Piston up too far?

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mikedevore

mikedevore

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Any length difference between a 5.9 Magnum rod vs an LA 360 rod?
A friend of mine is building an engine.
It started life as a 5.9 Magnum, that he had bored .020 & installed KB107 pistons in it.
He was going to have it zero decked, but was suprised to see the pistons were .005 to .007 above the deck.

Anybody seen this before?
Is there something that isn't right, parts wise?
He is wanting to install a pair of Eddy Magnum heads on it & worried about the pistons being above the deck.
Welcome for any input.
 
both use the same length rod...

i think the magnum has a shorter deck height then the LA...

use a thicker head gasket...

found this...

magnum spec block's 9.58 deck height { old pre-magnum spec was 9.60}.
 
70aarcuda said:
both use the same length rod...

i think the magnum has a shorter deck height then the LA...

use a thicker head gasket...
Click to expand...

That is his first thought, was to use a thicker head gasket.
Has any one done that?
 
Pistons too high is better than pistons too far in the hole as mentioned just use a thicker gasket it will work fine
 
I put those pistons in a LA 360 block and they were above the deck. Later on I bought a MP 360 short block that was setup for LA heads but used a Magnum block. It was the 10 to 1 version and the pistons were above the deck on that too. Both times I used a regular parts store head gasket and didn't have any problems.
 
Machine shop had zero-decked my big block, my pistons were about .010 out of the hole as well. Just do a clearance check with the head and gasket torqued down to verify everything has room to move.
 
I routinely do pistons proud of the deck. There's no issues with running them that way as long as you account for the ususal stuff - piston to valve, head gasket overlapping the bore, the top ring getting into the chamfer, etc.
 
It just seems odd to me at first.
I have used that KB107 piston on a couple of 360's & had to cut the deck to put them @ zero.
Thanks, Guys
 
In my 94 360 mag, with no decking I got lucky with the 107 and they came out at 0 +/- .002"
 
MP 360 short blocks use the spreed pro 116HP...got one that is the high compression version with the piston out .015...and low compression one with pistons down .037...both using the same piston...

both are 91 Roller blocks...not magnums..
 
Yup, Magnum blocks have a Shorter deck height than the LA blocks by .020". The std head gasket in a std Felpro gasket kit is .054", if you use that you will be fine. I dont know if I would run a tight .035-.033" quench with stock rods and stock rod bolts, So I would run a thicker head gasket.
 
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