Everyone:
Been a while since I've used the sage advice of this site, but since I've been sitting in Iraq I've had time to ponder my sins. Here Goes. Before I left (darned Army anyway) I finished the assembly of a small block 406 (intake to oil pan) that is still sitting on an engine stand (never run). I thing I missed some steps in the assembly of the motor.

1. I forgot to put thread sealer on the screw-in rocker arm studs. The motor has GM Performance Parts Stage III iron heads. I understand some of the GM pieces have blind holes, does anyone know if these heads do? The last three numbers of the castings are 034. Or will I have a nasty leak from the water passages without correcting this?

2. Motor has a hydraulic roller cam, .509/.528 280/292 I think my Camshaft Endplay was way to excessive. I'm using a Crane camshaft button and an older style ribbed timing chain cover (the one with the three raised spokes that lead to where the center of the cam would be). I failed to address this before I put the intake and timing chain cover on? (I was pressured for time to wrap this project up so I could get to the dessert). Is there a different cam button length or stock type cover that someone could suggest to fix this. I think the recommended endplay is like .005 to .007 and I like had .035 or .040 again I didn't have the chance to check (how do you check anyway?)

3. I'm debating putting a different set of heads on this motor when I get home (before I even run it). The new iron Vortec 206cc units that have hit the market in the last couple months are the likely canidate. Any advice? The GM Performance Heads that are currently on the motor are brand new, very good conventional style units (non Vortec) with 184cc intake runners and 64cc chambers. The have had about $400 of port work done at a very reputable local race shop, this work focused on low RPM flow (the short radius area). I don't think these heads will keep up with the cam from 4000 to 6500 RPM?

3. If I opt to switch the heads, can I reuse the head gasket? GAASP!! I wouldn't normally consider this-- but they haven't been run, they were installed dry, and they were about $30 a piece. I don't want to throw the money away without at least asking. The gaskets are middle line FELPRO race pieces.

4. Bottom End. Mains were assembled with bolts. Can I open the motor back up and switch to studs on the mains w/o complete dissassembly? The idea is to remove one set of main cap bolts at a time, flush the threads with brake cleaner, install the studs (with the recommended thread sealer), snug nuts down. I'll do this work on all the caps before I retorque any of the mains. This would give me the opportunity to install a windage tray.

Thanks for the help guys!!

Unless the casting has changed since the Phase 2 heads, your 034 castings have blind rocker stud holes.
You can check endplay with the pan off and the rockers backed off by prying the cam gear forward. There are a few different length cam buttons, or you could weld an appropriate thickness spacer to your current front cover, or you could buy a super nice aluminum front cover from Cloyes that has the endplay adjustment built in.
I'd keep your bowties personally, and they will handily keep up to 6500, my bowtie equipped 408 will happily rev to 6800.
If the main studs thead in easily with your fingers you should be ok, but if you need to shift the cap at all to install them your housings could distort slightly. A middle of the road approach would be to buy the ARP bolts instead.


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Custom Auto, your source for quality machine work, cores and new parts at competetive pricing right here in British Columbia 1-888-563-4050
A Canadian, EH? (with a 10 second street car)

Thanks for the information and advice. I believe the only real difference between the Phase II and Phase III heads is the Phase III's have a raised and machined valve cover rails to help prevent oil leaks. When I get home, I'll follow your suggestion and pull the valve covers and oil pan to correct the problem. Are you running a REV kit with your 408?

Exact same cam is only good for 11.18 @ 118 with no tuning.. in a 350

I also have the same timing set up and timing cover.
My solution was a water pump cam button stop
I took 1/2" square steel stock 3" long or so.
Drilled a hole in the center for a 1/4-20 bolt and nut.
I drilled a hole on each end to mount the block to the water pumps bottom two rear cover.

To set it up I tighten the center bolt up against the timing cover till I had zero cam end play then I loosened it about a 1/2 turn and checked the end play.
its about .007" and that is just fine.

I run a solid flat tappet cam in my engine, no rev kit.

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Custom Auto, your source for quality machine work, cores and new parts at competetive pricing right here in British Columbia 1-888-563-4050
A Canadian, EH? (with a 10 second street car)

The head gaskets can "usually" be re-used if the engine has not been fired up, depending on the head gasket. While I would personally never do this, I know of at least a few people who have done it with success. There's just certain things I would never re-use on an engine even if it has never been turned over once after being assembled, and head gaskets are one of them.