Light Hone removes how much?

[Drewster]

I have a block currently 3.8310 bore but it needs a hone before putting in new Diamond 21402 piston and ring set. I measured the 21402 pistons to be 3.8273. A clearance of .0037 before hone job. What is the max piston to bore clearance? ( I do have another standard bore block but I would hate to have to run it out to 30 over on its first rebuild)

How much material does a light hone remove?

Drewster

 

[V6gofast]

I have a block currently 3.8310 bore but it needs a hone before putting in new Diamond 21402 piston and ring set. I measured the 21402 pistons to be 3.8273. A clearance of .0037 before hone job. What is the max piston to bore clearance? ( I do have another standard bore block but I would hate to have to run it out to 30 over on its first rebuild)

How much material does a light hone remove?

Drewster

There are a lot of variables,are the same people who honed it the first
time going to do it? Second are you going to be using the same fasterners,
head gaskets torque plate. How much time is on the engine since the last
hone . How close is your tune up, any amount of time running rich will wash
the cylinders down and could possibly wear out a cylinder quickly. The true
answer is you really won't know until you do the job. At that time a decision
will have to be made how far to go .

 

[Drewster]

i was planning on having a different machinist do the work. use a torque plate, new fasteners,60k since last rebuild. i will be running alchy.
Just from past experience, how much needs to be removed to get the glaze off and let new rings seat. .002? .005? .010? just a general idea so i can figure out which block to use.

Andrew

 

[gnxtc2]

Look on the piston spec card. There should a clearance spec on.

Billy T.
gnxtc2@aol.com

 

[ijames]

I've read that if you bore with the block at room temperature and without torque plates that you should leave 0.006-0.008" for the hone, and after putting on the torque plates and running hot water through the block (if you want the best ...) there will be low spots the hone won't even touch for the first 0.001-0.002" or maybe more. Bore hot with the torque plates and you usually have full contact on the first pass and may need to only leave 0.004" for the hone. Either way you go through about 3 different grits to wind up at the surface finish you want, which is part of why you need so much to hone away (the rest of why is that you want to fully remove all the little "tears" and machining marks from the boring tool and get down to fresh metal, which also requires 0.003-0.004"). In your case you won't know about roundness and taper until you run the hone down the first time and see what the contact patch looks like, then you will have to hone until full contact, and then another 0.002-0.003" at least to get a good finish, which is why Dan said you won't really know how much you have to hone out until you actually do the job. That all assumes a precision honing machine. If you are already at 0.0037" clearance before the hone I doubt you could get a good hone and wind up with less than 0.009" clearance which is pretty loose even for a forged piston unless it's an all-out race motor. Blocks that need boring and will clean up at 0.030" should be available for under $250 so if you really want to save that std block for a potential future overbore of less than 0.030", just buy another block to use for this motor. That way you won't have to worry about poor ring seal and blowby on your new motor .

 

[Drewster]

Thanks for all the good info. I'll look into the availablity of a .020 over block.
A