77orange

Is there a difference between using an after market open style air cleaner verses a snorkel Oem style"? My engine is idling a little rough when really hot outside. I am wondering if my air is too hot causing carb issues. Mine is

Easy Mike

The idle issue is probably not the actual air cleaner, but you might have an air cleaner element which needs changing. Is it dirty?

77orange

Nope-clean albeit nothing fancy (not a k&m). I’m getting a rough idle and a drop of about 150 rpm when the motor has been run for a while at hiway speeds. Plugs are a little on the white side making me think it might be running a little on the lean side at idle once hot. During startup and choke period it has no trouble. Even slow around town doesn’t seem to upset it. But go 75 for 15 minutes and it happens.

HeadsU.P.

There are C3s idling in the hottest deserts in 110* temps w/o issues.
You have something else going on. Fuel filter fairly new?

77orange

Thanks for the reply. Not sure but I think I installed a new fuel filter a year ago, but will need to confirm. Easy enough to change.

HeadsU.P.

I have also seen perfectly good appearing plug wires perform flawlessly when cool, then seek the path of least resistance when hot, grounding on valve covers, exh manifolds etc. Double check that #5 and #7 wires are no where near each other too.

77orange

Thanks HeadsUp. I’ll look at them to see if they are contacting to arc. I did a night check even with mist a while back, but worth revisiting again. I know I have a couple in very close proximity to the manifolds near their boot. In fact I put a silicon sleeve on one that was touching. I will need to go down the “possibility of a miss” trouble shooting path.

I will be at a u pull it yard in a couple of days and was pondering searching for an air cleaner with snorkle- hence my op.

At this point as the summer heats up I will take another swing at my hi temp rough idle.

Jim

REELAV8R

Your high temp poor idle is most likely due to percolating fuel in the bowl.

get a 1/4" thick insulating carb to manifold gasket.

mine did the same thing when it was stock.

7T1vette

When it is hot and idling as you described, just remove the lid on the air cleaner to see if the idle changes. If not, it's not the cleaner/filter.

REELAV8R

If you are using an open element then you will experience mixture changes once the air under the hood gets up to temperature. It will run richer vs what it was jetted for without the elevated Underhood temps.

bobs77vet

I used both on my 77 with a higher HP motor and headers....hands down the dual snorkel OEM filter from a 79 gave it the best cold air intake... and the car ran better.

do you have the front air dam in place? if not you need to put one in and it will make the car run better