Lotus Elan

Elan S3

PostPost by: Panda » Fri Feb 28, 2014 3:03 am

I have recently purchased and commenced restoration of S3 Elan 36/7050 Eng No. LP7681LBA.
I would like to find out if this is the original engine or if not, what was the correct number?
The car came to Australia in approximately 1981.
many thanks Alan P.
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PostPost by: robertverhey » Fri Feb 28, 2014 4:29 am

Hi Alan

According to database engine number should be LP7681

Robert
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PostPost by: Craven » Fri Feb 28, 2014 11:02 am

Hi Alan P.
Good news for you by the looks of things, can you help me by giving some details of your engine if possible please.
Your engine No is just 20 away from my own and I would like a cross check on a couple of points as our engine numbers are close to a type change over point given in various books etc, at engine number 7800, Mk1 over to Mk2
Can you confirm your engine is a 4 bolt with a Mk 1 head.
If you are not familiar with differences will post what to look for if you can oblige.
Many Thanks
Ron.
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PostPost by: Panda » Fri Feb 28, 2014 10:00 pm

Hi Ron,
My engine is 4 bolt crank with MK1 cylinder head, but not for long. The crank has been previously balanced and an extensive amount of metal has been ground of no. 4 crank web, to the extent that I wouldn't trust it to survive high revs. I am expecting to convert it to a 6 bolt crank as I have most of the parts to do it. The car had a successful racing history in the hands of the late David Haydon. But I think it was due more to his ability rather than the condition of the car.
cheers
Alan Pate
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PostPost by: 1960.seven » Sat Mar 01, 2014 12:28 am

Hi Alan

If your restoring an Elan for historic racing you may be interested is some J A Pearce mag wheels I have with Elan offsets

Regards

Allan C
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PostPost by: Craven » Sat Mar 01, 2014 12:38 am

Thanks very much Alan,
Certainly a better rear oil seal on the 6 bolt, and careful balance will help to hold things together if you intend high RPM.
As your car was used in competition does the engine have any interesting mod?s, my engine a BRM tuned unit uses a CPL 2 cam.
Ron.
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PostPost by: vstibbard » Sat Mar 01, 2014 8:40 am

Hi Alan,

That is the engine that was with the car when I purchased it from the English chap who imported it to Melbourne then moved to Sydney.
The LBA after the number indicates that it will take large bore as the wall thicknesses are more uniform.

Does the head have the same number stamped onthe rear face of it?

Regards

V
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PostPost by: rgh0 » Sat Mar 01, 2014 9:27 am

Craven wrote:Hi Alan P.
Can you confirm your engine is a 4 bolt with a Mk 1 head.
If you are not familiar with differences will post what to look for if you can oblige.
Many Thanks
Ron.


Hi Ron
Can you explain more about what you mean by a Mk1 head? I am familiar with most of the head variations and changes over the years but was not aware of a specific head change at the time of the change to 6 bolt crank "Mk 2" twin cam.

cheers
Rohan
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PostPost by: Craven » Sat Mar 01, 2014 11:03 am

Hi Rohan,
You have put your finger right on the point that I?m trying to get a handle on, those of us that are familiar with the Twin cam recognise the two distinct castings ( excluding Stromberg ) of the head.
The change from 4 to 6 bolt crank is widely published at engine No 7800, but there is some evidence that the later casting of head was fitted to the 4 bolt bottom end.
You will note I?m avoiding the Mk1 Mk2 term as, as you know, are not actual engine types, a bit like 2000E for gearbox, most know what is meant but it?s not a factory designation.
So if you or anyone has come across this with actual corresponding head and block numbers it would be of great interest to me.
If there is further interest perhaps a new thread.
Regards Ron.
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PostPost by: rgh0 » Sat Mar 01, 2014 11:45 am

The early die cast heads were used for only the S1 and early S2 cars ( plus others such a Cortinas made in this period) as far as I am aware. I don't know the exact date or engine numbers covered as you see so few on cars these days. The later sand cast heads were used on the 4 bolt crank engines for a couple of years before the six bolt crank engines were introduced.

The first version of the sand cast head ( introduced late S2 or early S3 I believe) did not have a cross drilling at the rear for oil drainage from the exhaust to inlet side. I have one of this type with engine number LP6078 stamped on it.

cheers
Rohan
Last edited by rgh0 on Sun Mar 02, 2014 10:34 pm, edited 1 time in total.
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PostPost by: Panda » Sun Mar 02, 2014 8:54 pm

Once again, many thanks to the enthusiasts who responded.
Allan C. thanks for your offer, but the car came with 12 steel knock on's and I want to keep it original.

Ron. the engine is just about standard, a little bit of work has been done to smooth out ports. Cams are std. S/E
Weber jetting is as per the book.

Vaughan. The head is stamped with the engine number at the back. The cam caps all have a FF stamp and it is also stamped on the head at the centre adjacent to the cams on both sides. Not sure what this means.

Rohan. This head is an early one and doesn't have the cross drilling for oil drainage.

Robert. Nice to see you at the parts sale on Saturday, thanks with your help with the engine number

Alan Pate
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PostPost by: vstibbard » Mon Mar 03, 2014 9:38 am

Rohan,

I've got 3 S1 and S2 heads in the Shed and one on Gordon's car, none had/have the cross drilling present, this was definitely a feature of later heads.

Geoff who helps me came up with a simple external drain back to the fuel pump blanking plate which fixes the smoke on start up as the oils drains away avoiding the pooling of oil which seeps past follower and guide on #4.

Easy way of achieving the same result without risk.

the only variances as I understand was the introduction of sleeves for followers on both cams.

Cheers

V
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