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Discussion Starter #1
been searching but cant find straight answers.
95 k1500 suburban, 265's 3.73's tbi 350 all stock. 126k
first thing i should mention is im not looking to make a screamer, or even add any top end, just a few minor bolt ons to help low end to move this heavy beast, and get a few more mpgs, will be used as family hauler and to tow jeep at most 3 hour trips 1 or 2 times a year. 1 st 6 hour voyage got 17mpg on hi way cruising 70-75 at 17-1800rpms.
So far plans dont include anything invasive.
1. spectre air filter (k&n knockoff)
2. towmaster chip from tbichips.com
3. replace stock muffler that looks like a 30 gallon trash can:eek: with a flowmaster i have that i took off jeep.
4. ditch cat (no smog test here)
5. 1.6 roller rockers self aligning
what can i expect from theses mods, i know nothing crazy. but i dont have time to do a cam swap or heads till the motor needs to be yanked and rebuilt which probably wont be for a long time. as it runs great. what do you guys think.
 

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you'll need to play with the tune several times, or you'll probably start running lean with the exhaust changes & air filter. You can't just change a tbi and expect improvement, it's all in the tables.

Maybe a throttle body spacer if you can find one for cheap/free.
 

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x2 on the throttle body spacer, and on
your plan so far.
 

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Couple of things to look at first.

As has been pointed out already, a good tuneup to get the ball rolling. Doesn't sound like there are any problems with it, but it's just a good way to get a baseline.

I don't know much about the towmaster chip, other than the rep of TBICHIPS. Personally I would hold off on any kind of chip until you have some of your other mods done, and would do some datalogging first. No point in spending 2-300 dollars on a chip that is unsuited to the mods you are doing. Do the mods first, and see what it needs to run best.

TBI spacers seem to be a good start. another thing to look at would be your fuel pressure. No point in changing it, if it is not a problem, but you won't know what it is, till you measure it. Start adding modifications in the airflow, and you may need to look into upping the fuel pressure.
 

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Couple of things to look at first.

As has been pointed out already, a good tuneup to get the ball rolling. Doesn't sound like there are any problems with it, but it's just a good way to get a baseline.

I don't know much about the towmaster chip, other than the rep of TBICHIPS. Personally I would hold off on any kind of chip until you have some of your other mods done, and would do some datalogging first. No point in spending 2-300 dollars on a chip that is unsuited to the mods you are doing. Do the mods first, and see what it needs to run best.

TBI spacers seem to be a good start. another thing to look at would be your fuel pressure. No point in changing it, if it is not a problem, but you won't know what it is, till you measure it. Start adding modifications in the airflow, and you may need to look into upping the fuel pressure.
This is great advice. If you were using TPI, and sent me a datalog from chip"X". I'd have a tuning point to start from. TBI chips can do the tune better if you work with him.
 

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Discussion Starter #7
wow most people say throttle body spacers are a gimmik but have seen alot of people recomending them for this motor, i will look into those further. I will start with new plugs, filter and easy shit like then am going to mess with the timing, i have read on third gen forums to advance timing 6* ,would that be a good start?
 

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TBI spacers depend on the engine and what you want done to it. They don't add HP like most think but move it around in the existing power band to a place you might find it more useable.


Personally on that engine I wouldn't get one and just find a good aftermarket intake for it if you have the skills to swap one. If you don't then try a TB spacer out.
 

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Spacers work well on the TBI because it's a wet intake system. You can also look into an injector pod spacer and the ultimate TBI mods, but those really aren't needed until you've swapped that tiny cam out.
 

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Discussion Starter #11
i was reading a little on the fullsizechevy forum, about most of this stuff. i really dont have time to swap out intakes right now, and i dont want to pull apart tb at the moment to modify regulator to make adjustsble. I know cam is tiny, i have been thinking about 1.6 rockers to bump up lift a little, or from what i have heard 1.6 on the intake side will up low end tq.
 

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do the tbi mods off of third gen site. use air filter like you said. bump up fuel pressure. put new fuel pump in out of a 96 vortec motor. pump fits right into stock float assembly. if you can do rockers you should be able to do the tbi mods start to finish in under 2 hours. they are free is the best part. then throw a second gasket under the injector pod = pod spader. Just my 2 cents worth. This is what I did to mine and was happy w/ the results. But I also run vortec heads.
 

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Discussion Starter #13
where is the fuel pump located, is it in the tank? I dont really feel like dropping that beast of a 42 gallon tank. What about the mod for heavier sping for fuel pressure regulator.
 

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There is a company out there (cant remember the site) that sells a kit that allows you to check and adjust the tbi injectors them selves. When GM was building tbi engines they had a certain allowance between fuel pressure at tbi, and what they sprayed.
305's and 350's were set anywhere between 11-13 psi from the factory, most 11 and 12psi. The lower the # the more it effects your hp. The stock pump puts out usually around 15-16psi which means you can adjust it up.They said 14.5 psi is around where you want it to maximize hp without hurting the pump. I have the kit on my sas'ed chevy that I recently built the engine in and it is a huge difference. The stock injector in the 5.7 sprays 50 in lbs/hr at 11 psi. Bump the pressure to 14.5 and it sprays 58in lbs/hr. That is a good bump in fuel delivery, or you order the police 5.7 injectors that spray 68 in lbs/hr at only 13 psi. Also I made an air cleaner spacer that is wider due to the original being so close and tight to the tbi it cant breath. I will look through some files for the reciepts if your interested.
 

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air cleaner

I added several of these bolton's. Try gettin the Jet perf salad bowl air filter spacer. And run a Dominator air filter base it really unsheilds the injectors. Sorry if the description is vage.... Its called the "Salad Bowl mod". JUst my 2c$
 
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