Welcome to the DoItYourself Forums!

To post questions, help other DIYers and reduce advertising (like the one on your left), join our DIY community. It's free!

briggs cylinder and piston(honing)


l.mitchell's Avatar
Member

Join Date: Jul 2003
Posts: 68

08-02-05, 10:28 PM   #1  
briggs cylinder and piston(honing)

i found another 8hp briggs with a 3by1 crank but someone had put an .010 oversize piston in it. it wasnt honed right and was too tight. the piston has big grooves in it and the cylinder does also. the engine i blew also 190702 has small scrape marks on cylinder wall and piston but i was told it was not worth repairing. rings are shot on both. i was told that with rings removed clearance between cylinder wall and piston should be.005-.008 with feeler gauge. the oversize piston block has virtually no clearance and in my block clearance is .004. are either one of these blocks worth salvaging? can a piston or cylinder wall with small grooves be smoothed on my block and a new set of rings put in and work. on the oversize piston block with large grooves, can it be rehoned and piston smoothed and with new rings will it work. is one scenario better than the other or are they junkola? i need a backup engine for my snapper so i dont have any down time in case the engine goes i just put a rod and crankshaft in.

 
Sponsored Links
cheese's Avatar
Forum Topic Moderator

Join Date: Jul 2001
Posts: 16,567
GA

08-03-05, 12:04 AM   #2  
If the cylinder walls have pretty significant scrapes down them, then boring it oversize would be the only appropriate way to salvage it. On the engine with the tight fitting piston, you might be able to hone out the scratches and refit it with a new piston if the scratches aren't too deep. If they're deep enough to hang your fingernail on, then they're probably too deep to keep the same bore size, and would need to be bored again as far as required to remove the damaged surfaces.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
l.mitchell's Avatar
Member

Join Date: Jul 2003
Posts: 68

08-03-05, 09:51 PM   #3  
the old timer looked at both blocks. he agreed with you the tighter 010 block could be bored to 030. he said honing would not be anygood. it has to be machine bored. with a new piston and rings, this could cost more than buying another block. i was told top threaded briggs cranks for pull starters are getting hard to find. will this 8hp threaded crank fit 10,11, or 12 hp aluminum blocks? i notced blower housing has holes on 12 hp. that would match my recoil starter on the 8 hp or am i barking up the wrong tree here. i am thinking i could buy a good 11 hp engine and change cranks and bolt on my starter for what it would cost to have the 8hp block bored, and fitted with piston and rings. the carb and coil on this block are excellent.

 
cheese's Avatar
Forum Topic Moderator

Join Date: Jul 2001
Posts: 16,567
GA

08-04-05, 01:31 AM   #4  
The cranks don't interchange. Boring the engine block shouldn't cost too much...probably 40 to 60 bucks.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
Search this Thread