History of a Lola T492 Sports 2000 chassis?

[911thillclimber]

Got down to basics this afternoon!

Firstly, my thanks to all offering help/ loan of equipment (I got your message Dave D).

I am now'fully equipped by DIY means

going to plan:
Stage one:
Just what is leaking and where

Made a simple air line to place 40 psi into each cylinder in turn. Threaded together an old compression tester to a Guyson Easi-Bleed brake supply pipe. This allowed me to use a spare tyre as a reservoir and to apply known equal pressure to each cylinder in turn.
Thus a 'Loud' hiss is a bad one compared to a 'light' hiss....all very techie.

Results are shown below.

to recap on the repairs to the engine and the heads in particular

#1 was refaced and a new exhaust valve
#2 was refaced and a new exhaust valve
#3 was refaced and a new exhaust valve
#4 was refaced, new seats new inlet and exhaust valve, new guides.
#5 was refaced and a new inlet seat/guide, original valve
#6 was refaced and a new exhaust valve

Looks like #3 inlet needs looking at, #4 inlet (new seat/valve), #5inlet (new seat)

All exhausts are OK
All rings seem ok

So, next stage is all carbs etc off, heads off and a lot of lapping starting with coarse this time...

[ogits]

Before you pull the heads, can you check valve clearances (particularly the leaking inlets) and the valve to piston clearance on overlap (several degrees either side of TDC) ?

[911thillclimber]

Too late, all apart!


This car IS going to work (next year...)

Heads off this morning, flew apart.
I conclude I'm good at taking things apart, 5/10 when putting them back together.

It is very clear #5 cylinder is not working (leak test showed huge inlet valve leak)
The head is as clean as when i assembled it.

The cylinders 4/6 which sit either side of it show combustion. #4 is fed from the same float bowl as #5.
#4 is burning, 5 is not.

Thus ignition in the wrong place or no fuel. My bet is no fuel.

Will re-lap all the valves so no leaks hopefully.

[ogits]

Before you pull the valves, try sticking a torch up the ports to see where the leak is. Also try a fluid leak test. If they are that bad it is unlikely to be a poorly lapped joint. They should seal well without a spring.
Before reassembly, after lapping, try fluid again, wiggle the end of the stem etc.
Any chance of valves touching pistons?

[911thillclimber]

I flooded the valves (port side) before taking them apart in #4 and #5. Both inlets leaked quite badly.
I've re-lapped the valves in #4 and #5 heads. Both inlets leak a little cellulose thinners, the exhausts none.

I have flooded the port side of the valves installed with full valve springs.
Thinners is a very searching fluid!

There are no marks on the pistons from the valves.

Not sure if the same results will be had if I fill the combustion chamber with thinners. Doubt if direction of flooding matters.

[JasperClan]

I find shining a small torch around the valve and looking for light leaks into the ports the best check for valve leakage. Better than any fluids in my opinion.

Pete Richards

[911thillclimber]

Going to try that when the moon is in the sky and I'm alone in my garage with this spooky engine....
Champion if it works!
Will let you/us know.

[911thillclimber]

After some messing about and my wifes birthday treat away, got back to work on the engine suitably refreshed.

Bought all new inlet valves and set to lapping them in. Using the cellulose thinners and high intensity torch method of leak detection all heads 1/2/3/6 lapped in a treat, fluid and light tight inc the exhausts.
(torch up the ports is magic!)

Heads 4 and 5 were a different matter, these heads having had new guides and seats by the engine machinist I will never go to again and I doubt they went in as well as Porsche did it way back....

After a lot of course/fine lapping got #5 tight as the others.
# 4 exhaust is tight and the inlet is just weeping fluid and I can see about 30 degrees of light in one area of the seat. I can't get rid of it so I hope some carbon deposit will do the trick.......

All this because of a shabby machine shop.

Got the heads on and came to the cam timing.
Came to turn the engine over and it locked-up solid. Why me?

Turned out the timing chain had come off one row and it took a full hour to fiddle it back on.
What a game.

Anyway, all timed up now and should be back in the car next weekend with a good following wind.

Will it run on all 6?

[sirdigby]

Hi 911hillclimber- i have been watching and reading this thread for a while but i wasn't a registered forum member so i couldn't post but i felt compelled to sign up so i could say a few things. Firstly following the tracing of the history of your car has been fascinating and secondly please don't put the engine back in the car yet! I was an engine builder for Cosworth's CHAMP car program for several years and have quite a bit of experience. There is no way that a valve that isn't sealed on the bench will magically repair itself. In fact if the seat is seriously off concentrically from the valve head it could cause flexing of the valve stem at higher revs as the valve tries to get down onto the seat and this could be disastrous- whether that cylinder is firing or not. It sounds to me as if the chap that replaced the guides did not re-cut the valve seat after guide installation. Hoping that removing and installing a guide will retain the level of concentricity required is not going to work. You need to fix that head by having the seat re-cut- preferably on a Serdi or similar machine. Lapping should really only be used as a way of checking the width of the sealing band and making sure there aren't any dents in the valve/seat. Also be aware that it is very easy to bend a valve just by bumping them into the pistons accidentally- like when the cam timing is incorrect. Better do a leakdown test one cylinder at a time on TDC compression stroke for each cylinder before you put it in the car. that way you will be sure all is well- or not...
Please don't think i am being nosy or poking into other peoples business-even though i am! i only want to see you succeed and know how heart breaking and frustrating these things can get. So do it properly. Good luck and ask questions

[Andy Turnock]

What excellent advice! We all wish you well with this rebuild.

[911thillclimber]

Sometimes I wish I didn't post on any forum!

just when my mind was settled, I get some sound advice!

I will put 40 psi into the plug hole on #4 and listen for the hissing.
With the carbs off I can touch the head of the valve.
Being very old (this car has not helped me) my hearing is a bit 'dull' (too much drag racing when I was in my 20's) so I could always put some soapy water in the port and see if bubbles errupt...

If there is some hissing, then I'll strip the one side of the engine when I'm asleep tonight 'cause I can do it in my sleep.

I have then to find a DECENT machine shop then to correct or re-seat the valve.

Just WHY am I bothering?
This car has put up a fight at every every inch of the long journey so far.

[Clive Brown]

I find it hard to believe that any competent race engine machinist did not as a matter of course recut the seats after fitting both new seats and new guides.... To effect a proper seal without recutting could have resulted in your grinding and lapping for a very long time; if you lap valves the traditional way, you'ld have ended up with blistered palms. I do not recommend this; I am sure that there are other, more pleasurable, ways to end up with blistered palms.

sirdigby is perfectly right; until such time as you have at least a continuous seal on the inlet valve seat, and a somewhat wider seal on the exhaust valve seat so as to best to conduct heat from the exhaust valve head back into the head casting via the exhaust valve seat, it ain't worth putting the head back on the motor.

If your machinist has been that inept, are you even confident that the new valve seats have the correct interference fit, and are properly bottomed out in their register in the cylinder head?

In my experience, if a valve seat moves whilst the engine is running, then bad things happen!

[sirdigby]

ok, good to hear you are going to check it. Just to reiterate about the possibility of bent valves; after you get this #4 sealed up if at all possible i strongly recommend you do a cylinder by cylinder leak down test. i realize you have limited resources but if you have to take your spare tyre pressure vessel to the station to refill it it is worth it. Ideally this would be after you get the cams re-timed and lash set. Turn the engine over at least 2 full revolutions. There is plenty of time before the next outing right?

[911thillclimber]

I must be VERY obedient!

Put 40 psi in the devil # 4 cylinder and it hissed a treat.
Did the same in all the other cylinders to be met with silence.

The engine was turned a gazillion times timing the thing up and i did several revs testing the 'hissing'.

the side of the engine (cylinders 4/5/6) are all off the engine, the 'old' sealant cleaned off (it had barely set) and i have found another machinist with direct 911 aircooled experience who built my Lola's 911 gearbox in Kendal.

I hope to post it up to Mike Bainbridge Eng and get the thing re-seated, cut and lapped by Mike, also resetting the spring lengths.

The seat looks firmly down in the counter bore, but I take Clive's point.

My next outing is in March 2013!

What a game.

About 1/8 mile before the Big Bang..

[sirdigby]

excellent. i'll leave you alone now. sorry if i "sounded" bossy. I have to deal with this sort of thing a lot at work.

[911thillclimber]

Please :
Zero offence taken.

You were correct and very helpful, and I thank you for taking all the effort to pass your thoughts on.

Head goes off tomorrow to a different machinist, and spoke to him today.

He might fit a new seat to get a fresh land to work from.
He will do this and lap the valve etc so should be silent on assembly.

About a week so will be twiddling my fingers until its back.

[911thillclimber]

Just had an email from Mike Bainbridge.

Head all sorted, a kiss to the inlet cleaned that up, the exhaust seat was pittes so cleaned up (the machine shop previously used said they had fitted a new exhaust seat....) all ground in, new seals fitted over the valve guides again new by the previous m/c shop which Mike says have been fitted too deep into the ports...

A cage of monkeys in that m/c shop then!
Wish I could say I had paid them peanuts.....

Springs reshimmed to nominal length, in the post tomorrow!

ACE!

[Clive Brown]

I trust that you will re-check the seating of the valves in the head yourself, just to make sure y'understand, prior to refitting the head to the bottom end....

[911thillclimber]

For sure I will!
Light torch first then the cellulose test.
I know this engine guy well, just never knew he had this m/c'ing in house.

Wish I had gone there for the lot but he is twice the distance (and very busy).

We are where we are, and I hope this will be progress.
Well, it is because I know the engine does not leak, so if the thing runs on 5 then it will be external (carb/dist etc) and if so time to INJECT it!

Got a lot of bits of hols owing to me in Nov so should get it done.
If the engine works well I will change the CW&P in the box for taller gearbox, less wheel spin and more traction = better times.

I hope.

[sirdigby]

It sounds like he got everything sorted out for you. That's great.

[911thillclimber]

I should not have had these issues with it all in the first place, I did not ask him to make a flat plane crank!
The machine shop reluctantly paid me back £100 as compensation, so at least that will off-set some of the cost.

I want to move on and get the engine running, gearbox uprated and the whole car readied for a winter sleep.

I have the box to fix on my 911 and Mrs Hillclimber wants a heater fitting!
The engine in the 911 is much the same as the Lola's, a 3.2 litre on Bosche fuel injection.
It is 110K miles old, had ONE set of spark plugs in that time fitted and a new dist cap.
The tappets have never been touched, and it runs a dream.

If you can find a road without traffic and open it right up it is surprisingly quick and very charismatic.

Head is here on thursday so the rebuild again will be under way. Plan is to have it all done and dusted by end Nov.

[911thillclimber]

Head back in the garage today, just a few days after Mike got it. Service and a very very fair price!

Did the usual checks, high intensity torch into the ports in pitch black garage, not one wavelength of light anywhere on either valve.
Flooded the ports with thinners, not a damp spot anywhere.

Onto the engine tomorrow (got a day off!) and time it up saturday, carbs on etc and back into the car.

Pity to miss firing it up on Bonfires Night!

[911thillclimber]

Bolted the #4 head onto the block, torqued it up and added 40 psi just to be sure....
Silence!

Built the one side back up now and timed the cam in in record time, getting used to it all now.

Double checked everything and ready now for the carbs, exhause and re-installation.
End of Nov deadline looking good.



Crude makeshift 'non-flexing' chain tensioner meets high precision DTi guage for cam timing to 1/100 mm.


Rockers are mounted on expanding pin that is inserted into a hole with near transition fit, awkward to get in straight and nipped-up tight.



Special Porsche feeler gauge used on inlet and outlet. Near impossible to do the gapping without this tool. They only cost £27! (£8 when I bought mine quite a time ago)

#4 is on the left, finally defeated and bought in-line!

[911thillclimber]

Back in business, but have to stop short of firing it up because of a Club Treasure hunt...
Pity, as it is all back in the Lola and just needs fuel and some more oil to allow it to fire up hopefully on all 6.
If it doesn't run on 6 then the fault will be external to the base engine, so oil leaks allowing, the engine should stay in one piece for a while(?)

Was tempted to stop last night and progress the installation of the fuel injection 'mod' but I think I need to prove the base engine first, then have a go at the ITB mod.

I have too many things motoring to do....

[911thillclimber]

Got it going tonight.
On 4 cylinders.
No heat in #4 and 5 cylinders, all others hot.
Got compression, got sparks, must be fuel.

Carb in a 1,000,000 pieces, looks as clean as a whistle inside.

Back to normal, a fight with it every night.

Simply amazing, but must never give up.