32 replies to this topic

[R1minimagic]

I always use the 70 valve rule on the Veyron, so when valve 64 is fully open, i adjust valve 6

[dklawson]

When I fly my personal jet to the U.K. you will have to show me how you adjust the valves on the Veyron.

[R1minimagic]

Ok, i will show you how to adjust the valves on your compressor housings too

[Andrew22-10]

Hi i dont no if anyone is still on here but i have a firing problem. 

 

I recently fitted a new head gasket to my 93 1275 Italian job mini, the replacement went smoothly up until the point were i went to start the engine. it started first time for about 10 seconds then died and wouldn't start again. there is a good a spark at all spark plugs and it is getting fuel into the cylinders the only issue that i can see is the compression being a bit low (ranging from 85-95psi). the valves are all seated properly and are not leaking, the tappets have all been set to 0.30mm. i have no idea what else the issue could be.

 

if anyone has any suggestions it would be appreciated. 

[MRA]

compression is very low, did you take a reading before you did the head gasket ?

[Andrew22-10]

no it was a mechanic that told me it was blow but he could remember what the compression was at. It was defiantly blown, about a 15mm hole between 2 and 3 

[dklawson]

Remember when performing a compression test that you need to hold the throttle wide open while cranking and let the engine turn over 5 to 10 times until the reading reaches its highest value and stabilizes.

 

You took the head off and put a new gasket on.  Did you do anything else?  You said that the valves were all adjusted to about 0.012".  I assume you made this adjustment after the gasket replacement and are not assuming what was right before is correct now.

 

Did you torque the head on in sequentially higher values until you reached about 45 ft-lb?  Have you re-checked the torque since your initial quick start of the engine?

[Andrew22-10]

i torqued it down as per the manual, the valve clearances were set after the gasket was replaced, nothing else was changed on the car, all push rods are straight and put back were the came from, the head was skimmed and the valves were ground in with fine grinding paste, the compression readings were taken after the gauge had stabilized. ignition timing was set before the gasket was done and hasnt been changed since.

[Andrew22-10]

I still haven't fathomed out the problem, if anyone has any ideas t would be much appreciated, i am really struggling now.

[MRA]

Did you check the valves sealed against the seats ?  if so how ?

[Andrew22-10]

i never checked or even thought about it. would that cause low compression.

[gazza82]

Yup!

Had it on a 1098 .. next to no compression on 3 & 4 ... Engine ran but not if you pulled 1 & 2 leads off ... First 2 cylinder A-series!! Valves and seats damaged.

Edited by gazza82, 27 March 2016 - 10:33 PM.

[Andrew22-10]

i checked the valve seats by flipping the head and filling them with petrol and it held fine, so the seats are ok but i will check the oil seals (wasnt burning oil before)

[Andrew22-10]

Ok, i have checked everything everyone has suggested and still low compression. it is really starting to annoy me now because the car is sitting in the garage and it is totally useless. I appreciate all the suggestions, if anyone has more i would be grateful.

[gazza82]

If the head is OK and the head gasket, then there is only one more thing that affects compression .. bores and rings ..

 

A bit more history about the car and why you changed the head gasket might help ....

 

Have you checked the plug leads, etc??