Has anyone here had to notch their Type S pistons? Seems like i am having a piston/valve clearance issue with a fully built cylinder head we had made recently. Engine was started up this past sunday and bent two exhaust valves. We ran the car and at about 7500 rpm's, we noticed a strange noise in the engine and immediately shut it down. Sounded like two pieces hitting each other.

We immediately took off the cylinder head and found one clearly visible bent exhaust valve. We assumed it may have been valve/valve contact but we found that the #3 piston was marked. The cylinder head was completely disassembled today at the machine shop and we had the two exhaust valves replaced on that same chamber from piston #3. All other internals of the head are fine.

I am going to have the engine clayed and work from there. The cylinder head we are using is supposed to have been milled about .015 at most. Seems like this may not be the case and thus may be causing this problem. Is it common for just one or two valves bending and not all of them? Before installing this particular cylinder head, we had a completely stock head with JUN internals and although it did not run many miles, it did rev to about 8K and had no problems.

Has this happened to anyone running Type S pistons?

Any feedback will be appreciated.

 

something is incredibly wrong.....

i have cam gears and also running STAGE 3 camshafts which almost to have no room for error, and running type-s pistons and i can still advance the intake cam to +3 and retard the exaust up to -5.

I clayed mine and was perfectly fine....

did you jump a tooth in your timing belt ?

because something is very wrong here...

 

Hey, whats up? Before removing the cylinder head, my tech verified the timing belt, camgears and timing and everything was perfect. This situation has got me really confused as such a thing should not happen. Especially with Type S pistons.

I am going to have the engine clayed this time

Any suggestions?

 

I clayed mine twice.... i could go even as wild as +5 and -5 with stage 3s. only 5 thousands mill off a new head, and stock 3 layer honda gasket. type-s pistons 0.25 oversized.

DO YOUR VALVE LASH BEFORE YOU CLAY because you could do damage there also...

only other issue is i'm running FERREA SS valves, not sure if that makes a difference (for valve height)

mesure the seat height, valve etc....

also the HEAD mill makes a big difference also....

 

I posted about this before but I can't find it now. Check out this article:

http://www.hondatuningmagazine...rhead/


Claying is not a bad idea, but be sure to check valve clearances with the pistons and other valves at various crank angles. This is more important with milled heads, decked blocks, big cams, etc. One way to do this is to lock the VTEC pins manually then just install the valves for one cylinder with the inner valve spring only. Then you can put the head on and rotate the crank to any position and push the valves down with your fingers to see how much further in they will go before hitting something. You can also put a micrometer on them at this point to get more precise figures. There are probably some published figures that seem to work for 4 valve heads. This can also give you an idea of how far you can go with cam gears before getting into trouble. I did this without the head gasket on and had plenty of clearance, so with the gasket in place for final assembly you have another ~.030" confort zone.

Also, might want to check the #3 rod and make sure its cap is not loose. That would let it hit the valves. Good luck and keep us posted...

 

Thanks Flyrod. Good information.

 

I was just searching, and questions on the Type S pistons turn up a lot. Maybe we could compile some of this and add it to the naturally aspriated FAQ thread?

 

ive heard of it happening with 1mm oversize valves before,but not on stock valves though....

 

The exhaust valves come into light contact with the edge of the stock notch on the type s pistons. I will have to notch the pistons for sure.

 

it's very odd that it does it to begin with..... factory pistons shoudln't cause a problem, u sure you don't have them backwards ? hahaha... (just a thought) because i can't see this happening.. unless your head would be milled crocked or something blotched...

defenetely a first.

 

I am very shocked as well. We checked again to make sure timing was fine and it was. The valves come into really light contact with the edges of the stock notch. I am going to have the pistons notched as shown on the picture included in this thread. To make sure i'll have all 4 stock notches modified to be on the safe side.

This is definitely a first and am really surprised. The individual who worked on the cylinder head said it was milled about .015. Maybe its milled a bit more and i know now for a fact that the H22 is very sensitive and clearance issues must be verified before installing aftermarket parts. This is the lesson i have learned with this experience. Hope this can help anyone else in the future.

Unbeliveable, but true.

Thanks for all the input guys.

 

wow. I remember someone asking me about this so I tried to search for this thread. It took 10 minutes, and I knew what I was looking for. I searched for type s, piston, pistons, notch, type*, etc. I finally found it by searching for notc*
Anyway, just wanted to bump it so a friend could find it...

 

Is there a cheap and easy way to see if the head is actually milled .015"? Who had the head milled? Where? I have a friend who is running Crower st. 2 cams/valvetrain with stock valves and .015" mill, unmodified type-s pistons, stock head gasket and has taken it up to 8000RPM without incident several times. If you know someone with a similar setup in your area you can have a compression test done and compare numbers, though I guess that your engine is apart now. Otherwise good luck.
the Pirate.

 

nothing happened to this one kid i know, everything with his job is fine

 

Maybe they put the piston in 180 degress backwards hehe...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by satan_srv &raquo;</TD></TR><TR><TD CLASS="quote">Maybe they put the piston in 180 degress backwards hehe...</TD></TR></TABLE>
i wondered that myself, but didnt wanne be the first to say it

trhe valve relief sizes are noticeably different between the intake and exhaust sides

 

yeah by like 4mm