Looking for those who have this setup that would like to either e-mail or PM with Pro's and Cons you have had, or have, using the 350, and the 700r4, please, Thank you

 

you have to buy an adapter plate
you have to buy a linkage bracket
you have to do some fabrication

other than that, just a few hurdles.

 

you can mod your stock throttle bracket to work. all you have to do is rebend the arm that attaches to the intake bolt. jsut flatten it out so it is a 90degree instead of the funky angle the stock intake puts it at.

later
tim

 

WOW, only 2 people have this setup. Must have been a "stupid" question.

 

I did the same thing and I found it to be a very disappointing performance for TBI. Also, with the vortec intake there isn't a routing passage for the EGR valve. Sure it looks like it, just slap that EGR valve right on top of the intake like the old manifold but there is some kind of valve system you have to buy. I am not sure what it is...maybe some other people know what I am talking about. I just decided to scrap it.

 

Are you referring to a 350 motor or transmission? I have a 355 motor and had to set the idle so high so the car would not die when shifted into drive. The idle was taching around 1800 or so. A good idle should be around 1000-1200. Again, this could have been because of the EGR but one thing I do know. TBI for a 350 and a real performance don't mix. The TBI unit simply cannot supply enough air in my opinion for the motor. Will it run? Sure. But if you are looking for a car faster than 14 seconds in the 1/4 its not going to happen with a TBI without major changes (nitrous, etc.)

 

I disagree. I've handed enough low 14's cars there asses to know you can easily get into the 13's with a 350 TBI.

Also, I idle at 650 RPM's. You might want to check the PROM your running.

 

cam specs on that 350 would help with this discussion.

 

Your right about the 13 seconds, I dont know why I put 14. It depends on what kind of rear end you use as well. I will say this though, I haven't seen a 350 TPI dip into anything lower than 11's without major mods. Now it could be because I am blind....haha

 

Then your statement would be true. To get a N/A TBI into the 12's, you would need to support about 375 HP or you could get away with less horse power, but HUGE gears and a MASSIVE stall.

 

Hey thanks folks, I guess I should have supplied more info. I was lookin for info to determine my direction to go. I have 170,000+ and hopefully longer on TBI motor. The replacement is a 99 model 350 Vortec long block. Tryin to decide whether to go with GM TBI Vortec intake or go with aft. market Vortec carb intake using adapter for TBI. Whether to use EGR or not. I do have a good start on DIY tuning, so the chip will not be a problem. A cam is a possiblity, but not a must. It will be a daily drvr, 100 mi. round trip, to work, so I'm lookin more for the longevity side. The performance would be nice on the occassions when needed, but not a neccessity. Just lookin for good and bad, thats all. Thanks again folks

 

I just upgraded to the vortecs as well. Other then the egr, the manifold install will be the same as any other carb manifold. The throttle bracket is easy. Just bend, cut the excess off, and drill the hole and use a stud plus a spacer to mount it to the intake. Other then that its pretty much like any head swap. The vortecs flow reasonably well at the intake but the exaust ports could use some porting. Theyre bascically stock light weight castings with a reconfigured intake port and chamber. That being said, if you do any porting, be careful. These heads look pretty thin in certain spots. GM also uses a longer plug to get the spark as close to the center of the cylinder as possible and more efficient chambers, which are a nice feature.

I think theyre a good head for stock to mild performance build ups, but the heads will need some mods if your going to be going over around .450" of gross lift.

 

I am running 9.8s in the 1/8 with a TBI 350 in a full size G20 van. That is equivalent to roughly mid 15s. That is with the stock TBI intakes, a stock 350 TBI, ported "193" swirl port 350 heads, and a LT1 roller cam. My idle is dead smooth at 550 with 22 in/hg of vacuum.

 

ok, so you run mid 15's in the quarter.....like i stated after being reminded of my error of stating 14 seconds instead of 13....so what was the point of quoting me? Unless someone has a 12 second or lower TBI please let me know.

 

Working on it.

 

squirrel

I went the GMPP TBI Vortec manifold route and love it. The difference between the old 305 and the 350 I have in there now is night and day. But a car can never be to fast so now I want a bigger cam and a bigger TB but to do that I need to mod the heads for more lift.

ryan

 

The reason why you don't see it too often isn't because it can't be done with TBI. The reason is that people don't take the time to properly tune these systems. Air flow is not the limiting factor of these systems. Fueling is. There are some people who have 12 second combos but run 14's because they don't do the necessary chip work. They get frustrated, slap a carb on it, run their 12's and then say that TBI was junk and that it was hindering its performance.

 

Theres even more to it then that. There is alot of hidden stuff in the stock code that will literally drive you crazy. Even to this day Im still digging up things that I didnt even know where there. This weekend I found out about the opening throttle transient spark control that alters the ammount of spark the motor gets depending on how rapidly the rpms are changing. This table is so far off from being tuned it isnt even funny and yet it doesnt even appear in the ECUs Ive seen. I disabled it and it was like night and day. Another little interesting thing thats in all the thirdgen tbi ecms is a slow *** filtered multiplier that controls how fast the ecm transitions from the base time to the timing in the tables when the motor first starts. I dont think anyone even knew of this before. Its definatly important, though, if your having startup issues.

If I had started with tbi 3-4 years ago, Id defiatly be running carb by now because there is just so much stuff thats completly hidden in these computers that it could make tuning literally impossible.