Briggs 243400 Measurement Help

[LanceR 1]

Any one have access to a shop manual on a Briggs 243400??? We are punching it to +.020 and need the following measurements. Cylinder Wall to Piston clearance?? Piston Ring gap? Any help would be greatly appreciated. Thanks, LanceR

[fast_orange 0]

I checked the manual it doesnt give that information it says to bore/hone the cylinder exactly to the oversize you are going to. the standard is max inches 3.0625 min 3.0615 Jared

[gregc 3]

Ring gap rejection size for comp. ring is .030 and oil ring is .035

[fast_orange 0]

quote:

---

Originally posted by gregc
Ring gap rejection size for comp. ring is .030 and oil ring is .035 I saw that table of ring gap reject size. Does that mean a new set of rings is pre gapped to factory specs? Jared

---

[LanceR 1]

Well, that's kind of the problem. This is part of my sons' school project and the instructor recommended only honing the cylinder. They have honed it to the point that a +.020 piston just fits with only about .002 clearence. When the rings that came with the piston are placed in the cylinder (off of the piston), they cannot be placed in normal position due to NO ring gap. Instructor recommended filing, but I would like them to know what the specs should be. Definately do not want to over-hone the cylinder, but want the piston to have enough room to expand. Thanks to all comments/suggestions so far.... Any other suggestions??? LanceR

[UCD 14]

Instructor should go back to school and learn what he is doing before trying to teach others. IMO cylinder should be checked for round and true bored true to .020 over spec's then piston will have room to expand and rings will have end clearance with out filing. it will then be done the correct way and not mickey moused

[PatRarick 1]

quote:

---

Originally posted by UCD
Instructor should go back to school and learn what he is doing before trying to teach others. IMO cylinder should be checked for round and true bored true to .020 over spec's then piston will have room to expand and rings will have end clearance with out filing. it will then be done the correct way and not mickey moused

---

Exactly. Had an instructor like that in school for my sons. Ridiculous to try to hone a cylinder to specs when spending the money for the new parts.

[HubbardRA 19]

I had a friend who rebuilt his own engine. It ran pretty good but seemed sluggish. He took it back apart, and could see where the piston had been trying to wedge in the cylinder. Scuff marks all the way around. He originally only had .002 clearance. On that one I think the minimum clearance was supposed to be .008. Better to be just a little loose, than too tight. Too loose and you use oil, too tight and you break a rod.

[BrianP 1]

This was one of the major hurdles I encountered in rebuilding my Briggs which I detailed in my "Adventures in Engine Rebuilding" topic at the url below: http://www.simpletractors.com/club2/topic.asp?TOPIC_ID=77269 Lots of books said what size to reject, but only one book gave the end gap for new rings mated to a renewed (in my case bored and sleeved) block. The stated end gap for new rings is 0.010 - 0.018. I still don't know why this was such a big secret. I ruined my first set of rings by filing the gap too big. Second set I installed factory fresh. I checked the gap anyway, and it came out to 0.012 for the compression ring. I buttoned it up, threw it back on the tractor and have mowed with it several times with no problems.

[fast_orange 0]

Why is it the Briggs repair manual says its ok to hone your cylinder to resize it if you start at the bottom and slowly work your way up? What do shops charge to bore blocks? Jared

[PatRarick 1]

quote:

---

Originally posted by fast_orange
Why is it the Briggs repair manual says its ok to hone your cylinder to resize it if you start at the bottom and slowly work your way up? What do shops charge to bore blocks? Jared

---

Because the "hone" they are telling you to use is not actually what most of us consider to be a hone. It's more of a boring bar to hone the cylinder correctly. Boring at a shop is anywhere from $40 to $70. Most in my area are at $45 per cylinder.

[fast_orange 0]

quote:

---

Originally posted by PatRarick

quote:

---

Originally posted by fast_orange
Why is it the Briggs repair manual says its ok to hone your cylinder to resize it if you start at the bottom and slowly work your way up? What do shops charge to bore blocks? Jared

---

Because the "hone" they are telling you to use is not actually what most of us consider to be a hone. It's more of a boring bar to hone the cylinder correctly. Boring at a shop is anywhere from $40 to $70. Most in my area are at $45 per cylinder.

---

Pat I don't buy your answer the hone in the briggs manual is not like a boring bar the head swivels and it has stones. A boring machines boring bar is solid and has steel cutters. Jared

[fast_orange 0]

I take that back it is a different type of hone. could good results be obtained with this hone set?

[fast_orange 0]

At 347.05, for the aluminum hone set and 523.00 for the cast iron set I think I will take it to the machine shop. You could almost pick up a used small engine boring machine for that price. Jared

[PatRarick 1]

quote:

---

Originally posted by fast_orange

quote:

---

Originally posted by PatRarick

quote:

---

Originally posted by fast_orange
Why is it the Briggs repair manual says its ok to hone your cylinder to resize it if you start at the bottom and slowly work your way up? What do shops charge to bore blocks? Jared

---

Because the "hone" they are telling you to use is not actually what most of us consider to be a hone. It's more of a boring bar to hone the cylinder correctly. Boring at a shop is anywhere from $40 to $70. Most in my area are at $45 per cylinder.

---

Pat I don't buy your answer the hone in the briggs manual is not like a boring bar the head swivels and it has stones. A boring machines boring bar is solid and has steel cutters. Jared

---

Take it as you want. You are correct in that it is not a boring bar. I never said it was. Read what I said. "...the "hone" they are telling you to use is not actually what most of us consider to be a hone. It's more of a boring bar to hone the cylinder correctly." When speaking of a hone, most of us picture the three stone job with spring loaded stones and flexible drive shaft. A $20 to $30 item for a good one. That's a COMPLETELY different animal than what Briggs recommends. It's nowhere near as true or accurate as the hone Briggs is speaking of. The hone they are talking about has different grits of stone for cutting, for finishing, and different stones for aluminum or cast iron cylinders. The hone Briggs recommends will cost you upwards of $300. There's a reason for that difference in price.

[HubbardRA 19]

I agree with Pat. The hone that B/S is referring to is designed for use by small engine shops, to do this type of job. That way, every shop does not have to buy a very expensive boring machine in order to rebuild engines. Almost anything you need done to an engine can be taken care of in a good machine shop, but most small engine shops cannot affort those machines and don't have room for them. This is why some of these specialty tools have been developed. It is not your standard hone/glaze-breaker, like I have hanging on the wall in my shop.

[UCD 14]

This is the type of boring hone that Pat is talking about. It has 2 or more stones that do the cutting and 2 or more wipers that are set with Mic's to the depth that you want to cut and are designed to cut cylindrical and parallel. The best and most accuret tool is still a bridgeport and boring bar or boring machine. [img]http://buy1.snapon.com/catalog/objects_lg/21200/21111.JPG[/img]
This is a cylinder hone. Its purpose is to cut the glaze and establish a cross hatch pattern to seat the rings after boring. It is only spring loaded and follows the contours of the cylinder if bore is egg shaped or out of parallel this hone will only magnify it. It is not intended to to be used to resize a bore. [img]http://buy1.snapon.com/catalog/objects_lg/33500/33403.JPG[/img]

[fast_orange 0]

Pat I corrected myself in the post I made after saying I did'nt buy that. Maynard you can use a milling machine to bore the cylinders? Jared

[UCD 14]

Yes you can use a Bridgeport vertical mill. Set up right you could use a lath or even some types of drill presses