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how to adjust thrust

Posted: March 18th, 2012, 4:20 pm
by herbiehind
pre-build going well , all mains perfect. rods in spec . but thrust on crank is .0005" . or half a thousandth . what to do guys? this is one tight motor . while i got ya, i'm at .038 on deck clearance . is it worth it to go ahead and zero this thing ? i imagine i'll have to get push rods plus the machine work. but is it worth it? will i get a good h.p. boost? or good mileage or 87 octane ? what say you strokers? :deadhorse:

Re: how to adjust thrust

Posted: March 18th, 2012, 5:57 pm
by IH 392
Take a BMFH and a wood block and WHACK the crank from both ends three or four times and then measure your thrust, on the quench I'd deck the block, I wouldn't exceed .050", I'd have them take at least .030" off and maybe even .035"

Re: how to adjust thrust

Posted: March 19th, 2012, 3:43 am
by herbiehind
thanks IH 392 . seems easy enough . yeah, guess i'll get it decked . dont want that regret. thanks again .

Re: how to adjust thrust

Posted: March 19th, 2012, 7:53 am
by SilverXJ
There is a bit more than that. You don't want the caps tightened all the way.

Re: how to adjust thrust

Posted: March 19th, 2012, 10:37 am
by dwg86
herbiehind wrote:pre-build going well , all mains perfect. rods in spec . but thrust on crank is .0005" . or half a thousandth . what to do guys? this is one tight motor . while i got ya, i'm at .038 on deck clearance . is it worth it to go ahead and zero this thing ? i imagine i'll have to get push rods plus the machine work. but is it worth it? will i get a good h.p. boost? or good mileage or 87 octane ? what say you strokers? :deadhorse:
Do you have the thrust bearing on the correct journal? Some on have tried to install it on the rear bearing cap. It goes on #3.

Re: how to adjust thrust

Posted: March 19th, 2012, 1:36 pm
by herbiehind
dwg86 wrote:
herbiehind wrote:pre-build going well , all mains perfect. rods in spec . but thrust on crank is .0005" . or half a thousandth . what to do guys? this is one tight motor . while i got ya, i'm at .038 on deck clearance . is it worth it to go ahead and zero this thing ? i imagine i'll have to get push rods plus the machine work. but is it worth it? will i get a good h.p. boost? or good mileage or 87 octane ? what say you strokers? :deadhorse:
Do you have the thrust bearing on the correct journal? Some on have tried to install it on the rear bearing cap. It goes on #3.
yeah lol it's on #3 .

Re: how to adjust thrust

Posted: March 19th, 2012, 1:37 pm
by herbiehind
SilverXJ wrote:There is a bit more than that. You don't want the caps tightened all the way.

silver; can you elaborate? i need to do this right. thanks

Re: how to adjust thrust

Posted: March 19th, 2012, 5:11 pm
by SilverXJ
http://www.enginebuildermag.com/Article ... ilure.aspx About halfway down is a good description.

Re: how to adjust thrust

Posted: March 27th, 2012, 8:25 am
by gonridnu
Your last "whack" needs to be from rear to front before tightening the cap. The thrust bearing primarily sees loads towards the front of the engine from pump pressure on an auto and clutch pressure from a standard. It is perfectly acceptable to lightly sand the thrust bearing on a flat surface to gain thrust clearance.