Hitchcocks Forum

Having treated my well worn Meteor Minor to a +60 rebore and new pistons i have been struggling with clearance issues between the piston, gasket and head.

The parts book suggests thin (0.5mm) copper gaskets are standard for my 1958 model, so new ones were purchased, but after reassembly the engine was very noisy from the top end when started and a quick check indicated the piston was catching the edge of the gasket - requiring me to open up the bore diameter of the gasket.

After fitting the modified gaskets the noise was still there and after further disassembly and examination it would appear that the very edge of the pistons on both barrels are also just touching the head in a few places.
I can get around the problem by fitting the thicker head gaskets (1.0mm) from the 700 Meteor models, but was wondering if anyone else had come across similar issues?

Hi, what sort of noise is it? Vince

A metallic tapping sound from the cylinder head. I'm pretty sure its not tappets/rockers.

I should have mentioned that at TDC the piston edge sits proud of the barrel by approx. 0.5mm, too much to pack out the barrel height using a stack of the standard paper gaskets.

Hi, Have the barrels been machined at anytime in the past to raise compression? Vince

Not since its been in my possession.
The pistons fitted by the previous owner were not Enfield (hardy any dome - BSA is my best guess), so there is a chance that the barrels were skimmed to make the CR better.
If anyone has the dimensions of a standard barrel length that would be very handy please.

I will try the thicker head gasket for now and in the mean time look out for some replacement barrels.

Hi, difficult to measure because of fins but it looks like 55mm. Our hosts can supply compression plates which may solve your problem , part no. 46193. Vince

Thanks for the advice - very helpful!

I think the spacer plates are .022” (0.5mm near as damn it), so with those fitted and the standard 0.5mm head gasket the clearance issues should be solved.
Alternatively I could use the 1.0mm head gasket and no spacer plate.

Decisions, decisions....

Hi, remember to make the head gaskets 060 oversize to fit. Vince

Thanks Vince,

Fortunately I have the worlds biggest collection of thick and thin copper head gaskets modified to +0.60”

All annealed and ready to go.

Cheers
Darren

A quick update on progress.

The fitment of the spacer plate (part no. 46193) between the barrel base and crankcase successfully solved my problem! Once assembled the piston was no longer proud of the top of the barrel.
For future reference the spacers were 0.96mm (nom. 1mm) thick when measure with a Vernier calliper.

I'm still not sure about why the spacers are needed, as they are not standard fitment for the Meteor Minor models as far as i can tell?

Finally - many thanks to Vince for his suggestions and support!