Is there a way to put 400 in my 91 rs and keep it with the tbi? Where can i get the biggest tb unit at? Do you think it will work with a t-56 tranny behind it. Thanks for any info.

 

i'm sure it would work, the big question is how well it's work. not many aftermarket tbi preformance parts to chose from, the 454 is a bigger tbi unit. that's what i'd be looking at and you'd want to consider getting into burning chips to maxamize preformance.

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ICON Motorsports
1st & 3rd

 

i have an 89 rs 305 tbi.i also have a sb 400. will the 400's oil pan clear the crossmember? will the 400's flexplate bolt to my 700r4? since what i am looking for max torque and trying to slide this by the inspecters i was considering using the 305's heads and intake.is there anything else i need to know? i am hoping to reuse the serpintyne belt system

 

Been there with a friend, done that, won't go back ever. And his was even a 350 truck TBI to begin with, a far better starting point than the crap you're stuck with.

The 400 is externally identical to a 305 so things like accessories and oil pans are not a problem. What will be a problem, is that at any given RPM, you have to feed it 33% more fuel, assuming that the motor's characteristics are the same. But of course, who's interested in building a peanut-cammed retarded-timing 170 HP 400 that's the opposite side of CAFE and CARB fleet averages from the performance cars? In the real world, by the time you equip a 400 with a good cam, free-flowing non-swirl-port-BS heads, etc. etc. etc. its fuel curves are so far different from the 305 that you're into custom chips and some other TBI unit, none of which ever seems to work right.

While it would appear to work on paper, in practice it's far less than satisfactory. You will waste an unbelievable amount of money and still have garbage, like my friend when he realized that his TBI was too weenie and bought a Holley 900 4-barrel one, which wouldn't stay working for more than about a week at a time before an injector broke or some other thing would happen; and he got Howell to burn him chips, a good chip guy as ar as that goes, but I think he had at least 10 chips and had paid 3 or 4 times before he finally gave up and bought a Haltech, then after another some hundreds of hours of fiddling and dozens of sets of spark plugs and repeated replacement of all 4 injectors, IAC motors, etc. realized that the TBI was just junk and bought an Accel DFI.

Bottom line: you're setting yourself up for failure by planning that combo. There's 2 guys on this BBS that were die-hard TBI proponents; both of them got 350s and struggled mightily with the TBI and told us all about how good they worked; then they put carbs on their cars, and I don't think either of them has ever mentioned regretting that.

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"So many Mustangs, so little time..."

 

I agree with RB...I installed a 406 into a 91 RS,It was basictly a carbed motor. Right down to the performer intake. I put some larger injectors into the stock throttlebody. I never could get the car to run to its potential. It idled and ran fine, but the best I could get out of it was a 14.0. It screemed in the 70 I took it out of with the carb on it. I know the stock throttlebody is small but I still expected alot more out of it.

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Black 90 IROC, L98, A4, 323 gear. SuperRamed 406 in the works!

 

ok i'm going to respond to "ZENISH" 305 heads on a 400 need to be steam ported or you'll get really, really hot. also you build loads of compression. but it will work! also you can use your serpentine system on a 400 easily with a few mods. a matter of relocating bolts and taking some out. as for t.b.i. used to have it on my car and its extremly senssitve to any and all changes so i'd carburate the thing to save time and headaches. or go with a nice tuned port setup.

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1989 firebird formula

Mods: converted from T.B.I. to a carburator 305 to a 350. Flowmater exhaust,hedman shortie hedders,202 heads,350 horse cam,bored.40 over, Edlebrock torker2 intake.

Future mods 400 performer rpm intake (polished) and 600 edlebrock carb, comp roller cam, and way better heads. orpossibly a 383 stroker?