My 350 made 350 HP with a 650 Edelbrock, so when I swapped the TPI setup onto the motor, I went with 24 lb/hr injectors. After the swap, the motor has been running pretty rich and I'm still trying to figure out if it's the cam (lobe separation) or the injectors causing the rich condition. The cam is a 212 intake 222 exhaust and 112 lobe separation (I think). It's the cam that came in the GM Performance 350 HO Delux crate 350. Anyone have a similar experience? Thanks in advance.
Blake

 

What is your fuel pressure set at? I dont think that you should be running overly rich with a 350hp motor and those injectors. More that likely the reason that you are is the chip is not set up for them and it is using the 22lb settings on the 24lb injectors. An easy (but not necessarily the best) would be to run and AFPR and turn down the pressure.

 

Cam does not sound that radical. I would say that the ECM is not calibrated for that cam and the injectors are probably wrong. I believe they should be 22 pph for stock applications. You now need a EPROM programmed for that system Either DIY or get someone to do it for you. I would not get an off the shelf unit because they are probably not right for your system. Only 2 places I know of and have tried for this sort of thing. www.lingenfelter.com and www.fasterproms.com which are both good and slightly different. LPE needs your car there for a week while fasterproms will burn a chip based on your specs, have you do a diacom reading, reburn, take another reading then do a final burn. Cost at the end of this procedure is $500. If you do other mods that require it like head changes, cam, induction or displacement or larger injectors, you repeat the procedure and it costs you $150.

Just a happy customer.

 

I figured it was a calibration issue. My fuel pressure is 42psi before start up and runs around 38psi at idle. I have a factory PROM (minus VATS), so I may just swap the injectors for a set of 22lb/hr injectors because I'm not in it for power (HP = heat = no fun off-road). Thanks for the input.

Blake

 

Well first off, after putting that TPI on the motor, its not making 350 hp anymore. It makes a hell of a lot more torque though doesn't it?

As for the reason you are running rich. Yes it is because of the injectors. Your cam is slightly larger than the stock TPI cam and doesn't need 24pph injectors. I could burn you a chip in a matter of minutes to combat the rich problem. I wouldn't charge you $500 either

 

is the TPI that bad? what makes it so bad for HP? how is it that is loses HP and gains substantial TQ? If you want to run 1/4's which is a better tradeoff, TQ or HP? I would think HP, what good is the TQ? Higher lift cam to move the powerband higher? just not enough flow?

 

The TPI made a world of difference on my torque curve (exactly what I was looking for in the Jeep) but I lost around 80 HP at the rear wheels. This significant HP loss is because I could only find a 305 TPI setup in my area for the price I wanted to pay, therefore I am running a 305 throttle body on a 350 CID motor...but I plan to swap a 350 throttle body on the plenum as soon as I find one (1985 plenum, in case anyone has a factory 58mm throttle body laying around that they wouldn't mind selling for a reasonable price). I would take you up that offer Brad, but I still need to smog this thing in May, so I may end up just tuning the motor down and learn to be happy with it. I miss HP, the first small block I had in the Jeep made 420 HP and it broke my heart to step down to 350 HP, but I just couldn't keep all that power cool off road.

-Blake

P.S., if you have a 58mm throttle body you wouldn't mid parting with e-mail me: CJJeeper78@hotmail.com

P.P.S. Beautiful IROC Brad

 

Well, I guess I will be the first person to say that there is no difference between a 305 and a 350 throttle body in response to the above quote. And incase you are still assuming that the stock throttle body is the source of your HP loss, the stock t-boddy is good for the HP you are expecting out of a stock TPI unit. I have seen pretty sick amounts of power built on stock t-bodies and lots of people upgrade with out needing to.
Second, I see no reason why a 24# injector can not work in anything more than a mildly tuned stock engine, especially one that is pushing over 300 horse. To say that an engine that makes 240 horse off of a 22# injector can not be made to run properly at 300 horse off of a 24# injector is silly. If you actually have a 350 horse engine on your hands, it is not out of the question to throw in 30# injectors. As stated above, your problem surely lies in your prom burn, take a look at that, but be fore warned that if you are planning any future mods that will require constant chip re-burning, consider your options before laying down a single dollar for that first chip.

 

I'm done building the motor up, I am actually considering building it back down to stock specs, or get it close enough to pass smog. This idea probably seems blasphemous on a high performance oriented board, but you guys know your stuff when it comes to EFI, I'm still figuring it all out. I just got sick of dealing with a carburetor when I wanted to take a drive up through the mountains. I wasn't aware that the 350's and 305's share the same throttle body, all I know is that the motor has not run correctly since I completed the TPI swap, but I'm slowly getting there. I love the consistent power that TPI creates, but I can definately feel a significant loss of power compared to the carb. Anyways, I feel like I may be making an *** of myself, so I'll stop there.
Blake

 

Dont worry about making an *** of yourself I have done way worse than what you have said to this point. It seems to me that you are doing a pretty good job so far. I would say that the loss of power may be because of the powerband. The carb setup will go until the cows come home but the TPI setup will stop breathing at 4500 rpms, being untouched that is. I am not sure if you will ever see those kinds of RPMs in what you are using it for but if you want you can port the garbage out of the plenum and lower intake and increase the airflow a little bit. Another thing to help out air flow would be to (some agree some dont) put an airfoil on the throttle body. I agree with the fact that you should stay with a 48mm tb because you are not going to need as much air as a 58mm will put out until you go to 400ci or larger. Also if you are running the 305 computer (since you said the TPI is out of a 305) that is going to be your loss in power. Your computer is saying that you are running 19lb injectors and you are actually running 24lbers. The PROM tuning is going to do wonders for you I will guarentee that. Also are you running Speed Density or MAF? If you are running SD tuning will make an even larger difference with the fact that you will be able to get into the VE tables and tune to exactly what your Jeep needs. Good luck and happy motoring.

 

I have almost no knowledge of custom tuning my PROM, so I don't feel that I can effectively communicate the changes that need to be made to someone who does know how to tune. The computer is a 7730 computer with a factory 350 manual chip. Unfortunately, I'm still working on a motor miss, so I'm not really ready to jump into a tuning project, but this is the first place I'm going to come when I'm ready. BTW I tracked down the cause of my miss: my gas tank is rusting from the inside out, so I decided to junk the factory 15 gal tank for a new 21 gal poly tank. At any rate, I have found a shop in town that can test and clean my injectors (rust isn't very easy to get out of injectors with compressed air and carb spray). I really appreciate all of the advice you guys have to offer. Thanks again.
Blake