Here's my other post for more background info:
http://www.nastyz28.com/ubb/Forum5/HTML/013412.html

If you read my other post, you'll see that I am contemplating eventually when my 89 suburban dies (approx 350,000 miles I would bet it'd make it, 120K to go), I would get an old GMC Suburban 63-66 most likely, and put more current brakes, power steering, and engine in it.
I have a 307 that I may use the block for this project possibly. I'd like to have a smaller displacement V8 with a long stroke, possibly a 305, but if I could build it with parts I have plus vortec heads and intake, and a 305 or 350 crank, that'd be really nice.
Anyhow, my two concerns are this...
My 350TBI in the 89 has a knock sensor or something in the side of the block. If I were to use an older block for this swap, would I necessarily need that?
Secondly, what would I be looking at as far as wiring when switching from a 64 or so truck engine to something with TBI and a computer? what all parts would I need? Is there just an engine/computer wiring harness that I would need? I know there would probably be a few extra dash lights in the wiring on the newer truck. How straightforward would this be? What all parts would I need if I had a TBI vortec intake? computer, harness, distributor, what ignition stuff? any extra relays or anything? I am fairly unfamiliar with anything but carbs, so explanations would help.

Thanks!

Chuck



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'71 RS/SS pile of parts: full roller 406sbc / 9.76:1 w/ E-Tec Al. heads / 750 Competition AFB / 12"/11.1" 4 whl discs / big sway bars / 4 speed 3.23 posi / 81 Z28 & dual snorkel vette Air Induction

I'd need exhaust manifolds I'm sure, for the O2 sensor or whatever, but I actually saw a set of factory shorty style headers with a spot for this sensor that I could pick up out of a box truck in the boneyard.

With TBI, could I get away easily with no cats and some V-tube type mufflers? Maybe a turbo muffler. Change a chip or something? When the muffler fell apart on my 350 TBI, it ran noticeably smoother after I put a new one on.

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'71 RS/SS pile of parts: full roller 406sbc / 9.76:1 w/ E-Tec Al. heads / 750 Competition AFB / 12"/11.1" 4 whl discs / big sway bars / 4 speed 3.23 posi / 81 Z28 & dual snorkel vette Air Induction

Any opinions on what would have more torque, and the difference in the gas mileage between an early 60's GMC big block 305 V6 vs a chevrolet 305 V8? I'd probably get a 305 with TBI and a 5 speed manual or 200R4 4 speed auto.


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'71 RS/SS pile of parts: full roller 406sbc / 9.76:1 w/ E-Tec Al. heads / 750 Competition AFB / 12"/11.1" 4 whl discs / big sway bars / 4 speed 3.23 posi / 81 Z28 & dual snorkel vette Air Induction

Chuck,

As far as the TBI system goes, if you get the complete computer & wiring harness for everything it would be an easy swap to do.
Although limited, they are capable of good performance and fuel mileage plus have excellent reliability!

The knock sensors on 89 TBI trucks were mounted in place of the water jacket pipe plugs so that should be the same for almost all years of small blocks.

The Scoggins Dickey/ GM Performance TBI Vortec intake would allow you to run Vortec style heads and keep a functioning EGR system.

I think your going in the wrong direction but it's only my opinion. I would say you're better off going with at least a 350 or larger engine especially if you are using a 350 TBI system.

There are options to the stock GM wiring harness as Howell engineering, and Painless Wiring makes harnesses for retro-fit apps. You would need to get a high pressure TBI fuel pump since the stock 89 is in the tank.

The exhaust manifold from 96 and later small blocks would be the best if you intend to keep the EGR system and run Vortec heads. If EGR is not important, and you use an aftermarket wiring harness, you can run aftermarket regular full length tube headers as long as they have the bung for an O2 sensor.

As far as exhaust goes, you could keep it simple and run a stock type single 3" monolythic cat & a replacement performance 3" muffler like a Flowtech Afterburner or Terminator.

If you went to a true dual system, you would have to have a different wiring harness and dpossibly dual O2 sensors to give the correct range of information to the computer so it doesn't run the injectors too rich. It is theoretically possible to run without the cats but I feel this would be a mistake for performance and mileage.

The early 60's GMC V6 was a low speed torque motor. It would not rev high and the gears needed to run were usually pretty steep. They're fun to play with but as far as performance goes, the newer TBI engine would out-do it in almost any catagory.

If you were to get a manual tranny, you need to get the right computer and calmap chip for that combination.

You've got a lot of ideas and need to decide what the best overall plan for this vehicle would be.

My suggestion is to go for a 350 TBI and a 700R4 as they are the easiest to modify and enhance for performance and mileage. There are millions of them out there and alot of aftermarket parts still available.

Hey, thanks for the reply Kamikaze! That's a big help.
As far as you saying I may be headed in the wrong direction... I would easily just go with a 350, except for the prospect that the price of gas may never drop again, and I need a little better mileage out of something that will be my main driver. I would consider going with a late model 305 if I found a good deal on one, but a unique engine combo would be interesting, and I already have everything except a 305 crank (dime a dozen) and rebuild parts. Found some pistons I think will work for this application. This way I'd have a slightly smaller displacement than a 350, slightly larger than a 305. It would be around a 331 sbc depending on overbore needed. A 327 has a shorter stroke, and larger bore, but I was really looking for longer stroke and smaller bore for a truck engine.
The factors were basically just that I had most of the parts I'd need minus vortec heads and tbi vortec intake, and that it would be the middleground between a 305 and 350.
I would probably plan on doing a 200R4 or 700R4 if the truck I found was auto, but if manual, I would definitely try to swap in a 5 speed manual trans so that I could have OD and some low pulling gears to make up for the fact that I didn't use my 350 or 400 in it. Borg Warner T-5 trannies out of blazers and s-10's are easy to come by, as well as transfer cases to use with them if I were upgrading running gear. Might be a 4WD as well, that would be nice.

Well, that's what the idea is now. I guess a 305 with a 5 speed tranny wouldn't really be all that bad for power I suppose.

I probably would just stick with a single 3" exhaust. No need for duals, as those old Suburbans look cool enough as is... Plus I will still be using it for utility purposes, no showing!

The reason I was thinking of using the TBI and computer off of a 350 is because I would probably have a little larger cam in it, whatever computer cams I could find, and thought the 350 tbi would be more fitting. Would I be better off using the TBI from a 305 and putting a performance chip in it, if I did the 307 block with the 305 crank?????

All just thoughts now, just wanting opinions.

Update: My mom says my dad is probably going back to buy the 64 Chevy Suburban with non-running engine for $1200... I wanted a GMC, but if I can't find one, maybe they'll part with that!

Thanks!

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'71 RS/SS pile of parts: full roller 406sbc / 9.76:1 w/ E-Tec Al. heads / 750 Competition AFB / 12"/11.1" 4 whl discs / big sway bars / 4 speed 3.23 posi / 81 Z28 & dual snorkel vette Air Induction

[This message has been edited by Chuck78 (edited August 09, 2005).]

Chuck78,

Consider this...

If you use a smaller (305) engine, it would probably not get better mileage than a 350 since it would have to work a little harder than a 350 to move the weight of the suburban.

I understand your feelings about running something interesting but is it practical?
Not very likely. You contradict yourself about being concerned with fuel cost rising and getting better gas mileage if you want to make it a daily driver with 4WD!

Even if you built the 331 and got it TBI'd, you'd still need to find a good match for the gear ratio and a good performance chip to get the best performance and fuel mileage out of it!

The engine combo you are considering would have limitations for efficiency and performance due to the small bore size. The stroke is good but if your bore is smaller than 4.00" you run into limited cylinder head flow potential. The problem will be due to the swirl and turbulence in the combustion chamber being limited since there are few if any good performance heads out there to accomodate the small bore small bocks.

World makes S/R torquer for 305's and I believe RHS now has some in their Pro Topline heads. You'll have to see if they have 8-bolt intake pattern for TBI late model intakes.

Earlier you stated about using a Vortec head. I don't know if the 305 bore & vortec head would run into a "shrouding" problem with the chamber running over the bore diameter.

I'd stay away from the S-10's & Blazer trannys since you intend to put a V-8 in front of it. The main thing is torque here soe if you did use it, you'd have to have someone go through it and build-it-up to handle the torques of the V8.

If you seriously consider going 4wd, than you obviously need to go for the 350 and stonger V8 components. Remember, 4WD will throw fuel mileage out the window!

If you get a TBI, computer and system from a 305 and make it work with the 307 or 331 engine you build, it would cost you about the same to run a 350. If you get a performance E-Prom chip for the 305, you're already in the territory of a stock 350!

As for the stock cams in the truck 305's and 350's, they weren't much different and many actually had the same cam.

I'm telling you, for what you want, it still sounds like you'll be happier with the 350 and an 700R4, and it'll make the conversion process easier!

The other option is to hunt for a late 80's Camaro with a 305 TBI and 5-speed to make the conversion easier.

<font face="Arial,Verdana" size="2">Originally posted by Kamikaze:
Chuck,

If you went to a true dual system, you would have to have a different wiring harness and dpossibly dual O2 sensors to give the correct range of information to the computer so it doesn't run the injectors too rich. It is theoretically possible to run without the cats but I feel this would be a mistake for performance and mileage.


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No need to worry about the exhaust configuration. The stock TBI system only uses one O2 sensor, and it is before the stock exhaust Y's together. So you can run a manifold or header as long as you plug the O2 in somewhere near the collector. You will likely have to run a heated O2 for quicker closed loop operation.

Leaving the cats off will not be detrimetnal and most likely will help fule economy and power.

OEM chips are calibrated rich in open loop WOT mode, so opening the exhaust will probably force this to a better calibration.

So in short, a custom harnes is not needed, nor are dual O2's, and leaving the cats off will not adversly affect the TBI system.

They have alot more potential for performance than they are given credit for.

Jakeshoe has some valid information. However, there are some details that might be worth noting. As a former GM Tech and having owned several modified TBI vehicles I can tell you that the TBI is "forgotten performer".

It has been proven that an exhaust system with a well flowing monolythic catalytic convertor will run clean and provide more power & fuel economy. This was proven by David Vizard who does tons of dyno research and writes many tech articles for magazines, SAE, and also teaches at a major university. If you take off the catalytic, the TBI system is so forgiving that it will run fine!

Although the stock O2 sensor is located in the exhaust manifold before the Y-pipe, if you change the system to true duals, you lose the scavaging of a merged two into one system and it affects the "Light-Off" temperature of the sensor. A heated sensor is a a solution to this.

TBI systems are very forgiving. They have ton's of potential and react well to basic and simple modifications much like carburated vehicles. There are a lot of performance parts that work well and enhance the performance of the vehicle.

For the record, I had a '89 pick-up loaded with power everything, a shell and a high end audio / video system. The truck weighed a heavy 5200 lbs with a full tank and myself driving and would knock down high 13 sec 1/4 mile times and still pull 18-20 mpg.

The drivetrain consisted of:

396 Small Block stroker,
6" rods,
4130 forged crank, knife edged, internally balanced,
10.5 to 1 compression, custom Wiseco Pistons,
Trick Flow twisted wedge heads fully ported w/ 2.02 & 1.60 undercut valves,
1.6 roller rockers,
Edelbrock TBI intake,
TBI modified by Turbo City w/ matched high flow injectors, injector spacer, adjustable fuel regulator, and enlarged throttle body,
Upgraded Fuel lines to 1/2" with SPx Fuel pump,
Custom ground Hydraulic Roller Cam by Crane,
Custom stepped 1.625 to 1.75 Borla headers to a 3" Random Technologies Catalytic Convertor then to a 3" in and dual 2.5" out Borla High-Flow Stainless Steel Muffler,
MSD 6T ignition with Soft touch and adjustable timing dial,
Taylor Spiro Pro 8MM wires,
Prompaq Promchip switching box,
Custom JET Chip,
Custom Z-Industries Chip,
Laptop interface with GM computer,
700R4 built up w/ Corvette valve body, custom shift kit, extra clutches and higher pressure servo,
2400 stall convertor,
Gear Vendors Under/Overdrive,
Modified stock rear with Torsen diff and 4:11 gears,
275/60R15 tires on 10" wide billet wheels.

This thing was a "kick" to drive and started up and ran smooth and reliable. Put over 250, 000 miles on that combination and drove it hard! But, it just goes to show that TBI vehicles can be built to run and be reliable at the same time!

I have a TBI unit from my Dad's old van. It was a 305 with a TH-400, so you can't get much simpler. The harness for the computer is separate from the rest of the harnesses, the tranny might not have even connected to the computer. (No lockup or anything.)
IIRC you need the O2 sensor, (BTW, since it's a dual plane intake you only need one sensor, installed in either side of the exhaust, it does not have to read both sides.) knock sensor, MAP, coolant temp, air temp, TPS, proper distributor, fuel pump (electric), injectors, and I think that just about does it.