malcolmthurgood

Can anyone help us, we have a 42' Formula with triple 525sc Mercruisers with Holley 1050 Dominators, we have rebuilt the carbs installed new power valves set float height, set fuel pressure, set engine timing to 10 degrees and checked the vacuum (pulling 11" mercury), any suggestions would be appreciated.

DonRoc

They ALL stall when put in gear? Did they do this before the work or after? Do they stall independently of each other or do they all stall when you put anyone in gear.

Old Navy

You should check your idle speed, it may be too low. My 525sc did not come with a fuel pressure regulator to "set fuel pressure". Your timing should be 13 initial (which would be 35 total @4500).

malcolmthurgood

They all stall when individually put into gear, it would be OK if you had 4 hands, to shift from ahead to astern you need to select neutral with one hand kill the revs with the other hand and then select the opposite gear and at the same time try to catch it on the throttle while trying to steer!!

malcolmthurgood

Thanks for this info will try it and fingers crossed it works because it is embarassing trying to negotiate a fuel dock or loch gate.

DonRoc

So they all just started stalling at the same time? Not one stalled at times then another and so on. Just one day you went for a ride and you couldn't keep any of the motors running when shifting? then you rebuilt the carbs and nothing changed still they all stall. I'm trying to figure if it is something in common with the engines, or the carb repairs. If rebuilding the carbs started this then its a pretty simple issue with the rebuild or setup. If they just started stalling all together before the carb work then we need to diagnosis a totally different problem.

DonRoc

Sounds like you have to forward the throttles to keep them going. still before or after the carb work.

DonRoc

Last what is the idle speed out of gear and in gear? Did you set the 4 corner idle mixture screws to best vacuum? Then re adjust the idle and do the mixture again until the mix is at best vacuum and the idle is to specs? What procedure did you use to set timing and at what RPM?

Young Performance

Generally speaking, when an engine dies going in to gear and the idle speed is set at the correct rpm, then the engine is usually to lean. Do as previously mentioned and set the 4 corner idle mixture screws to the highest vacuum setting. Ideally, you want to set the idle mixture and in gear mixture with a wideband O2 sensor. That is the best, most foolproof way to do it. If that is not an option, then use a vacuum gauge. Good luck.
Eddie

malcolmthurgood

Don, the idle speed is 950rpm if you try to engage gear you have to blip the throttles or she stalls, ikt does this on all 3 engines, we set the mixture screws to one and a quarter turns out and then put a vacuum gauge and adjusted the mixture to give us best reading, we used a timing light to set the timing at idle but did not have any tape to check timing at 4500rpm so we do not know what the advance timing is.