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post #1 of (permalink) Old 08-30-2000, 08:24 PM
BigAl
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Holley TBI (A New Twist?)

I keep hearing about replacing the stock 2.8L TBI with a Holley 400 CFM TBI which is nothing more than a stock 4.3L TBI.

Holley, in turn, has a 670 CFM TBI which replaces the stock 4.3L TBI.

My question is will the 670 CFM TBI fit on the 2.8L engine since it will fit on a 4.3L engine in which its stock TBI fits on a 2.8L engine?

Has anyone heard of doing this? Is there a stock 670 CFM TBI that is on a different engine (5.0L or 5.7L) that can be purchased used or remaufactured/rebuilt? I wonder how much more power, etc. would come from this....

Thanks in advance.

Al

'87 Jimmy 4X4 2.8L

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post #2 of (permalink) Old 08-31-2000, 03:25 PM
 
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Re: Holley TBI (A New Twist?)

I would say that unless you're running a wild cam, and a big blower, that the 670 CFM TBI unit would be far too big to run right at all, even the injector pulses would literally just dump tons of fuel down the intake, actually killing your performance. Just my thought, anyone care to add anything or tell us if I'm wrong here?

Tim
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post #3 of (permalink) Old 08-31-2000, 03:31 PM
 
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Re: Holley TBI (A New Twist?)

Nothing to add, but I second what Sandman said!
It is ALWAYS better for performance, if your engine is a little thirsty for more fuel, Rather than choking on too much fuel !!!!!!!!!!!


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post #4 of (permalink) Old 08-31-2000, 06:18 PM
**DONOTDELETE**
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Re: Holley TBI (A New Twist?)

Hey Al. I researched the 4.3 Tbi before I bought the Holley Tbi for my 2.8. Two things first ,the 85-891/2 use a 1st gen Throttle position sensor and 90through 93 use a different 2nd gen Tps sensor.Secondly the 4.3 Tbi wont work,the throttle blades open the reverse direction -albeit the cable plate(fixed) is opposite side .It wont work. I looked at a 90 305 Tbi today and found i could work.Not 100% sure though. Besides the previos two posts hit the nail on the head,too much air and fuel wont help a near stock motor. I also found that the first gen tps sensors and 2nd gen are completly compatible by simply splicing a 1st gen Tps male connector,found at auto zone in electrical aisle ,and connecting the wires according to a haynes schematic . Thats how I run the Holley on my 92,no problems. http://614streets.rebondir.com/ -YOU CAN SEE My s10 on photo page.


post #5 of (permalink) Old 09-03-2000, 11:24 PM
BigAl
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Re: Holley TBI (A New Twist?)

Ok, so really my only option is the Holley 400 CFM TBI. What do you think about adding a TBI spacer to that? If so, what size, brand, etc.?

Thanks for all the help.

Al

'87 Jimmy 4X4 2.8L
post #6 of (permalink) Old 09-08-2000, 12:58 AM
jeeper131
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Re: Holley TBI (A New Twist?)

so how much did the holley TBI cost you and was it a direct bolt in? What did it do for performance ect and what happened to fuel mileage? I'm rather interested in this project, becuase it sounds like it could be the low-buck horsepower addition I need.

MudFlap
'87 YJ in the works
post #7 of (permalink) Old 09-11-2000, 10:55 PM
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Re: Holley TBI (A New Twist?)

Hey Big Al, in regards to the purchase of the 400cfm holley and an additional spacer, you may find the TBI spacer a plus . I unfortionately have not bored my Intake to match the new TBI unit,instead I am using the Supplied "step down" gasket, but the Increases in HP band have definatly increased. I do plan to bore the Intake manifold to match th TBI bores, as soon as I find out exactly whats the best way to do so. Here is one you may find interesting. I use a Nitrous Oxide system on my 2.8. It is a plate system . The plate provided is around 1/2 to 3/4 " thick and is placed under the TBI. I noticed a improvement in accelleration after I put that on ,that is with the nitrous off. This was with my old Rochester Tbi unit though and because I havent taken it off with the new Tbi , I cant judge wheter it is providing any extra HP now. A spacer on a stock TBI is worth the cash on any 2.8 tBI . The weakest part of the 2.8 engines found in S-10's is the narrow intake manifold and its lack of size. There is very little volume but a TBI spacer adds more capacity.

My s10 also has a crane 2030 compucam, so my increases in power are better than what you should expect, but I still feel this is one Mod you should not overlook. -Will

post #8 of (permalink) Old 09-11-2000, 11:26 PM
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Re: Holley TBI (A New Twist?)

Well Jeeper the Holley Tbi was like $300 bucks at JEGS. Basically performance was greatly improved in such a way that I felt It was although a little pricy, it was worth my money. I have a 1992 S-10 and I had been eyeing the Holley unit hanging on the wall at the 11th ave Jegs here in columbus for a year or so. The problem was the unit was supposedly only designed to fit 85-891/2 fuel injected S10's.
I repeatedly contacted holley to find out if the swap was at all possible. Interestingly enough I was told many different reasons why it was impossible to do so. Things like the TPS sensor on my 92 read the swing of the Throttle shaft was opposite the perscribed years and plain " Im not sure" were just a few of the responses I recieved by Fax and Phone. Ugg what a bad Deal I thought. But It was like it was burning inside of me to prove them all wrong .
So I did just that. I put it all on the line and traced the shematic (which by the way is the same from 85-93!). I found that by simply splicing an 1st gen connector to my wiring harness for the 2nd gen Tps corectly, I was a easy bolt on.

It is a 1 hour swap tops , It has an ultra smooth and adjustable Idle,adds needed top range pull,and compliments any mods.

I think my Mpg is a-ok unless Im feeling the urge to go fast.

I have yet to make a quarter mile pass with the Nitrous and the New TBI so I 'll make sure to post the results soon as I go to do so.-will

post #9 of (permalink) Old 09-28-2000, 04:28 PM
BigAl
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Re: Holley TBI (Additional Spacer?)

I am going to install the Holley (400CFM) [img]/wwwthreads_images/icons/cool.gif[/img] this weekend, but I was wondering if anyone has installed a Holley TBI and added a spacer on top of the step down gasket. If so, what size did you use?

Does anyone know what the maximum size space between the maniford and the TBI can be before performance loss or ability to fit under the lid? Holley claims that they have not done any research using additional spacers with the unit, [img]/wwwthreads_images/icons/frown.gif[/img] so they were no help. Would it hurt to add a spacer to the step-down gasket, which is 1/4" thick? Advantages? Disadvantages? [img]/wwwthreads_images/icons/crazy.gif[/img]

Thanks....

Al [img]/wwwthreads_images/icons/smile.gif[/img]

'87 Jimmy 4X4 2.8L [img]/wwwthreads_images/icons/crazy.gif[/img]
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