`pistons problem

[albercoc]

Good afternoon, today I dismantled the engine of my elan +2 "federal" 1972, I have this car for almost two years, and after some makeup work, I've used on several occasions, but had excessive oil consumption, and to smoke out the tailpipe, I thought it might rebore the block and put new pistons, but when removing the old pistons I have measured and measured 85mm, what I can do? Can withstand a far wider ? Is it advisable?

Moreover, I wonder if there is any way to know if the camshaft bearing seats are original or have been replaced, "have some kind of etching or reference?


thank you very much, Juan

[512BB]

Buenos noches Juan,

If you have a 701M block, which you should have, I believe, in a 72 +2, then you have already been very lucky in that the bores have not gone through to water.

You have 2 options in my humble. 1, fit new sleeves and take the block back to standard. Then you would obviously need to find standard pistons. Or 2, start again with a different block that has not been bored so much. Getting a GOOD machine shop on the beautiful island of Mallorca, to fit new sleeves, could be difficult.

Either way, you are in for quite some expense, and from the sound of what you say, your engine does not seem to be in top order, and there may well be other costs, ie. crank grind etc to be found out.

Sorry I dont have any good news.

Adios, Leslie

[albercoc]

thanks for the clarification,
I almost regret having dismantled the engine worked well, I've only taken out to solve the problem of second gear that makes noise by reducing hot. but since it was out I opted for repair.
What way I can know that my block is the type 701m,? my car has documentation from 1972, but I think it is older, has chassis number 502 121
this afternoon, the internet, I found pistons as 85'5, but what you tell me, is out. here is difficult, if not impossible , find a block of these,
all internal engine parts are really good, caps and crankshaft connecting rods are like new, just wear on the cylinders, and rings. I think this could be caused by wear operate without filters, when purchased had no filters, just the trumpets,

uploaded some pics of the pistons old, if someone know the brand of them have a logo do not know.

thank you very much, Juan

http://i295.photobucket.com/albums/mm12 ... CN0274.jpg
http://i295.photobucket.com/albums/mm12 ... CN0275.jpg
http://i295.photobucket.com/albums/mm12 ... CN0276.jpg

[512BB]

Hi Juan,

The block is marked with the numbers on the exhaust side, just above where the sump fits, towards the rear. And I do not recognise your pistons as being from any Lotus that I own. Of course your engine oil consumption could have been from a worn cylinder head, ie. valve stems, and not from worn bores and pistons rings.

Leslie

[JJDraper]

I would be tempted to source some new rings & gaskets and put it all back together and find an air filter! The original problem seems to be oil consumption rather than any other issue, so address that. The cast iron oil control rings seem to be a weak spot on twin cams. I understand composite oil control rings do a better job, so if they are available for these pistons they would be worth a go. If you can also include a stepped top compression ring (also known as a 'ridge dodger'), this would be a good idea.

The pistons have an AE marking (Hepolite?)which should make identifying and sourcing a correct set of rings possible. However, given your location I can see some serious web searching.. Measure the existing pistons & bores very accurately!

re engine block identification, look for numbers (1cm high) cast into the block, on the exhaust side towards the back of the engine.

Jeremy

[types26/36]

Juan,
If your block is a 701 M then it will have this cast into the left side behind the exhaust. (see pic)
As mentioned 85mm is pushing it for that block although I have seen several engines bored to that size.
Although I am not sure it looks like the pistons could be "AE" which is a brand supported by Federal Mogul.
http://www.federalmogul.com/en/Aftermar ... /Brands/AE
It also looks like you have the "L" shaped top compression ring which is called a "Dykes Ring" http://www.mecoa.com/faq/rings/ringtypes.htm
I had a Seven which was bored to 85mm (711 block) with "L" type rings and it was smoking, I stripped it, horned and measured the bores which were within spec, the problem was with the piston ring grooves, the grooves were badly worn with a lot of side play between the ring and groove meaning new pistons were required.The "L" shaped rings in my engine did not go to the top of the piston as described in the Dykes link.
My solution was to get a set of piston rings for a Datsun 1800 (85mm and cheap) these are slightly wider then the Lotus pistons, then I took the pistons to the engineers and had the piston ring grooves machined out to suit the Datsun pistons rings, it worked just fine with no smoke or oil consumption.
This will only work if the bores and pistons are not too badly worn.....good luck.

[albercoc]

Thanks Brian,
seems like a good idea, I'll take the block to the machine shop to see if can still save with this system, it is cheaper and can do well.

[albercoc]

Today I started cleaning parts, I have seen a number, but not like in the picture, is it bad news?. I put a photo if possible identify

Thank you. John

http://i295.photobucket.com/albums/mm12 ... CN0277.jpg

http://i295.photobucket.com/albums/mm12 ... CN0279.jpg

http://i295.photobucket.com/albums/mm12 ... CN0282.jpg

[types26/36]

Juan,
Its not necessarily bad news, the 681F is the genuine Lotus block just the early and weaker version then the 701M.
As I said 85mm for the Lotus blocks is dodgy but if it has been running for a while then unless you are going to give it a hard time than the chances are that it will be O.K.
It could have been sleeved previously to accept 85mm sleeves anyway.

[rgh0]

No practical difference between a 681F or 701M block - you have to be very lucky to get a 85 mm bore out of either and generally you need to offset the boring based on ultrasonic wall thickness measurements to maximise the wall thickness after boring to get an acceptable and consistent wall thickness above 2.5 mm all around the bore

You can reuse the block with a light hone and removal of any ridge at the top of the bore if needed and new rings for the pistons. If possible I would try to find an engine shop with ultrasonic measuring equipment to measure the bore wall thickness in detail . Less than around 2mm in any location and it is almost certain to crack relatively quickly and you need to decide whether you want to take the risk with a rebuild at 85mm that you may need to repeat in a short time plus source a replacement block.

If the current wall thicknesses are below 2.5 mm I would sleeve the block back to the original 82.5 mm. However you need to find a good machine shop capable of doing this work which may be a challenge where you are. The right machine shop should be able to find 85mm OD sleeves suitable for your bores which could be fitted with minimal additional block machining.

cheers
Rohan

[types26/36]

No practical difference between a 681F or 701M block Rohan

.....Except for the 701 having the stronger square main bearing caps as opposed to the weaker rounded main bearing caps of the 681F

[rgh0]

No practical difference between a 681F or 701M block Rohan

.....Except for the 701 having the stronger square main bearing caps as opposed to the weaker rounded main bearing caps of the 681F

Guess i was talking about the blocks in terms of wall thickness. Yes the square main caps are better and stronger on the 701M block but in practical terms the round caps are fine for use with the cast crank and short block

cheers
Rohan

[albercoc]

block yesterday to carry the machineshop, two of the cylinders are 0.15 mm oval, it seems very little, but it is much more than the maximum recommended.
I have no other option, again stardart far,
where I can buy spare parts of motor?


Thank you very much. John

[rjaxe]

John, Westwood Cylinderliners advertise flanged sized cylinder liners for a twin cam at around ?175 a set. The O/D is 85.79mm and I/D 82.55mm so they are sized for standard pistons. I have not used them but could be worth you getting in touch if you decide to go the liner route.http://westwoodcylinderliners.co.uk

[albercoc]

thanks for the information, the liner is the only thing I think I have solved, the rectifier has found liners that go well (I think are some nissan model), this work is almost controlled.
I got in touch with qedmotorsport, (did not know them, found them by chance) for the remaining parts, they have everything I need, unless the pistons, i have to wait a few weeks

given that I have time, I disassembled the gearbox to change the synchronizer rings and bearings,
I will tell you how it goes.

Thank you very much, Juan