Lotus Elan

URGENT please help-castle combe aftermath

PostPost by: phatmendus » Fri Jun 02, 2006 6:27 pm

Hi Everyone,

Advise really badly required. I took my lotus to the day at castle combe last Sat, and indulged in some pretty heavey driving on the track. All went well, the day end so I drove back to Bristol without any probs. I have not driven the car since, then today started it up. It sounded well rough, and a puff of oily smoke came out of the exhaust. The engine runs and revvs freely but it sounds very lumpy and when I tried to drive it I had very little power. Basically i need to diagnose this and get it sorted asap as in 2 weeks I am supposed to be going to Le mans in it!! I have a horrid feeling I may have burnt a valve out or something, but the mystery is why did it not play up driving back from the circuit. I plan to do a compression test on monday which may reveal something, however I really need some advise on what it could be.

Also as I have no time does anybody know a garage nearish to bristol which may do (worst case senario) head rebuilt in 2 weeks!!!

all advice welcome, time is of the essence!

Thanks

Simon
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PostPost by: types26/36 » Fri Jun 02, 2006 6:42 pm

Simon,
Dont panic, could be something simple, start at basics.
First determine which cylinder/s are misfiring, at idle pull one HT cable off at a time and see if the idle speed drops (with insulated plyers) unless you like a shock........well it wont kill you anyway!
Once you have found out which cylinder(s) are mis-behaving take out the plugs and check their condition......maybe just oiled up (yer right)
Do a compression test and post findings........advice will be forth-coming.
Brian
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PostPost by: phatmendus » Fri Jun 02, 2006 6:49 pm

Thnaks for the advise. I wil lonly be able to look at it on Monday as I have gone back to my parents to collect my tools in a panic. I took the HT leads off as you suggested, but to be fair it was running pretty rough so it was hard to hear which cyilinders were playing up. All i di know is that I have a good spark at each plug. The oil is clean in the engine and the oil pressure was also fine. I did however think that the car water temp got hot v. quickly ,but I was in a hurry so didnt check everything as I should.

I shall post the results of the compression test on Monday.

Thanks

Simon
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PostPost by: types26/36 » Fri Jun 02, 2006 7:07 pm

O.K. increase the idleing speed (via the idle screw) untill it stops jumping about and has a steady (if erratic) speed where you can do a plug lead test. (The idle screw NOT the balance screw.....I hope we are talking about webers/dellotors)
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PostPost by: alaric » Fri Jun 02, 2006 8:19 pm

If it drove all the way back to Bristol ok, then is it possible that the heavy driving stirred up some dirt in the fuel tank, which has found its way into one of the float chambers. Over the week since you got home, the fuel could have evaporated and left a deposit on the bleed valve or seat so now the float chamber level is too high. Or, is the fuel filter now blocked so too little fuel is coming through?

Hope you get it resolved.

Sean.
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PostPost by: phatmendus » Sat Jun 03, 2006 10:17 am

Thanks for the ideas, I will check all of that on Monday. I think I shall do the dreaded compression test first to see if its the worst case senario. Ill let the forum know the sad oucome.

cheers

Simon
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PostPost by: phatmendus » Sat Jun 03, 2006 10:18 am

p.s yes its on dellorttos. Also I have just paid a small fortune to have it tuned on a rolling road so I hope the carbs arent the cause!!
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PostPost by: types26/36 » Sat Jun 03, 2006 11:39 am

phatmendus wrote: I hope the carbs arent the cause!!


Better that then a head off job! while you are looking round check for air/vacuum leaks on the carbs/headlight pods/pipes/servo/pipes and connections etc. Pay particular attention to the thackery washers on the carb studs, they have a habit of breaking, the carbs then become loose allowing air to be drawn in.
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PostPost by: 1964 S1 » Sun Jun 04, 2006 4:04 am

Here's another possibility, slim as it may be, easy to check out. Camshaft timing. Some think it impossible, but maybe a cam jumped a tooth during your track time. My weber carbed S1 did it to me when I was drag racing it. Felt like I had hit a rev limiter. Later (like a year) found out I didn't have a rev limiter and the timing had jumped. It ran "lumpy" and smoked, not much suds off the line but still ran "ok." It's quick and easy to check the timing marks...
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PostPost by: steveww » Sun Jun 04, 2006 8:12 pm

Start with the simple things. Check the ignition, point gap (if you still have them) and static timing.

The static timing on my S4 was 20 BTDC after Castle Coombe, it was not running too well with that either.
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PostPost by: phatmendus » Mon Jun 05, 2006 11:51 am

Well, it feel so nice when news about a lotus is good news!

It turns out that I had burnt out 3 of the 4 plugs, no wonder I had v. liitle power!!! I bought the NGK ones as I thought they would be good plugs. They are six months old, right heat range etc, but obviously not man enough for castle combe!

Anyway, Thanks for everyones advise. I am now a happy man who will hopefully make it to Le mans and back!

cheers

Simon
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PostPost by: steveww » Mon Jun 05, 2006 11:59 am

It is nice when it is inexpensive to fix :D

I would try to investigate why the plugs burnt out so quickly.

Are you going to Classic Le Mans as well?
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PostPost by: phatmendus » Mon Jun 05, 2006 1:25 pm

eeer, not to sure abotu classic le mans. when i s it? I am booked to go out on the thrus night ferry from portsmouth, and am returning on the monday evening. Im obviously going to see the 24 hour, but wasnt sure about any other events goign on during. If you know any more please let me know.

cheers

Simon
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PostPost by: ElliottN » Mon Jun 05, 2006 1:54 pm

Simon,
Which NGK plugs were you using?

On collective recommendations that I've read here - BP6ES are for road use, BP7ES for extended high speeds and BP8ES for track work. If you were running BP6ES then your track session could indeed have brought on the burn out I expect.

I'm a very happy BP6ES road user.
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PostPost by: phatmendus » Mon Jun 05, 2006 2:12 pm

I was using BP7 ES as was recomended to me when I was re-building the car. As I said earlier, they were only in for 6 months. The car ran faultlessly on the track day, it was just after it had been parked up for 6 days, then restarting it fit the troubles arrise.

I will see how the champions fair.

Simon
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