October 6, 2004Need advice.
October 6, 2004Ok, I screwed that one up. Lets try it again.
I have a 91 Silverado extended cab with TBI 350. It has a Flowmaster 1 into 2 exhaust system, MSD 6a ignition amplifier with an MSD high energy coil, and a set of 1.6 ratio full roller rockers on the stock heads. It runs really well, but appears to be under fueled now that I'm flowing more air with the better breathing exhaust and dropping the valves down a little more with the 1.6 rockers. It peeters out and almost goes dead when you first press the gas and then goes on. I'm looking for any and all sugestions any of you may have. I'm keeping the old truck because, well, it's a Chevy. Need I say more. I'm thinking of a possible 383 upgrade, but there's issues with the computer controlled TBI. Maybe just a head swap with a beefed up TBI unit (again, computer issues). Do any of you have some tried and proven very serious horse power mods in mind you would like to share with me? I plan on dumping $3000 or so in this truck.
December 23, 2004try cfm-tech.com for your fuel problems I have the same problem with mine cutting out when you press the gas pedal........try them out they will make that truck run real good......
December 24, 2004Well, first off you could get rid of the TBI system and get an Edelbrock multi-port system. You would a little HP and would likely gain a good bit better gas mileage too. Edelbrocks system comes with everything you need.. new manifold (ready to bolt on), wiring harness, and it's own ECM...
Check out their site:
On top of that, you can upgrade your cam and get a little hotter one..
And if you feel like spending a lot of money, go ahead and get some new aluminum heads.
December 24, 2004I installed Crower stainless 1.6 full roller rockers. They fit perfectly under the stock covers and work with the stock floating studs. They were pretty pricey though. Almost $400 for the set. I could have gotten some other brands a little cheaper, but they don't fit under the stock covers. The stainless can be made small enough to fit and still be
December 24, 2004I will probably do that. If I'm going to spend the money, I may as well replace the entire top end. Heads, cam and mpi system from Edelbroc. They supply the new chip for the stock ECM. That set up is really expensive though. I would like to know if anyone has done this and is satisfied with the performance.
December 27, 2004well after the issue with the fuel, I was thinking about getting some roller rockers for the truck are they worth it? any noticeable gains?
December 27, 2004Roller rockers will give you a gain... whether it be noticable or hot is hard to say. It will create less friction due to the rollers... however, the amount of gain may not be noticable unless you go with the roller cam and roller lifters as well... With all three, I guarantee there will be a difference. Also, if you get a different rocker ratio than what you currently have (1.5:1, I would assume if stock), then you might notice a little improvement there as well... truthfully, I wouldn't spend the money unless you are going to do it all the way...
Get a roller cam, roller lifters, roller rockers... then when you go with the roller cam, you can get a little hotter than stock and you can get a little better ratio with the new rockers (1.6:1 or 1.7:1).
December 28, 2004Unfortunately I will have to agree with NitroCoupe on the full roller cam and rockers. Learn from my mistake on buying the Crower stainless full roller rockers. They are really expensive. I have the 1.6 ratio so they do open the valves a little more and you can feel it in the midrange response. I can definitely feel a few more ponies, but if could do it again I wouldnâ€™t buy them. One problem is that it is breathing more air in so I've got to figure out how to dump a little more fuel in to balance the mixture. Right now Iâ€™m running a little lean.
December 29, 2004thanks guys for your replies I might as well do it all.. ChevyMan try and use a adjustable fuel regulator and a gauge to read how much fuel pressure you have, and by increasing the fuel pressure it should solve your lean problem. well I have the same problem my tbi 350 seems to run lean as well. good luck. and thanks NitroCoupe.....
January 27, 2005Ok, I finally discovered what was causing my problem. I thought I would post my findings so others having this problem could benefit. I have been having a fuel pressure problem all this time and didnâ€™t know it. After installing an adjustable fuel pressure regulator with a fuel pressure guage I noticed I my pressure was barely 6.5 psi. I took my fuel supply line off the fuel pod and closed it off completely to see if my fuel pressure would increase and it didnâ€™t. I did this by connecting a jumper wire from the data link connector pin G to the battery + terminal to turn on the fuel pump. Same problem. I did however discover that with the engine off and the pump running you could hear pump problems a lot better. It sounded like high-pressure fluid spraying against the inside of my fuel tank. I bit the bullet and ripped off the fuel tank, (a real pain in the ass), and pulled the sending unit out. My problem for years was a 2-inch long section of fuel line that connected the pump to the sending unit was deteriorated. It had a split in the center and fuel was spraying out thru the split and hitting the inside of the tank causing the tremendous lose of fuel pressure. Needless to say I went ahead and replaced the pump with a higher-pressure pump so I would have more options for future modifications. I purchased an AC Delco pump that was actually designed for a 94 Chevy 454. I backed off the fuel pressure regulator to get it down to 12.5 to 13 psi. and man what a difference. My 91 TBI 350 has never had this much power. It runs and idles smooth, has strong acceleration and runs like a bat out of,â€¦ Well, you know what I mean. The pump is capable of delivering up to 40 psi and with the adjustable regulator you can put the pressure where you want it. If I convert it to an MPI system later I will not have to change out the pump. Just wanted to share this with everyone so maybe I could save others the heartache that Iâ€™ve put up with for years.