AutoXRacer
forum member
So I posted this question in my build thread, but didn't get many replies probably due to the subject title.
This is the situation:
My local engine builder is assembling the short block. He ordered the same Speed Pro 149M main bearings as was installed originally. When he checked the clearances, he says they were too tight. Not sure what that clearance was.
So he is putting in +0.001" extra clearance bearings to achieve 0.0025"-0.0028".
Ford Specs for the 4.6L main bearing clearances are:
0.0019"-0.0009" (GT500 5.4L: 0.001891"-0.0009")
My JDM build sheet speced them to:
0.0022"-0.0021"
My local builder is aiming for:
0.0025"-0.0028"
What is this going to do to the motor overall?
Why is he trying to go with so much clearance?
My local builder is not using the Ford specs. He is using some formula to calculate clearances.
What advantages/disadvantages are there running a larger clearance?
He keeps saying its the formula that dictates clearances plus adding in performance application factors.
He had me order two sets of bearings...
Clevite MS2259H (std) and MS2259HX (+0.001" extra clearance)
This is so frustrating. I know my builder knows his stuff, but I just hate it when things stray so much from OEM... Plus you have all these opinions.
I would have felt every comfortable with a final clearance of 0.0021"-0.0022". I'm just uneasy with the 0.0025"-0.0028" range.
So what is your motor clearanced to?
How many miles?
Do you race your motor/car?
Hows it running?
What oil do you run?
This is the situation:
My local engine builder is assembling the short block. He ordered the same Speed Pro 149M main bearings as was installed originally. When he checked the clearances, he says they were too tight. Not sure what that clearance was.
So he is putting in +0.001" extra clearance bearings to achieve 0.0025"-0.0028".
Ford Specs for the 4.6L main bearing clearances are:
0.0019"-0.0009" (GT500 5.4L: 0.001891"-0.0009")
My JDM build sheet speced them to:
0.0022"-0.0021"
My local builder is aiming for:
0.0025"-0.0028"
What is this going to do to the motor overall?
Why is he trying to go with so much clearance?
My local builder is not using the Ford specs. He is using some formula to calculate clearances.
What advantages/disadvantages are there running a larger clearance?
He keeps saying its the formula that dictates clearances plus adding in performance application factors.
He had me order two sets of bearings...
Clevite MS2259H (std) and MS2259HX (+0.001" extra clearance)
This is so frustrating. I know my builder knows his stuff, but I just hate it when things stray so much from OEM... Plus you have all these opinions.
I would have felt every comfortable with a final clearance of 0.0021"-0.0022". I'm just uneasy with the 0.0025"-0.0028" range.
So what is your motor clearanced to?
How many miles?
Do you race your motor/car?
Hows it running?
What oil do you run?