[Stoppy]

Put a set of vortec heads and holley 2 inch throttle body with chev high performance intake that I punch out to match the 2 inch throttle body and headers on my 92 GMC 4x4 truck. Was looking for more power for plowing and pulling my trailer. Now after this not sure if it will even pull the trailer at all. It runs that bad. It acts lean but it also run cool on the temp gauge. Has anyone ever done things like this to a throttle body and how do you get it to run good?

[Ripper 410]

I've done a lot more mods than that, if you want it to run right after you do all the mods that you deside upon contact superchips, hypertech, or sct and have them custom cut you a computer chip they will need to know everything you have done (heads,cam,intake,compression,headers,etc.)and about 200 to 300 dollars later it will run like a champ

[Stoppy]

Where do I find there info?
Thanks Joe

[ap72]

Id megasquirt it. I'm planning on converting my cutlass to TBI when I. Get through the other 30 things on my list.

[Ripper 410]

hot rod ,truckin,mini truckin any mag with aftermarket info, I personally contact Summit Racing, or Jegs hi-performance anytime I need contact info on these types of companys for the simple reason they use there products before anyone else Summit's phone no. is 1-800-230-3030, and Jegs no. is 1-800-345-4545. Talk to them if you have questions about any aftermarket companys me I use Superchips they are cool and will actually talk to you on the phone about you application where Hypertech sends you a form online or by mail. if you have a problem getting there info just send me a reply and I'll get it for you from my shop and reply back with it tomorrow

[Stoppy]

I did get a chip a number of years ago from Jet. They wanted 5-6 hundred bucks to build one. I know I am going to have to do it but if there are other companies out there. I can shop around. Thanks for the info and I picked up most of the parts from Summit. Thanks Joe

[Ripper 410]

Superchips They will cut a custom chip for around 2-300 bucks for your app, I just had one cut for a 90 model chevy not even 2 weeks ago

[American Muscle]

what year cutlass you have ap

[Pre-Tuner]

Been there. Done that. Spent thousands.

The only way you are going to get a chip worth a damn is to either learn and make one yourself or pay someone else to do it properly, which isn't cheap. Mail order tunes are a waste. Two identical 350's will still end up with different requirements. It's like playing darts in the dark. And if you got one that worked decent, I guarantee you there is still some being left on the table.

I spent the money and months of my time on mail order tunes and it was NEVER right. Then I spent a few years learning to do it my self along with over a 1K plus invested. It ran good but I thought there was more. I had come that far, so I spent another $500 at the dyno only to get 6 more hp out of it. Finally, after years of other people (mechanic friends, hot rodders)telling me to dump the TBI and switch to a carb, I finally did. It ran and pulled a lot better out of the box and I couldn't be happier.

There are people that have made it work, but it really wasn't worth the hassel since you can spend less and get more with a carb. Or you could spend more and get more with port fuel injection, which is where I will go with my next project.

Keep in mind that a TBI is nothing more than an electric carb. That's it. If it takes so much to make the electric carb work why not just do the carb in the first place?

Anyway, you are already where I was so may as well continue. When you switched TBI's, did the injectors come with it? The 2" TBI is for big blocks and the injectors flow more, so be aware of that. Also, some of them had different fuel pressure requirements, though most were 11-13, but if the injectors you got need more, then that would explain the lean surges. The fuel pressure is EXTREMELY important with TBI, or any fuel injection for that matter. If it is off, the amount of fuel getting to the engine is off. Sure the oxygen sensor will report it, but it could be off further than the ECM can compensate for. Also, the factory oxygen sensors aren't worth a damn, expecially the one wire sensors because they don't work unless they are hot.

The heads are completely different than what you had and the fuel maps on that chip you have won't match them. Throw a different cam in it and it will be even further off.

The TBI blocks are set up for factory roller hardware, so if you are going to spend the dough on the chip, you should really consider finding a donor truck and getting the rollers out of it. Leave the cam in the donor because it is weak and not worth taking. Get a computer friendly cam from a company like Comp Cams. Make sure you don't use the TBI cam with the rollers because it is not a roller cam.

I've done everyting and more to mine so I know where you are at. I did the vortec heads, big block TBI with matched injectors, vacuum adjustable fuel pressure regulator, the special GMPP intake, bigger cam, etc.

Another site you might want to check out is thirdgen.org. There are a lot of people on there than are really good at this stuff. Just don't mention you have a truck because some of them get, ummm, "jealous"? Since it is a car site.

[ap72]

Originally Posted by Stoppy

I did get a chip a number of years ago from Jet. They wanted 5-6 hundred bucks to build one. I know I am going to have to do it but if there are other companies out there. I can shop around. Thanks for the info and I picked up most of the parts from Summit. Thanks Joe

Just throwing this out there- I'm working on my second megasquirt conversion and both have been under $200.

The 1972 Cutlass Supreme will also have a megasquirt controller.

The one I'm installing on the bobcat will only be used for ignition and datalogging for now as I will be running IR carbs. I may switch to IR injection some day but probably not.

[ap72]

Originally Posted by Pre-Tuner

Keep in mind that a TBI is nothing more than an electric carb. That's it. If it takes so much to make the electric carb work why not just do the carb in the first place?

Because the "electric carb" is MUCH easier to tune, and responds to a lot more variables than a carb which is dependant almost exclusively on airflow and vacuum signal. Its the same reason manufacturers switched to them.

A carbs tune will need to be adjusted depending on a lot of environmental factors too, efi does that for you once you set it up right.

With a little work the big block tbi units can be modified for around 700cfm, that's more than enough for most warmed over street engines.

Port injection is better yet, primarily because it allows for better intake design, but for most mild street engines id take a tbi over a carb any day, assuming its been properly tuned of course.