Question about 1990 Chevrolet K2500

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(95 Gmc Sierra idling problem- Rebuilt vortec block with Tbi heads.) I bought a truck witch latter died on me. I had a vortec block lying around pulled form a 96, So i pulled my Tbi motor out and put my Tbi heads and intake on my vortec block. I did a master gasket set, their are no vacume leaks, And it has proper compression. But when i start it, It idles around 400Rpms and when i put it under a load it dies, I tryed advancing the distributor 2-4 degrees nothing. I replaced the Egr,Plugs ,wires,cap,rotor. And nothing has changed. It dose shake a bit when idling, but not while driving. Also i hear a small ping coming from in between the #2-#4 cylinders. I havent yet checked my valves spaceing yet, But hear that can be a problem when converting like i have.Mabey a knock sensor? Any and all answers will be most apreciated.

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Check the throttle pos sens

Posted on Jul 03, 2009


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Ok I am wondering if my motor in my 91 gmc 5.7 l b8 is a vortec or a 350 it has throttle body carb and not sure thought if I could interchange it with an older 350 ..

Here, is what I think you are asking. The TBI intake from a 91 will fit the same size engine from 88 to 95. The Vortec didn't come out till 96 I believe. So if your 91 is the original engine then it is not a Vortec motor. If you want to swap your 5.7 with another 5.7 (5.7 = 350) Then the 88-95 should work, Just double check your sensors and locations as the plugs may be different and or in different locations. I know my 88 GMC and my 94 chevy (both K1500's) were a little different. Hope this helps.

Jan 17, 2015 | 1991 GMC Sierra

2 Answers

Where should my rotor bug be pointing to when num 1 is at tdc on a 5.7 TBI in a 1989 1500 4x4 chevy

The rotor button should be pointed at the number one cylinder on the contact of the distributor cap. Be careful because on some of the GM distributor caps can be a little confusing. The contacts on the inside of the distributor cap can sometimes be a little confusing. Also on another note, those 5.7 vortec heads on a older 5.7 TBI block will make a very noticeable difference. Make sure and check the exhaust and intake ports and see if they are the same size. Some vortec heads have what they call a "Cathedral port". Lastly if you are kinda handy around a shop you can port and polish the inside of the cylinder head yourself. The main thing is to get all of the rough casting burs off the inside of the ports. I have used a flex head dremel tool and sanded them smooth. You will not believe the increase in torque, horsepower, and throttle response. Good luck.

Dec 11, 2014 | 1989 Chevrolet C1500

1 Answer

Can a 5.7 tbi be used in a 5.7 vortec truck

I think the heads are different too.
A salvage yard or auto machine shop could probably tell you for sure.

Jul 16, 2013 | Cars & Trucks

1 Answer

What year motors, can I use to replace my blown 1996 305 vortec t.b.i.? I own a 1996 GMC 1500, sl, ext. cab. Does it have to be a vortec for my current computer to work properly? Will engine mounts, bell...

Untill recently GM didn't change much of anything as far as bolt paterns You could bolt up a 350 from 20 years ago to your transmission and motor mounts. But that is not really what your wanting to do. The question is do you have a "vortec" or is it TBI. The vortec motor says vortec all over it (they were pretty proud of it I guess) The earlier TBI motor, at first glace look just like the old carburetor versions until you take of the air cleaner and find a throttle body instead of a carburetor. The two are not interchangeable as to the electronics, they are way diffract.

Jan 22, 2011 | 1996 GMC Sierra

1 Answer

95 gmc 5.7 spitting back and losing power after warmiing up

Have you checked fuel pressure? You said TBI so it needs to be around 11-12-13 psi

Sep 02, 2009 | 1995 Chevrolet Blazer

1 Answer

Upgrade 1996 Chevy 4.3L V6 to 5.7L Vortec V8 electric conversion

Different computer for sure, and probably a bunch of sensors, distributor, wires , starter, plug - ins, etc. The only way I would ever attempt that is if i had a whole perts truck to pick off of. You'd be far better off to fix the head gasket, sell it, and buy a truck with a V8 in it already, than to try that.

Aug 19, 2009 | 1996 GMC Sierra

2 Answers

Swap a 86 350 into a 91 camaro with a 305 TBI

good idea, use 350 block,305 heads &intake.the reason is, if the 91 305 heads are 4 bolts in center of valve cover the are what you call vortec heads,they have better flow.the tbi will respond better &still have bettergas milage than old style heads.the 350 block will add more overall shouldnt have any problems doing so,you will notice a diff.have fun, good luck.

Aug 01, 2008 | 2008 Ford F-350

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