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Mopar engine build questions for the real builders

wvracer821

wvracer821

Well-known member
Joined
May 27, 2020
Member Number
1546
Messages
688
Loc
Morgantown, WV
I’m working on stuffing an engine in a ram charger for a buddy and we ran into a snag with push rod length.
The block is a typical LA360. The heads are from an old 340. We’re using the normal stamped rockers on the shaft that came on the older mopar stuff. We are on our 2nd set of rockers because we thought the ones we bought where wrong The heads have been decked at least twice that I know of but we do not have any idea how much was taken off. We found that the valves are hanging open after we tried to fire it up for the first time. We’re currently using 6.900” pushrods and ordered a pushrod measuring tool to check with but I’m waiting on the softer valve springs to use with it. I’m looking for some insight if anyone has any. I’m not sure if the difference is from the machine work done on the heads or if we using the wrong shit. Sorry for the Tuesday questions on a Thursday.
 
Sounds like a bad valve job if their hanging open, unless your springs are binding i dont know how softer springs would solve the problem.

You are sure you don't have some W2 heads or something that requires offset rockers right? the rods "look" like they clear in some but when they lift and rotate they touch the intake ports.

Decked twice would net you with some decent compression, did you check valve to piston clearance prior to final assemble? Playdoh on top of the piston works great
 
Small update. Got a pushrod length tool and decided on a 6.650” pushrod down from the 6.900 we had in there. Those should be here Wednesday.

Valve to piston clearance is all good and was checked before it made it to my shop. We also cranked the thing over a bunch when it was here and nothing hit anything before we stuck a bore scope In the spark plug holes and found the valves hanging open.
 
wvracer821 said:
Small update. Got a pushrod length tool and decided on a 6.650” pushrod down from the 6.900 we had in there. Those should be here Wednesday.

Valve to piston clearance is all good and was checked before it made it to my shop. We also cranked the thing over a bunch when it was here and nothing hit anything before we stuck a bore scope In the spark plug holes and found the valves hanging open.
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that's almost 3/8" that's a pretty big difference! I bet your issues is gone with those new rods
 
That definitely explains why we had to fight the intake on. We filled the cooling system and don’t have any leaks on that side of things. With any luck it will fire right up this week when I get a chance to work on it.
 
What year is the block? I am pretty sure the 88 and up was set up for roller cams and had some different oiling passages to the heads to lube the rocker shafts.
 
v2win said:
What year is the block? I am pretty sure the 88 and up was set up for roller cams and had some different oiling passages to the heads to lube the rocker shafts.
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They do. My brother has some extra long mcmaster-carr drill bits to rework the block for LA heads from stock car days. Hand drilled. Ya gotta be patient for that operation.:laughing:
 
Update, we put the new pushrods in and fired it up. It ran fine and carried 25psi of oil pressure at idle after warming up. Sounds good overall but we have some interference issues with the Holly stuff I think.
 
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