maximum head shave 4g54

[simon]

Hi all,I have an astron 1 4g54 short motor that came with my lancer .It has acl duralite flattop pistons,balance cams removed,balanced.I plan to finish it,I have an M7 magna head ,I would like to know the maximum I can shave off the head without putting valve reliefs in the pistons or reseating the valves deeper[the bottom end is all together so I don't want to pull it apart and want to keep it simple] I have a couple of cams I can use ,one I was told is a 40/80 and the other I read the tag properly .I think I would use twin webers or efi with ITBs. The motor would be used for knanacross/autocross etc .I want to get the compression up a bit without too many hassles
Simon

[A112H]

I have heard 3mm but taking 1.5 to 2mm off should be fine.

[Cottees]

I am not too sure how much my G52B/4G52 head has been shaved since it has been done a couple times, but the height of the combustion chamber is 16.1mm. That along with oversized pistons worked well with a compression ratio of 11.4:1.

[simon]

Thanks for that,I forgot to say before I know I would need to adjust cam chain tensioner and cam sprocket.Since I put the post on I talked to the bloke doing the shave ,he has already taken 2.5mm off the head [a bit of a mix up] so I guess my question is will it fit without mods.
I think this topic might be of interest to a few people ,there are a lot of astron 1s out there and flat top pistons and magna heads sound like the way to go

[A112H]

Thanks for that,I forgot to say before I know I would need to adjust cam chain tensioner

Yes you do. If you don't you will end up with the same result as cottees did with his Lancer.
You need to make a spacer in the back of the tensioner to allow for the extra reach needed to tension the chain.

[cheaterparts]

Hi all,I have an astron 1 4g54 short motor that came with my lancer .It has acl duralite flattop pistons,balance cams removed,balanced.I plan to finish it,I have an M7 magna head ,I would like to know the maximum I can shave off the head without putting valve reliefs in the pistons or reseating the valves deeper[the bottom end is all together so I don't want to pull it apart and want to keep it simple] I have a couple of cams I can use ,one I was told is a 40/80 and the other I read the tag properly .I think I would use twin webers or efi with ITBs. The motor would be used for knanacross/autocross etc .I want to get the compression up a bit without too many hassles
Simon

if its any help I have taken 3+ of my head but with the cam I run I did have to releve the pistons for clearance on the inlet side of the piston
it was a simple enough thing to do
I would say to dummy assemble the head with the cam you are going to use ( dialed in ) put some modling clay on the piston and give the valves a squirt with inox before assemble
then turn the engine over by hand after doing a complete 2 turns of the crank rip the head off and you can measure the clearance as the modling clay will be dented bythe valve

2 more things you will need a vernier cam gear to dail the cam in ( I do redrill them and a few guys have used them here on the site )
and you will need to space out the chain chain plunger so the timing does not slip on start up when there is no oil presure

if you need a redrilled gear PM me

[simon]

Thanks for that info cheater,I will see how I go with the cam sprocket ,I hope my son might be able to do it at work for me
If he cant I will give you a yell
Simon