manifold guage on 5.7 volvo

[Bushwacker]

Just realized I sort of got off on a rant and didn't answer your question regarding other gauges! Monitoring key parameters is a good idea and something we always did on experimental engines to catch problems before they caused a failure. Sometimes it even worked! Did performance work on jet engines for the first 10 years of career at Pratt, and became a bit of a fanatic on instrumentation. It used to drive me nuts when guys would use a 500 psi transducer to measure 30 psi, when they should have used a 50 psi 'ducer! Accuracy is always a percentage of full scale reading, so smaller ducer was 10X more accurate. This is why I prefer mechanical gauges with their 270 sweep where you can use a large scale, instead of the small, compressed 90 degree scale on electrical gauges. Electrical gauges are less reliable, especially on a boat. Digital gauges can provide tons of info, but take some getting used to. Our brains don't process digital info as quickly as position of a pointer on a dial! That's why you don't see many digital gauges in race cars!

The vacuum, water pressure, oil temp and fuel pressure gauges will give you a good idea of what's normal for your engine. Helps to stick a small piece of green tape on gage at "normal" pointer location; then a quick glance will pick up a potential problem.

We used audible alarms for the really critical stuff on the Pratt engines; they can be a pain, as they go off when key is turned on, but many industrial engines use them, so could consider for oil pressure and water temp. Only other thing I can think of is some way to monitor oil temperature in lower unit, but don't know if Volvo makes anything for that; might check the aftermarket.

Be careful with the plumbing on that fuel pressure gauge! I believe Autometer uses a diaphragm with theirs to minimize amount of plumbing with gasoline in it. The diaphragm goes between the fuel pressure source and the tubing running to the gauge, which I think is just a very sensitive air pressure gauge, but calibrated to read fuel pressure.

That sounds like a very efficient power package in your Seafari . . I'm sure the Forum members would be interested in some performance numbers, especially those considering a conversion to outboards! Denny

[cdavisdb]

Thanks very much for the imput. It confirmed my suspicion and I will be adding a manifold pr guage. On the fuel pressure, volvo has a nice access point in the high pressure line, very simple, for once. I like manual guages, too.

I get my baby back from the mechanic this week and will publish some specs as soon as I can get them. My last boat, 24 Seabird, 5.7/duoprop, (its for sale, cheap, hint hint) with stainless props) is very fuel efficient. The weight is the same, so I'm hoping for good things.

Connor

[nestorpr]

Connor, is that the 570SP engine? If it is I have the same one but mated to a 280 drive, I'd love to change it for a duoprop. How does it work for you?

[cdavisdb]

(I think) The 570sp is a pre-vortec GM block. Mine is a 570gsi, the first fuel injected model and I think the block is a vortec, the water pump looks the same. My old setup started as a 570dp, same engine as you with a 290 duoprop Basicly same engine in all of these. The vortec is a lot quieter, but I don't know why.

You would LOVE a duoprop. For me it was kind of like power trim. The idea makes sense, but you don't really appreciate it until you have one. I would no longer even consider an i/0 without a duoprop. Warning, the difference in handling, particularly backing up, with make you crazy for until you get used to it. For me the greatest advantage is low end torque. My Seabird would stay on plane down to 11 knots(oversize tabs and drive all the way down). The ability to run slow, but still solidly on a plane, when it gets snotty is a huge boon. I can't say it runs any faster, but it sure is efficient.

[cdavisdb]

The one thing that is a potential disadvantage of the duoprop, which might be important to some, is the instant acceleration; the thing doesn't slip at all. Hole shot is very fast. Put it in gear and don't give it any gas until it starts moving. If you do goose it even a little and are not holding on, it will jump so quick that you will end up sitting on your rear end in the back of the boat. Conversely, if your carburetor is a little large, or the engine doesn't like a bunch of gas before its rpms can catch up, it may stall.

[nestorpr]

Thanks for the advice and the great mental picture of me on my ass and the boat running wild, ha! As soon as my economic condition improves I'm going to try and improve my boat with a duoprop.