5.3 build pushrod help please

[1BADAIR]

trend stock any lenght in .05 increments

[hoogiesngrinderz]

trend stock any lenght in .05 increments

Please repeat, did not copy.

[hoogiesngrinderz]

Let's keep this thread alive, for my sake

• I sent an email out to Lingenfelter to see what the base circle is for the GT1 cam. I measured it but I cannot find the paper I wrote it down on
• Block has been milled, was not given a final number but I was able to compare to 2 other 5.3's here, measured .010"
• Heads received a valve job and .020" mill at Visner Engine Development
• OEM lifters (not LS7)
• OEM 5.3 MLS gaskets

Using OEM pushrods (~7.385") I actually measured .158" preload, which is in the video below. With #5 cylinder at TDC, I set both intake and exhaust rocker to 22 ft-lb torque then set the dial on it before I backed off the rocker bolt.

This is the way I've always checked preload on the genIII builds I have done. I ordered a pushrod length checker to double check, but it will not arrive until Thursday.

Thoughts/ideas why the preload shot up so high with .030 total mill? LM7 cams are 1.552" on the base and I've seen Comp (they grind LPE cams) likes to use ~1.497", which means a difference of .0275" difference.
Gaining .0275" with the smaller base and losing .030" to the mill should mean preload should have gone up only .0025".

I know I'm assuming at this point in time, but I'm baffled as to why the calculated numbers are so far off from actual.

[1BADAIR]

Trend sells any size in .05 increments

[hoogiesngrinderz]

Ahhh, didn't realize Trend was a company I was trying to cypher thinking it was autocorrected. Comp has nearly every size in .050 increments, looks like Trend has them in .025 increments. Good to know

Any idea why a LPE cam and .030 mill would cause the preload to jump up around .070" over stock?

The stock 5.3 in the '60 Impala has a 02-04 z06 cam and stock pushrods (.025" less base radius) and that still had a preload of .060"

[farmington]

remember that when a valve job is done, the valve sinks in a little which raises the valve stem a little, then you have the 1.7 rocker ratio too. It all adds up. theoretically, if the valve job goes .010 deeper, the pushrod would need to be shortened .017

[hoogiesngrinderz]

remember that when a valve job is done, the valve sinks in a little which raises the valve stem a little, then you have the 1.7 rocker ratio too. It all adds up. theoretically, if the valve job goes .010 deeper, the pushrod would need to be shortened .017

Close, but you have to divide when coming from the valve side

.010 up from the pushrod side would result in the valve going down .017
.010 up on the valve side would result in the pushrod going down just under .006

[farmington]

that'll teach me to sleep through calculus classes

[hoogiesngrinderz]

I'm still stumped. Haven't heard back from LPE and still waiting on my length checker to arrive.

[hoogiesngrinderz]

How did it come out, Chris?


I ordered some pushrods from Summit that looked like OEM but they were listed as 7.325" on their website and in the description for the ebay ad....I took a chance...they were OEM rods

LPE had no clue what the base circle was, no help there. What a mess.

[sweet_87_iroc]

I ordered 7.35 pushrods from tick performance. I got them today. Should have the engine installed nov or dec timeframe.