288 cam/ head gasket questions

Post Tue Dec 01, 2015 6:21 pm

Hey guys, just wondered if anyone has any experience running an m20 with a shrick 288 cam? I have bought an engine with one fitted, running a standard head gasket it seems that the valves have been clipping the pistons as they are slightly bent. The engine is apparently a 2.7 but I have no proof of this, the head is an 885. I don't want to lower the compression by fitting a thicker headgasket
Thanks for your thoughts, matt

Post Tue Dec 01, 2015 7:21 pm

The last thing you want to do to an engine with a long duration cam is to reduce the compression ratio.
You need to reassemble the engine with a used head gasket and plasticine on top of the pistons. Turn the engine over by hand, take the head off again, and measure the thickness of the plasticine in critical areas, such as under the valves and the squish area. This will determine if you need to deck the block or have the pistons pocketed for the valves.
Check the timing is correct as well, as the piston at TDC can hit a valve if it's still out too far at that point.

Post Tue Dec 01, 2015 8:04 pm

OK thanks, to do this does the head need to be torqued down or would just nipping the head bolts down be enough to give the same result?

Post Tue Dec 01, 2015 8:16 pm

Dont think it needs to be correctly torqued, just make sure its pretty tight.

Post Tue Dec 01, 2015 8:40 pm

OK thanks, should the timing be OK just using the factory marks?

Post Tue Dec 01, 2015 10:05 pm

Cam timing should be whatever Shrick specify. There's a bit more to the engine building lark than just bolting a few bits together, especially if using non standard parts.

Post Tue Dec 01, 2015 11:15 pm

In all honesty I would look for a cam with a bit less duration. You haven’t mention specs but id guess its way more cam than you need

Normally with stock pistons setup in the correct position with respect to block and OEM gasket you'd need to deepen the pockets to run a 288 as there is too much lift around TDC and either side, this means when the inlet valve lifts it chases the piston down the bore and beats it often occurs between TDC and 10* ATDC, and on exhaust side the piston beats the exhaust valve ”ahome”a in the 10* BTDC to TDC region. I would invest in some clay and a dial indicator and stand. you can live without a degree wheel, though it is the correct way to do it.

you want the piston to head clearance to be 1.0mm and OEM 1.75mm gasket to get best compression and deepen piston valve pockets as needed theres enough meat there.

Post Wed Dec 02, 2015 5:59 pm

OK, apparently it's had head work done and it's meant to be a 2.7 bottom end and had some porting. I was looking to sort the intake and maybe get a better exhaust manifold. It's not going to be a daily driver so driveability isn't that important. The engine was from an autocross car and apparently was running on carbs but I wasn't planning on going down that route.

Post Wed Dec 02, 2015 8:39 pm

matt325drift wrote:OK, apparently it's had head work done and it's meant to be a 2.7 bottom end and had some porting. I was looking to sort the intake and maybe get a better exhaust manifold. It's not going to be a daily driver so driveability isn't that important. The engine was from an autocross car and apparently was running on carbs but I wasn't planning on going down that route.

IMO if you're running good compression, ditch the OEM cast intake, use a decent 6 branch BTB, RD etc and get a proper tune then you'll get the best from the cam

Post Sat Dec 05, 2015 8:34 am

When u say ditch the intake you mean use what sorry? And exhaust manifold wise it looks like a btb is the only thing available, is that correct? Really appreciate the advice so far thanks.

Post Sat Dec 05, 2015 9:05 am

intake wise youd want a RHD ITB kit. there are other manifolds for the exhaust around but ive not looked into quality recently

Post Sat Dec 05, 2015 12:35 pm

I don't have much knowledge of ITBs, who sells them as a kit? I am going to need help with setting up/ mapping etc when I manage to get it together, I'm trying to work out the best setup engine wise as it's going in my 325 that's having bodywork done. Unfortunately the guy doing it has to look for a new workshop so the car won't be ready for the engine as soon as I had hoped. Hence why I have time to weigh up engine options. Any recommendations for someone who could set it all up, I'm in the Midlands?