Jazzy

Hi all,

I've been restoring a 21 ft. '76 Reinell with cutty. OMC stringer drive.
It has a 289 cu in 165 HP GM straight 6 with a 2 brl Rochester carb / heat-rise choke.

Engine sarts and runs good - a little rich until the choke opens up. After running at operating temp (~170 deg.) for 20-30 min. it starts cutting out. Just won't open up. I opened the HS needle about a quarter turn & that helped a good bit.
It almost seems like it is vapor-locking. I've run all kinds of fuel cleaners & conditioners through it - even octane boost.
Someone mentioned the coil could be goin' bad...?
Just wondering what the deal could be...?
Any help out there?

TIA,
Jeff

Tommygun

My Feedback: (2)

How long has it been since the carb has been rebuilt? I'd start with that. If you opened the high speed needle and it helped, you're probably going lean. I know an abnormally high amount of guys losing fuel pumps this year, including myself. Do you have ethanol in your fuel? Does your boat have a fiberglass fuel tank? If so, you'll need to get that swapped out with an aluminum one, since the ethanol will start dissolving the resin. This resin will then mix with the fuel and go straight to the carb. It will gunk everything on the way to the combustion chamber, and eventually damage the engine. What have you found so far?

Bud Faulkner

My Feedback: (1)

Had a similisr problem this past weekend on my cousins grady white, seemed to be vapor locking. Turning the blower on cured it. Is your engine vented to the outside?

Bud

on pipe

If it is really triggered by the heat, then that usually means that the secondary ignition is breaking down. Check rotor, cap, wires, plugs. Rochester Dualjet carbs are pretty trouble free. The mixture screws are for idle only. Also make sure there isn't water in the gas. Ross

Beagle RC Air

The Rochester carburetor on those older GM straight 6's were very good and relatively trouble free. But, that probably is a 30 year old carb! I would take it to someone who still has carb rebuilding skills and have it gone thru. Just a simple thing like a float that is saturated will cause all sorts of running issues including fuel economy. Those motors were 230/250/292 CID, not sure but I would imagine you have the 230 or 250. No HS needle adjustments. An analysis of the ignition system by a qualified tech would be good idea also, given the high cost of fuel. Of the marine engines I have owned in the past, these 6 cly GM marine engines were the best by far. Don't trade out any electrical or fuel components for automotive counterparts.[:@]

werdonmorris

My Feedback: (7)

I HAD A 1956 GMC PICKUP, AND A 2-BBL CARB FROM ROCHESTER SAT UPON IT. I HAD DONE A COMPLETE CHECK UP AND NOBODY, NOT EVEN TECHS COULD NOT FIGURE IT OUT. SO, AT A VERY EXPENSIVE AVENUE STARTED TO REPLACE, ANY POSSIBLE BAD PART UPON IT. I HAD REPLACED THE CARB-DISTRIBUTOR CAP AND ROTOR-SPARKPLUG WIRES-SPARKPLUGS-FUEL PUMP-RE SET THE TIMING-REPLACED THE FUEL PUMP-REPLACE THE SOCK FILTER IN THE TANK-REPLACED THE GAS TANK ! ALL TO NO USE, THEN I TRIED A STRANGE IDEA. I TOOK A SPRAY BOTTLE, AND PUT DISH SOAP AND WATER IN THE BOTTLE, AND STATED THE ENGINE. I THEN SPRAYED THE INTAKE MANIFOLD, AND NOTHING. BUT I DECIDED TO LET IT GET WARM, AND FOUND THAT WHEN IT WAS WARM, THE SOAP SUDS DISAPEARED. MY INTAKE MANIFOLD GASKET WAS BAD, AND THE SURFACE OF THE MANIFOLD WAS WARPED. I BOUGHT TOP OF THE LINE GASKETS FOR HIGH HEAT, AND RE-MACHINED THE INTAKE MANIFOLD. ALONG WITH MICROFLUXING-CRACK FINDING, AND HAD TO HAVE IT WELDED. SINCE THEN, IT HAS RAN FANTASTIC, AND NOT ANOTHER PROBLEM. WITH THIS PROBLEM, IT WILL BOILD THE GAS INSIDE THE FLOAT CHAMBER, AND CAUSE IT NOT TO ATOMIZE PROPERLY, AND MIX IN THE MANIFOLD. [email protected].