PatriYacht

Idle screws only affect idle mixture. As soon as the carb butterflies start to open, they're done. The power valve could be open or it could be torn. You want to use a low number p.v. on a Dominator. I was just about to change to a 4.5 when the season ended. Float bowl level is important too. A leaking needle and seat will cause the level to get too high also.

boatman747

Thanks for the info.

PatriYacht

I just reread some of your old posts about this engine. It is just like my old one except I had Merlin heads. The cam is very large and it is difficult to get to idle. I used a 1" thick 4 hole spacer to improve signal to the carb. Initial ignition timing was set at 17 degrees. MSD dist provided another 19 for a total of 36. The cam was installed with 4 degrees of advance. Compression ratio was about 9.5. If you have less it will hurt. This cam does like a lot of compression.

razor1115

Set your SECONDARY butterflies so that they are open enough to slide a tag wire through the opening when they are resting on their stop adjustment screw.

Get a vaccuum gauge and adjust the air idle mixture screws one at a time at each corner until you attain max vaccuum. Then keep repeating the process until no more vaccuum can be attained.

Your power valve on the primary side should be approx 2 sizes under the max vaccuum reading at idle to come in supply the correct amount of fuel when on the primary circuit.

If the engine has trouble idling after setting the idle mixture, slowly adjust the SECONDARY butteflies to open them. This will increase the air to the engine while NOT providing more fuel and will increase your idle RPM...

I have an iron headed 540 with the same cam (0.632" lift)

Orkyl

OK, a little checklist:

1.Fuel bowl levels is ok.

2.Use a vaccuum gauge and adjust the air idle mixture.

3.Check if the power valve is ok, a bad PV can be hard to see so just put in new ones.

4.Check your timing, when do the "weight" go in ?

If all above is OK then there is an old dragracing trick, drill a small hole in the primary butterflies to increase the vaccum trough the carb at idle.

Do NOT mix with the jets after the dyno, they are fine.

/Orkyl

boatman747

Yea, I tried the drill hole trick in my last blower motor . Worked quite well actually.

Orkyl

It migh work, a cheap test.