rssteiny

my blue 500hp holey carbs work great except when put in gear they drop from 950 idle to like 600 rpms and the one wants to stall unless i bump up the throttle and it make it tough to load on trailer and dock. I dont realy want to turn idle up any higher due to going in and out of gear on the drives.

Thanks

cubicinches

Put a vacuum gauge on the engine and see what you've got for vacuum at idle, both in and out of gear. You may have go to a power valve with a lower opening point.

tinman565

Check your filters first...all of them (water sep included). There may still be filters (small ones) in the bowls (where the lines go in). Always start with the easy stuff first.

jeff1000man

How many hours are on the engines? It may just be time for a carb re fresh or valve adjustment. Those carbs if they are still stock, and the engines are still stock need little adjustment over their life span.

Either you are loosing your signal at idle, and that would be from the flow in your metering blocs slowing from dirty gas and buildup in the idle circuit.

Or your valves just need to be run and this is normal after a couple hundred hours.

You could try opening the idle circuits a little more and see if this helps your idle strengthen. you don't adjust your idle on those carbs at the throttle screw. make sure that is closed all the way. That gives you a stronger idle through the metering block.

jeff1000man

Have yoiu removed your carbs at any time in the past. You could have a leaky gasket between the engine and the intake. This would allow a little air in and will affect the signal at idle, but will not affect anything at WOT.

Take a small 5/16 wrench and test the tighness of the bowl screws. Make sure that they are snug. Over time the gaskets can shrink and a tightening of those screws wil tighten the gaskets back up and this will fix your signal through the metering block.

Good luck and let us know what helps.

Usually it is not a filter if the engine will still run hard under load. Typically a clogged filter will idle properly and at low RPM's. the clogged filter will restrict at WOT and then the engine will just not run as hard as it should because it is not getting the proper volume.

rssteiny

So if i dont adjust at the allen idle screw where is the idle setting you mean, heads and all valves all new good stuff last year and like i said carbs work great no hesitation run up to 5500 no problems just in gear low idel and stalling out of ger idles perfect at 950 i keep them up some for reversion reason with my 741 cams and gill exhaust.

jeff1000man

I was just assuming that these were stock. The 741 cam is going to idle rough, but you should be able to get them smoothed out.

I am not saying that the valves would not be good etc. Just might not be adjusted evenly. It is pretty common for guys to adjust the valves on a brand new engine before actually running it and there is no pressure built up in the lifter. After you run the engine and the pressure is built up, then it is best to re adjust them to ensure that they are all even. with a big cam like that one, if 1 or 2 of the valves is opening a little more or less than the other, it will cause a rough and week idle. It is also common to re adjust the valves once a season on a high lift cam like that one.

You idle mix screws on those carbs are on the metering blocks. Disconnect the throttle cable and remove flame arrestor. Turn throttle screw to the left until the butterflies in the carb are completely shut. let them slam close with the return spring a few times to ensure that they are closed. turn throttle screw back to right until it just bumps the butterflies in the carb. Back to left to ensure that they are closed.

I can't rememebr if those carbs are 4 corner idle or not, but there will be at least 1 very small needle screw on each side of the bowl on the front of the carb and if they are 4 corner, there will be 1 on each side on the secondaries on the back.

Start by closing all four screws all the way and then opening each 1 of them 1.5 turns back to the left.

Start the engine and see if the idle is stronger. If this does not cure the problem, and the valves are adjusted smoothley, then slowly close each screw 1 by one and the engine should slowly die out each time, but recover when you open them back up. This will let you know that nothing is clogged. Take them all back to 1.5 turns and then open each .25 turn further and test again and see if this makes the engine idle stronger.

Once the idle is strong, then turn the throttle screw back to the right slightly until you are idling at the rpm's that you desire.

Also check your spark plugs a couple times a season. If you are running a fat carb while you are cruising and at high speeds then it is slowly building carbon on the plugs and will make a weak idle.

rssteiny

Mine only have 2 screws on the primary side both were 1 turn out, also my float levels are at the bottom of the sight glass is that ok.

jeff1000man

Did it idle right when you first put the engine in last year?

LV

mine did the same thing after putting a big cam in, so my builder added some spacers that had adjustemnts to them, it helped a bunch, they look cool as well.