Can't get past 2000rpm

Engines, Shafts, Steering, Struts, Rudders, etc.
Leviathon
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Can't get past 2000rpm

Post by Leviathon »

Hate to do this, as am sure it has been addressed somewhere on the site. But what do I look for on an engine that will not get past 2000rpm? I am thinking maybe springs in distributor? Don't see any issue with fuel, but who knows. Just frustrating as the Port goes to 3500, while the starboard will not get past 2000. :?
Steve and Mary Levi
1973 32' Marinette Fisherman
SBC Crusaders
El Ohssa
St. Joseph, Michigan
TinLizzy
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Location: Lake Superior-Michigan's U.P.

Re: Can't get past 2000rpm

Post by TinLizzy »

Start with a timing light, check timing, and check that every cylinder is firing when it is at 2,000 rpm. Also check that it is advancing. It could be a whole bunch of different things. Distributor not advancing, no spark on a couple cylinders, fuel line restriction, carburetor has gunk in it, low compression. Start with the ignition system and work towards fuel. I was recently working on a boat with a 305 chevy engine with a Prestolite distributor that would loose spark on two cylinders under load past 2,220 rpm. Changed cap, rotor, points, condenser, plugs and wires. Pulled distributor out and cleaned and inspected it thoroughly, That did not fix the problem. Apparently, after getting some load on the engine, the distributor had enough play in it that it would wobble enough to loose proper clearance between the cap and rotor. Installed a new Delco electronic distributor in it and it ran great. I know there are differences between Chevy and Chrysler distributors, but they still function the same way.
Rodney
1975 28 Express-Twin 350 Chevy's, SOLD
1990 32 Express--Twin Mercruiser 454 with Bravo I outdrives
Portage Canal Waterway-Upper Peninsula,Lake Superior
jralbert
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Re: Can't get past 2000rpm

Post by jralbert »

First try the simple step: change the fuel filter at the mouth of the carb (where the fuel enters the carb). It's the small (finger sized) filter and I think the number is CG 11. Don't know why, but when that thing clogs, the engine wants to stall if you push it above 1,800-2,000 rpms
-joel-
former owner 1988 '32 FB Sedan
Chesapeake Bay
twin 318 / 240 hp
Potomac MD
CaptainOpus
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Location: East of Cleveland

Re: Can't get past 2000rpm

Post by CaptainOpus »

I had something like that come on very suddenly this spring. Went through the whole ignition. Ended up being a failure in the 5 pin ignition module. replaced it with a heavy duty version and viola, ran good. Also found out that there is many levels of performance with these. Make sure you get one rated for around 6000 rpm. Just my experience. Hope you get it fixed.
Chris
ericinga
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Re: Can't get past 2000rpm

Post by ericinga »

Second Rodney's comments. Start with a timing light and tachometer. See if the distributor is advancing. Should see initial timing of 3-5 degrees BTDC and advance of 24 degrees at 2500 RPM. In my experience, 318s/360s seem to be happier closer to 8 degrees.

The Mr. Gasket advance spring set 925B works well for the lower RPM advance (lighter spring). You can also try the 928G spring kit. Both kits are available through Advance, Autozone, NAPA or O'reillys. The trick is to use a fish weighing scale and measure the spring tension. Finding the perfect spring is trial and error.

If the ignition is advancing, check the individual plug wires. My test is to pull one wire at a time and watch the diagnostic tach. The RPM should drop about 12% for each cylinder. If you pull a wire and the RPM does not change, it is not firing correctly. Check the plug and wire.

If you're lucky, a friend might have one of these tools to make testing easier. http://gtc.ca/Products/TA500.html

If timing is correct and plugs / wires are fine, check your grounds and power. The ECM is sensitive to proper ground and voltage. If the ECM receives less than 12 volts, it will not provide enough spark at RPM higher than 2,000 (in my experience). One simple test for grounds: Add a ground wire to the ECM or the coil. If you're problem improves, work through all of the grounds and clean them up.

If that doesn't work, check the vacuum and fuel pressure. Vacuum pressure will tell you alot about the engine health.
Eric Spies
1989 32 SDFB
Twin 318s
Lake Lanier, GA
Marinette Boat
honestcharlie56
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Re: Can't get past 2000rpm

Post by honestcharlie56 »

Just a thought to add. Do not start adjusting things. Its a very common rookie mistake to start adjusting timing, carb screws, etc. when a small problem shows up. Also, always solve one problem at a time. As posted above. I would make sure that advance mech. is free in the distributor and that you have a free flow of fuel to the carb. Feel free to to check the plugs to see what they can tell you, don't react immediately to what they tell you though.
1990 Marinette 32 Sedan Flybridge "Hubba" Lake Charles, LA
Twin Chrysler 318's
Leviathon
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Re: Can't get past 2000rpm

Post by Leviathon »

All good thoughts - let me catch up and see what I can find out based on what has been shared!
Steve and Mary Levi
1973 32' Marinette Fisherman
SBC Crusaders
El Ohssa
St. Joseph, Michigan
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tundrarules
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Re: Can't get past 2000rpm

Post by tundrarules »

If anyone has been messing with plug wires make sure all plug wires are in correct firing order on cap and plugs. One plug wire mixed up will kill your power. Found this problem on my boat when I bought it. :roll: :roll:
1985 29 Sedan
Edelbrock 1409 carbs
Mallory distributors
Pertronix Flame-Thrower coil & wires
780 hrs/eng
TN River, MM 213.8

:mrgreen:
spdracer
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Re: Can't get past 2000rpm

Post by spdracer »

Distributor advance will only get you 200-400 rpm max assuming it was timed correctly when it was right. I would start with a compression test. You can't tune a sick engine.
Chris Hamann
Lakeland Auto & Marine
Port Clinton, Ohio
bobv
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Re: Can't get past 2000rpm

Post by bobv »

I had a simalliar problem, turned out to be barnicals on the hull.
Bob
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