Crusader 270 not getting rpm

[buladave]

Any ideas, I cant get full rpm at full throttle (4200) per manafactures data. I am getting only 3200 rpm and speed of 23kts.I have checked timing and general engine condition all seems ok?Running rochester quadrajet crbs with the manafactures 4 bladed props.OH the boat is a 1985 Carver Monteray.

 

[pasogrande]

Re: Crusader 270 not getting rpm

Start by looking at two very different areas. If this is an old problem you may be overpropped. Try borrowing one with less pitch. If it has only started recently, I bet it is the Quadrajunk carb. I have the same problem on a Santego 27 with the Mickey Mouse engines. I swapped carbs, and the problem went with it. I will pick up the overhauled carb this afternoon.
Hope this helps; but come to think of it you could just have fishing line around the prop.

 

[buladave]

Re: Crusader 270 not getting rpm

Thanks for the reply. Interested what are the mickey mouse engines? Since buying the boat as a great deal with an untested new r/h engine and a operating l/h engine.I have since found out that the new engine is the incorrect rotation Arghh.We have had to change out the cam to get it turning the correct way, and unfortunatley with my style of transmissions the engine installation is opposite to most twin engine installations.I must have the same Mickey Mouse set up!! Back to the carbs I am thinking of getting new ones as well just so to eliminate that as a cause.Will hop into the water this weekend to check the props again.

 

[pasogrande]

Re: Crusader 270 not getting rpm

Sorry I took so long to check back.

The engines are Mercruiser 3.7LX. They took one heavy cast iron cylinder head off a Ford V-8 and made their own aluminum block with steel sleeves. The result was a four cylinder with excellent torque and power for its weight. They also put the alternator inside the block! By changing the distributor from points to electronic, and changing to an automotive style (but marine) alternator, you have an unreliable engine which produces 180 hp.

My biggest problem has been the Rochester Quadrajet carbs. I replaced one with a "new" one from National Carburetors in Jacksonville Florida and just received a second one from them. With a bad carb one engine simply would not go above 3000 rpm (and not above 2500 if just one engine was used) I have been working with a top carb shop and they and a couple of mechanics are completely baffled. Maybe the new one will solve everything!

 

[Megaslime]

Re: Crusader 270 not getting rpm

Any ideas, I cant get full rpm at full throttle (4200) per manafactures data. I am getting only 3200 rpm and speed of 23kts.I have checked timing and general engine condition all seems ok?Running rochester quadrajet crbs with the manafactures 4 bladed props.OH the boat is a 1985 Carver Monteray.

I have a 1985 Monteray 29' and have the same trouble after new carbs Rodchesters seems to run better but not real great as yet, Please keep posting I need all the help ya give.

 

[Tommyfmu]

Re: Crusader 270 not getting rpm

With a bad carb one engine simply would not go above 3000 rpm (and not above 2500 if just one engine was used)

If just one engine is being used, I'd recommend not going above like 2000 rpms (hull speed). If your boat has two engines it's for a reason and chances are you'll never plane off on one so will just burn a ton of fuel and put undue stress on the one motor.

Make sure your fuel filters are clean.

Although my new (to me) boat is supposed to have Rochester Q-Jet carbs on my Crusader 350XL's, the guy before me had Holley 4 bbl carbs. I just had them rebuilt because they were all funky but now work great. My mechanic though told me that they're way higher performance than I should have, and they will probably give me many more problems than the Rochester's.

 

[Captain Pierre]

Re: Crusader 270 not getting rpm

Hi, I have a 3207 Aft with twin Crusaders 270 (350 GM V-8) and my port engine played all kinds of tricks. It was spurting white from the exhaust and sounded weak last summer. At high speed the rpm would drop from 4000 to 26 to 3000. If I took the throttle and brought it down to zero and back full the rpm would get back up for a while.

This year it ran ok. Had my mechanic adjust the timing and change the plugs in the port engine. It ran strong foe a while. Last week en we returned from two days off the Rideau canal and put the boat in the slip at our marina for a bite to eat. When I went to go out the port engine died and refused to start again.

My son, being a military mechanic, started trouble shooting and got to the fuel and the lines were dry. I immediately went for the fuel pum. I have one ordered and will be installing it tomorrow and will let you know.

An old sea woolf told me that mechanical fuel pumps will usually send you warning signs before quitting completely.

Stay tuned.

 

[Tommyfmu]

Re: Crusader 270 not getting rpm

At high speed the rpm would drop from 4000 to 26 to 3000. If I took the throttle and brought it down to zero and back full the rpm would get back up for a while.

When I went to go out the port engine died and refused to start again.

Same exact problem occurred with my port motor as I was driving her home for the first time last summer, as you described. It turned out not to be a fuel supply problem, but the distributor was going [not the dist. cap], then died. Changed it out and problem solved.