Posted: Sat Jan 26, 2013 10:50 pm Post subject: Tractor Build Update, and Small Block Chevy Question
So, the truck-tor build is progressing well... We've already pulled and scrapped the body, and tonight myself and a buddy of mine removed the engine/transmission, and decided what to plasma cut off first thing tomorrow (front end components, etc), at which point the frame itself, the suspension, and the remains of the cab will be ready to junk out... will be ready to haul off as well. We've formed a huge pile of good parts, to keep. Things seem to be going great!!
Anyway, to my question...
We've pulled the computer and related wiring from the dashboard, and lets face it, wiring all that back up is going to be a bad time...
How hard would it be to convert this thing back to a carbed engine?
Best we can figure, we'll need a different intake manifold, and of course the carb itself... We'll have to do all new linkages and re-wire everything, anyway, so why not?
Ideally Id even like to have a gravity-fed fuel system...
Has anyone ever gone from fuel injection to a carb setup? The engine itself is a 1993 305 v8, that needs a head gasket...
Any thoughts on this?
Anyway, thanks in advance guys... I'm pretty tired, so I hope this post came out alright... Enjoy part one of the build series, guys
Posted: Sun Jan 27, 2013 1:59 am Post subject: Re: Tractor Build Update, and Small Block Chevy Question
As you may or may not know..any welding on this unit could smoke the computer or any components related to it. Not sure if the plasma cutter will do the same..so caution is always advised around computerized units like this. A snubber atached to the battery will most generally help..so be advised! I would think it would be a simple switch to a carbureted system and I think a gravity fed fuel system would work just fine. Most carbureted fuel systems in cars and trucks would usually have fuel pump pressure between 4 and 6 lbs more or less. And gravity will not be close to this. Every 2.1 feet of head (height) will provide 1 lb of pressure and you sure won't have the tank 8 foot over the engine..all the same, gravity will probably work, if not then you can get a low pressure electric pump to put inline. Older small blocks would have a spot to hang a mechanical fuel pump but I would guess this engine would not. You will need an earlier distributer that was not computer controlled but there should be lots of HEI units around for this application as well as intakes and carbs.
Posted: Sun Jan 27, 2013 2:32 am Post subject: Re: Tractor Build Update, and Small Block Chevy Question
Just get a manifold and carb off another older 305 (My 1979 C-10 305 had a carb) and bolt it on after you do the head gasket job. Simple as that for what you are building. 12 volts to the distributor to power the ignition, manual choke conversion kit, single wire to the alternator and away you go! Cheap mechanical gauges if you want to bother. I would use an aftermarket electric fuel pump to feed the carb instead of gravity flow though.
Posted: Sun Jan 27, 2013 5:47 am Post subject: Re: Tractor Build Update, and Small Block Chevy Question
An older carb manifold WILL NOT fit that engine, unless you find an 87 Caprice manifold with a Qjet. The center four intake bolts on the TBI engines run at a different angle than the 86 and back engines. I would keep the TBI, simple, efficient, and not hard to wire at all.
Posted: Sun Jan 27, 2013 9:35 pm Post subject: Re: Tractor Build Update, and Small Block Chevy Question
Lanse I have been messing with chevrolet engines and vehicles for two decades, both carb and fuel injected. I've done this when I was poor and broke and when I had money to spend. Here's what I say:
Go with the carb. The TBI is not a bad setup, but:
1.You will have wires running all over the place.
2. The setup you have is already 20 years old. Sensors and wiring connections can deteriorate and develop intermittent problems. These systems tend to get cranky when they're older, just like an older desktop computer.
3. If you go aftermarket computer you will spend way more than a good used carb and manifold.
4. Small block manifolds are everywhere and insanely cheap.
5. Carbs are everywhere and cheap unless you insist on a brand new one.
In '87 Chevrolet changed the angle on the four most center bolts of the manifold to go straight up and down. That's two on each side of where the carb goes. The other 8 at the corners are the same. The advantage of an aftermarket intake is that you can get one without the EGR valve and a dual bolt pattern for the carb. (will work with Q-jet or Holley).
You want a pre-'81 HEI distributor with the 4 pin module. Billions of them out there. Only needs a single 10 gauge wire to run.
Now for some clarification. By 93, Chevrolet was using the "Vortec" name on their engines and in their advertising. The better performing "Vortec" heads that you may have heard about did not come out until '95! You can spot those because it will have only 8 bolts on the intake manifold and they all go straight up and down (relative to the ground).
You said it needs a head gasket, when you get it apart look for cracks and any sunken valves. The good news is that any small block heads will bolt on! However, you want to try to stay with 305 heads or Vortecs or you will lose significant compression.
Posted: Mon Jan 28, 2013 6:50 am Post subject: Re: Tractor Build Update, and Small Block Chevy Question
There's a difference between being afraid and recognizing the practical limitations of re-purposing what is now an antique electronic control system. Every day at work I get to deal with high end, highly specialized electronic systems. Recognizing their limitations is how I keep people alive.
Posted: Tue Jan 29, 2013 4:12 pm Post subject: Re: Tractor Build Update, and Small Block Chevy Question
Certainly a carb is old tech.
It's just that the sensors tend to degrade over time and a lot of external connections to maintain. The computerized system has more opportunities for degradation as it ages.
Depending on how well used the starting truck is, there could be a significant amount of troubleshooting to do in the near future. It makes it easier if you have the knowledge not just to read codes but also to troubleshoot the sensors themselves.
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