350 aft cabin

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sabrejocky

Member
Joined
Sep 11, 2003
RO Number
12195
Messages
557
Hi,
everyone. I was hoping to get some performance and propellor specs from other owners.
My friend has a 1993 350 with Volvo 740 engines (GM 454), the port engine is a new long block and the other has a fresh top overhaul. Both engines have new manufolds & risers, carbs and fuel pumps.
For some reason we are only getting 3100 port and 3300 on the other, this translates to 18.5 knots.
Both engines run smooth and strong with no indication of there being any engine issues.

Looking to hear from others what kind of numbers they get and what props they have before we remove the props to have them reworked.

Thanks
 
Spec rpms for big blocks are 4200-4500. First checks are if the hull is clean, props in good shape-if yes, check timing and proper advance-springs on advance weights are problematic. After that...tune up. If al things check out, assuming this is a new boat to the owner, maybe it is over propped? As boats age, get heavier....props pitch needs to be adjusted to compensate. If the boat ran at spec rpm's previously, sounds like tune-up or timing issue.
 
It is a "new" boat to this owner. He bought the boat with a damaged port engine, so we have no idea how it used to run in the past. All the stuff you described has been done and checked and double checked. So now it is down to the props. That is why I am looking to get some numbers from other owners to compere to.
 
Even over propped, top speed should definitely be better than 18.5 knots. I would expect that speed at the RPM's the boat is running, assuming proper props are installed.
 
A little disappointing, I had really hoped to get some feed back from other owners.
 
Call Carver yachts and ask for Rich Brown in the archives section. He can tell you what the factory specs were for those particular engines.

Bob
 
No you are not chopped liver, I was hoping to get real world numbers from owners with the same boat so we can see if it is the props or that there is still something not right with the engines.
I have called Carver in this and they where not helpful, some how they do not have the specs for this build.
 
You are not getting anywhere near the WOT R.P.M.s you should be getting.

I assume the Volvo is very close to the Merc/Crusader brother 454's. My 1994 370 is getting a 20-21 mph cruise at 3200 RPM and 32-33 mph WOT at 4400, my boat is heavier, wider, and longer than the 350. My props are 22 X 23 Four blade props and are factory original.
 
My '89 Santego 380 (34' with 4' of bow pulpit and swim platform) 41'8" overall cruises at 17-18 MPH at 3200 RPM with Crusader 454/350 hp engines-knot speed numbers would be less. At 18.5 knots at 3100-3300 RPM, that seems inline if not higher than what would be expected-I have 4 blade props as well. The only issue seems to be WOT which is well below the spec RPM.
 
Thank you for the responses, those give me something to work with.
It sounds like these props could be about right after all and that we still have issues with the engines not producing the power. We have not pulled the props to have them scanned but the survey reports them as 4 bladed 22x21.
I have been reading up on others that have had problems with engines not getting much over 3000 rpm and found some saying that they found the distributor to be the issue, guess something else to give a closer look.
 
Well I contacted Rich Brown and this time got a response.

Cor,

The factory installed engines were twin Volvo 740/MS5, 2.4:1 gear reduction, 305hp rb2@gr5t 4400 rpm. Factory recommended props are Michigan Wheel, 22 x 21, 4- blade. Performance testing for this model/engine combination indicates recommended cruise, 3200 rpm rb2@gr5t 21 mph. WOT was 4500 rpm (trimmed) reaching 33 mph.

Rich Brown
Int’l Aftermarket Support Mgr.
Marquis Yachts, LLC

Looks like the speeds I was seeing might be a little high for the rpm, 18.5 knots at 3100, maybe a little over propped.
Going to take an other very close look at the ignition systems, probably swap distributors and see if the port side will run up higher than and the starboard losing some.
This would indicate a problem with the electronics, this is on advice from prestolite. Will be swapping out the coils to for upgraded ones, weak coil(s) could also be the cause.
 
I hope your rpm gauges are right if they are sounds to me you might have a bad fuel pump.
 
Yes it looks like you are right, Here is what I could find with the serial# 4100140606

Technical data

Engine 740B

Production period 1992-1993

Operation 4-stroke

Cylinder configuration V-8

Bore (in.) 4.25

Stroke (in.) 4

Compression ratio 8:1

Displacement (cu. in.) 454

Power (hp) 330

Max engine speed (rpm) 4400
 
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