1.9 Mi Dfw Compression Issue

[pp205 17]

Hi Guys,

 

I'm having a problem with this engine - the background info is that is is a DFW Mi engine that had the block skimmed by 1.4mm to give approx 10.8:1 compression, it is also running a Peter T stage 1 inlet cam.

 

So i've suspected that the head gasket is on it's way out and checked the compression on Saturday. Starting at the left on the cam pully side the readings I got were 260 - 250 - 220 - 270. This seems to be very high so a thicker head gasket is needed (also number 3 seems to be lower so will require some investigation) but I must admit I'm not really sure what thickness of gasket I should be going for, if anyone has had similar issues I'm hoping they can guide me in the right direction?

 

Simon

 

By the way, I've just moved house and have no wifi or even 3G in the area so can only check this at work when I can get away with it!

[petert 554]

What pulley(s) are you running? The inlet cam may be too far advanced. Once you sort the difference, just retard the inlet a few degrees. I wouldn't fit a thicker head gasket. You'll kill it.

[Anthony 1,000]

Unless you have good reason to believe the accuracy of the compression tester, I would personally not read too much into the absolute values and instead concentrate on the differences between each reading.

[pp205 17]

I'm running BBM verniers Peter. So after sorting cylinder 3 just run a srd gasket a retard a couple of degrees?

[welshpug 1,626]

ot so much retard but set it to spec

[petert 554]

If you have verniers you should be able to get it spot on. Inlet should be 0.065" @ TDC and exhaust anywhere between 0.035" and 0.070" @ TDC depending on whether you want power or torque.

 

If you don't have a dial indicator, retard the inlet 1º (2º crank) and see what happens. I'd be happy with 220-230psi, assuming your gauge is accurate. Is it pinging?

[pp205 17]

Hi guys, thanks for the replies.

 

So I took off the head yesterday as I was sure the gasket had gone and was hoping that the lower compression on number 3 would be due to the gasket going on number 3.

 

Sure enough as you can see in the photo that the gasket has gone and it was on number 3 where the gasket has gone to an oval shape! It went on the front of the block.

 

From what Peter has already said I shouldn't be getting a thicker one but my question is - will it be worth getting a steel gasket as opposed to a std one? This is to cope with the rather high compression.

 

Any info, as ever, is greatly appreciated!

 

Simon

[welshpug 1,626]

I don't recall seeing a standard steel gasket used on an alloy XU, they're only standard on the RS iron block engine, and the EW alloy blocks, though their liners are cast in.

 

your compression isn't particularly high, only 0.4-1 more than the standard D6C, I would check the liner protrusion and get the head checked over

[pp205 17]

The head is being checked in the week, the liners were professionally skimmed at the same time as the block so there shouldn't be any issues there but I will get them checked.

 

So the standard gasket should be fine?

 

Cheers

[petert 554]

I've run that head gasket at 11.5:1. So should be fine.