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I just had the Howell TBI installed in my '76 Wagoneer. Did not do it myself; had my mechanic do it.
Truck appears to be running very well, but I now hear a new sound in the cab. It's a low hiss (sounds like air, maybe) and it gets louder when I compress the gas pedal. Is that normal? It's definitely in the cab and not a wheel sound - makes the sound at idle in parked position.
I know there are components to the system in the cab. It's a little annoying, so I'd love to be able to put a stop to it.
1980 Cherokee wrangled & mangled
MSD complete system
Eddy intake
Holley 650
Comp cam 270H
4" Rusty's
Ramsey 12K winch
208
Built to drive not sit in the garage.
No longer strangled. I didn't build it for anyone else.
If you can't improve it why waste your time?
If you switched from the factory enclosed air cleaner, to an open element air cleaner, it will sound different. The open element will sound like more carburetor noise.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.
Yeah I would trace it out. it does sound like a vacuum leak but could be carburation as suggested. There are several vacuum lines under the dash of that model. If you only hear it in the cab then I would search under the dash around the glove compartment & over by the heater switch.
1980 Cherokee wrangled & mangled
MSD complete system
Eddy intake
Holley 650
Comp cam 270H
4" Rusty's
Ramsey 12K winch
208
Built to drive not sit in the garage.
No longer strangled. I didn't build it for anyone else.
If you can't improve it why waste your time?
I did a bunch more Googling and it seems that the hissing sound is just the sound the injectors make on the Howell TBI. People seem to say they stopped trying to "fix it" and that it's "normal."
I did read that one way to silence this sound is use some kind of snorkel air box type thing.
Most carbs/TB setups with an open element air cleaner have a very audible intake sound. My J10 hisses at low idle, and had a very deep sound at higher throttle levels.
Yeah, you basically need something that will muffle the intake sound. On late model cars this is with an air box, which acts as a muffler. There are setups that will connect to the top of the TB and then rub tubing (like a newer car) out to the front passenger side of the engine bay, and put the air cleaner there. This will quiet it down a lot. You will still get some of the lower tones associated with heavy acceleration, but none of those higher pitched sounds that you are getting now.