[Z Code 400]

Anyone take a 'real world' measurement of the OEM Pontiac dual spring and compare it to the Crower 68404/68405????

I am trying to see if the 68405 will fit in a Pontiac splash shield....Robert

[screamingchief]

Yep,I have.

Oh,,,maybe you want that info???

The ID of the sheetmetal shields is right @ 1.440" give or take a couple of thou.

The OD of a Crower #68405-16 is spot on the stated 1.405" OD spec,as were the set of #68404-16 springs I checked (1.400") a while back.

So yeah,the Crower springs fit inside the shields no problemo,as long as the retainers fit as well.

The only springs I've run into that consistently had problems with the shields were the crane "single w/damper" spring part #99840-16,as those were too large an OD for those shields (1.460" OD IIRC).

Also with no inner spring to locate the lower part of the spring,those things would walk around on the head a bunch.

Those Crane single springs were total junk on pontiac heads IMHO.

Only thing I dont have is the actual OD of the OE dual springs,I dont keep any around,they get tossed in the trash as soon as I get them off the heads,as I never use them myself,all my builds get new springs as SOP.

Anyhow,hope that helps you Robert.

Bret P.

[Murf'sDad]

Robert, I checked a set of OE springs that were still kicking around from my #13 heads. They mic'd at 1.405, 1.406. I've got a set of stock 6X heads I can check but I'd have to un-pile some stuff to get at them.

Stewart

[Z Code 400]

This is great. Thanks to you both....

I do not want to cut my guide bosses down for PC seals with the K-Liners as I think the extra material is critical to cooling of the valves. B-Man has a set of my old #13 heads I put on a 400 in 1988. When I pulled them in 2002, the K-Liners looked and felt like new.

I'm just going to slap the splash shields on the 68405's with the 'O' rings and call it good....Robert

[Kenth]

Pontiac did not use the shields for any RA engine due to the stronger springs used would break the shields regardless of diameter of springs.

[Z Code 400]

Thanks for that tip, Kenth....but what did they use for valve seals???? I've never seen a factory positive seal on a Pontiac.

I have used the shields on SBC's with over 300lbs open pressure with no issues. My 68405's are only about 280lbs open....Robert

[Kenth]

All H.O., R.A. GTO 4Bbl., GP 4 Bbl., 428 and 455 engines uses O-rings on all valve stems and umbrella (positive) type seals on intake valve guides.

I guess you´ll be safe using the shields with only 280lbs open spring rate, as the H.O. engines using the shields have around 325lbs open spring rate@1.586".
Also 1970 RAIII uses these springs only without shields.

RAIV have 391lbs open spring rate and 1969 RAIII have a whopping 430lbs open spring rate due to the "square" lobes of the #744 camshaft.

[Z Code 400]

Umbrellas inside a dual spring????

Wow, that's a little one!!!!