main cap question

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Princess Valiant

Princess Valiant

A.K.A. Rainy Day Auto
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ok, i bought a 440 over the summer and it was missing 3 main caps .....but it is a good date code and an HP block and mega cheap so i bought it anyway despite the missing caps. (you all know i cant pass up something like that anyway)

so last night i had a friend show up at my house and he told me he found another 440 that was overheated and two of the cylinders are cracked ....basically the engine is junk ......he says i can have the caps since he knew my problem before and he is going to scrap the engine, so im thinking i can take the main caps from the junk engine and put them on my 440 to complete it.

can i do that? i can just transfer them with no issues right?
 
You may be able to. But the mains will have to be line bored regardless. Main caps and rod caps are not just interchangeable they are machined once they are assembled to make them round and since we are talking about thousands of an inch it is very precise. I hope this answers your question Good Luck
 
RaniDart70 said:
ok
so last night i had a friend show up at my house and he told me he found another 440 that was overheated and two of the cylinders are cracked ....basically the engine is junk ......he says i can have the caps since he knew my problem before and he is going to scrap the engine, so im thinking i can take the main caps from the junk engine and put them on my 440 to complete it.

can i do that? i can just transfer them with no issues right?
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You can put the main caps on the other block, but have to re align bore the main bearing caps. Make sure to mark them for the new locations after you have it re machined. You then have to keep them in that same position and orientation (Line up the anchor slots together).

If you don't remachine (align bore) the caps, they could not line up properly (just a .001" or two misalignment can cause the crank to not turn). Same for rod caps, you have to keep them on the same position and orientation as they were machined for.
 
x8....I've done it a couple times...line bore it and mark them so no confusion in future...aint worth the risk to just put it together and not work,makes it tough on the next guy trying to figure out WTF..Is why i only buy blocks with the mains and bolts intact,rods I resize anyway if I reuse them....
 
Oklacarcollecto said:
Xs7.



I would have thought that would have been covered in school.
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in school they tell you to keep the main caps in order but never talked about bring caps from another engine ...they assumed you are working on a late model engine that came to you complete.
 
RaniDart70 said:
in school they tell you to keep the main caps in order but never talked about bring caps from another engine ...they assumed you are working on a late model engine that came to you complete.
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Once you take a cap (for a rod or main bearing) off of the rod and put into anywhere else other than the original piece that it was machined with, YOU HAVE TO REBORE/ALIGNBORE IT!


You cannot take a main bearing cap from #2 position and put it in #1, #3, or #4 position on the block, It has to go back on #2 position. Every cap must be put back to the original position and orientation (anchor slots lined up butt together) for it to function properly. I've seen cases where mixing up the order of the main bearing caps won't allow the crank to turn when the main bearing caps are tightened down.


If you don't believe it, just try it next time you put an engine together and see how it works. Switch positions of a couple of main caps and torque them down and see if the crank turns and how free it turns without pistons installed. Then put it back together correctly and see if the crank turns any better.... It will make a difference.
 
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