2.41 to 3.73 gears story, and TBI can make power.

So this is likely the 3000th post of the same subject on the internet, but what the hell. Why not?

So my engine swap occurred in in 2011. 4.3 TBI V6 to Gm performance 350. For sake of ease kept the throttle body injection. Had other challenges to work out so it seemed like a good short term solution. Thought the car had 2.73 gears all the while. While slow they at least approached not horrible territory, or so I thought. That was until I ran my RPO code and it said GU1. Which is 2.41(no posi). Two forty F***in 1. They had to go. The motor ran good and I had no complaints, but it was time. After some debate it was decided to rebuild the 10 bolt. 3.73 gears, posi and such. That threw the transmission into a tizzy. As documented here.

https://gbodyforum.com/threads/had-...exposed-transmission-problems-resolved.63268/

Once that was worked out through the use of BTO's throttle linkage kit and a GN Governor sourced from TransDepot, the car was running really good. I read time and time again the car would be useless on the highway but that wasn't the case. It was loving the higher RPM ranges. Car was cruising comfortably at 75 mph with pedal to spare.

So I finally got the car to the track tonight. Lancaster Speedway, NY. Only 1/8th mile only. I only made one pass, 9.41. Beat a 2000 Trans Am LS1 by a narrow margin. Nice condition car with exhaust and other standard mods. Had him the whole way. I could hear the guys car well, he drove it fine and hard, but the Monte pulled. After the race dude wouldn't even look in my direction. He just got beat by a brick shaped car with the 4.3 emblem on the back.

Before the rear end setup the car ran exactly 1 second slower. Worthwhile upgrade to say the least.

And for all the people that said Throttle body can't do that. It's not a performance setup, that ain't half bad. For all the headaches and costs associated with changing fuel system's, I'm not sure the effort will net me that much.

Not saying my car is hot sh*t or something. But for what people said this car can't be, it far exceeds those expectations. Just happy about that.

Thanks for reading.

olds307 and 403 said:

With a 2004R and the right tires, there is nothing wrong with that gear even cruising. The TBI is a reliable system and can perform. Get a bored out throttle body, it will run even harder.

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I do. It's a 46mm bored TBI, thin throttle shafts and such. Company did a nice job on it(I forgot who I sourced it from 6 years ago.) I'll post some pics when I get home.

Opie Knievel said:

Hell yeah! I loved this story! I've got an '86 Monte Carlo 4.3 TBI. I've got a Vortec 350 to put in it and I had toyed with the idea of keeping the TBI. Which intake did you use? Did you have to change the tune very much?

I really love that you beat that Trans Am!

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I use the GM performance TBI intake. It's a pretty nice unit. Aluminum and such.

https://www.summitracing.com/parts/nal-12496821

Boy the prices have gone up on those since I bought mine. I'd look for one used if you could get it. Edlebrock makes one as well. Edlebrock makes great stuff, but with these beware before buying. Edlebrock lists theirs as being .250 taller than stock and won't fit on B body Caprices. So I don't know what that means for the Monte but it could be trouble. Also with the GM there may be 2 part #'s depending on what year heads you have.

As far as tuning you'd probably want a custom tune done in person. These old ECU's are kind of a pain because you can't plug in a tune, you actually have to pull the chip, put it in a reader, make adjustments and then put the chip back in. It takes a few tries to dial it in. Doing that with a shop on the other side of the country via the mail is very slow and difficult.

As far as what he changed the changes are moderately significant. He turned off EGR. Remapped to the fuel curve to match the new injectors, intake, headers and engine specs. Added 2 degrees of timing at WOT.

All in all though I think it's a very simple and very solid system. I've never worked on fuel systems in my life before this car and I basically feel comfortable with all aspects of it now. If you really want to do with start a thread and I'll give you the best advice I can on what to buy and I'm sure the others here can chime and in help too.