My 240z has been running rich for a while. The replacement cylinder head was sparkly new-looking when installed 6 or 7 years ago. Thinking about running a spray can of Seafoam through the SU's to clean up the top end. Read some threads on this site about it but they don't mention using the spray type. Seafoam site recommends using spray type except for professional applications. I guess I'd do it by spraying into one carb about 15 seconds and switching to the other one for 15 seconds etc until the can is empty.

Not sure I want to do this but read mostly good reviews of it.

When is the last time you replaced the air filter?  I've got the Nissan P/N if you want to try one, they're much better quality than chain parts stores.

Check out the seafoam tests on youtube on lawn mowers... not a big result.

16 minutes ago, 240260280 said:

Check out the seafoam tests on youtube on lawn mowers... not a big result.

That's where I get the air filter remark.   Every single time my commercial mower starts running bad it's ALWAYS the air filter, cleaning them a few times is okay but I buy a new one every spring.  

Another thing is the summer gas blend the do in California.  Could that have an effect on you Z?

Edited June 28, 20177 yr by siteunseen

My 78 liked decarb with water a fine mist from garden sprayer in the brake vac hose. 

I usually throw a can of seafoam into the tank once a year and it keeps things pretty clean but if I have an engine that I know is crusted up with carbon I'll either spray it in or let a vacuum hose suck it straight out of the can until it drowns the engine, let it sit over night and start it up again. Stand back cause you will be in for a smoke show, I guess I am assuming that all that smoke is the crap that the seafoam has loosened up overnight but I have no proof other than I have used the stuff to clean carb parts and it does a great job.

1 hour ago, grannyknot said:

I guess I am assuming that all that smoke is the crap that the seafoam has loosened up overnight but I have no proof other than I have used the stuff to clean carb parts and it does a great job.

That's the image they've created.  But run the stuff through a freshly rebuilt engine you'll probably get just as much smoke.

Check the SDS - http://seafoamsales.com/wp-content/uploads/2017/01/Sea-Foam-Motor-Treatment-SDS-v20161205-ENG.pdf

"Hydrocarbons" come from oil, anything/everything from methane to diesel could be in there.  But they're all just crude oil fractions.  A bottle of rubbing alcohol and a gallon of paint thinner and you might have the same blend.

http://www.gcelectronics.com/order/msds/226.pdf

 

 

 

Edited June 29, 20177 yr by Zed Head

Seafoam is mostly Colemans Camper Fuel (naptha)

1. Pale oil 40-60% (diesel)
2. Naptha 25-35% (camper fuel)
3. IPA 10-20%  (rubbing alcohol)

I think that they must add some butane or pentane so that intake vacuum will cause it to foam.  So it probably does foam up and get the solvent in to areas it might not otherwise reach.  But it won't dissolve the typical hard carbon deposits in an intake runner or back of a valve, I think.  Somebody wrote about that somewhere out on the internet.  You just end up with clean carbon deposits.

Edited June 29, 20177 yr by Zed Head

No offense, if you're a Seafoam fan.  There just doesn't seem to be much evidence behind it.  You'd think that they'd have a video that actually showed a dirty engine getting cleaner inside.  They do have one though - https://seafoamsales.com/sea-foam-official-video-how-to-clean-a-fuel-injection-gasoline-intake-with-sea-foam-spray/

"backwash" vapors at 2:25.

 

Is that the lawnmower stuff?  I didn't search the youtube tube.

 

Edited June 29, 20177 yr by Zed Head