Ok so I torqued the head back on without rocker gear and spark plugs, when I turn the engine backwards it didnt hit, but as i moved it forward i would feel a kind of hit as it reached TDC, i turned it a bit harder and was able to over come this spot.

 

I'm pretty sure the gasket bores are too small, would the engine wear this down after a run in? or do i have to go with a custom headgasket?

That won't work, if what you think is actually happening!

 

The piston will mark the metal ring of the head gasket and that is the crucial part of it. It would burn through quite quickly.

 

If you just placed the head gasket on the block the combustion ring should be not inside the bore at all. It can be around the very edge, or outside, but not a smaller diameter at all.

 

I think try that first and decide what size head gasket you need. If that one does actually fit OK then we need to find out what is jamming at TDC.

Nothing else could be possibly jamming as when the head isnt bolted down it turns fine, only when it is torqued do i feel that resistance.

 

I guess toyota 5K gasket is the next step

so when u put the headgasket on, was the hole bigger or smaller than the bore?

 

its not just because your turning the valve train over etc once the heads hard done is it?

 

how much effort is it taking?

I havent bolted the valve train back on, I have just bolted the head on without valve train and spark plugs, I am pretty sure the gasket is smaller than the bore.

 

So do I go custom gasket for the 4AGE pistons or stick with a genuine toyota 5K one?

As long as cylinder bore is less than 82mm a regular 5k one should be ok

What HG are you using at the moment? a 4k one?

I just checked my notes from my engine build my ACL (or whoever it is) 5K head gasket ID was 83mm. I had a 40 thou overbore giving me a minimum .5mm clearance diametrically.

 

They were also slightly oval, elongated longditudinally. When I measured I'm pretty certain that 83mm is the NARROWEST part of the gasket bore.

 

You can not run the gasket like this, the steel rings are designed to crush and withstand combustion pressure. If it's inside the bore it won't hold comp and you'll have the head off in a weeks time.

 

One more question: are you 100% that you have got your valve-piston clearance correct and the cam is in the right spot. Looking you your pics you have a 5K head, very little deck clearance and very shallow pistons.

 

It is surprising how easy it is to bend a valve turning a motor over by hand, and that "little hit" you speak of is a little concerning.

I am using a 5K one now, atm the pushrods and rocker gear arent bolted on and i still feel that hit. So i don't see how i can bend a valve?

 

How do I know if my valve-piston clearance is correct and the cam is in the right spot?

 

I havent touched the cam since I bought it off the guy who bought it off KE25 Racer, I havent even taken off the timing cover

 

Ok i did some quick measurements, the bore is 82mm and the bore on the gasket is roughly 80, in areas a bit less

Edited November 11, 200916 yr by anastasios

What head you using? 5k now?

 

Does it have the protrusions under no1 and no4 spark plug holes? If so it should be used with 16cc dished pistions. I suggest you CC the head and check the compression ratio.

 

Valve-piston clearance can be measured with some plasticine on the piston crown... oil the valves, dummy up the head and turn over the motor. You take the head off, slice the plasticine at the thinnest point and measure the valve/piston clearance.

Edited November 11, 200916 yr by Felix

I am using what I believe to be a flat top piston head, it doesnt have the protrusions, and the engine reconditioners i took it to, shaved it to suit a 10.7:1 comp ratio using the 4age pistons.

 

I will have to go with a custom head gasket won't I?

Got the part number of that gasket you used?

Nope but the brand is Bovic Automotive, why do you ask?

Edited November 11, 200916 yr by anastasios

Just wanted to know so I could work out whether or not it was a 3/4k headgasket or a 5k one.

So what do you guys suggest for me to do?

 

Go with the Genuine gasket?

 

Or go with a custom one to suit a 82mm bore