rocker/pushrod adjustments - how much is OK?

[defiance]

So the efforts to put my engine together continue -

Just got rockers in, and now I have a question

So I found some chrome moly pushrods a while back that had been bought and didn't fit the guy's application.  He sold the whole set to me for $20.  They're 9", so probably too short, but I thought for $20 it can't hurt to try, right??   If they don't work, no biggie, I'll just get some new ones... I just couldn't turn down that price


Anyway, here's a pic.  The rockers are adjustable with cups on the ends of the adjusters.  The adjusters in the pics are backed out so that the distance the adjusters would cover is visible.  I'm holding the rods approximately lined up with the cups.  The cam is rotated to a 0 lift point, lifters are all the way down, rods are seated in the lifters, rocker shaft is bolted down snug, and rockers are all the way up against the valve.  For reference, these are hydraulic lifters (I know, several people here recommended a solid, that's another topic ).

So the question I have is, are these rods too short to work OK with these rockers?  I've heard that if they're too short, I'll have problems with adjusters breaking, but I honestly have no idea how short "too short" is...

[Rob R]

It looks to me that it's going to be too short...you'll have 5-6 threads showing maybe more...if it's a hyd cam with a 100 lbs on the seat it shouldn't give you too much trouble...it really depends on where the feed hole is in the rocker and the angle of that feed hole.I've seen adj screwed out to the max(1/2 inch) and the guy said he's never had a problem...

[defiance]

Just got a chance to check it out - It seats at 4-3/4 rotations in from flush, so I figure 5-1/4 would be where it would run for preload... spring pressure is 130 on the seat.

[defiance]

Thanks for convincing me

Just ordered some 9.136"-ers.  I measured .045" between threads, so taking down three threads (from 5 to 2) would be .135" longer than the 9" rods I have now.  .136" was the most reasonably priced set I could find in that range.
Better safe than sorry

[firefighter3931]

I like to see 1-2 threads below the rocker arm for proper lubrication....you made the right call going with longer pushrods. 



Ron