Author Topic: My block 0.0015" over last oversize - still usable? (Read 3855 times)

rallydiesel · « **on:** September 09, 2007, 11:54:30 am »

Just found out that my cylinder block (1.6TD) is about 0.0015" over the third and final overbore. I measured it with a digital caliper before I decided to rebuild and I thought I could go to the third oversize but I guess the caliper method wasn't that accurate.

I am thinking I will go ahead and use this block anyways, with just a cylinder honing and put in the new pistons and run synthetic. 0.0015" over doesn't seem that huge but what do you guys think?

:cry:

rallydiesel · « **Reply #1 on:** September 09, 2007, 01:53:29 pm »

The pistons are brand new kolbenschmidts (sp?) 1.00mm over from MykeW.

Doug · « **Reply #2 on:** September 09, 2007, 03:34:19 pm »

Best measuring results come from an inside guage and a micrometer. Your average set of calipers are only a rough guide. I installed new rings on old pistons with about .005 inch bore clearance with good results. Use a ball style hone from Brush Research. Do not use synthetic oil for at least 10,000 km as the rings have to conform to the bore wear or lack of concentricity. Synthetic oil will prevent the kind of micro wear that is necessary for a good break in. Once you are satisfied with the oil consumption and performance, then switch to synthetic.

Vincent Waldon · « **Reply #3 on:** September 09, 2007, 03:58:48 pm »

Quote from: "Doug"

Use a ball style hone from Brush Research

Doug: do you know of a Canadian supplier for such a hone ?? Everyone here only stocks the stone kind.

thanks,

Vince

bigblockchev · « **Reply #4 on:** September 09, 2007, 04:53:14 pm »

Measuring your piston to bore clearance with a long feeler guage that is the most accurate way. If you can't lay your hands on one take the block to a really good machine shop like a racing machine shop and get them to do that for you. If you don't handle calipers and mics everyday it can be difficult to get the feel for precision usage. A lot depends on the results of this measurement so it is a good idea to have it done properly. Another way to get a fairly accurate measurement is to check the end gap on the rings that you are using. This is 3 times as accurate as measuring the diameter since you are measuring the circumference , if your ring end gap is OK you are probably good to go. If the gap is way too big then you may be in for a new block Cheers Dan

Doug · « **Reply #5 on:** September 09, 2007, 05:59:41 pm »

Vince,

I have the address in the shop for C&C Valves in Hanover, Southern Ontario. I will look it up and send it to you.

Doug

Doug · « **Reply #6 on:** September 09, 2007, 06:02:20 pm »

Have used the feeler guage method as you describe and yes it is accurate and low tech too.

Doug · « **Reply #7 on:** September 10, 2007, 04:04:34 am »

Okay, Vince, here you go.

C&C Valves Inc.
RR 1, 261248 Con 17
Hanover, Ontario
N4N 3B8

519-364-6051

Vincent Waldon · « **Reply #8 on:** September 10, 2007, 08:05:42 am »

Quote from: "Doug"

Okay, Vince, here you go.

C&C Valves Inc.
RR 1, 261248 Con 17
Hanover, Ontario
N4N 3B8

519-364-6051

Thanks very much Doug... another thing to add to the "shop must-have" list !!

rallydiesel · « **Reply #9 on:** September 10, 2007, 01:38:08 pm »

The 0.0015" figure came from the machine shop. I had measured it at home with a caliper, but I guess it wasn't accurate enough.

jimfoo · « **Reply #10 on:** September 11, 2007, 10:04:05 am »

Get Total Seal rings....

bigblockchev · « **Reply #11 on:** September 12, 2007, 07:51:48 pm »

How did the bores get too big, did the machine shop bore the block without having the pistons there to check, did someone go nuts with the cylinder hone? History please if you got it. Cheers Dan

rallydiesel · « **Reply #12 on:** September 12, 2007, 10:19:48 pm »

I don't know the history. The car has over 360 000 kms. The pistons in it were 3rd oversize. I imagine it is just because of wear?

bigblockchev · « **Reply #13 on:** September 12, 2007, 11:08:58 pm »

How do the bores look is there a significant ridge at the top or is it smooth. If it was running before with reasonable compression, not burning too much oil then I would be tempted to as jimfoo suggested throw in some total seal rings and give it a try. It won't last forever but you might get another 100K which is quite a bit for most of us. Boring out and sleeving is kind of pricey as are new pistons. I am not aware of any larger pistons than the ones that you have , someone may make them. Cheers Dan

fatmobile · « **Reply #14 on:** September 13, 2007, 12:57:16 am »

There are 1.7 pistons you can get, they are about 80mm but it takes awhile to get them from europe,... and no one I know has tried them yet.
I'm working on getting my set installed.... in a block that was bored 3rd over. The pistons were $420 when I got them but the dollar has fallen a bit since then. Still cheap when you concider the price and hastle of finding a new block with one more bore left in it.... and buying stock pistons,... kinda like buying a block for $120 and getting a rare 1.7TD when you are done with it.