1990 Blazer TBI Replacement w/Holley TBI

[lcdrbadar]

I have a 1990 Blazer w/a worn out TBI unit. I have researched the Holley TBI direct replacement units and found them to be an excellent replacement for the stock TBI unit.

The options from Holley are the 502-6 and 502-9 TBI's. The 502-6 fits 87-89 5.7L models and the 502-9 fits 90-95 models. Even though the obvious choice is the 502-9 for the 90 model, I think the 502-9 may be for the K1500/K2500 model trucks, not the 90 blazers so which Holley unit fits the 1990 blazer?

If you've replaced your TBI in your 90 blazer w/a holley unit, please let me know which holley unit works

Thanks

 

[Jason4x4]

I think there is also a difference on the linkage hookup, when they went to the 4l60, they got rid of the tv cable nub, on the older ones with the 700, it has the nub to hook up the tv cable. The tbi that I put on my truck didn't have the nub, so I had to mobify it to work.

 

[pseudomike]

No Good

I've had a lot of problems with the Holley units. The bodies themselves aren't too bad but the the injectors are lousy. The earlier units had better injectors...but that was some 10yrs ago and they are probably just as worn out now if you could find one.

In my experiences there are much better ways to replace your worn out TBI than the Holley route. First thing you got to decide is whether or not you want to retain the stock TBI bore? My reccomendation is no as the stock TBI only flowed about 440CFM and any V8 should be flowing 600CFM or more. The Holley Flows about 670CFM.

The Holley will run you $450ish - $500. I went a little different route with mine. I bought a bored out bare TBI that fit my truck from http://www.rvmorsemachine.com/orders.htm. ($229) I also purchased a set of flow-matched injectors ($69). Chances are your IAC and TPS are fine. If it bothers you to re-use them go buy some lifetime warrantied ones from the local parts store for about $120 for the 2. Now you got a new TBI for a little less than the price of the Holley.

Just my experiences, but the truck runs great now. I would also recommend giving Brian from TBICHIPS.com a call. He's happy to chit chat and can probably point you in the direction of the best deals going. He's got a lot of experience and can probably tell you some horror stories about the Holley units.

Just my 2 cents.

 

[lcdrbadar]

Thanks for the great advice. However, I went ahead and purchased the Holley 502-6 today just prior to reading your advice. I'll give it a try and if it doesn't work. I'll definitly try your route.

Thanks once again.

 

[BGKYK5]

I had heard the opposite, that the early Holley injectors were the bad ones and that the new ones were much better.

 

[pseudomike]

I'd say good luck with it.

I bought one a year ago for $499, returned it 3 times due to failed injectors, and then ended up selling it on ebay for $125 because they would not let me return it any longer.

I bought one about 10yrs for a TBI swap into my Jeep....it still runs fine...it has BOSCH injectors.

Maybe they got the problem sorted out? Just trying to pass along my experience.

 

[BGKYK5]

Just out of curiosity, how did the injectors fail? I heard the early ones leaked (didn't shut off all the way). Did Holley replace the injectors each time and the new ones were bad too?

 

[pseudomike]

The ones in my old unit leak if you turn the fuel pressure too high. You can actually see them dripping over say 24lbs...which is quite a bit..enough for well ovr 300HP. You can replace them with off the shelf injectors if you want to.

The new Holley unit had Delphi injectors, they were proprietary meaning I couldn't just goto the parts store and get a new one. These injectors seem to just plain old stop pulsing..gonzo..no more fuel. Holley wanted $220 per injector..needless to say wasn't going to happen.