Connecting rod big end to crankshaft clearance

[nkosi]

hey guys im assembling my new engine and wanted some info on the rod to crankshaft clearance ...i use the feeler gauge and the clearance is over 0.030 on both sides of the rod end cap ...is this a safe amount of clearance or too much ...i plan on running up to 35psi of boost on engine ...any help would be much appreciated

 

[jmelocik]

way to much.

Josh

 

[GRAVEDIGGER]

Maybe these links will help.

http://www.dsmtuners.com/forums/cyl...clearance-between-rod-bearing-crankshaft.html

http://www.dsmtuners.com/forums/cylinder-head-short-block/224090-6-bolt-rod-question.html

 

[nkosi]

Maybe these links will help.

http://www.dsmtuners.com/forums/cyl...clearance-between-rod-bearing-crankshaft.html

http://www.dsmtuners.com/forums/cylinder-head-short-block/224090-6-bolt-rod-question.html

thanks for the reply gravedigger the links are very helpfull but im talk ing about the rod big end to crankshaft clearance ...my oil clearance on the rod bearings to crank journal are good ... it the area between the side of the rod and the crank journal walls

way to much.

Josh

if i have too much how do i get it reduced ...do i need to take it to a machine shop and whats the procedure to fix the clearance

 

[GRAVEDIGGER]

In the second link I provided they list connecting rod big end to crankshaft side clearance as .004-.0098" although I would prefer to see .004-.008" to be safe.

 

[nkosi]

In the second link I provided they list connecting rod big end to crankshaft side clearance as .004-.0098" although I would prefer to see .004-.008" to be safe.

So if u have too big a clearance for the rod big end to crankshaft side ...whats the procedure to reduce the clearance to within tolerances ... would i have to take the bottom end to my machinist and how would they fix that

 

[Colt4G63 also]

It seems to me they couldn't. You would need thicker rods or a tighter crank.

Are you sure that spec is right?

 

[donniekak]

So if u have too big a clearance for the rod big end to crankshaft side ...whats the procedure to reduce the clearance to within tolerances ... would i have to take the bottom end to my machinist and how would they fix that

See which part, or parts is out of spec, and replace the rod, crank, or both.

 

[nkosi]

Well i had the crank and rod align hone all together they told me everything is within spec ...maybe im checking this incorrectly ...

 

[GRAVEDIGGER]

You're not trying to put 7-bolt rods on a 6-bolt crank are you? The 7-bolt rods aren't as wide as the 6-bolt rods and if you're trying to use them on a 6-bolt crank you will have alot of slop like you are describing.

 

[nkosi]

You're not trying to put 7-bolt rods on a 6-bolt crank are you? The 7-bolt rods aren't as wide as the 6-bolt rods and if you're trying to use them on a 6-bolt crank you will have alot of slop like you are describing.

Im pretty sure im using a 6 bolt rod ...i measured the big end and wrist pin is 21mm so im pretty sure i have the correct rods

 

[GRAVEDIGGER]

Yeah, sounds like you're using the correct ones then. I think the only way to fix that is to get a new crank, but I'm no expert on engine building, so maybe someone else can chime in with some more information.

 

[nkosi]

thats not good news at all ...im gonna get the machinist to check it for me just to make sure im doing it correct

hey guys i emailed the manufacturer of the rods im using and they said with a floating wrist pin rod the clearance im getting is ok and they warranty the rods with the clearance im getting so imma roll with that thanks for all the hekp boys much appreciated