Hi, just wondering if there was any way of identifying what pistons are in my cvh. i bought the engine a fair while back from somewhere thats been slammed by a few peeps on here for charging for work and mods not carried out. so anyway gonna whip the head off and check that but want to know if the pistons are in fact the low comp items i believed them to be. can i measure bore and stroke etc to work out comp ratio accurately?

also if anyone knows the size of standard head ports that would be great.

thanks in advance.

ste.

 

Take some pics.
Should be easier to figure out what you have.

 

As Perry says pics will probably identify them, as stock, skimmed stock, after market etcetc. The valve cut outs will say a lot.

 

stock crowns are flat arent they? been a while since I had a head off one. supposed spec is low comp stage 3 head running piper t2 cam. as it stands I've only got the inlet manifold off cuz I gave it a lick of paint but after reading about the said engine builder I'm in two minds whether to strip it down snd check. was running ok with no noises. suppose a good place to start would be checking port work. I'll see how I'm fixed for time and might whip the head off. busy with sunroof cassette's and under side clean ups at the minute.

 

Stock crowns are flat with a cut out for the inlet and exhaust valves. When they are skimmed the exhaust cut out is very small/not there.

Forged piston crowns are machined so will have crisp/sharp edges around the cutouts, im not sure but they may also have a slight dish machined into them also.

Rob,

 

PS, you can probably see enough with a good light with the plugs out.

If its long enough ago that its out of guarantee etc and it was running fine i would just let it be.

Rob,

 

it's way out of guarantee mate, but only done 100 odd miles though so not even run in yet. long story! lol. was thinking maybe just leave it as it is till it's run in and I'm ready to up the boost and get the dekas in there then strip it and check things out? not sure it will mate much difference to the tune process knowing what state of tune the engine is in but kinda would like to put my mind at rest as to whether I got stung or not.

don't remember seeing valve cut outs on my old s2 pistons when I did the head gasket was like 9 years ago or something. lol.

how's your ms mapping getting on (bit off topic) been reading through a few of the threads on here in the hope I'll pick up some top tips. haha.

 

pulled the exhaust manifold off earlier as it's due a fettle too. does look to have had somehead work done so that's a plus.
will a straight forward cylinder comp check show up if there's low comp pistons in to save pulling the head off?