Valve to piston clearence on a 2jz ge

[dazla100]

I've been building my 2jz-ge engine and I have installed 2jz gte forged cp pistons and manley roads and keeping the ge head I've installed a hks 1.2mm head gasket and after installing the cam shafts at tdc I've noticed that when you turn the intake and exhaust cam shaft they stop at a certain point obviously the valves hitting the piston on cylinder 6.

 

Is this normal I always thought the 2jz engines where non interference engines. I've taken a picture to show you at which location the 2 camshafts are at before piston to valve meet the white markers on the cam gears represent the tdc marker.

 

Any help would be greatly appreciated before I carry on my build I'm just paranoid that will cause issues upon start up

 

Many thanks

 

 

[Scooter]

The standard Pistons have quite deep pockets machined/cast into them to give the valve clearance, what did the forged Pistons topsides look like flat or with similar pockets?

[dazla100]

This is a picture of the pistons I have ensured that the deeper valve pocket on the piston is on the intake side due to the ge having big intake valves and small exhaust valves.

Thank you

 

 

[pedrosixfour]

Are both sets of GE valves a bigger diameter than their GTE equivalents?

 

Is it possible that the recesses in the GTE pistons aren't machined wide enough to accept the GE valves?

[dazla100]

The intake valves are alot bigger than the exhaust valves they seem to sit in the recess fine and don't make any contact outside of that recess

 

 

[Chris Wilson]

Measure the clearnces physically with soft valve springs, you can swap two out with the head on if you know what you are doing, a good way either side of stock timing at TDC for intake and exhaust strokes, and for both valves. DO NOT guess this...Mixing and matching bits means MEASURE and MEASURE again.

[Tricky-Ricky]

Yes mixing different parts calls for a thorough approach, used to do this with bike engines, and found that a small lump of Plasticine or similar was good for assessing valve to piston clearances, but don't forget to factor in expansion rates for when the engine is up to running/WOT temps.

[dazla100]

Am I right in saying the clearence between the valve and the piston is .100" for exhaust and .80 for intake?

 

 

[Chris Wilson]

There's no hard limit, depends on RPM used, rod stretch, piston rock, valve bounce potential, carbon build up, blah blah. If you use Plasticine you'll have to take the head off again. Using a soft spring instead of the normal valve springs on a pair of valves will let you physically measure how much further a valve will open before touching a piston, by using a dial gauge and pressing the bucket down with your finger or a dowel.

[dazla100]

Thank you chris do you mind to explain on how you take the valve springs out when the head is on so i can replace it with a soft spring and measure it

 

Thank you mate

 

 

[Chris Wilson]

Compressed air down the plug `ole with both valves closed. If you lose air pressure it's good night Vienna. Thin rope pushed down the plug `ole and then the piston brought up near TDC to compact it and hold the valves shut while you compress the spring and remove it. Snap On make a special tool for compressing the spring and catching the collets which is very clever. It reverses to refit the collets. One of my most treasured tools!