compression and head gasket

[Jon_nova1]

after i fitted the skimmed head i got, the headgasket blew pretty fast due to the compression, i went out and got a compression tester...

cylinder 1,2,3 were all around 90-100PSI, and cylinder 4 was at 150PSI, i thought this strange, i put some oil in cylinder one and got the same result, so i assumed the gasket had gone on 1, 2 and 3, so i took the head off and its only gone on cylinder 4:wtf:

i've been told compression should be around 120PSI, so the only conclusion i can come up with is the valves haven't been growned on properly?? and cylinder 4..well:confused:

oh opinions wanted lol

[Adam]

If the oil test had no effect then yeah, must be valves.
HG usually just goes inbetween two cyls.

[Jon_nova1]

not on this:confused:

I was going to try and explain, but realised the gaskets still outside lol

its placed as if you were looking into the bay from the front, the gaskets gone on the top right
http://img.photobucket.com/albums/v166/Unicorn007/DSCF0255.jpg

[tom reid]

Was it pinking?

[Jon_nova1]

yes, well it sounded like it

[tom reid]

HG looks as though it's been burnt through, what fuel/ign are you using?

[Adam]

Stupid question, but was it the right size gasket? Correct block size?

[Jon_nova1]

im using the standard carb for fuel, it was the right size gasket, i thought the 1.2/1.4 were the same bore size??

i've changed the gasket and put two on, but i appear to be getting no compression at all, the timings all fine though, would i need to turn the engine over abit to get compression as i've changed the oil pump and have yet to put the screw in the top of the oil pump that acts as a bung?

would you also need the inlet manifoldon to produce a compression reading? i thought the piston movement would be all thats needed?

[Welsh Dan]

The fact that you have no compression is most likely linked to the fact that you've fitted 2 head gaskets. All you need to get compression is the head securely bolted to the block with the right headgasket between them, and the cambelt properly timed up.

[Adam]

Dont need inlet/exhaust for compression.
Just a good heal to block seal, properly sealing valves and piston rings.

[burgo]

wtf, why did you put two on lol and it wont have been been the compression blowing your head gasket as mine has 170psi and is fine. that head gasket looks more like fuel starvation to me and as for the fluctuation between the cylinders try re lappng the valves and taking plenty of time to do them as it is worth it in the long run

[atokley]

Theres no point in running two head gaskets as that totally takes away any power gain you may get from fitting a skimmed head.

Go to an engineering place and get the head pressure tested, may be leaking from bad valve lapping and need relapping.

Fit one headgasket, and put engine together as normal, compression test it at full throttle.

Sounds as if the heads either cracked/warper or bad valve seating.

Also dont forget to adjust ignition timing accordingly, needs to be adjusted as you have a skimmed head.

[Jon_nova1]

i put two gaskets on as the compression was too high, the head has been skimmed and theres about 1-2mm left between the bottom of the cylinder head and the thread for the spark plugs

what litre is yours though Burgo??

[Stuart]

define "too high"......


If it was detting its tits off then maybe but then backing the ign off would have sorted that...

I know people whos compression tests yeild 200+psi and they run fine.

[Adam]

Did you measure the CR?

[Stuart]

from the sound of it, its barely been skimmed 1-2mm away from the plug thread is MILES away.

try cutting into it lol then yovue got a high CR.

Get your block face flatness verified aswell as the head

[Jon_nova1]

too high appeared to be knocking, i just put one gasket on it,the reason there was no compresion was due to the headbolts not being tight enough, i did 28NM followed by 3 60 degree turns, but i've had to tighten it alot more? i cant finish tightening it as i snapped the socket which is a starone E9, i've been loads of places and no one sells them :(

[burgo]

what do you mean youve had to tighten it alot more?? you should only take it as far as the haynes says and no more. and as said if you were getting detonation then adjust the timing. oh and as for your question mine is a 1.6

[Jon_nova1]

there was no compression, i tightened the bolts abit as there was no other way for the air to get out after doing varous tests, and as i tightened them more the compression went up (obviously i didn't test the compression the same time as tightening the bolts) which would mean the compression was going the the head gasket, it cant be because its compressed more as its going from no compression to 100+ psi eventually as i tightened the bolts

[burgo]

next time make sure you tap the holes out then and make sure theres no water or oil down the holes aswell.

[Jon_nova1]

i never thought to tap the holes, but i always twist some toilet roll and prod it down the holes till theres no water lol

[burgo]

kitchen roll is better as its less likely to break and get stuck down the hole

[Adam]

Lol, so you just kept tightening the headbolts until you had compression?

They have a specific tightening procedure for a reason...

[Lee]

hmm, any porus head gen? lol

[Jon_nova1]

so you'd suggest not tightening them and turning the engine over hoping for the best?

has anyone else ever had problems finding an E9 star socket? i've even looked on the internet an no one appears to do them, they go from E8 then E10 :(

[Adam]

Halfords.
Pretty sure my head bolt socket is a E12 tho.

I'd suggest not using two gaskets, thats just a bodge.
Get the right headgasket, and torque the new bolts up right.

[Jon_nova1]

i went halfords before, they dont have E9, seperately or in sets :(

[burgo]

only tighten the head bolts to the specified amount. no more - no less

[Jon_nova1]

doh i just had a pm of the lad i bought the head of saying i should use extra washers lol

[Adam]

You re-use the washers off the old headbolts...

[Jon_nova1]

he means use extra ones so the bolt bottoms arn't hitting the block

[Lee]

They wont if you bought the right ones!! Did you use the washers from the original bolts?

[Jon_nova1]

they have a washer on each, but they're just standard bolts?

[burgo]

whats that saying about a monkey with a wrench??

[Jon_nova1]

shhh lol

i'll have it all sorted in a day or two when i get none E9 head bolts :p

[tom reid]

We all make mistakes when carrying out procedures like these for the first time, the trick is to learn from them, hope you can remember all the lessons you have learned from this lol

[Stuart]

sounds like a combo of the wrong bolts and wrong process followed lol.

[Jon_nova1]

im sorry to shame you all, but i've done a cylinder head gasket on lots of cars before lol , but yes, i will learn to either get shorter bolts or use an extra washer, although i tightened the bolts in the right order, but i've got some of the normal socket bolts on the way so it'll all be coming apart again because i cant do anything with bolts i cant find a socket for, but ill come back and say check it ouuuttt....meh :p

[Stuart]

I tend to go a bit further with the bolt tightening.... i know your not supposed to but meh, the alst turn i do bettween 60 and 90 degrees... or untill i get tired lol