Loading up @ WOT

[jvest]

I'm sure this is something simple, but I've not had much time to hunt for the problem. About a month ago I installed a 4L80E in my 68 Camaro. Ever since then it seems to loading up on fuel from 1/2 to full throttle. It does it a full throttle everytime and 1/2 throttle when under a load. Until the tranny install it's ran great. I'm running an MSD 6T with a blaster 2 coil and gutted HEI distributer. At first I thought it was a weak coil, but I replaced it last night with no change. Today I replaced cap and rotor, but still no change. Now I'm leaning towards something with my mech secondary 750 speed demon carb. The float levels are prefect, but during the tranny install I had to pull the 2 small vacuum port tubes on the side in order to make clearance for the throttle position sensor. I'm curious now if the internal plugs I used to plug these two holes are blocking something inside the port causing this problem. I keep leaning towards something I done installing the tranny since the thing has ran good for 3 years now and all of a sudden it's doing this. If no one has any suggestions, I guess the next step is to pull the carb to teardown and clean.

Thanks,
Jim

[Gitter Dun]

What did the two small port tubes connect to?

[jvest]

What did the two small port tubes connect to?

I wasn't using either one of them. One is timed vacuum (above the butterflies) and the other is manifold vacuum (under the butterflies). I had to pull the tubes/hose barbs in-order to allow for my TPS bracket. After pulling them I had to install and internal rubber plugs to seal the holes in the side of the base plate.

Jim

[Gitter Dun]

I wasn't using either one of them. One is timed vacuum (above the butterflies) and the other is manifold vacuum (under the butterflies). I had to pull the tubes/hose barbs in-order to allow for my TPS bracket. After pulling them I had to install and internal rubber plugs to seal the holes in the side of the base plate.

Jim

Thats wierd, did you try advancing the timing?

[jvest]

Thats wierd, did you try advancing the timing?

I did pull the distributer during the tranny install, but I set it back to 38 degree full advance, just like always. I've not tried to advance anymore. I'm already having to run 50/50 mix on 93 pump gas & C12 race fuel due to a 11.75 static compression, so I'm not sure how much more it'll handle.

Jim

[Gitter Dun]

I did pull the distributer during the tranny install, but I set it back to 38 degree full advance, just like always. I've not tried to advance anymore. I'm already having to run 50/50 mix on 93 pump gas & C12 race fuel due to a 11.75 static compression, so I'm not sure how much more it'll handle.

Jim

It's worth a try...., sounds like the culprit to me.

[jvest]

It's worth a try...., sounds like the culprit to me.

I'll bump it up a couple of degrees tomorrow and see if it helps any. I guess it could've moved on after setting it.

Jim

[Gitter Dun]

I'll bump it up a couple of degrees tomorrow and see if it helps any. I guess it could've moved on after setting it.

Jim

If it wasn't pinging when loading up you should be fine. Hope it works, good luck.

[jvest]

Before I bumped it up I checked it and it was 38 degrees @ full advance. I brought it up to 42, but no change. Although I'm not sure why it started after the tranny install, I guess I'll pull the bowls & metering blocks to see if a cleaning will help.

[Gitter Dun]

Before I bumped it up I checked it and it was 38 degrees @ full advance. I brought it up to 42, but no change. Although I'm not sure why it started after the tranny install, I guess I'll pull the bowls & metering blocks to see if a cleaning will help.

Seems strange that something like that would occur just from tranny swap. Must have something to with plugs you installed on carb. Maybe partially plugged air inlet/bleed .

[DoABarrelRoll]

sure it isn't the automatic trans?

[jvest]

sure it isn't the automatic trans?

I don't think it's actually an issue with the tranny because it shift properly and cruises from 0 to 65MPH with problems. To me it sounds when you have the primary floats set to high and runs out of the overflow tube and right down into the carb when you try to accelerate hard. It's like it can't burn the fuel when you go WOT or 1/2 throttle lugging. Anyother time it sounds great with crisp throttle response when jabbing the throttle while out of gear. If it wasn't for the TPS setup for the tranny controller on this demon I'd stick an old Eldebrock carb I've got on the shelf just to see if it's in the demon.

Thanks for the help,
Jim