I was wondering what you guys have been getting back from your machine shops. As in, what variances have you measured from cylinder 1 across to cylinder 4? Does your machine shop reference from the main bores when decking your block? Reason being, I just got mine back and checking piston to deck and I have an unacceptable .007" variance from cylinder 1 to 4.

 

whats the setup, piston,rod, and crank

 

Je pistons custom pin height 89mm, eagle rods h22 length, stock honda f22 crank, 95mm.

 

To all of the engine builders, when you are measuring your piston to deck height, are you just doing one cylinder, or are you doing all of them. Or at least from cylinder 1 and 4 to check variances? I'm wondering because I am getting variances between all four cylinders.

 

are u meaning how far the piston sticks out of the hole?

 

Measuring like this?

 

Are you sure its not the pistons or rods?

 

 

Yes, what have you come up with when measuring piston to deck? I'm not "out of the hole" but I am curious how much variance people have seen when checking all four cylinders like we should be.

 

sorry i cant help with that i dont have a crazy gauge to measure it mine is flush with the deck

 

that isnt a "crazy gauge" its the proper tool for the job.

how are you measuring?

 

^^those pistons look a bit out of the hole in pics, maybe .005 or so....


to the op, who did the machine work on the block?

you may want to measure those eagle rods because theres a good chance some could be longer than others

also if the bores are slightly different that will also give you different measurements since your rocking the piston when you measure.

 

Yeah, I 've measured this block when I got it back from the machine shop. Just got back from talking to them and I'm gonna have them do it again. I wrote down measurements that I took and I will have to specify how much from one end to the next, so It's going to have to get redone. I was curious what you guys are getting for measurements.

 

does it gradually increase as you go form cylinder 1 to 4. if so sounds like the machine shop didint have the block square in the machine...

 

ok so crazy gauge = i dont build engines every day or once a month no need to buy every tool if its an issue it will be taken care of the guy that did my machine work is allso degreeing the cams in. and i was just kidding when i called it crazy i forgot how serious honda-tech damn

 

Yeah, cylinder #4 has an avg, of .00225" in and #1 has .00575" so it's gonna have to get squared up. I don't know if they referenced the main bores when they decked it or not. Looking at my measurements, it doesn't seem so. Just something to remember if you guys are just checking one cylinder when you check piston to deck. Being .0035" off from one side to the next drops my compression .15 points of compression so.... I just didn't know if you guys get blocks decked and have similar results. Thanks for the input.

 

The important thing that needs to happen is the short block gets taken apart and everything measured. You can't determine what needs to happen next if you don't know what is causing it. Its easy to say the block was machined wrong, and in all likelyhood it was, but there are a bunch of other things that could cause it too. Rods that were slightly different lengths, uneven compression height, etc. could all add up to cause this problem. If the deck is, in fact, not parallel to the crankshaft main bearing centerline then it will need to be corrected. Another thing to consider is if this shop bored the cylinders and used a 'boring bar' which locates off the deck (this is a pretty common machine) rather than the main bearing centerline. If they did bore it off that deck surface, then the cylinder centerlines are not exactly 90 degrees to the crankshaft and you will have problems.

 

^ Exactly. There can be small tolerances in rod c2c length, piston pin heights, etc; differing combinations of different pistons on different rods on different journals can change those numbers around. If, however, there is a steady increase in the gap, that certainly lends itself to the block not being decked straight. However, you could possibly counteract that with appropriate parts matching (put the longest rod and tallest compression height piston in the hole with the biggest gap, etc). This would take a fair bit of time to measure each part out (by testing combinations), and that's assuming there is a moderate variance between them.

 

Its quite possible that there was some debris under one end of the block when it was being machined causing the mill to be un square.

 

The averaged out measurements.

cyl1 cyl2 cyl3 cyl4

.00575 .00575 .00375 .00225

I also switched out piston and rod combo 1 and 4 for variance, and still came up with the same results. It appears the block will have to be decked to remedy this situation. Another thing that is possible other than rod lengths, piston pin heights, journal diameters, oil clearances, bore sizes, temperature when measuring etc, etc, is possibly bent crank. There are infinite variables that could contribute to this scenario, human error during machine setup, measuring, assy,etc. What have you guys come up with when measuring piston to deck when you assemble? And how much variance between cylinders do you accept, before you decide to continue with assembly? Thank you for your input!