BB windage tray studs

[Barth C.]

I believe the windage tray studs in the attached pictures are from a 1966 L72 big block. However I am not the original owner of the car from which they came nor the person who disassembled the engine. My questions:

1) Are they correct for a 1966 L72 big block?

2) If so, why are there two types and what is the correct orientation for assembly?

[Ray K.]

Re: BB windage tray studs

Barth

The original studs for big block windage trays were of the design that required a bolt ( cap screw ) to be inserted into the threaded shoulder as referenced as the top units in your photo. The second design utilizes a nut that screws onto the threaded portion of the stud. Either design will work in any of the four positions. I am not sure when the change was made from the first design to the second design, although I would try to make them all the same. Also, don't forget the fifth bolt ( stud) for the oil pump attachment.

Ray

[Clem Z.]

Re: BB windage tray studs

if you use the studs that use the bolts not the lock nuts do not use split lock washers but instead use red loctite with a flat washer. if the split lock washer breaks you will a problem with loose parts in the oil pan.

[Bill W.]

Re: BB windage tray studs

65 #16120 came with the cap screw type.

[Patrick B.]

Re: BB windage tray studs

The 65-66 style with the threaded hole are subject to breakage of the end that clamps the main bearing cap. I have a friend whose 65 396 crank and block were trashed by breakage of these in 1970, and I have had several of the early style studs break while being torqued. Two of yours probably broke and were replaced with the newer 67 style studs. I would not use the early studs.

[Barth C.]

Re: BB windage tray studs

The 65-66 style with the threaded hole are subject to breakage of the end that clamps the main bearing cap. I have a friend whose 65 396 crank and block were trashed by breakage of these in 1970, and I have had several of the early style studs break while being torqued. Two of yours probably broke and were replaced with the newer 67 style studs. I would not use the early studs.

Interesting information. This particular motor had a catastrophic failure at some point and one of the cylindars has been sleeved.

thanks for all the information

[Joe R.]

Re: BB windage tray studs

Barth,

The studs and nuts are still available under pn 3902885 for the studs and 9422297 for the nuts.

JR

[Joe L.]

Re: BB windage tray studs

I believe the windage tray studs in the attached pictures are from a 1966 L72 big block. However I am not the original owner of the car from which they came nor the person who disassembled the engine. My questions:

1) Are they correct for a 1966 L72 big block?

2) If so, why are there two types and what is the correct orientation for assembly?

Barth-----


The 1965-66 studs which use the cap screws for baffle retention were GM #3866372. The 1967-74 studs which use nuts for baffle retention are GM #3902885. The 3902885 replaced the 3866372 for 65-66 SERVICE in October, 1967.

One thing to keep in mind: you can be sure that GM did not change the design of these studs because the first design worked just as good.

[Anthony P.]

Re: BB windage tray studs

I had to bring this thread back to life, and how i found it Ok so I pulled my engine (427/390) a few weeks ago and brought it in the basement for a winter project (no heated garage and live in northern MI) in the mean time I cleaned the engine compartment, "regreased" the Steering Gear box. (Thanks to Gary R for some advice on that) the engine was running just fine for the 40+ years that I have owned the car, I'm bored this winter and thought what the heck I'll refresh the 66 corvette motor, being all others are up to snuff. most of the last few years I've spend building tuning and maintaining my boat engines at 1200 HP apiece, serviceing the drives and gereral high maintiance upkeep on that front. Last night I pulled the oil pan and removed the baffle and guess what happend THE STUD ON #4 CAP FELL OUT (broken) so i thought wonder how long it been like that never gave me a problem but I never drove it like I stoled it. pulled the cap off inspected the brg. all great. Then I get on line and search the archives and fined this thread. I ordered the new designed studs from our local GM dealer for $14.95 each and I NOW have justified why I pulled the engine and will proceed with the refresh, rings, brgs, get rid of the Nylon timing grear etc.etc. Sorry for the long story but sometimes we get lucky before damage occurs. Also it is great to search threads and get the info needed to answer my question as to why this happened. Many thanks to this site and all that make it great.

[Patrick B.]

Re: BB windage tray studs

I'm glad you were able to replace the studs before they lead to a crank bearing failure, like my friend's 396.

[Anthony P.]

Re: BB windage tray studs

yes so glad I decided to go though it now, as my wife and I would like to do route 66 sometime soon with that car.

[Joe R.]

Re: BB windage tray studs

Hi Tony,

Timing is everything! I'm glad you caught it when you did! I'm guess you've heard the horror stories about the first design valve springs (GM 3970627, I think are the second design / ones to use). Are yours original? What do you plan to use for valve springs?

Joe

[Anthony P.]

Re: BB windage tray studs

Joe not positive yet thinck I want to go with an aftermarket retro flat tappet hydrulic with the same stock specs and put in new lifters and springs that are recomended with the cam. I know Crane makes a retro grind and I would have them machine in the rear journal oiling slot. Just a thought. I don't want to go roller cam,