L18 engine back fires through the caburator.

[Russel]

Afternoon. Just swaps a J15 by an L18. Fire the engine and it back fires. My question is how far can i advance my cam. Which markings to follow cz it seems to me there are a lot of markings on the sproket.

 

My previous gearbox was longer. Which model propshaft must i use now for the short 5 speed.

[banzai510(hainz)]

So your distributor in correct and timed correct?

 

maybe the condenser is bad?

 

so you removed the the cam and reinstalled?

you use the Brit links on the chain

you turn the crank Turing right you run it up to zero on crank and stop then look at the cam they the hole and should see the mark where the v on cam lines up with the dash.if that is correct then it’s good

the look at the dist and the rotor should be lined up on plug #1 if it in between 2 cylinders and you can’t more adjustment you need to pull the dist and look at the oil pump spindle and make sure it’s like in the 11/25 11/28 position.if not you got to lower the oil pump

Edited May 10, 2020 by banzai510(hainz)

[datzenmike]

For the spark plug to fire when an intake valve is open causing a back fire, it would have to be advanced at least 116 degrees above it's 12 degree setting. This is impossible unless the distributor drive gear was put in wrong.

 

Check your firing order 1,3,4,2 in a counter clockwise direction. 2 and 3 may be reversed.

Check that all valves have some clearance when closed. If an intake is not closing it will stay open and a back fire when the cylinder fires.

 

There are only 2 sprocket timing marks, one on the crank and one on the cam sprockets and these are lined up with the bright links on the timing chain. It's fool proof.

 

OR

 

Are you meaning the pulley marks on the crankshaft?

[Russel]

I will go through the sequence again. Will also replace the condenser. I am confidant on my timing the dash and groove are in synch. But let me go all the seqeunce again will check firing order ro certain myself.

 

Thanks.

[banzai510(hainz)]

Mike that’s a good drawing

 

the punch mark is usually in the 3.30 position a little higher but that is right

ley is having the brute links on the chain and a cam sprocket(Japan) made one with the 4 holes

or if one has a used brite link chain one can put a newer Taiwan chain next to it and put white paint on there instead of counting links

i also suggest do not buy the Melling or Cloyes brand kits as they have the 3hole sprockets and won’t be able to see the v notch and dash to cheaply cam timing

Edited May 10, 2020 by banzai510(hainz)

[datzenmike]

 TDC on an L18 is when the timing pointer is on the last groove on the front pulley. Then check the V on the top sprocket's relation to the horizontal etch mark behind it.

 

[Russel]

4 minutes ago, datzenmike said:

 TDC on an L18 is when the timing pointer is on the last groove on the front pulley. Then check the V on the top sprocket's relation to the horizontal etch mark behind it.

 

I have the exact markings lining as on pic. Could the chain has streched.

3 hours ago, banzai510(hainz) said:

So your distributor in correct and timed correct?

 

maybe the condenser is bad?

 

so you removed the the cam and reinstalled?

you use the Brit links on the chain

you turn the crank Turing right you run it up to zero on crank and stop then look at the cam they the hole and should see the mark where the v on cam lines up with the dash.if that is correct then it’s good

the look at the dist and the rotor should be lined up on plug #1 if it in between 2 cylinders and you can’t more adjustment you need to pull the dist and look at the oil pump spindle and make sure it’s like in the 11/25 11/28 position.if not you got to lower the oil pump

Will check the condensar. Its the only old component in the engine bay

 

Thanks

[Russel]

Thanks to all for yours responses with such feedback highly appreciated. 

 

My second question is the propshaft?

[datzenmike]

To test the condenser just disconnect it. If engine stops backfiring then replace it.

 

 

This is a 620?? year??? I forget, maybe put this info in your profile.

 

Short 5 speed like 26" (66cm) Did any of your 620s come with a short transmission?

[banzai510(hainz)]

If I remember right condenser will make it worse If not in there. If bad but I could be wrong
 

also a worn distributor shaft bushing. See if the dist shaft wiggles side to side causing Point bounce

[datzenmike]

The condenser reduces arcing when the points open. Without the condenser they only last 150 miles or so.