426 JE Piston Problems

[fuzzyb]

It's time for a rebuild, I am going from a JE 416 (10:1 I think) to a JE 426 11:1. The valves were barely kissing the piston before but OK - Hot Cams stage II. The head has been milled from a valve job earlier.
My problem is: the shop I am having do the work wants to put on two base gaskets on the jug to "raise it" up for proper valve to piston clearance.

Shouldn't they cut valve reliefs in the piston?

Is this normal or is my shop hokey?

[SHADETREE101]

the stock head clearence is huge, there should be no reason to relief cut anything. i am running the 426 13:5:1 piston with no base gasket and xr head gasket to make it a tighter fit. i know 911kid has decked the head alot to raise compression to 15:1. i would ask another shop to check the clearences. they are probably just scared since you smacked the valves already. your 10:1 should have never done that. something else to consider. what tolerance did they already deck off. did they take to much off to begin with. do they know your engine or are they just guessing.

[johnsls]

You made some good points shadtree.

I just sent my cylinder to C&D Racing had them remove the cracked cylinder, install a new one from LA Sleeve and then after he put in the new cylinder I beleive they smoothed down the cylinder & sleeve to the same height.
If I got this right thats what a lot of other shops suggested to me.
Too many people in my area wanted too much money to resleeve etc...
I went from a 440 down to a 426 JE. Now if I can only get someone with some experience to help with the install I'd be running...:(

[SHADETREE101]

buy the honda service manual. they are worth every penny. the install of your cylinder is a snap. put your engine together once or twice and you will have it down pat.

[xc416ex]

If you were to have two base gaskets installed your valve timing would be retarded due to the distance between the center of the cam to the crank. Once you raise the cyclinder the cam is then raised lenthening the untensioned side of the cam chain and advancing your valve timing. One guy down at the shop pulled the three layer head gasket apart to run one layer. He got more compression out of the deal but it was horribly under powered. The top end job is pretty easy just get the right manual. The honda manual is the most expensive but the Clymer manual has alot of missprints, some of which have even got me in trouble.

[MIKE400EX]

Unless you are sure it's due to actual clearance, check the valve springs to make sure they have enough pressure (open & seat). Are you using a higher rev limit box with stock springs?

[fuzzyb]

Originally posted by MIKE400EX
Unless you are sure it's due to actual clearance, check the valve springs to make sure they have enough pressure (open & seat). Are you using a higher rev limit box with stock springs?

When I got my head redone last year, I think the builder said it had after market springs. When my original cam went out I replaced it with the Hot Cams. I couldn't find the replacement for the cam that was in my ATV when I bought it used.
It does have the WB high rev box in it.

I would have to check on the decking done to the head, I did it once & I am pretty sure it was done by the previous owner.

.

I talked with the shop, he was wondering what clearances you guys are seeing.
Did anyone ever happen to measure this?
He couldn't tell if the springs were factory or aftermarket by looking at them.

[cory]

The only way you can tell if you have enough clearance is to bolt it up and check it. Since you don't know what you have, there really is no easy way to measure. Roll the motor over slowly with a breaker bar. If everything passes, get you some acid core solder (I use the thin stuff) and bend it in an L shape. Stick it in the sparkplug hole in the area of the valve in question. The piston will squash the solder to reveal the valve piston clearance. Remember to take into consideration rod stretch, heat expansion, etc.
Messing with base gaskets and removing material on the head messes with valve timing that has to be corrected with a slotted cam gear. I wouldn't mess with it. Also remember to check your compression. I think anything under 180psi is good for 93 octane pump, but it's been a while since I messed with those figures.
A good shop wouldn't have a problem cutting valve reliefs. Its' just a trip to the mill. Make sure your piston deck is thick enough to cut, however.

Hope this helps.

[fuzzyb]

Ok, it is becoming clearer now. I have a stroker motor. My piston deck height is 1mm shorter & the skirt is a lot shorter.
With just one base gasket my piston to valve clearance would have been 8 thousands, not the 35-40 that JE recommends. The skirt was hitting the rod too.