1957 35HP Big Twin (hitting hard Knocking)

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

Update, after looking at cables, battery, connections I narrowed it down to Starter. It worked well without plugs with nice cranking, but once under load (plugs in) struggled weak... So, installed new one and the motor that wouldnt even budge is now turning over. Now to replace the lower unit that is well rusted beyond its years and replace with my other lower unit. Thank god for a spare engine!

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

Question, this motor is LOUD.... I mean its pretty loud compared to my other. Is seems like the pistons are hitting hard... Since it has been dormant for over ten years, Can I put some kind of lubricant in through where the spark plugs are? Will that do anything?? The compression test upper 110 and lower 100 Not bad and I can feel the power its producing compared to my other motor which was 70 each plug on compression.

 

[kfa4303]

Re: 1957 35HP Big Twin (hitting hard Knocking)

HI big. While you could spray some lube into the cylinders, you shouldn't have to. Are you using 24:1 mix? What brand spark plugs are you using? Perhaps they're too long and the piston heads are hitting the. You should be using Champion J6C or J8C plugs. Here's a vid of a motor similar to yours running so you'll know what to expect.

1957 Evinrude Big Twin barrel test - YouTube

Evinrude Big Twin 25HP Outboard - YouTube

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

Ok, plugs are exactly what u spec out...as for mix I'm at a 30:1 mix...I will add a tad more oil...TY

 

[nwcove]

Re: 1957 35HP Big Twin (hitting hard Knocking)

30:1 as compared to 24:1 wont cause "knocking " or loud running. your timing may be a bit advanced. you could do a decarb on it and see what happens.

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

Question.. Carb settings 1 1/2 slow and 1 fast.. I end up with 1/4 left from closing on slow (TOO LEAN RIGHT) and 1/2 left on fast... I adjust the slow 1st? or do I adjust fast 1st? If I leave at initial settings engine dies. Did a carb rebuild, float set at level to slightly up...

 

[nwcove]

Re: 1957 35HP Big Twin (hitting hard Knocking)

Im a bit confused by your post earl. Are you setting the needles using the numbers on the cowl, or starting with them gently seated and opening the slow speed one and a half turns and the high speed one turn?

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

seated slow and opening

 

[nwcove]

Re: 1957 35HP Big Twin (hitting hard Knocking)

I get ya now. Not uncommon to have the ls needle at 1/4 turn out for best idle. You really cant do much with the hs needle until you are on the water. ( spark plug color will tell if you are running on the lean side)

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

The reason I question is because I cracked the block if you recall on my 35 Big Twin and I dont want to run to lean and do that again? Now, 1/4 out and say 3/4 out on the HS... WHEN COLD I try to start and it wont until I get it back to 1 1/2 and 1... After it runs for 15 secs then dies.. I adjust the needles to 1/4 out 3/4 and it starts back up and keeps running. Why do I have to play around with these nobs everytime it gets cold. Is that normal?

 

[nwcove]

Re: 1957 35HP Big Twin (hitting hard Knocking)

Is the choke working?

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

yes, unless I go to lean, then I cant choke it out...

 

[nwcove]

Re: 1957 35HP Big Twin (hitting hard Knocking)

Are you using the choke for cold starts? You would have to do alot of pulling without choking a cold motor.

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

I have to turn knob all the way in then dies or all the way out (1 1/2) then dies.. Im able to choke out and kill engine only if Im about 3/4 turn in from 1 1/2 (or in other words about the 1/2 way point)

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

Electric start, but yes using choke, then turns on, then eventually dies.... Then I turn knobs in some to start and finally to about 1/4 SS and 1/2 HS or so... When cold again (next day) I cant get started unless I back it out all over again

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

Does Idle screw effect any of this?

 

[nwcove]

Re: 1957 35HP Big Twin (hitting hard Knocking)

Ok, but are you using the choke when starting the motor cold?

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

Yes

 

[nwcove]

Re: 1957 35HP Big Twin (hitting hard Knocking)

Does the motor have the neutral safety stop ( will only open to half throttle in neutral?

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

Yes