The head has got to come off again!

[chrishewett]

After problems fitting my new carbs I have just had a compression test to make sure that all is in order. Bad news - 180, 125, 165, and 170.
The engine was out about four years and 2000 miles ago. The block was rebored and +60 thou pistons fitted with new shells, bearings etc. The head was sent to PNM engineering and supposedly sorted at a cost of ?500. I have always thought it was a bit noisey and on start up there is one loud tapping for a few minutes until it warms up. I dont seem to have a head gasket problem. The compression test was done properly and the figures are not significantly improved by putting a little oil into the bores. This looks to me like the problem is the head so it is coming off in the next couple of weeks.
Can anyone recommend a good head doctor?
Chris

[steveww]

Have you checked the exhaust manifold studs and nuts are tight? My Elan had a bit of a tapping noise that I thought was the cam followers but it turned out the exhaust manifold was slightly loose.

[Petter Hval]

Chris.
Check the valve clearance befor you rip the head off.
Petter

[chrishewett]

Steve, Alas I don't think that is the problem.
Petter, yes I will check the clearances first, good advice. However I am a pessimist. The optimist believes that we live in the best of all possible worlds and the pessimist fears that this is true!
Chris

[Hamish Coutts]

Chris,

Courage mon brave!!

We are both going through a troublesome lotus period. Try the readings again and be very certain that they are right. Check that the valve clearances are accurate so that the compression readings are accurate. I know this is old hat but was the throttle FULLY open when you did the test?? (forgive but the question has to be asked)

Only 2k miles since the rebuild - is that enough to run the engine in fully? Maybe try another couple of thou miles to see if there is any improvement? Hmm?

May not be quite as black as you think. Give the engine a chance to run in?

Hamish.

[1964 S1]

I'm in the states and am no help with a head doctor but I agree with the others, check the valve clearance before yanking the head.... and cam shaft timing... how does the car run?

[cliveyboy]

Chris
You could have similar problems to me. My original engine was refurbed and then stood around for a few years doing very little mileage.
I was expecting a few problems such as sticking vaves and I did get them.
As suggested check the valve clearances first.
Clive

[M100]

Chris, build or borrow a cylinder leakdown tester (you will need a compressor too) It will give you far more accurate results than a compression test and will point you in the right direction for a fix.

http://www.motorcycleproject.com/motorc ... kdown.html

If it needs any work there are plenty of places in Lincolnshire, you've got Guy Croft over in Lincoln. I'm not sure if he regularly touches twincams but he has lots of experience with Fiat / Lancia twincams - he did the engine on the Lotus "Lada") and Len Paterson (cylinderheadshop.co.uk) who does a lot of vintage motorbike and classic car head work near Cleethorpes. Of course you could always ship it off to QED.

With the noises you are describing I'd not run the engine any more until you get an accurate diagnosis. Pulling the head might be a cheap way of finding out but the leakdown test will tell you lots more and you might get away with just removing the cams to unstick a valve.

Remember pistons cost and arm and a leg, dropped valves and damaged heads two arms and two legs!

[chrishewett]

Thanks all.
I have decided to take the head to a guy called Dave Walker in Newark who comes highly recommended as a twincam man. I have spoken to him and I am confident that he will sort it out. He has a twincam in bits at the moment that had supposedly been proffesionally rebuilt and is in a bit of a mess.
I will report back in due course.
Chris