Hey. I was wondering if you guys could help me out with something. I had my 400 motor done this spring. He bored it .060 over and a bunch of other stuff. I put it together and had 135 compression.

The other day i checked b/c it wouldnt start and i was down to 110. I pulled the head and clyinder, they still look perfect. I called to order rings, because i had like 1/8 inch end gap. He wanted me to get the numbers from the piston, well, its a .040 piston.

I dont really know whats going on, he said it was bored .060, but the piston he sent is .040, i asked him and he said it must be bored to .040, b/c if it was .060 it wouldnt run. But if it was right, then i dont know how i got 1/8 inch end gap, the rings dont look like they have worn that much.


I am in ny right now, so i dont have any of it in front of me, but i am hoping to get it figured out before i get home.

Any thoughts?

Thanks guys.

 

Is there a lot of side clearance between the piston and cylinder. If he did bore it .060 and you have a .040 over piston, it should be pretty easy to tell!

 

This is the first motor I have done, so I have nothing to relate it too. There was a definate gap, like, it would move back and forth some. Not a lot, but again, i have nothing to relate it too.

I have run, and raced this thing for over 6 months, do you think it would have run enough to do so with this problem? I know with cars, the rings have a range they will work with, like, a .020 over set they say will work for .020 - .039, then you go to a .040 set. So if these rings are like that, then that may be whats happened, the rings, even though they are too small, took up most of the space, so it still worked... I dont know. Just looksing for some opinions.

Thanks guys.

 

No things rings aren't like that. The rings for a .040 over piston are for that piston only. If you have the head off put the biggest size feeler gauge that will fit fairly easy between the piston and sidewall and see how much clearance there is!

 

I talked with Troyer and have a package of parts on the UPS truck to him with both 40 and 60 plus rings . From the numbers on top of the piston that he can make out it sure sound like it is a 40 over piston .


A 40 over will say 675M08400 on the crown .

A 60 over will say 675M08450 on the crown .

Troyer says I told him I bored the cylinder to 60 over last go around . I really don't know what it is bored to .

I do know if the cylinder is bored to 60 and it has a 40 piston that quad would hammer like you would not believe . I have sent all the parts we could possibly need to him and when he gets them I will help him sort all this out and take back the rings not needed .

What would really help is a set of micrometers to measure things but thats not in everyones toolbox and I certainly understand that .

Troyer , don't sweat this my friend , what could go wrong ?? *grin*

Rick Ritter

 

Rick is the man, no worries he will take care of it!

 

If there was a .020 difference the rings could move from their pin place and catch a port, breaking them. And like Rick said, you wouldnt want to run it because of the bad noises it would be making. I am willing to bet the exhaust side of the rings are worn down a bit and that is where the end gap is coming from, you will be able to tell when you pull them off. If that's the case then your filtering system is not good enough or had a small leak somewhere. Hope all goes together well for you,Bubba

 

Something to note . When checking ring gap the rings do need to be in the bore squarely as if they were on the piston .

Also before we check gap , look at the numbers on the rings , they are right near the ends . Look for a number like *N100* or *N50* , this to will help us decipher what size we are .

Rick