now it's a core engine that appears rebuildable with time and money. Cost depends on existing condition, unseen damage and what purpose you have for it. It also depends on how much assembly work you are willing to do yourself.

Most of the labor involves the machine work in the head and block. It should be done by someone well experienced and preferably respected for Twincam work.
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PostPost by: Chancer » Mon Aug 27, 2018 9:47 pm

And the value will be greatly influenced by what you find on further strip down, are components stock or modified?

Steel crank, forged rods, forged pistons, bigger valves, ported head etc.

The dry sump pump and exhaust headers are indications that you may have something special, if you know what class your father raced ina dn what modifications were allowed that will guide you.
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PostPost by: benymazz » Tue Aug 28, 2018 1:08 pm

trw99 wrote:Is there an engine number on the intake side engine mount? I might be able to identify which Elan it came out of and date.

Tim


Tim, before I started tearing this engine down I took a look for a number there, but it was painted over and I could see no traces of any markings. When I get back home (some time in the next couple of days) I'll use a chemical paint stripper and let you know if I find anything.

StressCraxx wrote:Hello Beny,

By the exhaust, it looks like it was used in a formula B car or a sports racer such as a Lotus 23, Genie, or Bobsy.

As far as rebuid, an old gas turbine engineer once told me, "there isn't anything that your time or money can't fix."

I'm sure it can be rebuilt and returned to service. Right now it's a core engine that appears rebuildable with time and money. Cost depends on existing condition, unseen damage and what purpose you have for it. It also depends on how much assembly work you are willing to do yourself.

Most of the labor involves the machine work in the head and block. It should be done by someone well experienced and preferably respected for Twincam work.


Chancer wrote:And the value will be greatly influenced by what you find on further strip down, are components stock or modified?

Steel crank, forged rods, forged pistons, bigger valves, ported head etc.

The dry sump pump and exhaust headers are indications that you may have something special, if you know what class your father raced ina dn what modifications were allowed that will guide you.


StressCraxx, you're right on the money. Below is a picture of the car it powered for most of its life. This was a SCCA B/Sports Racer, raced primarily in the Northeastern US from its inception in 1970 until the late 70s. I have been unable to identify what kind of sports racer it was, maybe you can help me out.

Chancer, I'll do a more detailed inspection of the engine when I get back home. Before I left I didn't really have time to do anything but rip parts out, photograph, and label :| . I will keep a special eye out for the modifications you mentioned.

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PostPost by: alan.barker » Tue Aug 28, 2018 1:40 pm

Looks like a good project.
The fact that the Cylinders have been sleeved is not always good news as it depends what type of liners were used.
Good luck
Alan
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PostPost by: benymazz » Fri Sep 07, 2018 10:59 pm

Updates:

1) I wasn't able to find a serial number.
2) The bearings are wasted (shocker) but the journals (both rod and main) are in spec and not oval
3) The cylinder bores measure at the stock dimension, never been bored out
4) The oil pump was a pump intended for dry-sump use, made by Vegantune

I did find one thing though which has me worried this might be the end of the line for this engine (or at least the head): I pulled the valves this afternoon, and this is what I found on cylinder 3's exhaust valve. The picture was taken looking down at the part where the valve spring seat rides. I have no idea what could have caused this.

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PostPost by: rgh0 » Sat Sep 08, 2018 12:00 am

The valve spring pocket bases often do not centre well on the castings due to core location variation. While it looks like the lip of the steel spring base that fits in the bottom of the spring pocket has broken at some time ( maybe due to a valve spring failure) it is not uncommon for the alloy casting to be very thin or even missing over a section when the pocket base was machined to align with the valve guide centre.

I would not view it as a major problem but it would need some careful assessment to ensure the spring was aligned and seating correctly to determine if any rectification work was required.

cheers
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PostPost by: benymazz » Sat Sep 08, 2018 9:23 pm

rgh0 wrote:The valve spring pocket bases often do not centre well on the castings due to core location variation. While it looks like the lip of the steel spring base that fits in the bottom of the spring pocket has broken at some time ( maybe due to a valve spring failure) it is not uncommon for the alloy casting to be very thin or even missing over a section when the pocket base was machined to align with the valve guide centre.

I would not view it as a major problem but it would need some careful assessment to ensure the spring was aligned and seating correctly to determine if any rectification work was required.

cheers
Rohan


Thanks Rohan. The spring base that I pulled out of the pocket was intact, but I think you're right that it probably broke at some time in the past. I'll investigate the alignment further and I'll have my machine shop take a look at it too when the head goes in for work (probably next week or the week after). On a somewhat related note, my machine shop comes recommended from several mechanics that I know, but if anyone knows of a machine shop in the upstate New York area that has experience working on these engines I'd be willing to use them instead.

Here's some more updates:
1) Camshaft lobe measurements
Base circle diameter / total lobe height
Intake
1 - 1.000"/1.413"
2 - 1.001"/1.413"
3 - 1.002"/1.413"
4 - 1.001"/1.413"
Exhaust
1 - 1.000"/1.413"
2 - 0.998"/1.411"
3 - 1.001"/1.413"
4 - 1.000"/1.413"

Valve stem diameters
Intake
1 - .3105"
2 - .3105"
3 - .3105"
4 - .3105"
Exhaust
1 - .310"
2 - .314"
3 - .310"
4 - .310"

I'm puzzled by the stem diameter on #2 exhaust. Maybe it's related to the chipping on the camshaft on the same lobe?

2) I haven't done that much research into it, but I can't find any cam profile that corresponds to the lobe height of ~.413" that I measured. The camshaft has no grooves. What other markings should I be looking for?
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PostPost by: rgh0 » Sun Sep 09, 2018 12:41 am

Have a look for any numbers stamped on the front face of the cam which is where most cam grinders mark their work.

The nearest cam grind I can find of the right vintage is the Dave Bean 114 with 0.413 gross lift. Do the cams have the long cam bolt modification that Dave Bean recommended for these high lift cams?

cheers
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PostPost by: benymazz » Mon Sep 10, 2018 11:55 pm

rgh0 wrote:Have a look for any numbers stamped on the front face of the cam which is where most cam grinders mark their work.

The nearest cam grind I can find of the right vintage is the Dave Bean 114 with 0.413 gross lift. Do the cams have the long cam bolt modification that Dave Bean recommended for these high lift cams?

cheers
Rohan


I'm not sure what you mean by this. Do you mean that the studs that go into the head would be longer? And the face of each cam is stamped with a "B4" on the top and a "KH" on the bottom. They also have the MC23929 and B26E351 markings on the shaft, so they're original B cams as far as I can tell that just have had the crap ground out of them.

It's too bad that it looks like the end of the line for these cams... although I suppose they had a good life. I don't know much about cam work, so would it be a better choice to ditch the cams and buy new ones or try to get the chipped parts welded back up and smoothed?

Also Tim, I struck out on the serial number on the block, but I did find one on the back of the head: LP6215. This is an interesting situation now because of the 2 engines that I have, the block in my Elan is stamped LP5494, the head on the race engine I'm rebuilding is LP6215, and the "Engine No." section on the nameplate on my Elan is stamped LP3367. So nothing matches.
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PostPost by: rgh0 » Tue Sep 11, 2018 12:08 pm

The B4 is probably the grind and KH the grinders company but I dont recognise them. Maybe someone in the US will. With a 1 inch base circle the cams will be a regrind of original standard cams and probably not ground from new as you dont need that base circle for a .41 lift to fit these days (but maybe you did back then ?) The shaft markings are the original Lotus casting marks. Yes the cams are past their use by date in my opinion as costs to re-weld and regrind would be more than new cams and better cam grinds are now available anyhow.

The long bolt conversion is to drill the end of the cam and fit a longer bolt that retains the sprocket down past the first bearing to keep the cast iron cam in compression in that area with the bolt tension as high lift cams typically break at the first bearing due to the chain loads bending the cast iron and introducing excessive tensile loads that the cast iron is weak in. People use steel cams to avoid this issue but that introduces a whole set of new issues with cam and follower wear that I prefer to avoid

If any number on an Elan and a race engine in particular matches it has normally been faked.

cheers
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PostPost by: elj221c » Tue Sep 11, 2018 1:43 pm

Could be based on the Burton BLL4.

It was available in era and it still is along with seven other profiles.

http://www.burtonpower.com/parts-by-fit ... _group=155
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PostPost by: elancoupe » Tue Sep 11, 2018 4:53 pm

KH - Kenny Harmon. He did regrinds for Twinks here in the States. I believe that Bean?s 112 and 114 cams originally had KH designations.
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PostPost by: benymazz » Thu Sep 13, 2018 9:48 pm

So, I went on a safari through filing cabinets in my basement, and found a file folder titled "racing expenses". It contains almost every receipt for the engine in question and the car that it powered. Here's what I've gathered:

1) The car that it powered was built mostly from scratch, but the suspension was built with parts for a LeGrand Mk4B. Given the competition at the time and the pictures I've seen, I also think it was heavily influenced by the Lotus 23s of the time. The brakes were Lotus parts, and I'm assuming most of the drivetrain was as well.
2) The Dutchess Auto Company (where Lotus East was based from I believe) billed my dad for 20 hours of cylinder head work on December 2, 1970, for a total of $160 (!). The description unfortunately only says "modify cylinder head".
3) I think this is the biggest revelation: on January 19, 1970 my dad bought the Tecalemit-Jackson fuel injection system. I don't know how long this was used for on the car, because the only pictures I have of the engine area are from when it was being tested in spring of '71 (which show the FI system fitted, but given how notorious they were for turning race cars into race car flamb?, I doubt it stayed around for the life of the car). I have no idea what became of this. My guess is it's long gone.

Aside from the receipts, I've found out some more. The engine has the upgraded "125 E C" conrods, but the crank seems to be just a normal road crank. The casting marks on it say 116E 6303, but there's also what appears to be a stamped mark on the last counterweight that says "2B". The pistons markings say "HEPLEX 16100" on one side and "L64" with "AM 413" below on the other.

I also have some bad news regarding the engine that's in my Elan right now. Despite the fact that it runs pretty well now, overall it seems pretty old and tired. I'll let you see for yourselves though, the images of the log are in this album: https://imgur.com/a/bDcS4mp
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