Vmax

My 454 was already set up with a B&M 174 when I purchased it. One thing that has perplexed me is the vent tube from the mechanical fuel pump leads to spark arrestor top to dribble any fuel if diaphragm fails which is normal. However the plastic tube from fuel pump also has a T in it and another vent line to a tap that screws into the top of the intake. I 'm guessing tap leads to the #2 intake runner. Any ideas why the builder would have done this? I'm thinking this hole to the intake should be closed off. Is this a normal 174 set up or some add in attempt to control fuel pressure with boost? There is no fuel regulator which was my first thought. I find it hard to believe this hole would not pull vacuum or feed back some boost pressure. Boost pressure tab is to #7 runner and also provides boost reference to carb with a T and pressure line.

I'm also trying to figure out the correct method to change the gear oil to the blower. I can not see any obvious oil fill or drain holes externally on the case. Taking off the case ends appears to cause a nice bilge mess. Do you take the hole gear drive housing off and drain out of the boat. Also where do you obtain replacement gaskets or are the reusable. It's a 100 hour maintenance item and I have a ways to go yet, but would appreciate any worked for me advice. Also is there any way to check oil level between changes in the blower drive?

Gary Anderson

Lose the tube to the manifold. If anything, you're losing boost pressure into the spark arrester AND intenally in the block unless it's fitted with a one way valve. You only need to increase fuel pressure on blow through carb supercharger systems.
I've had 177s, they have a plug on each end cap that is removed to check oil level. That was removed with a syringe and tube. You sure there's no plug/screw?
Gary

Vmax

Did not see any obvious oil check ports on the end caps. Could be missing them. Are they high or low on a 177. Never thought of the valve issue. Maybe this port is a poppet valve designed to open at a predefined boost pressure? Makes since to feed gas back into the carb for explosive atmosphere issue. Anybody else with a put?

duunoit

iTrader: (1)

On my B&M 174, there is a allen head fill screw on the top of the case stb side. If you look at the front of the case directly below this fill hole, there is another screw about two inches down that looks just like the fill hole. You may not be able to see it if you have the stock thermostat housing on the offset from the manifold.

Chris

Vmax

I have the offset installed for the thermostat housing. That must be issue. Looks like I'll have to remove the offset to drain case.

HiPerf2000

iTrader: (2)

You will have to pull the blower off to change the oil. There is a fill plug on the top of the front plate, and a "sight" plug in the middle of the same plate.

I usually take out both screws and support it upside down overnight at an angle where the oil will drain. Then to fill with oil, put it on a level surface and fill the top plug hole untill the oil comes out of the bottom plug hole.

you may be able to see the top plug in this pic. it is the purple plate in front of the chrome bearing plate.