Why should I not go fully old-school carbed (OBS)?

[1995Tahoe]

Any idea what kind of torque headers will make with these trucks?

Also including the TB rebuild kit and both spacers and also a cotton washable air filter. Any round about estimate for power gains? For exhaust I plan on going with straight pipes and these single chamber mufflers.

http://m.ebay.com/itm/PAIR-of-Single-Chamber-Performance-Mufflers-3-FB428-center-center-/

 

[drakon543]

You will have a noticeable gain with shortys or long tube headers. Ill probably be drowned out by the masses telling you to get a set of long tubes so ill keep it short. Shortys help low end power more long tubes help mid to high end power more. If your going for the long haul adding more and more upgrades as you go you can get long tubes now and work on your low end later with the proper cam and intake setup. As long tube header will net you higher max numbers. But back to your question about a geuss on gains total probably a max gain of 20 hp probably. Probably the biggest thing you will notice is the increased throttle response. Also with those mods if you keep your foot out of it on long drives your also probably going to see better mpg. 2 other simple diy mods you can do with your tbi is number one doing a catch can and removing that pointless spacer ring thats sits on top of your tb. Next while you have the tb off for the work, using a dremel or something similar remove the raised lip at the top of the venturi channels. The basic design of the tbi on these trucks is they should be operating efficiently as a good 2bb carb. I forget the write up on it but there is a pretty stupid reason why gm decided to try to force tb to pull the air straight down. With the air trying to move around the injectors and thier mount it makes for a very inefficient setup. Ill try to find the write up about it and post back.

 

[drakon543]

http://www.thirdgen.org/ultimatetbi/
"Take note of the gold iridite finish spacer ring on the TBI unit. This serves to lift the stock drop aircleaner so as to not interfere with the TBI components which surround it. Talk about compromises! GM used a spacer to raise the drop aircleaner! The spacer greatly limits flow since it forces air to flow only through the top of the TBI unit this causes the injectors over the TBI to be another flow restriction."
Yup that was the stupid reason for that spacer ring ontop. Anyway skip down on that first link till you get down to that "" i posted.
http://www.thirdgen.org/ultimatetbi2/
This one you only need to be concerned about the first part about the ridge removal. Anything else that's on either of those tbi mod links either doesn't apply to your truck or is just wasted effort. Like shaving the throttle plate shaft wont get you anything except a weaker throttle plate shaft. The stock rated cfm flow for the tb is around 375 cfm and until or if you do decide to start doing a cam swap and or higher flowing heads 375 cfm is plenty. Your just trying to allow the engine to get that 375 cfm easier. Also take note on the first link. Before you remove that spacer riser plate you will need a new air cleaner assembly. Preferably a flat bottom style as without that riser plate the stock air cleaner housing will hit the linkage and other parts.

 

[JonnyTahoe]

I have the same year truck as you do and have owned it for ten years. I too thought about getting rid of the TBI but its to much work and expense. These are low HP motors but very reliable and dependable, they are not intended to be fast notice the red line. The TBI seems to dump more fuel into the motor than the Vortec injectors and you end up with more Fuel Vapors in your oil. I have the same fuel smell in my oil after every oil change and I change my own oil a lot. I have replaced everything on the motor as far as tune-up parts go and would suggest you replace all the distributor parts including the Control Module if you have not already.

 

[SUBURBIAN]

I'm just not feeling the advice you're getting here, OP. Seems like a lot of speculation and inexperience talking and naysaying. Ooohhh, something you have to tune with screwdrivers and a vacuum gauge. Ohhhhhhh it doesn't have a computer so it MUST be slower. Annnnddddd you're going to need all these expensive parts. I don't agree.

A little 4V carb (Holley 600 VS with electric choke) on top of a phenolic spacer on top of a performer RPM/equivalent intake with a GM HEI distributor and you can dial in your fueling and ignition with MORE ease than you can with a TBI. You can more easily modify the spark/timing curve with weight and spring changes. You can more easily adjust the idle mixture, idle speed, and air/fuel ratios. There is no need for MSD this or that. There is also no burning chips or piggybacking computers to program "tunes", you actually tune it yourself with tools you already own.

 

[drakon543]

The only one who ever seems to appear and nay say is you suburban. Generally appearing and nay saying anything performance related. I went back and read through the posts and dont recall commenting on anything relating to tuning. Besides me stating he would probably need and msd ignition(totally based off whatever choices for parts he would make) you have basically just restated the parts i told him he would need to do this mod. I also stated that he would gain hp switching to a carb setup as you also commented. As the tbi setup is extremely inefficient but can be remedied with the mods i have listed. Which as i stated several times these mods are done for the purpose of changing the design back the idea of a carburetor. As far as inexperience and Speculation ive done these tb mods on my 94 Suburban and my 91 camaro and assisted several others doing these mods. As they are free mods all vehicles have noticed a positive difference.

 

[SUBURBIAN]

The only one who ever seems to appear and nay say is you suburban. Generally appearing and nay saying anything performance related. I went back and read through the posts and dont recall commenting on anything relating to tuning. Besides me stating he would probably need and msd ignition(totally based off whatever choices for parts he would make) you have basically just restated the parts i told him he would need to do this mod. I also stated that he would gain hp switching to a carb setup as you also commented. As the tbi setup is extremely inefficient but can be remedied with the mods i have listed. Which as i stated several times these mods are done for the purpose of changing the design back the idea of a carburetor. As far as inexperience and Speculation ive done these tb mods on my 94 Suburban and my 91 camaro and assisted several others doing these mods. As they are free mods all vehicles have noticed a positive difference.

I'm the naysayer, because I naysayed the naysaying? A difference in opinion from yours (that was actually partially similar to yours...but after you said it first) makes me a target to you. I understand. Happy motoring.

 

[1995Tahoe]

This one you only need to be concerned about the first part about the ridge removal. Anything else that's on either of those tbi mod links either doesn't apply to your truck or is just wasted effort.

Before you remove that spacer riser plate you will need a new air cleaner assembly. Preferably a flat bottom style as without that riser plate the stock air cleaner housing will hit the linkage and other parts.

\

Will do the ridge removal. Thanks.

I thought if I get the TBI spacer (between the TBI and the intake manifold) that would make up for needing to get a different air cleaner assembly? I could be wrong, though.

I have the same year truck as you do and have owned it for ten years. I too thought about getting rid of the TBI but its to much work and expense. These are low HP motors but very reliable and dependable, they are not intended to be fast notice the red line. The TBI seems to dump more fuel into the motor than the Vortec injectors and you end up with more Fuel Vapors in your oil. I have the same fuel smell in my oil after every oil change and I change my own oil a lot. I have replaced everything on the motor as far as tune-up parts go and would suggest you replace all the distributor parts including the Control Module if you have not already.

Glad to know someone else has been keeping these wonderful trucks in great shape. Mine was completely neglected. No one wants to do their own work anymore which leaves (most of the time) shady mechs doing crappy work on top of other mechs crappy work. It all piles up and I'm the one fixing everything now. So for the distributor parts, I have done the cap, rotor, wires... what else would you recommend? A list perhaps? Thanks. (I can see the Control Module you recommended.)

A little 4V carb (Holley 600 VS with electric choke) on top of a phenolic spacer on top of a performer RPM/equivalent intake with a GM HEI distributor and you can dial in your fueling and ignition with MORE ease than you can with a TBI. You can more easily modify the spark/timing curve with weight and spring changes. You can more easily adjust the idle mixture, idle speed, and air/fuel ratios. There is also no burning chips or piggybacking computers to program "tunes", you actually tune it yourself with tools you already own.

Yeah, I appreciate the advice. I guess I've just determined after finding out how badly this machine was neglected that any kind of major mods are too far off in the future to think about right now. Thanks tho. About the burning chips and piggybacking and tuning chips etc thats exactly the crap I didn't want to have to deal with. But again, that's too far down the road for me to be dedicating budget and brains to it.


NEW: So after changing the thermostat, come to find out, there wasn't one in there before. They had just the stat housing metal piece but no actual stat. So after putting a 195* stat in it, it now runs extremely hot, even almost reaching 265*. What I'm thinking is that they told the guy they put a water pump in it, but didn't and just put the stat core in instead. When I squeeze the upper radiator hose, it feels pressurized and doesn't flow freely. So new water pump??? Thanks

Also, the oil pressure is running almost at 0 at times. This worries me because I have a noisy lifter and no oil pressure sure isn't going to help it any. Ideas? Thanks.

 

[SUBURBIAN]

If you're keeping the TBI, complete ALL of the "Ultimate TBI mods", and bump up your initial timing a few degrees. You'll notice a difference in performance.

 

[JonnyTahoe]

I'm sure the guy just pulled the stat to see if that would help the overheating problem and maybe it did somewhat so he just left it out and never finished the job. I too had cooling system issues but not overheating. My 95 was leaking from the water pump the day after I bought it so like most repairs it started out as a water pump replacement and that turned into replacing all the hoses and the heater hoses as well that turn out to be expensive and were hard to find not everyone had them in stock. Wait till your intake starts leaking that's a fun filled job, it may have already been done years ago.