Chrysler 70 HP SKIER does not idle warm

[volundur]

I'have a 15' speedboat up here in Iceland with a 70HP Chrysler on it. It starts good and idles for a bit when it's cold but after cruising, when I disengage the gear it simply dies instantly. It starts after that and by moving quickly enough I can engage (both forward and revers) and rev it up again to keep going.

It is newly rebuilt (new pistons and sleeves), has 150-160 compression on all cylinders, rebuilt carbs, new fuel pump diaphram, new fuel lines.

It also seems to idle on muffs on the trailer, but obviously it would not get very warm on there.

I'm going to clean out the fuel drain this week, but I'd like to hear if you guys have pointers about other things that might be off.

A video showing the fuel recirculation line (I don't really know how it should look, but you might: )
https://www.dropbox.com/s/9wtej24jure3fcq/2013-05-10 17.10.09.mp4

Here is another one that shows how nicely its working when running: https://www.dropbox.com/s/m937jidcjb9db9r/2013-05-15 22.50.15.mp4?m

 

[Nordin]

Re: Chrysler 70 HP SKIER does not idle warm

Do a link and synk as Franks post in the top of the page. You have to adjust the air/fuelmixture needle. As you have rebuilt it, do the link and synk and even a timing. If not you can melt the pistons and that isn?t nice.

I have just bought a 75Hp 1975 with the #3 piston melted. Going to rebuild it with rebore and new pistons.
Why has the piston melt?....... Clogged carb? Have not checked yet BUT the timing was out. The engine has the Motorola beltdriven distributer ign.
The 0 dgr. TDC was out and the WOT BTDC was set at about 20 dgr.

 

[Frank Acampora]

Re: Chrysler 70 HP SKIER does not idle warm

Before you go tearing into the engine, clean or replace the spark plugs. Then see how it idles warm. You should have a tachometer. Idle speed warm IN Forward gear IN the water should be 700-750 RPM. If it is too low the engine will reliably stall when put in gear. You do not need to clean the oil recirculation system: You can CLEARLY see in the video that it is pumping puddled fuel and oil back into the manifold as it should.

What are the carb low speed needles set at? starting point should be about 1 to 1 1/4 turns out. Read my sticky in FAQs: Synchronizing carbs and timing. It will tell you how to set the carbs.

Nordin: One piston melted is almost always due to detonation damage from lean running. These multi-carb engines will run with one carb very lean. instead of losing power, the other two pistons carry the third and it detonates. SO: After you rebuild the engine, pay particular attention to cleaning all the carbs. THEN put a fuel filter between the fuel pump and carb inlet.

WOT timing advance should be 30 degrees BTDC, 32 if you only used auto pump gas is acceptable.

 

[volundur]

Re: Chrysler 70 HP SKIER does not idle warm

Before you go tearing into the engine, clean or replace the spark plugs. Then see how it idles warm. You should have a tachometer. Idle speed warm IN Forward gear IN the water should be 700-750 RPM. If it is too low the engine will reliably stall when put in gear. You do not need to clean the oil recirculation system: You can CLEARLY see in the video that it is pumping puddled fuel and oil back into the manifold as it should.

What are the carb low speed needles set at? starting point should be about 1 to 1 1/4 turns out. Read my sticky in FAQs: Synchronizing carbs and timing. It will tell you how to set the carbs.

Nordin: One piston melted is almost always due to detonation damage from lean running. These multi-carb engines will run with one carb very lean. instead of losing power, the other two pistons carry the third and it detonates. SO: After you rebuild the engine, pay particular attention to cleaning all the carbs. THEN put a fuel filter between the fuel pump and carb inlet.

WOT timing advance should be 30 degrees BTDC, 32 if you only used auto pump gas is acceptable.

Thank you guys, and sorry for the late reply.

I didnt mention that I had already done the sync and link, and the timing is set to 30? - the video you posted on youtube Frank was so valuable to us, thank you.

I think my idle screw is pretty much out by now, but it does not make a thick "clunk" sound when I shift to forward gear. When I disengage the prop going from full speed to a stop (slowly though) it is sometimes pretty hard to shift to neutral - I have to wiggle the lever a bit, is this a problem?

I'm 1,5 turns out on each carb, they are rebuilt by me and my fried, There seems to be a small fuel leak from one of the carb bowls (despite new gaskets). - could that be the problem?

I'm going to hook the tachometer up next weekend. and get readings at idle, it just seems so weird that after 10minute run on WOT the engine just goes dead when I shift to neutral. - If I fish for a while (5-10 minutes) it starts right up again in less than a second.

I'll send you guys a new video I made last week - it's pretty awesome to have the boat running now, but we need to get it to idle perfectly : )

Sigling ? eyfirsku s?larlagi - YouTube