Question about adding TBI

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86cutlassrules

Greasemonkey
Dec 12, 2008
149
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Well think about it like this, I could buy a 403 Q Jet, then buy a lock up kit, Then test and tune and buy rods until I get it right. Or I can use the TBI and let the 02 tune it. The 350 tune should be similar to the 403 so I should have a decent baseline. If I remember right the 350 and 403 carbs were jetted very similarly. A TBI is just a carb that's always in tune. As opposed to me with a vacuum gauge trying to get it just right and then as soon as the temperature changes its not 100% but TBI would be thanks to the 02. I know a lot about fuel injection so its not foreign to me, the hardest part is just getting the gas tank and fuel pump right, and finding a harness. The only exotic thing is getting the chip burned. Ive had a few cars with TBI and all of them ran great and were trouble free and lasted well over 150k before I got rid of them. Yes I know you can rebuild a carb and run it again so please don't bother posting that. Maybe there's an extra 10-15 hp to be found in getting a Q jet tuned within an inch of its life but its also a huge pain in the *ss. The car is a daily driver so, things like idle, street manners, MPG and A/C are a priority over quarter mile times. Not to say I wont ever take it to the track for fun. I'm sure my 403 will move the car well enough just for cruising around, and with a TBI it should be nice and civilized. I know people think TBI was just for emissions, but it helped emissions by making sure everything was running right not just stifling the car. If you get some time google TBI swaps youll be amazed at the cars/engines people are putting stock GM TBI setups on and they work well with out any crazy mods.

Would the blazer fuel pump pick up work in the G Body tank? So are you saying the 4.3 was port injection not TBI? I could just use the 4.3 sender and put a lower PSI fuel pump in it if that was the case.
 

DRIVEN

Geezer
Apr 25, 2009
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Ignore the Blazer references. The 4.3 Monte was TBI and the tank would be an easy bolt-in. A GN tank and hanger assy would also work if you just subtituted a lower pressure TBI spec pump.
 

truracer20

Master Mechanic
Feb 16, 2014
492
31
28
western PA
I'm pretty sure an ESC distributor from an Olds 307 will work with the TBI. And since the throttle body has a regulator in it you should be able to use a pump from a GN. The injectors only see regulated pressure.
 
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86cutlassrules

Greasemonkey
Dec 12, 2008
149
0
16
I actually have the distributor from the 307 CCC system. So Im good there. I just have to search the junk yards for a 4.3 car. Will the neck be wrong from the Grand Prix Tank?

Im having trouble finding the hangers what would be a good source for a stock replacement? Also was the stock carbed 307 sender 2 or 3 lines?
 

truracer20

Master Mechanic
Feb 16, 2014
492
31
28
western PA
There is a member her named olds307 and 403 that did an Olds TBI maybe you could message him or maybe he'll chime in.
 

86cutlassrules

Greasemonkey
Dec 12, 2008
149
0
16
Ive seen all those links actually. Ive been researching for a while, they have these GM TBI's running on just about everything. The biggest obstacle for me really is just fuel delivery. I need to know if any other G body tank fits with out changing the neck, and where to buy the hanger for an EFI car. Every time I look I only find the carbureted ones. I was considering buying a new tank, but I had heard they had venting problems and poorly made baffles. These are the big questions I'm trying to get answered.
 
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