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Hi, I have a 1961 Bertram 31 with 2 1989 454. 7.4 gas engines. They have Borg Warner velvet drive transmissions. I would like to know if I can replace the Merccruiser distributors with new GM 1 wire distributor ? or is there something in the Merccruiser distributor that operates the shifting in the transmission.Also I have rebuilt these engines completely what is the secret of getting the air out of the closed cooling. They are water cooled .
Thank you Al

Wecome Al,

I think you meant that your engines are fresh water cooled (as opposed to raw water cooled)... There's no secret to getting the air out... Same as there's no secret to getting air out of an automotive engine... You'll notice that your header tank (the tubular tank where you'd expect to see a radiator in an automotive engine) is higher then any other part that has cooling water flowing through it... Any trapped air will naturally flow (be pushed by the FW pump) to this tank... After you have started your engine for the first time let it run until it has reached its operating temp and then some 10-15 minutes more... Turn off the engine and let it cool... Then open the header tank cap and make sure there's enough coolant... If you see that a lot of coolant has gone "missing" just repeat the exercise... If you have expansion tanks the process is similar...

As the FW cooling system is a closed system from this point on you should not see coolant loss... If you lose more then a couple of oz on a regular basis it means you have an issue...

The Velvet Drives are completely independent of the engine as far as operation. No electrical connections except for the neutral interlock switch which can be built into the shifter or mounted on the transmission.

FWIW, on my B31 with 454s I replaced the whole Thunderbolt ignition with an aftermarket electonic. Worked great and never had a problem. Like Rawleigh said, the gears are seperate. As far as the cooling, let her idle and she'll push the air through. Keep topping off until you get the right level. If she was going to take a lot of coolant, I used to add that once the motor cooled.

Just remember marine distributors are sealed unit. Don't just drop in a car distributor or you may create an explosion risk.

thanks so much for all the feedback ,appreciate all the advice
thanks al

I always had challenges getting air pushed through the 454 fresh water cooled Mercruisers. I think the root cause is the height of the goose neck considering engine pitch. I put small .375" diameter holes in the thermostats to help. The small holes help, but a few times I couldn't get all air out and good water flow until I cracked open the goose neck to water water pump hose. Seems like air just doesn't want to push through goose neck because the heat exchanger is at about same elevation.

On my small block's in the B28, I opened up the bolt on the top of the circulator(water pump) on the engine and it allowed the air to escape.

I always had the same issue Mike did. Real pain getting the air out. A small hole in the thermostat is one solution. The other is to just run her with the cap off and keep adding water. As she warms up and the thermostat opens the level will drop.

Then do yourself a favor. Buy an overflow tank like in a car and set it up. Will save you grief if you don't get all the air out. You can just watch the level in the tank and keep refill it easy enough.

Tony Meola wrote:Buy an overflow tank like in a car and set it up.

I have never been able to figure out why expansion tanks are not installed as standard in so many boats...

I bought expansion tanks from Advance Auto. Pretty cheap and easy. They come with a steel mounting bracket.

My buddy ordered specialty expansion tanks for his 350's. Spent a good portion of the day finding the perfect spot to mount, cable tied all the hoses and perfect.

That night I was checking fluids on my motors before we went for a dock and dine. Buddy said we should put them tanks on my boat so I don't get coolant in the bilge. His wife just finished a Bartel and James wine cooler bottle, I grabbed bottle shoved between bracket and hoses on motor, then stuck the overflow hose in it, grabbed a Poland spring, added some water. Been there a good 15 years now. I laugh every time I see it.

Carl wrote:My buddy ordered specialty expansion tanks for his 350's. Spent a good portion of the day finding the perfect spot to mount, cable tied all the hoses and perfect.

That night I was checking fluids on my motors before we went for a dock and dine. Buddy said we should put them tanks on my boat so I don't get coolant in the bilge. His wife just finished a Bartel and James wine cooler bottle, I grabbed bottle shoved between bracket and hoses on motor, then stuck the overflow hose in it, grabbed a Poland spring, added some water. Been there a good 15 years now. I laugh every time I see it.

Carl

What ever works. Looks kind of weird to the untrained eye.

Carl, I have the same setup on my B25.

Rawleigh wrote:I bought expansion tanks from Advance Auto. Pretty cheap and easy. They come with a steel mounting bracket.

It's pretty easy to "roll your own"... All you need is two pump type liquid soap bottles (preferably clear plastic), 1 qt size or somewhat less will do, some hosing and a couple of strips of (preferably stainless) steel... Remove the pump from the cap and insert the hose into the hole... It's best if you have to force the hose into the hole but running a bead of epoxy where the hose meets the cap will also work... Important, the hose needs to go to the bottom of the bottle!... Drill a small vent hole in the top of the tank...

Use one strip of metal to go around the bottle, leave bits "hanging" over the ends, this is where you'll use screws to install it in place... Use a second strip of metal to make a U shape, this will support the bottom of the bottle... Connect this strip to the other strip by welding or pop rivet... It should look like a simple basket... Depending on the shape of the bottle you may not need the second strip... For example, a bottle with an hour glass type shape or a bottle with a top that's wider then the bottom will be self supporting...

Install the bottle ABOVE the level of the header tank!... Run the hose to the header tank's overflow nipple... Usually found near the fill cap... Fill the bottle 2/3 to 3/4 with coolant and you're done... As the coolant heats up and expands the overflow will flow into the expansion tank... When it cools and contracts it will suck coolant back into the header tank...

As long as you visually check the expansion tank level remains between 2/3 and 3/4 full you'll never find yourself low on coolant in the engine... Don't panic the first time you use it and some coolant overflows from the vent hole... Especially if you used a smaller bottle... This would be normal... However, if, once everything has stabilized, you see coolant overflowing make sure to inspect and verify the reason as this might indicate a problem (e.g. head gasket)...

Joseph Fikentscher wrote:Carl, I have the same setup on my B25.

Great minds think a like!