TBI Questions

[paintyouup123]

I have a 5.7L in my 89 sub and I was wondering if you put in a 1 in tbi spacer do you have to get fuel line extensions or is it not necessary. also i was wondering what size are the three bolts that bolt the tbi to the manifold. Thanks

 

[southernspeed]

If you undo the securing bracket at the back of the block you'll probebly be able to pull the lines up enough but check for them chaffing on the chassis etc

 

[WhiteBurb]

I put a spacer on mine and did not have to lengthen the lines. There was plenty of slack to fit.

 

[Tabb]

how much of a differance has that TBI spacer made on your engine?

 

[WhiteBurb]

I noticed a bit more power at low rpm, mostly when taking off from a stop. It wasn't a big increase, but I think it was worth it. And it makes a cool whistling noise too.

 

[sarasotausmc]

I put a CFM spacer in mine, and even though the gas pedal stuck a little, I ran it for about 300 miles. Guess I didn't really notice much of a difference until I took it back off. Everything except the acc. cable fit just fine. I don't remember what size the bolts are, 3/8" is coming to my mind though.

 

[vortec]

i put one on my 94 c1500, about 5 years ago and i was able to pull the lines up to fit, no problem. i wouldn't expect it to be much worse on the blazer. i got a modest low-end improvement, a little better mpg, and can cruise on the highway at slightly lower rpms than before. worth the small amount of time and effort, imo.

 

[1985_K5_Silverado]

and can cruise on the highway at slightly lower rpms than before

I'm curious how a TBI spacer apparently alters the overall gear ratio of a truck, which is would have to do in order to let you cruise (at the same speed, I assume), at lower RPM.

 

[vortec]

gear ratio isn't the only way to affect something like that. could mean a lot of things. maybe the powerband flattened a little. maybe it shifted so that i make my power at lower rpms than before and peak out sooner. i've seen peoples' rpms change because of all sorts of things, with no gearing change. changes to cams, intakes, exhaust, forced induction, etc. can affect that. when my friend put a smaller supercharger pulley on his gtp, he got a similar, but more significant result.

 

[1985_K5_Silverado]

I assume that your '94 has either an auto with a lockup TC or else a manual trans. Unless you changed the gear ratio (or tire diameter) in some way, the engine's revolutions per minute shouldn't change unless the crusing speed in mph changes.

Do you mean throttle position instead of engine RPMs?

 

[sarasotausmc]

These guys explained it pretty well to me.

www.cfm-tech.com

 

[vortec]

tranny is a 4l60e. i'm no expert, but i'll put it this way, if an engine's power is increased, it should be able to overcome the same amount of resistance (friction, gravity, air resistance, etc.) with less effort. but i'm just going by what i've observed. i don't have any fancy numbers to prove it. dang. of course, new mods always come with a free right foot upgrade.