5.3 build pushrod help please

[sweet_87_iroc]

I am building a 5.3 for my iroc. I am using a comp cams 7702 length checker. I noticed that my exhaust pushrod would be small then my intake. Is this normal?

[farmington]

Can happen after heads have had a valve job. I think you have .060 range of preload. You just get pushrods with a length that will put both in this range. Or you could buy two different sets of pushrods and only use 8 of each length

[sweet_87_iroc]

What is the best preload for forced induction later on?

[sweet_87_iroc]

So my intake @ zero lash is 7.275. Exhaust @ zero lash is 7.3.

[farmington]

A 7.325 or 7.350 pushrods would work but would put one side at the min or max preload

[hoogiesngrinderz]

I'd run 7.35

[sweet_87_iroc]

I was thinking about running 7.375

[hoogiesngrinderz]

I personally wouldn't preload that much, not even with LS7 lifters

[sweet_87_iroc]

Can you explain? I read some where gm specs are .080 - .100 with ls7 lifters

[hoogiesngrinderz]

Do you have LS7 lifters? If your measurements are correct, push it to .100 as they are a bit deeper but I still stick to .060 for the older lifters and .080 for the new.

[sweet_87_iroc]

yeah I am running LS7 lifters. So you think 7.375 pushrods all the way around would be a good setup?

[hoogiesngrinderz]

You should be ok with them, apparently LS7 bottom out around .200

I just measured my preload on my 5.3 on the engine stand, .151 with stock pushrods I have a length checker to verify measurement, hard to believe I need a 7.300 pushrod

[sweet_87_iroc]

Wow that's a lot. Any suggestion on the brand and model pushrods are the best?

[hoogiesngrinderz]

I know, right?! Heads milled .020, block decked .010, stock MLS gaskets, Lingenfelter GT1 218/229 .561 cam. Heads have a new valve job, but still...even if the base circle of the cam is the same is stock, no way in hell did I get the extra 50 thousandths come from the valves

As far as what to get - using stock rockers I'd get 5/16 .080 wall chrome moly, any big name brand will work.

I'm going to go with the budget brand for this 5.3, will rarely ever see over 5000 rpm and the LPE GT1 cam is so mild that it would have worked with stock pushrods (if they weren't so long)

[sweet_87_iroc]

Sounds good thanks for the help!