Is there a gasket or O ring under the 420 blower?

While we are on the topic of the B&M 420's.

a) What is the measurement on the idler pulley shaft for the belt tension?
5/8-3/4"???????
b) the blower to intake mounting bolts torque....... 30ft.lbs?

BTW, I used 80/90w gear lube for my 250 blower

with the 575SCI there is no drain port. I spoke with merc Racing tech line, wanted to see if they had any tips etc- my main concern was not to chip the paint etc.

The tech I spoke with suggested I use something (don't drop it in there) as a dipstick just to verify there was no sign of oil contamination shavings or glistening small flakes etc. He said if the oil looks good and its at the right level in the window- run it. I asked why my service manual suggested changing it- he said they had to put something in there to make people at least look at the window. Laughing, he said that the merc hi perf gear lube in there would be fine with a bunch of hours, just change it when it's time for a rebuild.

Do what you want- I tend to believe him, yes theres some RPM's, but relatively no mesh load on the gears or side load on the bearings- pure spinning for the most part. Think about the kind life in there relative to what the Bravo sees.

Last time I looked, the 420 blowers on my 800SC's bolted directly to the heads (one piece manifold). The Merc manual does not stipulate a lube change interval for that blower. The intake manifold bolt torque is stipulated as 35 ft lbs. Again, nothing highlighted for blower vs intake manifold application. Like all BBC applications, manifold sealing is a bit touchy. Merc manual says their intake gaskets have 'up' marked on them. They recommend a 1/4" bead of Forma Gasket across the front/rear of block between heads with a 1/4" overlap of the intake gaskets. They call for Quicksilver Perfect seal on both sides of intake gaskets by the coolant holes. Follow normal BBC sequence for torqueing intake bolts starting @ 15 ft lbs. Everyone has their preference for gaskets, adhesives, etc. but this should provide a starting point. Good Luck!

Hi-Jack....

I could not find a drain plug on the starboard side of my 575 block- is that normal or am I missing something? I've got a single and a large bay, got my head in there pretty well with a light etc.

I got all the normal CMI, coolers, low hoses etc and of course the port side block drain. Supposed to hit 25 degrees tonight.