Ok guys yet another problem ugh.... ok i got my motor to fire but i cannot seem to get it to idle down. It will run at 1500 and soumds great, i have adjusted the air fuel mixtures, the idle screw throttle cabe, everything. And without getting it to idle down i can really ajust the timing. I got it to come down to a grand bit as soon as i brought out the timing light and started adjusting the timing it died. After a grand it just comoletely dies. Im lost thinking i may have a bad carb thats my guess. Any helo would be appreciated. Mercruiser 260, vortec heads, performer intake, quadrajet 4 barrel thru hull exhaust

Vacuum leak. Check your intake manifold and carb gaskets. Put a vacuum gage on it and check it out. Spray some carb cleaner around those areas and see if the idle changes, but if it is leaking air on the bottom side of the intake, most likely area it will not show up doing this. But a bouncing needle will tell you the story.

Everything except the carb is brand new and its running a como cams 262 cam i forgot to mention that. All gaskets are new and everything is tourqued to specs. Could it have a leak with in the carb or maybe even have a bad float? ?? And i have the edelbrock adaptor plate on the intake plus a thicker carb gasket could that be an issue

The Vortec intake gaskets are easy to over tighen. Also double check the initial timing...could be off enough to idle up tat high. My money is on a vacuum leak. While its running spray wd40 arond the carb base and the intake gaskets.

Sounds like a vac leak to me also. Check the carb base gaskets, intake gaskets again

John jr

Just a thought, you might check the gasket between the throttle plate & the carb body. It can get crushed on the primary side if the screws loosen on the back side & the bolts are too tight on the front. Randy

how many times did you go over the intake bolts?? just once wont do it,,15 ft lbs and thats it with blur loctight on the threads.. or they will loosen up..you have to go over then like 5 or 6 times to get all the bolts to 15 ft lbs,,also their is 2 differant style merc carb gaskets one will make a Q-jet leak causing a vacume leak..take the carb off and flip it upside down and match the gasket to the base of the carb,,you will see where it would leak vacume ..

Just throwing it out there,, since you have the Vortecs, which intake gaskets did you use?

I dont know the brand my engine builder gave them to me i think they were rubber coated and ss steel.

Just double check to make sure your throttle cable is not way out of adjustment at the barrel end which is not allowing the carb linkage to fully return. Unhook it to see if anything changes. if not most likely U have a vacuum leak.