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Discussion Starter · #1 ·
Hi Guys,

I am building a 331 Stroker for my 89 LX. I have been following the 331 Stroker build up from the Tech Dept and upon checking the clearances for the mains and the connecting rod bearings they read less than 0.001"

I mock assembled, lubed, and torqued bolts down and the assembly was impossible to turn. The crank manufacturer prepped and balanced the assembly so I assumed it would have been ready for install into my prepped block. Did I miss something or does the crank need to be machined?

Thanks for the advice,
Mark
 

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Even with .001 clearance, you should have been able to turn it. It sounds like something else could amiss.

Which "crank manufacturer prepped and balanced the assembly"???
 

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All of my rods were around .002 and one of the mains was .0017. When lubed the crank turned freely, only took one finger. I would double check the caps and make sure they are not reversed or mixed up.
 

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Discussion Starter · #6 ·
DSS Racing provided the Stroker Kit. I have been using a local machine shop to prep the block.

The Caps are in the correct position, and the assembly turns until I torque the mains.
 

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Something is wrong.......how did you determine the .001 clearance?

Just as a point of reference, the 1992 Ford factory shop manual lists the "desired" main bearing clearance at "0.0004-0.0015" for the 5.0.
 

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Discussion Starter · #10 ·
The shop align honed the mains and said they were "good".

Main Bearings - EngineTech 4125M
Connecting Rods - Clevite 77 8-2600CP

And I am not sure what Crank run out is... will comment on that in a bit.

Thanks for your help mstngjoe
 

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Do you have any precision measuring tools? Dial indicator, dial caliper, mic, etc.?

All other things being equal, my first thought would be the thrust bearing.
 

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Discussion Starter · #13 ·
I checked the runout and it is within 0.001" of round. My thought is the thrust bearing too. Documentation with the crank says that its oil clearance can go as low as 0.0008" so I am thinking it is not friction with the bearings but rather mis-alignment of the thrust bearing.

Going to compare diameter of the journals from the old crank to the new one just to be sure that there wasn't a goof up.
 

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For higher rpm, you want close to 0.002" on the mains. I like 0.002" to 0.0025" on mine. There is no way I'd use 0.001" without major fear of spinning a bearing from lack of lube.

Get the mains measured by somebody with an accurate micrometer and see where they are. If it looks to be in spec, measure the main bores.

There are specs for these listed at the King Bearings web site. Their specs are -slightly- different from the Clevite/Federal Mogul numbers, but will let you know where you stand. They show the housing bore, bearing thickness and crank diameter. If your crank or bearings are ground undersize, you'll need to adjust the numbers to reflect that.

http://www.king-bearings.com/cat/html/engines.htm

Good Luck!
 

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On 2006-09-09 21:01, markawatt wrote:
I checked the runout and it is within 0.001" of round. My thought is the thrust bearing too. Documentation with the crank says that its oil clearance can go as low as 0.0008" so I am thinking it is not friction with the bearings but rather mis-alignment of the thrust bearing.

Going to compare diameter of the journals from the old crank to the new one just to be sure that there wasn't a goof up.
That runout is within acceptable limits.

As Mike stated, .002+ is better on mains and rods.

I pointed out the factory 5.0 main bearing clearance spec to illustrate that even if you've only got .001 it should still turn.
 

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Discussion Starter · #16 ·
Thx Mstngjoe,

I included the crank published clearance so that you knew it wasn't some freaky crank casting. I would be much happier with 0.0015 or 0.002.

I'll include this for any newb engine builders out there (like me). The thrust bearing (bearing with the flanges) goes on the 3rd cap. Not number 5 - hence part of my problem.
 

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On 2006-09-10 15:56, markawatt wrote:


I'll include this for any newb engine builders out there (like me). The thrust bearing (bearing with the flanges) goes on the 3rd cap. Not number 5 - hence part of my problem.
Ummm....yeah.....that would tend to bind things up.
 
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