engine and drivetrain Carb Basics

[doug73cs]

Running out of options here.  

 

Tomorrows work includes:

 

Confirm correct valve adjustment

Compression test all cylinders ( curious about the numbers anyway)

Swap in old dizzy cap to compare

Confirm all plugs have good spark (done once - do again)

Test #1and #2 wires by switching them (remember to switch back)

Liberal but selective use of ether start spray to test for any vacuum leaks

 

The runners are full open unless the gas suddenly developed high cholesterol - no rags, tampons ,dead rodents  etc to be found.

  

I'm hoping the problem is with the plug wires but no one locally sells them so if I have to replace them I have to make them up our wait for Mr Blunt to ship if I order them.  If it's the dizzy I can get a rebuilt from IE but again that means delay in shipping to Canada.

 

Will report.

 

Edit:

 

Valve lash fine

Dizzy cap - no change with old so swap back to the new one

Good spark all

#1 and #2 wires swapped - no change

No vacuum leaks found

 

Still trying things - went to 45 140 (drop from 150) 185 and the lower rpm/cruise operation improved but still rough and lacks power at WOT

Edited October 24, 2014 by doug73cs

[doug73cs]

I said I would post my conclusions when this was sorted so here it is - spark plug wire set.  

 

At the end of the day the single biggest factor was a set of 3 year old plug wires that I replaced with OEM type Bosch.  All of the hesitation and sputtering accelerating from idle to cruise is gone, WOT is smooth and consistent from 3000 to redline (in the mid 12's A/F ratio) and cruise at light constant throttle is slightly lean (mid 15's A/F) until engine load increases and the A/F responds appropriately.  Still running one grade hotter plug which I may leave for now.

 

When this all started I was jetting 50 150 185 and now 45 140 185.  This was probably a contributing factor to improving the "performance" of the engine.

 

The one thing that needs attention is the richness at idle (A/F in the mid to high 11's) that I'll try to lean out a touch but if it has to stay rich to run right - so be it.

 

Thanks to all for the comments and suggestions.

 

Doug