907 ignition problem

[Gene Leasure]

My Jensen GT has the 907 engine with Stromberg carbs.  I have been trying to set the mixture to get it to run smooth.....When I pulled the plugs I have 3 running rich and one clean and dry.  I have change plugs and get the same results.

 

Any suggestions????

 

My email is  [email protected]

[johnpwalsh]

Check first to see if you are getting a spark, if thats ok it could well still be a fuel problem as if the carb ballance is so far out it will appear like a missfire. Check on here for pleny of posts on how to correctly ballance your carbs.

 

http://www.espritfactfile.com/carbbalancing.html

 

Good luck.

[jonwat]

Check first to see if you are getting a spark, if thats ok it could well still be a fuel problem as if the carb ballance is so far out it will appear like a missfire. Check on here for pleny of posts on how to correctly ballance your carbs.

 

http://www.espritfactfile.com/carbbalancing.html

 

Good luck.

That article is for Weber & Dellorto carbs, in fact I don't think I've ever seen a single posting on the forum regarding balancing Strombergs. 

 

Gene,

Have you checked that the dry cylinder is sparking by attaching a timing light to the plug lead?

 

What about air leaks, are all the gaskets ok etc?

 

If so what about compression? Check them all, they should be within 10% of each other. 

[xam69]

My Jensen GT has the 907 engine with Stromberg carbs.  I have been trying to set the mixture to get it to run smooth.....When I pulled the plugs I have 3 running rich and one clean and dry.  I have change plugs and get the same results.

 

Any suggestions????

 

My email is  [email protected]

 

I may be able to help on this. If you have a lean running cylinder then my guess would be that it's # 4 cylinder toward the back of the engine. If so, check that the vacuum take off hose for the brake servo is not leaking and also that the brake servo is not leaking air. The seals in the servo usually get worn out and leak air.  

 

The other option is that the manifold to cylinder head joint is leaking on that cylinder. 

 

The fault is not the carbs, as you'd have the same issues on the adjoining cylinder.

 

It's possible, but unlikely that the ignition system is malfunctioning.  Are you running a standard distributor ignition system with the vacuum retard module?

 

Let me know if you need any tips on setting up the carbs and ignition timing.

[johnpwalsh]

Yep, Max is correct, I made a boomer earlier as I never noticed you had Strombergs fitted, as Max says, check the vauum pipe comming off the inlet manifold first for leaks and the servo, then maybe get some plus gus or similar and spray around the joints between the inlet mannifold and the head while the car is running, if the revs pick up then this would indicate a leak.

 

John.