Finished rebuild. Starts and revs to the moon!!!

[brandonv]

So I finally got around to finishing my 120 L-Drive build (new crank, pistons...the works). I button her up and press the magic button and she fires to life. YES!!!!! And then begins to scream at high RPM's like there's no tomorrow.

Turn the key off, nothing. Pull the wire from plug 1, nothing. Plug 2, nothing. 3, nothing!!! It finally dies after pulling all 4 plugs. So I throw a few tools around, create a few new swear words and begin to think. I've either got an air leak on the intake side, my timing is way off or its possessed. Air leak is certainly a possibility. Timing off is a possibility also. Possession is for damn certain!

Any idears!?!? I'm not 100% sure the remanu crank I got was from an L-Drive motor. The gentleman sweared up and down it was, but I kinda had a weird feeling about the transaction. Could my timing be way off and cause this?
Isn't it heat that'll cause a 2-stroke to run without spark? Will a 40 cal. slug penetrate the block? About to find out.....


Edit: I checked the carb sync and it looks good. Both butterflies are fully closed with the throttle at neutral and it still revs like mad. Opening throttle has hardly any effect on RPM's since its already spinning so fast.

 

[lmannyr]

Re: Finished rebuild. Starts and revs to the moon!!!

Recheck your intake and carb gaskets. Recheck vacumes. Any pics?

 

[brandonv]

Re: Finished rebuild. Starts and revs to the moon!!!

Recheck vacumes.

What do you mean vacuums?
I can take any pics necessary, just say where.

 

[lmannyr]

Re: Finished rebuild. Starts and revs to the moon!!!

I'm not familiar with this PARTICULAR engine but on automobile engines there are vacuum hoses that can some times rev up the engine. Never heard of a vacuum hose rev up and engine as yours but it's worth a try.

Sounds more like a gasket leak on the carb or intake.

I'm sure someone with more knowledge with these engine will chime in.

 

[brandonv]

Re: Finished rebuild. Starts and revs to the moon!!!

It was the timing. I retarded it 2 turns (not sure how many degrees it was) and it runs like a champ now. Oh, what a relief!!!!

Thanks for the advice folks! Hopefully this post helps someone in the future.

 

[lmannyr]

Re: Finished rebuild. Starts and revs to the moon!!!

Good news!! Never knew the timing could rev up the engine as much as you described. Glad it's fixed!!! HAVE FUN!!!

 

[Bigprairie1]

Re: Finished rebuild. Starts and revs to the moon!!!

Glad to hear you got the problem solved Brandon. Not many people seem willing to take on the L-drives and actually succeed it seems. Its great that you stuck with it. Keep us posted on how it runs and performs as it is not often there is too many positives said about them. I know I'm curious as well.
Good luck.
BP

 

[brandonv]

Re: Finished rebuild. Starts and revs to the moon!!!

I took it out on the Willamette today for a trial run. Verdict is..... all systems go!!!!

I put about 1.5 hours on the motor today and it ran great. I have a slight hesitation off idle, but once it gets past that it pulls like a train. I'm surprised how well that little 120 moves a 19' cuddie cabin. I also didn't realize how tired the motor was when I bought it last year, but it feels much better now.

Thanks for the kind words! It feels great to rebuild it from scratch and enjoy the fruits of my labor.

Now I need to change the gear oil. Anyone know how much oil it takes? I dont want to buy 2 qts and find out it takes 4.

 

[Kajun37]

Re: Finished rebuild. Starts and revs to the moon!!!

did you do the proper break in for a rebuilt engine?

 

[brandonv]

Re: Finished rebuild. Starts and revs to the moon!!!

did you do the proper break in for a rebuilt engine?

My break in process doesn't quite follow the manual, but I do avoid anything beyond 1/2 throttle and constantly vary the RPM's with a 25:1 mix for the 1st 15 gallons. This was after 4 heat cycles in the driveway.

I probably only burned 5 gallons yesterday, so the break in continues next nice day. Thanks!

 

[daydreamer1252]

Re: Finished rebuild. Starts and revs to the moon!!!

Yup,

Sure is sad to HAVE to go out and use the boat like that! Hope your nice day comes soon!! Great to hear that another Chrysler/Force lives! Hope it lives a long life, too.

 

[CharlieB]

Re: Finished rebuild. Starts and revs to the moon!!!

Slight throttle hesitation is still a hair lean on idle mixture.

Adjust to best idle in gear plus about a blade width of a turn out.