93625 171 Small Block Mopar Assy Promaxx heads

[AUSA66]

Anyone had to change the springs on Promaxx SB heads took a new set down to be stripped & checked both were labelled Hydraulic roller the engine builder said the fitted springs come in at 100 closed 290 open said they were to light should have 135 - 325 open as per promaxx's website waiting to hear back from promaxx .
He checked the guides + skimmed 20 thou to get the comp up a bit commented the guides were spot on & from previous experience they were quite soft about the same as eddy sb heads

 

[rumblefish360]

I purchased a set of there CNC ported small block heads. Being that I am using a Lunati can, solid roller, the springs were never checked but simply swapped and it was easy enough.

Often I read the listed height of installed spring heights are not at what is advertised, but taller. (Example; 1.800 listed, 1.900 as delivered.) ProMaxx uses (IIRC) PAC springs. I would follow the cams manufacturer’s spring recommendations or a set from a other company like PAC that are the same or super close. Reinstall at the needed height.

 

[Bewy]

I just received a set of big block 240 Trick Flow heads. The installed heights were spot on, & shims were used under the locators to get the correct IH.
The only 'problem' was in the paper work that came with the heads. The closed spring tension was wrong, nowhere near what they actually measured. Maybe just a typo error.

 

[AUSA66]

The valve tip heights on the Promaxx are a bit here & there he is going to fit PAC springs then grind the valves to the correct heights.
My Victors come with Shims but had to change when I went to PAC beehives for solid roller.

 

[rumblefish360]

My ProMaxx heads were dead even across the valve tips.

 

[gzig5]

The valve tip heights on the Promaxx are a bit here & there he is going to fit PAC springs then grind the valves to the correct heights.
My Victors come with Shims but had to change when I went to PAC beehives for solid roller.

I have lightly used set of 171's and the spring heights and guides checked out nicely. There is a slight diff (0.010") between the intake and exhaust stem height but other than that they are good. Depth stop slightly off after changing the tool, I guess. Nice work on the bowls. I don't have a spring scale but I plan on replacing them anyway.