1974 55hp chrysler full throttle issues

[justlookin123]

i have a 1974 chrysler 55hp on the back of my bonito boat its like a 15'. Just off full throttle the motor seems to run fine just cant gain rpms when pushed to full it seems to cut out when turning or hitting a wake i was told timing may be an issue but im not sure as i have never touched it. Motor runs great otherwise starts right up carb has been clean countless times and the diaphram was just replaced in the fuel pump compression is 120 on both cylinders help would be very appreciated thank you. it has the ignition shown in the link

 

[Monte1961]

Re: 1974 55hp chrysler full throttle issues

Sounds like a fuel issue to me. but it also could be timing. What comes to mind, When was the last time a good tune up was done on it? Points and condensers, plug-wires? Post back and let us know what you find.

 

[justlookin123]

Re: 1974 55hp chrysler full throttle issues

is that a points ignition setup? and what type of fuel issue like a carb missadjustment or like clogged fuel line its a two cylinder single carb not much to it? any help would be great

 

[justlookin123]

Re: 1974 55hp chrysler full throttle issues

http://www.google.com/imgres?imgurl...age=2&ndsp=17&ved=1t:429,r:7,s:15&tx=41&ty=54

 

[justlookin123]

Re: 1974 55hp chrysler full throttle issues

that is the ignition setup. i here all of this magnapower talk. idk much about these motors ive always been a johnson-evinrude guy it came with the boat and ran so sweet.

 

[Monte1961]

Re: 1974 55hp chrysler full throttle issues

1. If you have or can borrow an inductive timing light.2. GO to the nearest water(can leave boat on trailer).3. Remove engine cover.4. Attach timing light to top or bottom spark plug wire..5. Start engine,(be careful not to touch anything moving) shift in to forward gear and throttle up slowly as far as you can go in-till your motor starts acting up.6. Check timing light to see if it strobes or very erratic. This will tell us if its electrical or fuel/carb issue! NOTE: also check the other plug wire too as it could be the culprit. If both plug wires check out good, then it tells me a fuel related problem.

 

[Monte1961]

Re: 1974 55hp chrysler full throttle issues

Back boat down onto ramp, and stop just before it wants to float. An extra pair of hands would be helpful!

 

[justlookin123]

Re: 1974 55hp chrysler full throttle issues

ok im a auto mechanic by trade so a normal light would work just fine i will try and see if it breaks up at a standstill on the ramp where would you start if its ignition related? and again i appreciate your help

 

[tater76]

Re: 1974 55hp chrysler full throttle issues

Ok, so I have a 73 55 chrysler that had the same issue. I re-routed all of the fuel/shift cables/electrical, etc. This helped as I found when the motor was turned all the way left it pinched the fuel line. I also rebuilt the carb, fuel pump, and replaced the ignition system with that of a 1985 force 50hp. My main issue with this engine IS timing. I just had it out today on the lake, and it just seemed to be not opening up all the way. I pulled the cowel, and adjusted timing two full turns out on the link. It was like awakening a beast. Before, it would stumble upon higher rpm under no load, and would run slow with a load. Now it is fully open, and happy but it is a little harder to start when warm now.

 

[wickware]

Re: 1974 55hp chrysler full throttle issues

Tater76: When you tweaked your timing and got better power, could you have gone too far out of safe timing range which could cause damage to your pistons? What is your method of timing and is it set to specs or close? I have a 70 35 HP Chrysler and my ignition problems of hesitating, backing off WOT and Etc. has always (since 1985) been dirty points (which I feel affected my timing). I hope I did not twist ?justlookin123?s thread? or magnapower does not have points??
jow

 

[Monte1961]

Re: 1974 55hp chrysler full throttle issues

OK if it starts to break up or not a good strobe on timing light, is it wires, coil/s ect.ect.ect. It will be in the electrical components if it does break up. If it doesn't, then fuel related. Try timing light first and then let us know. @Tater76. If running to far advanced, it will cause detonation witch will be bad JuJu on pistons. Good luck and let us know what you find!

 

[tater76]

Re: 1974 55hp chrysler full throttle issues

I am still within the safe limits (I checked it with a timing light). I thought I had it at 30 degrees BTDC, but it wasn't. I have melted a piston on this engine once before due to a lean carb, and I am not willing to rebuild it again. I learned my lesson I think I read upon a search, Frank A give a breakdown of the proper timing method, ie finding tdc, counting teeth on flywheel, etc. All I can figure is I counted one tooth off, and had the timing retarded too much. It started, idled, and ran well but had no top end power. Occassionally, at wot it would studder too. My adjustments out on the lake were in hindsight, foolish to say the least. I was just sick of only running 17mph at wot, knowing it had more. I got angry, said a few choice words and broke out the screwdriver :facepalm:. I put it in the barrel this morning to check everything over, and all I have to say is that I got lucky. The timing was exactly 30 degrees btdc . Next time I will step away, take a deep breath, count to ten, and use my non-crazy side before making any rash decisions

 

[Monte1961]

Re: 1974 55hp chrysler full throttle issues

Just a tip if you want. When your engine is retarded, you have more bottom end power but no top end power, when its advanced you will have top end power, but no bottom end power. But to much advanced will cause the cylinders to detonate to soon and cause pistons to melt as you already know. good luck and happy boating!

 

[jojowade]

Re: 1974 55hp chrysler full throttle issues

I have a 1985 50 hp with no top end and it has new points, plugs, wires, coils, carburator (rebulit) and it cranks with a touch of the ignition and idles great but throttle up it bogs down and burns alot of fuel. I am hearing a lot of useful information especially concerning timing advance and retard. Could this be my issue? Thanks to all and hope they have helped with your problem. (wade)

 

[Monte1961]

Re: 1974 55hp chrysler full throttle issues

jojowade:Many things come to mind. The first thing is high speed jet sucking to much fuel, or float adjustment. Here is what I would do to test that theory. If you can while your on the water, disconnect fuel line where it starts to bog down and in gear. and see if it will start to RPM. If it does, then you will know if it's carb or timing issue. The reason I say this, had similar problem with a rude motor and found it narrowed down the problem for me as a suggestion from someone else. Post back and let us know what you find.

 

[justlookin123]

Re: 1974 55hp chrysler full throttle issues

i took out for a spin again yesterday it started to stumble then shut off havent taken a look at it. but no restart. i belive i lost spark on lower cylinder any suggestions. how do you adjust the timing on these engines and what range should they be running 30deg. seems like alot but then again i am a auto mechanic not a marine mechanic and please begin your own post if you have a question or issue i to have problems but i dont bombard other posts