Pushrod Length with Hydraulic Roller Lifters

[KenG]

Hello, hoping for some insight on pushrod length. I have a 408ci I'm putting together with Morel Hydraulic Lifters, Cometic MLS head gaskets, Trickflow 190s, and Mancini 1.6 Roller Rockers. (block was decked .004).

I have the trickflow length checker and checked length on a few cylinders just to make sure there was consistency and they all measured out to 6.900 OAL factoring in a preload of .075. To get the BOC (ball to cup) measurement I subtracted .160 (half of 5/16") to get a BOC of 6.740

I could not find any installation instructions for the Mancini Roller Rockers but seeing as they are made by Harland Sharp I am using their installation instructions which recommends the adjusters be set so that 2 threads are visible below the rocker. I will call Mancini tomorrow to see if they have their own installation instructions. But, my pushrod lengths were measured with 2 threads showing.
Harland Sharp Installation Instructions: https://cdn.shopify.com/s/files/1/0569/2951/7720/files/7002K_Instructions.pdf?v=1630371422

I purchased a set of PRW 6.900 pushrods, thinking I was buying 6.900 OAL but they are BOC so after testing fitting them they are too long. The cup tip does clear the rocker throughout the full rotation of the motor, but its pretty close. Pictures below are of the PRW rods mocked up.

So my question, I guess, is: Does anyone have a set up similar to this and if so what did your pushrods measure out at? Also, what manufacturer did you use? (there seem to be very limited options for cup tip pushrods based on my googling).

appreciate any info that you guys have, thanks!

 

[str12-340]

Assemble the motor first. They make adjustable pushrods to measure the correct length (that you never ever run the engine with). There is a specific procedure regarding prep for the lifters that must be followed, then you order push rods specific to your motor. There are too many variables (heads, head gaskets, lifters, etc. to think there is a standard pushrod length for your engine.

 

[Demonracer]

In the last picture if the rockers are adjusted properly, it looks as if the push rods are going to contact the rocker arms. Invest in a push rod length checker and get the correct length push rods.

 

[KenG]

I have the trickflow length checker and checked length on a few cylinders

thanks for the replies. i do have a length checker: Trick Flow Specialties TFS-9005 Trick Flow® Adjustable Pushrod Length Checkers | Summit Racing

Is there a manufacturer for cup tip pushrods you all recommend? understanding that i will likely need a custom length

 

[moparmarks]

Smith Brothers are the go to for push rods.

 

[Demonracer]

Ditto on Smith Brothers.

 

[crackedback]

Why are you preloading the lifters with .075, that's ~1.5 turns on the adjusters. I don't tend to run hyd rollers with more than .5 turn.

Make sure the pushrods aren't contacting the pass through holes. TF might be larger than an Ede head.

Close? The cups aren't touching. How many sheets of paper or a feeler gauge to see the actual clearance? Stuff gets tight in valvetrain sometimes.

 

[KenG]

I'll double check the paper that came with the lifters when I get home today so that I'm not misreading the preload.

pushrods clear the heads with lots or room to spare. these are 5/16" pushrods the TF heads allegedly have clearance for 3/8".

I'll measure clearance of the cup w/ the valves closed and fully open. also calling Mancini and Smith Bros now

 

[KenG]

ok, reread the morel lifters paper (photo attached). Glad I did, the preload is stated as .040 - .060. So, I've adjusted my math accordingly (BOC length of 6.715).

I spoke to Mancini and they confirmed to reference the Harland Sharp installation instructions. And, I spoke with Tony at Smith Bros, he was incredibly helpful, order form is submitted and new pushrods in the works.

thanks for the guidance!

 

[RustyRatRod]

You need some light checking valve springs so you do not preload the lifters. That way you can put the valve at about half lift and measure for length.

 

[4eighteener]

I have a similar build with trickflow heads, and 1.6 prw. My decks had been severely cut and I measured an even 7" for pushrod length.
Unfortunately, when I mocked it up, I neglected to install the shim kit from B3 racing, so the pushrods came up too short.
Smith brothers were backed up for weeks, but Manton Pushrods had them to me in 2 days from California to Florida