Testing Different TBI Spacers on a SBC 

Hi, I have a 1994 3/4 4×4 7.4 liter , all original including brakes. This thing burns gas, too much! The breaking is inadiquate and the book in the tire section says to not exceed 120 kms. That is about 65 mph. I live in Alberta, between Calgary and Edmonton people are rolling 130. I am using about 8 to10 miles per gallon. The distance is 185 miles. I haven't driven it any distance and have a small car to go on that trip, because of costs. However I am going to need my knees replaced and the car won't work. So the pickup has to be modified. Do you have parts numbers for the chip or any other parts listing I could use to get the truck to be a little safer and cheaper to run.

What do you mean youve never seen someone who had to do it? You just listed a few things that had to be done to compensate then stated they never had to be done

The computer has the ability to adjust long term and short term fuel trim. This particular modification helps reduce a choke point for the air that is before the valves. Therefore, we are not increasing the maximum amount of air available in the cylinder but when that maximum amount of air is available. The fuel trims will compensate for this but with any engine, maximum performance cannot be achieved without some kind of tuning. I appreciate the questions!

That’s what I did on mine. Made it look like a velocity stack.

I did not get to test the Throttle Body Spacer as it melted. I have some new designs and materials that I am working with and hopefully will be able to test a prototype soon. I would imagine that the TV cable would need to be adjusted but idk about the throttle cable. In theory with enough gaskets you can space the injector pod up, but I think you would end up spending the same amount of money as the the aftermarket unless you have extra gaskets. Thanks for the comment!

That's how it was when I got the truck. I have plans for a new engine with a serpentine belt when I get a chance to finish building it!

Using the injector pod spacer definitely won't hurt the big block!

The 454 TBI has a 1/4 tall phenolic injector spacer from the factory. It also does not have the ridges on the TBI assembly.

I just recently finished a few prototype 454 TBI injector pod spacers. They are 3/8" thick and will be available on my ebay store soon!

@@rustyroadtrips That could definitely help on a 2" bore or larger TBI. The only TBI based engine I still own has the Edelbrock TBI to MPFI single plane intake and the TBI injectors with pod get removed entirely. It is on an aluminum headed 406 with 29 lb/hr injectors. Makes 150 HP more than the factory 320 hp 350 made. That TBI 350 was rather nice for a stock TBI engine. It had a 2" bore TBI, 46 lb/hr high pressure injectors with the 30 psi regulator good for ~ 80 lb/hr, GM 113 L98 aluminum heads and a GM 6395 roller cam. 50+ mph across the water turning 5,200 rpm. The 406 runs closer to 65 mph turning a lot more prop.

By googling stage 1 chip for you vehicle you should be able to come up with some good results. I have heard some good things about jet chips and harris tuning if you want to look there first.

@rustyroadtrips I appreciate the info. I'm going to do some mods on my TBI and I would like a tune.

The point of this test was mainly to see what affect the spacer had. Adding the new TBI was something I wanted to do because I had a rebuilt one laying around. I have done CFD on the intake assembly with and without the spacer installed and it does make a difference. The difference will not make this engine produce loads of power but the spacers are a cheap upgrade. Thanks for the feedback!

@@rustyroadtrips yeah people have much different views on the subject. One guy has a spacer that goes below it, not above, he claimed it did nothing after a dyno test, but his had only 166 HP... Some did say it depends on the upgrades. my g20van stock supposedly has 210hp 300ft-lb of torque. mine has a added 3"exhaust and a k&n air filter which made a huge difference.

With the aluminum spacer on the bottom works good and putting the injectors up higher works good and it dose help with horse power some there's a little difference

Normally they use a phenolic plastic. It is heat resistant, and does not transfer heat like aluminum does.