Ke70 5K Build

[tojo2]

There is nothing wrong with the pistons slightly protuding from the deck of the block. So long as at high revs any rod stretch isn't allowing piston to head contact.

 

Personally I'm thinking the old headgasket was a 3/4k item and the piston was contacting the firing ring of the HG.

 

 

Not saying there is nessesarily anything wrong with pistons protruding but it will affect compression ratio.

 

I`d use a straight edge across the piston as mentioned and then a feeler gauge between edge and block just to see by how much and do a bit of calculating.

[anastasios]

Yes they do protrude, I don't think the trick without the headgasket would work.

 

What to do now?

 

Wait for the gasket?

 

Or does the protrusion problem need to be fixed?

[Felix]

How far do they protrude? As previously stated, measure with a steel ruler and feeler guage.

 

I think your main problem was the firing rings of the old head gasket overlapping the bores and the pistons hitting them.

[philbey]

I second that motion about the wrong HG.

 

My point about the piston deck clearance is that I suspect you are going to have some seriously high compression. Your head appears to be a 5K 18cc head, your pistons look to have less than 9cc (ACL 5K Dish volume) and you have a negative value for your piston-deck clearance.

 

With your negative piston-deck clearance (ie piston above the deck), I would recommend that you try get hold of a dial indicator with a magnetic base and measure the actual amount. Your head doesn't have a circular combustion chamber so you need to be 100% that your head gasket will give you enough space.

 

My engine builder suggested that normal gasket crush is .030-.040 thou which is 0.75-1mm between deck and head. Id you're running any more than about .5mm above the deck I'd be worried.

 

1. Check your compression figures

2. Check your clearances.

[anastasios]

Ok so I measured the protrusion of the pistons to be 0.30mm, what should I do now? wait for the head gasket tomorrow?

[tojo2]

0.3 mm protrution will give you about 1.55 cc smaler combustion chamber that your engine builder might not have known about. This could affect your ratio by 0.4 - 0.5.

 

Realy think you should measure cc of pistons and head and do some

proper calculations. Mine are just rough since I don't know your specs

 

don't think your piston will hit the head though.

 

What you`ll need : + a dash of fluids. I prefere lampoil as its kerosine without the smell :S

Edited November 12, 2009 by tojo2

[anastasios]

Ok but the thing is the piston doesnt seem to be protruding that 0.3mm the whole way round, only on the front right corner (from drivers perspective) for piston 1 and the rear right for piston 4

 

This is strange, would my block be decked wrongly?

[tojo2]

Shouldnt think so . Turn and check 2 and 3 as well . Check block ...Try with steel ruler and a flashlight behind it for straightness

[altezzaclub]

Felix he can't really have the pistons protruding as the head is flat, so he has only the compressed head gasket as clearance. It would be different if the piston was humped in the middle. The half a mm between the piston and head is pretty thin!

 

Anastasios when you get the new gasket just make sure the pistons come up through it cleanly, then slap the head on and turn it over. If that's OK then fit the valve gear and try it.

 

If it works with no valve gear then the piston/head clearance is there, no matter how small it is. If it doesn't then you have piston/gasket problems... probably solved by two head gaskets or a metal gasket spacer.

 

If it turns with valve gear then it will run but be very careful changing cam timing. If it doesn't turn then your piston/head are OK but you have valve timing problems, which you might solve with an adjustable cam gear.

 

Should be an interesting weekend!

[Felix]

Yea, I guess it comes down to the compressed head gasket thickness.

 

Having a look around it seems .030" is the recognised minimum safe piston to head distance. Some have run lower, but everything needs to be spot on.

[anastasios]

Ok, it looks like my doubts have been changed, I picked up the genuine gasket today, and there is such a big difference in quality, the bores are actually circular, and larger than the Bovic brand gasket, the metal pressed ring design is better and there are also metal pressed rings around the head bolt holes.

 

I am pretty sure that the piston will now fit the hole nicely. I will test it without a head first this time.

 

 

 

 

[anastasios]

Ok so I put the gasket on the block and everything seems sweet, the gasket bores line up very nicely with the block bores and is nothing like the other bodgy cheap gasket.

 

I am going to go ahead and torque up the head.

[Taz_Rx]

There's a reason why I reccomended a stock gasket several pages back. :)

 

I used to use $23 permaseal ones. Now after forking out the bit extra for a genuine I'll never go back. :no2:

[anastasios]

Haha yea i've realised the massive difference now, I've now bolted the valvetrain back on, as I turn the engine it is slightly difficult and I can feel the compression and hear an air hissing noise, if I wait for a while after this hissing, it is easier to turn, this is the compression isn't it? and not piston hitting valve?

 

Ok! Now onto my next thought, the thermostat!

 

As you can see here there is a plug with two branches that I am pretty sure go to the stock carby.

 

 

As I am using a Holley 180 downdraught carb I don't think I need these two vaccum(?) lines.

 

 

Is it ok to leave these unplugged or should I buy a new thermostat from an earlier model corolla that does not have this plug hole, I think the early model KE55 had this type of thermostat

Edited November 13, 2009 by anastasios

[Taz_Rx]

Yeah hissing is compression.

 

Pull the spark plugs back out and give it another turn to see if there's much resistance?