They telling me tight is right.?

[Steve.k]

Working on a 460bbf with stock rods n crank. Both .020 undersize. I changed machine shops as my ol guy retired so this guy cuts the crank a little tighter. Im getting 2.2-2.3 thou on the 2.4802 journal. 2.4 on all mains. He assures me thats the way to roll. I’ve always liked 2.7 on main and 2.5+ on rods? Thoughts you guys? Do i open up? Steve

[swampbuggy]

Hello Steve: I would say that bearing clearances are kinda like octane in fuels, it is being on the safe side by having a little too much rather than not enough. I remember Warp Speed posting something like..the quality of your parts ( strength and machined accuracy to sizing ) has a lot to do with what clearances you can get away with. All of this as we know affects oil thickness variables also. Mark H.

[Steve.k]

Yes I remember that. The nascar runs tight tight. Im spooked this pump gas may get a bad shot then bad news.

[Baprace]

Working on a 460bbf with stock rods n crank. Both .020 undersize. I changed machine shops as my ol guy retired so this guy cuts the crank a little tighter. Im getting 2.2-2.3 thou on the 2.4802 journal. 2.4 on all mains. He assures me thats the way to roll. I’ve always liked 2.7 on main and 2.5+ on rods? Thoughts you guys? Do i open up? Steve

Make sure you have enough rod side clearance and keep the oil light and warm the engine up first, I like your numbers as they are more on the safe side , the numbers you have are on the tighter side , but with a little care and common sense your engine will live for a long time.

[tuffxf]

G'day,
If it's cut .010, can you get .009 bearings and half shell it?
Too tight for me especially with stock parts
Cheers

[mag2555]

One can only assume from reading this that since you are running stock rods and crank that you are not looking to make over some 600 hp.

If this is the case then the clearances the shop says will work are fine!
If there’s a chance of you stepping up to better or reworked heads and bigger Cams down the road to top 600 hp then go with the tad larger clearances since the crank will flex more in terms of a factory one.
Just note that once you get up to .003” it’s 50 weight oil time !

[Steve.k]

This engine be a mid 400 hp deal built with tq in mind. Hyd roller and shorty headers. 79 F150 4x4 and occasional towing of boat to lake. 9.5 compression.

[Steve.k]

G'day,
If it's cut .010, can you get .009 bearings and half shell it?
Too tight for me especially with stock parts
Cheers

Thanks tuffxf. Its cut .020 on both. Using a cb818p-20 clevite77

[Walter R. Malik]

This engine be a mid 400 hp deal built with tq in mind. Hyd roller and shorty headers. 79 F150 4x4 and occasional towing of boat to lake. 9.5 compression.

Unless this uses "bolt down" or "shaft rockers", a hydraulic roller cam and valve train will become a mistake.

O.E.M. Cobra Jet clearances, NEW, are allowed to be much tighter than that ... (.0006" minimum).
400 horsepower is merely above stock passenger car stuff.

[Walter R. Malik]

One can only assume from reading this that since you are running stock rods and crank that you are not looking to make over some 600 hp.

If this is the case then the clearances the shop says will work are fine!
If there’s a chance of you stepping up to better or reworked heads and bigger Cams down the road to top 600 hp then go with the tad larger clearances since the crank will flex more in terms of a factory one.
Just note that once you get up to .003” it’s 50 weight oil time !

This is not a small block Chevrolet ... O.E.M. big block Ford cranks hardly flex at all, even over 700 horsepower.
The rods are a different story.

[cjperformance]

At that power level and that use and rpm it will see I can tell you that you will have no problems at all Steve.
A 460 needs nothing fancy at that Hp level.

[PeterGunn]

It has been said: Run your bearings loose, no one will know. Run your bearings too tight, everyone will know.

[Steve.k]

This engine be a mid 400 hp deal built with tq in mind. Hyd roller and shorty headers. 79 F150 4x4 and occasional towing of boat to lake. 9.5 compression.

Unless this uses "bolt down" or "shaft rockers", a hydraulic roller cam and valve train will become a mistake.

O.E.M. Cobra Jet clearances, NEW, are allowed to be much tighter than that ... (.0006" minimum).
400 horsepower is merely above stock passenger car stuff.

Walter we bought the bolt down scorpion style roller rockers. Im maybe conservative on hp. It has ported d3 heads and cam lift in high .500 area. Flat top 9.5.autotec pistons.

[Steve.k]

864A077C-B78F-4134-A0E5-E4A8D9972AE1.jpeg

Cam specs smaller than first thought. Randy I decided to go hyd roller only because I’m not a 100% sure on this guy’s maintenance and commitment to oil services. This will be first one i did this way. Usually flat tappet. Its not to late to change if you dont think its good idea.

[Walter R. Malik]

Cam specs smaller than first thought. Randy I decided to go hyd roller only because I’m not a 100% sure on this guy’s maintenance and commitment to oil services. This will be first one i did this way. Usually flat tappet. Its not to late to change if you dont think its good idea.

With a "bolt down" valve train it will not slightly side load the valve stems from the more pushrod angularity but, transfer that energy to the fulcrum which won't twist like with a rocker on a stud.
'Look out for the pushrods side loading on the pushrod hole in the head; clearance if needed.