So as you all know I am running a 401 with a TA-25 cam and SP400 transmission and an Eelco 3x2 intake. My question is, is the 2 barrel enough for this engine the carbs are Rochester 2GC's. It may just be an intake tuning issue but for being a completely rebuilt engine she is hard to start and when coming to stop signs she bogs down as if she's not getting enough gas stop lights are the worst I have to either turn the SP on or put her in neutral. Any idea how I can alleviate this problem?
You are running the three 2's , right? Is idle your only issue? Idle circuits may be clogged up, or possibly too much idle air coming through. You would need to adjust idle mixture screws on all 3 carbs to try to get idle mixture correct.
Sitting idle she's fine when put in reverse or drive is when she's dying. I have to rev the eninge, pull the choke out or turn the SP on to keep the engine on either one or a combination.
How about having the trans SP converter go into high stall when the brake is applied? Isn't that what lots of the SP guys do? It's been many years since I had a SP in my '70 GS455 but, I had to run a wire from the brake light to switch the converter to high stall. Plus, I also had to run vacuum advance full time to the distributor so there was plenty of advance at idle. Just some thoughts.
Yeah, my SP's are set up with brake apply for high stall. I would recommend it, especially if you have a cam or anything else. Still have to get to the root of your other issue, have you checked timing weight tension and vacuum advance?
Yup, that is how it was from the factory. There was a separate switch at the firewall that put the converter in high stall at idle. Off idle was low stall, then back to high stall at 60% throttle and above. The stock 13" SP converter has a very low stall speed. It will lug the engine down if you are trying to idle in gear in low stall. Bruce Roe sells a very nice SP control box with a vacuum switch. It's very versatile with 3 different adjustable timers. I highly recommend it for any switch pitch owner. The only problem I had with it was the brake on high stall could not be adjusted below 3.2 seconds, and I have a modified 12" converter with a high stall that's a bit too loose for coming off a light in traffic. Bruce modified my box to command low stall off idle just like Buick did it back in the day. That shouldn't be a problem with the stock 13" converter. Just thought I would mention it. I also second checking your timing at idle. Is your vacuum advance functional and is it connected to manifold vacuum?
I agree with needing high stall while idling in gear, especially if you have a cam. The factory 13in ST400 converter is very tight in low stall, like Larry noted.
2 things in play here,,,, on a 3x2 set up only the center carb is supposed to have a idle circuit... and the end carbs are adjusted to where the butterflys are completely closed at idle.... and the switch pitch trans has to go to high stall at idle... how ever you choose to do it... simplest to do is the brake light type circuit... where the brake lite switch also makes it go to high stall....
