New head gasket?

[JamesRattenbury]

Hi Alan, I forgot to say that yes it does have a recuperator bottle fitted to the rad overflow pipe. It also had 1" of coolant (as per the manual) in it after the overheating.

[JamesRattenbury]

Hi all, a quick update as I?ve just completed the compression test, it seems low to me, but not sure if it?s too low and needs further investigation:

Cylinder 1 = 135psi
Cylinder 2 = 135psi
Cylinder 3 = 125psi
Cylinder 4 = 130psi

A wet test knock these figures up by 20psi

It?s starting fine, not loosing any oil or coolant, oil looks good, but i?m In too minds now, do I go through with it getting rolling road tuned this week (it?s booked in a Btec near Burford as the carbs aren?t running right), or do I get the engine looked at in greater detail, what?s people?s thoughts/advice?

[alan.barker]

looks like figures from an Engine that has done a lot of miles. So it will be a personal choice to refresh Engine or not. Maybe a nice job after the summer in the winter. I have found over the years that Twinks can do with a refresh after about 70,000 miles normal driving.
Alan

[Craven]

Did you have the throttle wide open when you did the test?

[JamesRattenbury]

Hi Craven, yes it was fully open

[nmauduit]

is it a Weber or a Stromberg head ?

[2cams70]

Those compression numbers look quite even which is good. I wouldn't worry too much about the absolute figure because that's a function of many variables including the cranking speed. If in doubt I'd just run a further check on the engine blowby and monitor the oil consumption for a while to see if it has gotten worse.
You can check the blowby by removing the air cleaner cover and looking to see the amount of fumes eminating from the breather tube. If the rings aren't sealing properly you'll see smoke emanating from there even at idle which will increase considerably with engine speed. You might see a little smoke but it shouldn't be excessive.

I'd say by what you are describing that you have escaped the overheating incident lightly. If it were me I'd just fix the oil leak, rebuild and tune the carburetors, check the distributor and it's advance curve and otherwise give it a general tune up and then leave alone.

[JamesRattenbury]

Just a quick update, I decided to get the timing chain gasket replaced and we noticed the cylinder head gasket was also slightly leaking at the back of the engine so replaced that. Engine looks like new so the previous owner was right that it had a recent ish rebuild. We sorted the carbs, moved to using electronic ignition (Tony Thompson Racing fast road kit), replaced the old fan with a modern one and rolling road tuned (after replacing oil and coolant). Running a dream now, and putting out just over 120bhp. Thank you all for your help with diagnosis and advice.

[2cams70]

Good news. Well done!

[richardcox_lotus]

Glad it?s Ok - Who did the work James ?

[JamesRattenbury]

Some of it was done by me, most of it was done by BTEC Racing / RJ Bradley & Sons up near Burford: http://www.btecracing.co.uk/index.htm I knew about them as they have a rolling road and deal with a mix of classic and modern cars. Their a proper bunch of petrol heads and i'd use them again. There about 20 miles away and took it there as I haven't been able to find a classic car garage in Swindon.