1969 L-71 427/435 power steering conversion

[Joe L.]

Re: 1969 L-71 427/435 power steering conversion

Joe, ah the ZZ427/502 cam, a very nice street cam. I like the main bear caps with "ZL1" on them and the use of studs. Very trick. Curious, is that a windage tray? Is it a GM part?

Chris------


Yes, the windage tray is a GM part. It was developed for use in the ZL-1 engine assembly which GM released a few years after they re-released the ZL-1 block. It's a very expensive windage tray and probably is not worth the extra cost over the GM #3873878 or GM #3967854 used in the original L-88 and ZL-1 (and, which I could have used).

By the way, the GM #12366543 camshaft is the one that GM subsequently used in the latter day ZL-1 engine assembly. I did not know that when I selected it because, at that time, the ZL-1 engine assembly had not been released. So, it happened that I selected the same camshaft for my ZL-1 engine assembly that GM subsequently selected for its ZL-1 engine assembly. So, in that sense, my selection was "validated".

[Justin S.]

Re: 1969 L-71 427/435 power steering conversion

Joe,
Are those bosses with freeze plugs on the center facing side of the cylinder walls? I've never seen that if I guessed correctly.

[Peter M.]

Re: 1969 L-71 427/435 power steering conversion

Joe,
Do those roller rockers clear the valve covers?
Thanks

[Joe L.]

Re: 1969 L-71 427/435 power steering conversion

Joe,
Do those roller rockers clear the valve covers?
Thanks

Peter------

Yes, they do using 5/16" Fel-Pro steel core valve cover gaskets. I use valve covers without drippers as drippers are completely unnecessary with roller fulcrum rockers. Plus, I don't like the external "scars" on the valve covers caused by the dripper spot welds.

By the way, I used these rocker arms primarily because of the roller fulcrum. The roller tips may or may not offer any benefit. However, I know of no big block roller fulcrum rockers without roller tips.

[Joe L.]

Re: 1969 L-71 427/435 power steering conversion

Joe,
Are those bosses with freeze plugs on the center facing side of the cylinder walls? I've never seen that if I guessed correctly.

Justin-------


Yes, but they are not conventional cup-type "freeze" plugs. In this case, they are threaded-type, machined aluminum plugs with internal hex drive.

The original GM #3946052 aluminum block also used threaded "freeze" plugs but they were internal square drive cast aluminum plugs. I believe the original blocks also had the lifter valley "freeze" plugs of the type described. External "freeze" plugs were the same. Cast iron big blocks do not have the lifter valley plugs.

By the way, you will note that just to the left and above the lifter valley plugs are bosses which extend to the block deck surface. There are 2 on each side of the block. These are the mounting points for extra cylinder head retaining studs, 2 per side. These studs are installed from the bottom and thread into tappings in the cylinder head. I used ARP studs for all cylinder head bolt and stud positions.

[Peter M.]

Re: 1969 L-71 427/435 power steering conversion

Thanks Joe!