[beemergary]

Installed my new repop bathtub intake. Had an 859 2x4 before. First started it wouldn't idle. No big deal now with the idle adjustment all the way out still idles fast. You have to only have the idle air adjustments almost all the way in. Throttle plates closed all the way also. Edelbrock 750"s and has quick response. Help

[Tom Vaught]

If the throttle plates are closed all the way,idle are adjustments almost closed, and the idle adjustment screws allowing the throttle plates to be closed all the way would imply a air leak somewhere in your installation of the intake.

Since you had a 859 2x4 I assume the repop bathtub is for the early heads and the gaskets/ports on the heads and intake SHOULD line up properly???

Tom V

[tom s]

Gary,make sure no vacuum leaks!Spray some carb cleaner around the flanges and carb bases.The flanges might have some interference with the valley cover.I had to grind about a 1/8 off at a angle on the bottom of the of the flanges to have the intake set flat to the head.Tom

[beemergary]

Tom and Tom I actually ended up trimming 1/8 all around valley pan. Test fit a zillion times without gaskets. Found a few slight clearance issues at intake runners and one spot at water cross over hitting valley pan. Just put some yamaha-bond on both sides of gaskets. Maybe carb bolts coulda been tighter. Will see in am. I am to old to do things twice and got a big race leaving thurs. Thanks Does have real good throttle response . Even got the original SD air Cleaners to clear under hood but no carb spacers.

[beemergary]

Update. Water neck may have been a problem after sliding ahead since I test fitted with it off. WELL I still have the fast idle (1500rpms) with idle screw out and Idle adjustment screws all the way in. Checked and the metering rods are down also. So where is the gas coming from. Have seen a brand new carb with a cracked casing.

[25stevem]

Are the secondary throttle blades closed all the way?

Put a towel over each carb one at a time to see if the motor is idling off of one carb more then the other.

[tom s]

Did you get a can of carb or brake cleaner and shoot it around to see where a vacuum leak might be?

[tom s]

Confirm they are the same carbs you had on the 859 and had no idle issues!Tom

[beemergary]

Tom --Same carbs and I did the carb cleaner but no change so all new gaskets-nos 62-63 sd intake and carb gaskets. Ok now it will idle down when you turn in idle fuel adjustment screws but takes a bit to come back to idle after blipping gas. Not driver friendly but has quick response. Not happy when I eliminated the gas from each carb to narrow a carb problem also. My bucket list is getting the best of this old man. The idle screw is still all out.

[tom s]

I will tell you mine is like driving a 2bbl car around!I have factory 421 SD NASCAR carbs on both of my cars.John can confirm as he drove my GP after I put the original scanned intake on.He said way better than his 66 tripower car.Tom

[25stevem]

What do you mean when you say the idle screw it all out?

Do you mean that the primary throttle plates are seated fully closed because the idle speed screw is dangling out all the way?

If so you still 100% have vacuum leak somewhere and of some size taking place.
Also the motor will never respond right without having some of the fuel transfer slot in each Bore exposed by the edge of the throttle blade.

This may be reaching at straws, but If the Intake was not seating right when you first bolted it on you may have cracked it!?
I know you only have today left to find out what's going on so I hope you turn up a solution.

[darbikrash]

As a suggestion I would look very closely at the carb to manifold interface areas. The factory used spacers to raise the carb up off the "table top" surface of the intake. We noticed with some trial AFB's that with just a carb gasket and no spacers the carb hit ever so slightly in areas near the driver side linkage reliefs. Check very carefully that the carb is not hanging up on some small interference and not sitting flat thereby causing a leak.

There is so much material in the head flange/bolt area I cannot see any way this could crack, and if you sprayed carb cleaner in this area and no change in speed was noted I think you can rule this out.

[tom s]

Im using a 1/4 inch gasket on my rear carb.Tom

[mgarblik]

I have my AFB's mounted on single .060" gaskets. Trying to stay as low as possible to fit under a flat hood. I did have to perform some very minor relief to the accelerator pump linkage and a slight notch in the bathtub top for clearance. I didn't mention this because I didn't want to generate complaints about this manifold that I think is great. Also, they were designed to use small spacers, so my application is "non-stock". But check the fit for sure.