Newbie question re twin cams and unleaded fuel

[Johnfm]

I assme that, unless the valves have been changed, the ?lan plus 2 needs leaded fuel?

[rgh0]

Hi John
It will run happily for many many years on unleaded fuel. Most engines will have had valve and seat changes in recent years. If you have an original engine in good conditon with original seats and valves ( unlikely) it is still good for unleaded IMHO

regards
Rohan

[512BB]

And I concur with everything you said there Rohan, and with experience.

I have 2 Elans that are still running on original seats and valves, and are fine with unleaded fuel, but I do use Castrol valvemaster plus in the petrol, all the time. That is an octane booster and has a lead substitute.

Both cars engines were rebuilt over 20 years ago, one by me, the other by the great man, Mick Miller. I remember well, a conversation I had with him at a fair, where he stated that he did not think it necessary to fit the new, at that time, hardened seats, as he thought that the Lotus product, was plenty hard enough.

Now I have not had just cause, to disassemble either engine, as they both run just fine, but I did have it in my mind, to re gasket the engine that Mick built, as it leaks just a little bit to much oil now for my liking, over the coming 3 months, but alas I do not think I am going to get the time. And NO, that is not because I am always on here writing drivel!

Anyway, I shall report back on this thread, if I can find it! when I eventually do get to work on the engine, and see what 30 odd thousand miles on unleaded, has done to the original seats.

You will all have to wait with baited breath!

Leslie

[peterako]

Have been running my Elan on unleaded since the day I got it.

Recent head rebuild did not show any problems from the Unleaded.

And our petrol (in Ireland) seems a lesser quality than, for example, in France....

[Pistacchio sprint 72]

Regarding How expensive are these little bottles of lead substitute, i always wondered if it was worth it in comparison to a good session of valve lapping or to some repair in extr?me case.
For my x flow only 8 valves are concerned so i decided to run on unleaded. When i swapped head for a race One, i reconditioned my old One to sell it. No pitting on the seat. I did lapped the valves by hand to do a clean job.

The twincam head is much more expensive and the 16 valves would for s?re require more work.... So the question Regarding the use of these expensive additives is genuine!

Hence my low mileage i think i wo?t beleive the hype, and run on unleaded 98 without extra stuff.

I am always able to change opinion. So please post if you think i should!

[types26/36]

The twincam head is much more expensive and the 16 valves would for s?re require more work.... So the question Regarding the use of these expensive additives is genuine!

16 valves???

[Pistacchio sprint 72]

Ah? I thought There was 16... How many then? Soory for my ignorance

[types26/36]

Only 8 in normal TC

[Pistacchio sprint 72]

U killed my dream! I thought it was more advanced than my xflow.... Sigh

[richardcox_lotus]

I think you'll find the TC design predates the xflow.

[Pistacchio sprint 72]

Damned, my world shatter into pieces...

[Chancer]

Its also very easy to check the cam bucket clearances from time to time to see if there is any indication of valve/seat recession.

In an ideal world it would equal the cam wear!!

My gut feeling is that if there were to be any it would soon stabilise as the contact area increases.

The industry made loads of money in the run up to unleaded fuel, many perfectly servicable vehicles were scrapped through fear and loads of money is still being spent on additives, that i do understand, what price do you put on protecting your engine.

However there has been very little anecdotal evidence of engine damage through running an unconverted engine on unleaded fuel even those without valve seat inserts.

[Pistacchio sprint 72]

I got a good answer Regarding engines history from turbosport forum: iquote

" the pre-crossflow came first in the 1950's, then the twin cam which was based on the pre-crossflow sub-assembly and it appeared around 1962, although was being designed in 1961. The first crossflow came on the scene in 1968 in the revised version of the Mk2 Cortina.

The Twink is better in that it revs better as the valve train is lighter and valve springs for a similar spec engine to a crossflow can be weaker thus putting less strain on the cams and chain and which allows it to rev better.
The problem with the Twink is that you can only fit a single row chain no matter what level of tune you have and that concerns me in an engine at the high end of the power scale as it's quite a thin chain. Having said that you don't hear of them snapping very often.

The hemispherical chamber is a better design (although not the best when compared to a BDA head etc) as opposed to the chamber in the piston crossflows which is technically a moving combustion chamber, plus the lighter pistons, crank and rods of the twincam help it to attain revs quicker than a 1600 crossflow.

The crossflow has never reached the magical 200bhp figure in any guise as far as I know but the Twincam has in larger bore/stroke versions.

For simplicity and cost/reliability the crossflow is much better than the Twink in my opinion, but it'd be nicer to have a Lotus under the hood!"

[Pastapesto]

Ok, let's turn this around:

Who has had valve seat problems on their engine where they did not use an additive but just went straight onto unleaded and has kept on using their car?

The thing is, I have never heard of anyone with valve seat damage from this problem and I would like to hear about it from someone who has suffered it. I'm not saying it does not happen but I agree with all of the above in that the Lotus seats were plenty hard enough and there was a lot of scaremongering about this for financial reasons. Am I wrong? Please tell me I am as I would like to know.

"16 valves?", (lol), sorry I had to laugh. The pedigree of the twink is fabulous if you look into it and you don't need 16 valves for this little beauty. I think Vegantune had a go at it but that was about it and does anyone know what happened or how it went? I'd like to know. I expect Rohan knows, come on tell us please.......


All the best

Adam