Hey everyone I have a 84 gsl that has been acting up lately and I could use some help diagnoseing the problem! I recently put a different carb on my engine from another 12a with blown water jacket seals that I had laying around. First of all the secoundaries arnt kicking in but the engine will easily rev into higher rpms, but when i rev it up to say 3k 4k or 5k and hold it there, i get little backfires and studers! However when i give it quick revs it seems to run through the rpms fine... Is it possible that the primarys are jeted and capable of spraying enough fuel to supply the engine at higher rpms?? Also im not exactly sure what vacum lines engadge the secoudaries... I checked for vaccum leaks and im starting to think the carb is no good! However my cap and rotor are a little ruff and im about to replace them and see how she runs!

 

Paragraphs are cool.

To clarify.. you think your secondaries may be mechanical or are just not being opened by the vacuum pressure? If they are mechanical you should be able to feel where they would open in the pedal (hard sport like ~half way down)

Does your car idle fine, cuz from my experience if you have primaries that will be able to go through the RPM range you will not idle at all. But that is just what i recall.

Definetly replace cap and rotor, and plugs, and wires if you havent ever done that. Check to make sure your timing is fine.

Someone else may be able to offer a bit more.

 

Paragraphs might be kewl but i have no time for them lol! Anyways I think my secondaries are vacum actuated but im not sure which vacum lines actually work them, could someone point me in the right direction... Yes my car idles fine when its warmed up but sometimes it does die at idle. Right now im just trying to figure this carb thing out the secoundaires are not kicking in period but the car does easily rev to high rpms... 6, 7k!

The primaries seem to spit out massive amounts of fuel but then again I dont deal with carbs alot so Im not exactly certain what normal fuel flow should look like! Like I stated in my previous post if i were to take the rpms up to say 4k and hold it there i get small studors, backfires and what seems to be the engine missing...

 

PM Sterling, he is the go to guy for carbs. Im surprised he hasnt posted here.

Just with my experience with racing cart carbs (havent done much on the nikkis so i cant compare), There is just no way for the primary to pump enough fuel through to go up to the high rpm.

The FSM or carb manual should show which hoses activate the secondaries.

Check for vacuum leaks or if your hoses are old and brittle, replace them.

Some more info, It is a (stock) Nikki right?

If you bring it up to 4k and hold it and it stutters, to me that sounds like a timing problem. But again i could be mistaken.

Could be worth a PM to sterling and maybe he can confirm/deny your carb worries

 

Yea it is a stock nikki and im thinking the carb is just fed... when i took it off the other motor there was a powdery gas residue in parts of it. Ive got a timeing light so ima re time it when i get the carb rebuilt! Ill give that guy a pm thanks for the advice!