Lotus Elan

Valve guides

PostPost by: daverubberduck » Sat Sep 28, 2019 1:12 pm

Does anyone have a feel for the cost of having valve guides replaced on a twin cam in the UK? I mean the whole job i.e. take the car in and have them remove the head. I presume that most of the work is in actually changing the guides. I'm guessing it's an hour's work for a professional to take the head off, another hour to put back(?). I could take the head off myself and take it somewhere, but I'm not very confident about doing that.
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PostPost by: Foxie » Sat Sep 28, 2019 4:20 pm

daverubberduck wrote:Does anyone have a feel for the cost of having valve guides replaced on a twin cam in the UK? I mean the whole job i.e. take the car in and have them remove the head. I presume that most of the work is in actually changing the guides. I'm guessing it's an hour's work for a professional to take the head off, another hour to put back(?). I could take the head off myself and take it somewhere, but I'm not very confident about doing that.


I've done this job many times, and I'd say you have greatly underestimated the times required for various sections of this job.

To start with the bonnet has to be removed, exhaust pipes and manifolds and carbs removed, hoses, rad removed (makes resetting the timing so much easier). It is very important to set at TDC before removing the head.

Then the head has to be stripped down completely, valves and springs labelled (you'll need a 4 x 2 valve, spring, retainer and collet box )

Replacing the guides themselves doesn't take that much time, but then new seats cut and valves lapped in.
Then the head has to be re-assembled, and valve clearances set. Normally shims will have to be ordered, or ground to size.

Replacing the head on the block doesn't take much time either, but then the cam timing has to be set, and checked carefully, and the ignition timing reset

Then you are ready to refit exhaust systems and carbs, and everything required to get the engine running again.

All this could run up a considerable bill. And with your vehicle parked in their premises for the period can incur extra costs, and pressures if there are any unforeseen hold-ups.

It is much preferable, and considerably cheaper if you can manage it at all, to bring a stripped head and valve set.

Then take a little care in re-assembling at your leisure.

:)
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PostPost by: tvacc » Sat Sep 28, 2019 5:19 pm

May as well do the water pump, or put in a cartridge front cover at the same time.
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PostPost by: elancoupe » Sat Sep 28, 2019 6:21 pm

Tis a slippery slope , once you start down. :) :)
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PostPost by: Citromike » Sun Sep 29, 2019 4:37 am

My 30-yr career was writing and publishing automotive service manuals for Autodata, Glass?s Guide & Haynes in the UK and Mitchell in the US.

As hinted at above, the Lotus Twin Cam head, with cams, water pump, chain, etc is one of the trickiest procedures you can attempt ? both the disassembly / reassembly and the machine work once it?s off.

I suggest you find a qualified person to help you or pay to have it done by a shop that does them regularly.

They are rare, fragile and expensive compared to most cylinder heads.

Good luck.
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PostPost by: daverubberduck » Sun Sep 29, 2019 8:47 am

Many thanks for your input. There is no way I'm going to take the head apart, the question is only about whether I take the head off myself. I will probably do that myself. I will report back on the cost of doing the valve guides.
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PostPost by: JonB » Sun Sep 29, 2019 8:50 am

Hopefully you have a copy of this to hand: https://www.amazon.co.uk/Lotus-Twin-Cam ... 1855209683

If not, buy and read it.
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PostPost by: DUKE » Sun Sep 29, 2019 6:06 pm

Just had my head skimmed, new valves, springs, guides, seats, re-shimmed etc. Parts and labour for this work without anything else as I removed the head and delivered it to the machine shop came in at just over ?1100. Factor in the cost of new gaskets, water pump...the list goes on!
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PostPost by: nmauduit » Mon Sep 30, 2019 8:05 am

DUKE wrote:Just had my head skimmed, new valves, springs, guides, seats, re-shimmed etc. Parts and labour for this work without anything else as I removed the head and delivered it to the machine shop came in at just over ?1100. Factor in the cost of new gaskets, water pump...the list goes on!


head work is indeed expensive, but if done properly a well rebuilt engine will offer many rewarding miles and the bills will not be regretted.
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PostPost by: reb53 » Fri Oct 04, 2019 5:56 am

Good grief !!

I guess I got lucky when many years ago I pulled the head off my Sprint, heated it up in my Mum's oven, ( she was out....), knocked the guides out with a drift I'd turned up, retrieved the new guides from my Mum's freezer, whacked them in, and when the whole plot had cooled down reamed them to size and re-cut the seats.

30 years later the car is still going fine.
You don't have to be a rocket surgeon.
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PostPost by: jono » Fri Oct 04, 2019 9:58 am

I had my head done by Paul Exon 4 or 5 years ago and I seem to recall it was ?360 to supply and fit Cosilbro guides, ream them, re cut the valves and re assemble.

This exluded transporting the head - I made up a courier jig out of two bits of 18mm ply with threaded studding to hold it all together and protect the head in trans.

I did the shimming myself - it was quite a bit more to get Paul to do it ISTR
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