Idle Problems With A Blower Motor HELP!!!

[DansBlown73Nordic]

I have this 454 with a B&M 250 blower. It has a pair of 800 cfm D.P Holleys. It is jetted 79 74 on Primarys. Secondarys are jetted 90. It has a 6.5 power valve.
It starts without any problems. But once its running it will not idle at less than 2500 3000 rpm,s.
It acts like a HUGE vacum leak. If you hold the throttle at 2500 it will start to fall off and the only way to keep it running is crack the throttle and then it will run for 15-20 seconds before doing it all over again.....:mad:
I checked all my float levals. Checked all my valve settings. For some reason I found a bent push rod. Not sure what caused that? Im going to go check compression.

[Snowboat]

You can check for a vacuum leak by spraying a very small, controlled amount of starting fluid around throttle shafts, carb gaskets, and intake sealing surfaces.

[Kindsvater Flat]

I prefer to use carb cleaner instead of the starting fluid. Its less harsh when you find the leak. Not to mention be careful because you just might find an ignition leak also.:eek:

[DansBlown73Nordic]

I checked compression. They were all between 120 and 125. This is a 7.5 to 1 motor.
When I bought this motor I ran it on my engine stand. I found one cylinder with very low compression (50) So I pulled it apart for a rebuild. Replaced the valves with stainless, new cam, lifters, complete rebiuld. The only other thing I did was rebiult both carbs.
When I bought the motor it would idle at 800 rpm,s. Never stalled or acted funny........NOW it runs like SHIT!!!!!!:mad: :yuk: :mad: :yuk:

[Snowboat]

When its fast idling, is fuel being pulled from one of the shooters, causing it to run fast?

[paradigm shift]

If everthing is the same component wise something has changed during the rebuild. Couple of questions I have that come to mind.
1. Cam specs? Same as the one that came out.
2. Cam timing set? (Why the bent push rod?)
3. Ignition timing set at. Initial and total?
4. Have you checked the carbs or changed jetting?
Hang in there you will get some good help from others here. I know I have over time. I am still learning too.

[Infomaniac]

Did you hook up a PCV?
Did you mess with any secondary butterfly stop adjustments?
It is getting air from somewhere.

[Fiat48]

Pop off valve stuck, blower gasket blown out are a couple more places to look.

[DansBlown73Nordic]

I found the problem. When I put my carbs together. The gasket between the carb plates and the carb body was wrong. I pulled them apart and found a passage blocked. It now runs at 800 rpms. :D :D :D :D
I figured it was something I did. It just drives me crazy when something is F....UP!!!!!!!!

[DansBlown73Nordic]

THANKS for all the help. Im still not sure on the bent push rod. I clayed the motor and had plenty of clearance.

[Dragboat Dad]

I can relate to your frustration, I had the very same problem. My son(Speedin' Ian) and I couldn't get our current blower motor to idle, it would get down to about 1500 rpm's and do a lean pop and die. I had a hell of a time trying to figure it out. Finally I discovered someone had put 750 throttle/carb body gaskets in our 850's. The idle passasge is in a slightly different position between the two and it totally blocked off the idle circuit. Now it idles great. As I was reading the thread I thought of this but before I could mention it you figured it out.

[GofastRacer]

Solution to all problems!..:D
http://www.***boat.com/image_center/data/504/1Alky_motor.JPG