Gain extra benefits by becoming a Supporting Member Click here find out how!

Classic Performance Products Nu-Relics Power Windows
American Auto Wire Hellwig Products IncPerformance Rod & Custom
Danchuk Catalog



Username Post: 91 into a 95 TBI question        (Topic#367687)
RayRob65 
Newbie
Posts: 5

Reg: 02-14-22
02-14-22 08:47 PM - Post#2836276    

I 've been looking around and can't find an answer so I will ask it here. I bought a 91 5.7 TBI engine, with low miles that runs great, out of a 2WD Chevy and putting it in a 95 GMC K1500 Z-71. What are the differences of these 2 years as far as engine components go? I saw where the TBI unit is somehow different. What is the difference in them and in anything else that might surprise me along the way? I know that the oil cooler adapter will have to be swapped on, what else? The 95 still runs but smokes and I think it has a burnt valve. The truck sat for almost 4 years and am even wondering about the 95 TBI unit needing gone through if swapped on, if necessary. It's a clean, rust-free truck or I wouldn't mess with it. Thanks in advance for any help.



 
stumppuller 
"11th Year" Gold Supporting Member
Posts: 962
stumppuller
Loc: Canada
Reg: 11-01-04
02-14-22 09:17 PM - Post#2836282    
    In response to RayRob65

Mechanically, I don't think there is any difference between the motors.

I know the 95 model year had many "one year only" changes to the wiring. It has been said many times here that a 95 can only use wiring harnesses from a 95.

Don't have any knowledge of physical differences between 5.7L TBI units through the years (7.4L units did change).

What you will have to swap is the knock sensor and heated O2 sensor. Those changed around 1993.

-91 Sierra C2500, now K2500
-81 Chev K20


 
65_Impala 
Very Senior Member
Posts: 4922

Reg: 12-29-02
02-15-22 11:42 AM - Post#2836320    
    In response to RayRob65

I don't think there is any significant difference between the long blocks. It's just bolt-on parts that might have changed line intake or exhaust, distributor etc. Overall, it should be a fairly easy swap, just keep any parts that are different.

If you're going to try using the 91 TBI then check the injectors. They need to be the same p/n or same flow to work.







 
CowboyTrukr 
"11th Year" Silver Supporting Member
Posts: 4796
CowboyTrukr
Loc: Salt Lake City
Reg: 06-20-09
02-15-22 07:38 PM - Post#2836357    
    In response to 65_Impala

With the exception of one part on the ‘91, everything will be the same. Everything you remove from the ‘95, electronics wise, must go back on the ‘91 block.

Greg

‘01 Silverado 2500HD 8.1/Allison 1000 Xcab/LB
'00 Explorer XLT 4.0 SOHC V6 Auto
'95 K1500 Z71 EC Short Step 5.7L+0.040/NV3500 SOLD

"The only thing necessary for evil to triumph is for good men to do nothing" Sir Edmund Burke


 
someotherguy 
Senior Moderator
Posts: 29599
someotherguy
Loc: Texas
Reg: 08-01-03
02-16-22 01:15 PM - Post#2836387    
    In response to CowboyTrukr

  • CowboyTrukr Said:
With the exception of one part on the ‘91, everything will be the same. Everything you remove from the ‘95, electronics wise, must go back on the ‘91 block.


Pretty much agreed. The long block assembly will almost surely be the same. There will be minor differences up top; some matter and some don't.

The 91 intake manifold likely still uses the paper gasket on the water neck. Somewhere around 93-94 they went to the split O-ring style which necessitates a little lip milled into the intake opening for the thermostat. Does it matter? Not a lot.. until you go to buy a water neck gasket beforehand then open it up and see you got the wrong one, and make a trip back to the store.

91 still has an external ESC module on a bracket next to the EGR solenoid. In 95 it's built into the PCM. The TBI may indeed be the same unit (they changed to that particular TPS style in 91, first year for it) but will have a stud on the throttle arm for the 700R4/4L60 transmission's TV cable, where 93-up doesn't need it. It's not in the way or anything.

91 *should* have the combination oil pressure sender/fuel pump circuit switch on the top rear of the block, vs. the earlier style separate switch (still up top rear of block) and dash gauge sender (down on the block near the filter) setup. The oil cooler adapter you mentioned just sandwiches between the filter and block so that's an easy swap.

In other words if the accessories on top of your 95 engine are good, just swap 'em over.

One real "gotcha" to watch out for is being super careful with whichever oil pressure switch/sender setup you have at the top rear of the block. It's on a brass adapter and the slightest pressure against it will break it off in the block. So, just be careful, even if you're simply trying to remove it for R&R.

Same goes for the heater core "quick connect" fitting in the rear of the intake. Look at those wrong and they break. Might be a good time while the engine is out of the truck to replace the OEM pot metal junk with a steel piece. Much easier to get a broken fitting out while you're not leaning into the engine bay.

Richard

06 Silverado ISS / 06 Silverado SS / 06 300C SRT8


 
CowboyTrukr 
"11th Year" Silver Supporting Member
Posts: 4796
CowboyTrukr
Loc: Salt Lake City
Reg: 06-20-09
02-17-22 11:13 PM - Post#2836468    
    In response to someotherguy

Thanks for reminding me about the ESC module, Richard.

Greg

‘01 Silverado 2500HD 8.1/Allison 1000 Xcab/LB
'00 Explorer XLT 4.0 SOHC V6 Auto
'95 K1500 Z71 EC Short Step 5.7L+0.040/NV3500 SOLD

"The only thing necessary for evil to triumph is for good men to do nothing" Sir Edmund Burke


 
udidwht 
Poster
Posts: 66

Reg: 08-08-17
04-19-22 12:23 AM - Post#2840035    
    In response to CowboyTrukr

Wasn't the 94-95 TBI fuel pressure 26-32psi whereas earlier was 9-13psi

1994 Fleetwood Southwind Storm 28ft
P-30 chassis 7.4L 454 TBI 58,306 miles and counting....as of 05/28/19
VIN# 1GBJP37N4R3314754


Edited by udidwht on 04-19-22 12:24 AM. Reason for edit: No reason given.

 
someotherguy 
Senior Moderator
Posts: 29599
someotherguy
Loc: Texas
Reg: 08-01-03
04-19-22 09:56 AM - Post#2840055    
    In response to udidwht

  • udidwht Said:
Wasn't the 94-95 TBI fuel pressure 26-32psi whereas earlier was 9-13psi


Correct, but only on the big block. TBI small blocks stayed same pressure (9-13) as earlier years, no change.

Richard

06 Silverado ISS / 06 Silverado SS / 06 300C SRT8


 
Stinky 
Senior Member
Posts: 1841

Loc: Whitewater, CO
Reg: 05-25-01
04-24-22 09:56 PM - Post#2840275    
    In response to someotherguy

Cowboy Trucker....what was the dif?

I just put a '99 Vortec in to a '93. Same thing as what you are doing, but different. All the sensors bolted up to the newer motor. The ECM doesn't know that the newer motor is there.



 
CowboyTrukr 
"11th Year" Silver Supporting Member
Posts: 4796
CowboyTrukr
Loc: Salt Lake City
Reg: 06-20-09
04-24-22 11:31 PM - Post#2840276    
    In response to Stinky

You’re absolutely correct, Good Sir. Same with what Ray’s doing. The computer doesn’t care. Just have to bolt everything onto the donor engine.

Greg

‘01 Silverado 2500HD 8.1/Allison 1000 Xcab/LB
'00 Explorer XLT 4.0 SOHC V6 Auto
'95 K1500 Z71 EC Short Step 5.7L+0.040/NV3500 SOLD

"The only thing necessary for evil to triumph is for good men to do nothing" Sir Edmund Burke


 
RayRob65 
Newbie
Posts: 5

Reg: 02-14-22
06-17-22 06:01 PM - Post#2843061    
    In response to RayRob65

OK, the mechanic shop finally got my truck finished, after 3 months, they called and said it was ready. So, my wife and I go and pick it up. I had sticker shock when I saw the bill, but that's another story. I told him I wanted to put a new rear main seal, oil pan gasket, timing chain, gears and timing cover gasket and front seal and valve cover gaskets. He did that but also put new head gaskets and head bolts in it. More than I wanted him to do but I can't cry about it now because it is already done. Anyway, I drive it home and it is smoking almost as bad as the original engine was. I know for a fact that the engine didn't smoke when I bought it, because I saw it run and messed around with it for an hour or so before buying it. What gives!!! It has to be something that was switched over I would think, but what could cause it to smoke now? I am in this truck too deep, more than I wanted to be, to give up now, but I have got to figure this out. I have, supposedly, all of the old parts and the old engine in the back of my truck just in case I need them. Any ideas on what to check out?? I wish I was still able to do mechanic work but can't do the heavy part like engine or tranny swaps anymore due to health problems. Did it my entire life, but I am going to have to do the stuff I can myself with the rates shops are charging now! Could it possibly be oil in the exhaust system? I drove it 35 miles home. All suggestions appreciated.



Edited by RayRob65 on 06-17-22 06:03 PM. Reason for edit: No reason given.

 
rittercon 
"4th Year" Gold Supporting Member
Posts: 76
rittercon
Loc: California
Reg: 06-19-18
08-04-22 01:15 PM - Post#2845440    
    In response to RayRob65

Late post here; maybe the issue is fixed by now.
Your last post says there was smoke with the old motor and then still smoke with the replacement ("non-smoking") motor. By itself, that may indicate the smoke is not specifically "motor" related.

Is the smoke the same color and consistency? Does it emit from the same location (exhaust pipe(s), under hood, under body)? Does the vehicle idle/run OK? Any codes?



 
RayRob65 
Newbie
Posts: 5

Reg: 02-14-22
08-04-22 09:37 PM - Post#2845479    
    In response to rittercon

It's still smoking especially on start-up and semi-hard acceleration. It smokes not quite as bad as the old engine did, but it is still smoking. I was thinking the same thing about not being the actual engine, but a common factor. I was wondering if the throttle body might be trashed up and making it dump too much fuel in the intake, washing down the cylinders and rings?? The truck did sit for 2 years after I bought it (not smoking) with an almost empty tank. Then about a year and a half ago I took it (started smoking bad when I started it up after sitting) to a local shop and had it tuned up and filled it up with gas. Would old gas cause the issue. The engine runs great as far as performance, but the old one did too, not quite as good as this one though. I bought a set of good valve seals and will be getting them put in and checking the throttle body as soon as I get a day when I think I will be able to do it myself. Not really trusting mechanics right now. Any other ideas will be greatly appreciated.



 
udidwht 
Poster
Posts: 66

Reg: 08-08-17
08-08-22 03:26 PM - Post#2845630    
    In response to RayRob65

What is the color of smoke?

1994 Fleetwood Southwind Storm 28ft
P-30 chassis 7.4L 454 TBI 58,306 miles and counting....as of 05/28/19
VIN# 1GBJP37N4R3314754


 
RayRob65 
Newbie
Posts: 5

Reg: 02-14-22
08-08-22 06:03 PM - Post#2845636    
    In response to udidwht

The smoke is kind of a dark blue and black mixed, which is what's kind of leading me to think that it's the valve seals because of the blue smoke and the throttle body dumping fuel causing the black smoke (rich condition). That or it's washing down the cylinders and causing both that way. What are the chances of the throttle body off of the 91, original to the engine that is now in it, to work on the 95 setup? The engine runs great. I drove it a while yesterday and it has great power, just that annoying smoking. If I can't get it figured out soon, I am going to either just drive it smoking or sell it for what I can get out of it. I am in this truck way too deep to keep putting money into it. It really sucks because it is a real straight truck with very nice interior.



 
Icon Legend Permissions Topic Options
Report Post

Quote Post

Quick Reply

Print Topic

Email Topic

1250 Views
FusionBB
FusionBB™ Version 2.1
©2003-2006 InteractivePHP, Inc.
Execution time: 0.089 seconds.   Total Queries: 17   Zlib Compression is on.
All times are (GMT -0800) Pacific. Current time is 05:19 AM
Top