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1984 1/2 Ton GMC

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ChevyMitch

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Hi.

The 305 V* in it is a weak engine, especially in a head wind lol and Im thinking of dropping a 1989 350 out of a Suburban in it, but dont know about all this electronic buisness? Anyone done this?
I'd like to get rid of as much of this electronic stuff and vacuum hoses as possible, but I dont know about these od automatic trannies either..? Should I leave it alone or what?
I could just put an over haul kit in the 305 too, but I want to pull a trailer occassionally.
 
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Well how big of a trailer are you hauling. If you can keep the bore stock put better pistons with 8.5:1 or 9.0:1 compression. And good lifters & tow cam will help the motor work a lot better and still save you gas. Oh other parts would be good is intake manifold make sure it a 4BBL carb on it better.
If it's really heavy and your working it a lot then get a 350 motor and both would be better with a 350 trans un less your looking to have a 4 speed over-drive like the 700R4 trans. do the same modes both motor's would be good .
 
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New here been lurking for a while since I got me a cherry 85 C-10. I have noticed alot of post like this. Seems everyone wants to pull the 305 and put a 350 in there truck. Shoot I like the 305 good low end, saves fuel and I ant driving no hot rod so I don't need the extra HP. I have been that route on other trucks guess I am getting old. Unless you want to build alot of HP and be able to tell folks that you have a 350 in it stick with the 305. You all ready have it, you know what kind of condition the eng is in. Make life simple, get yourself a refresh kit and rebuild it. My two cents.
Doug
 
Well, whats weird is that its really a dog in a head wind and I occassionally pull a car trailer.
Its also very hard on gas and has a Quad.
My dad said put a kit in it w/a tow cam, (like you).
I was thinking of having the tranny rebuilt too w/a tow package.

Thanks
 
what the rear gears in the truck?. I the trans is not good or is really got lots of miles on it some of the band getting bad that will help lead to the engine working harder. But a good trans cooler help perlong the trans if its a auto, if it a 4 speed auto keep it in 3rd when pulling (towing). I guessing it' a auto trans.
I beleave the 84 305 put out about 165-185 hp and are heavy square front not the best in med wind blowing from the front dead on make them work harder with all motor's.
I have about 200 hp in my 305 with a strong 350 trans and 3.07 (witch gm calles 3.08) not the best gear for towing. When I had the 454 in it it did tow better but it was like all TQ but drank the gas with the same rear and trans. med winds and hills would still make it work and eat the gas faster.

But the 305 will pull the same load now if I push it hard it will burn a bit more gas and out run the 454 in a distance not out of the hole but will eat the gas in the same way the big motor did. and get your carb tuned up good after. On the track the truck run 17.30 with the 454 now the truck runs 16.20 in a 1/4 mile. Just changing the motor my truck lost 200 lbs + 20 lbs more for the lighter intake manifold . I all so have the trans set pretty hard for shifting too. I will be changing the rear gear to a 3.42 to help the motor out for towing my trailer and car thinkingt of puting in a 700R4 save on fuel when not towing. I have the 1984 Montie carlo ss cam in the the truck now but a speed pro L79 would be a good cam too. I had it before nice power good TQ there a few more but but there is only really two types that most cam maker most times or only one. Oh and a nice flat top set of pistons to raise your compression a bit help lots.
 
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Last week, I decided to put a timing light on it and the mark was way advanced, so I turned it down to (4), what it calls for, but it could hardly pull itself down the highway. It has no power at all.. :(
The 305 is coming out asap and a 350 is going in!
If Im going to pay for the petro anyway, I might as well have the power ta' boot.
I'll probally have the tranny gone through later.
 
Your transmission is most likely a 700r4, so when you put the 350 in, make sure the TV cable for the trans is set properly. If you're doing the swap yourself you may want to have it towed to a shop. An improperly set TV cable can kill the transmission real quick.

If I remember right, the only electronics on the 700r4 is for the torque converter lockup.
 
Set the tv cable???

Well, I picked up an 89 4X4 Suburban w/a bad rearend and a good 350.
What do ya think?

Thanks
 
The Throttle Valve cable controls when the transmission shifts. If you are using the trans from the Suburban as well then you probably wont have to worry about it.
 
So I should keep the motor and tranny together then?
Saves time and keeps me from tranny trouble, etc.
Ive been thinking about fixing the rearend on the Suburban and putting snow plow on the front of it. Anyone know anything about those 4X4 axels?
The drive-line os off the rearend, but the front is hooked up and it just spins when in 4X4, but doesnt make the front wheel drive move. Is that some sort of front wheel assist thats only part-time or does the rear drive-shaft need to be hooked up for it to work the front?

Thanks
 
Forgot to ask, but if your '84 is 2wd, it would be easier to keep the trans in the truck. Converting a trans from 2wd to 4wd requires tearing it all the way down to replace the output shaft.

If the Burb has manual hubs (have a selector on the hub that you rotate from free to lock) you need to engage them when you put it in 4wd. If they are auto hubs (probably say 4x4 on the hub) then something might be broken- axle shaft, u-joint, hubs, etc.

I've never pulled a carrier apart, so don't know much about repairing an axle; but if you look for an axle from a '73-'87('91) pickup/burb/blazer with gears that match yours you can generally pick them up cheap.
 
The 84 is a 2 wheel drive.

The Burban has the full time thing 4X4 on the hub, no lock-outs here.
The front drive-line will spin to the pumpkin, but the front wheels will not move.
I wonder in the rearend has to be hooked up too in order to work?
Im going to start phoning some 4X4 guys to find out.

Thanks
 
1984 gmc truck

hello there i recently bought a 84 gmc truck 1/2 ton with a 350 automatic and a 4 barrel carb it seems to run rough first thing but after it warms up its fine but sometimes it acts like its missing it could be the distibitor maybe or the carb i don't know any suggsetions
 
I just recently put a 327 in my 83 p/u and I am running it with a 700r4 tranny
and it seems to be doing just fine. The truck orinagly had a 305 in it and even though it had been dogged and abused it still did pretty good. I have a 16ft bass boat and it pulled it with no problems. I took the 305 to a shop and I got really lucky the guy told me that it was still in fairly good shape and with the right "small cam" and a decent intake and carb it would have the power I need. I know you already got the other motor but do some shoping around and see whats out there you might be surprised. And if the truck is two wheel drive keep it that way alot easier on the pocket book. good luck on the project.
 
mac1 said:
hello there i recently bought a 84 gmc truck 1/2 ton with a 350 automatic and a 4 barrel carb it seems to run rough first thing but after it warms up its fine but sometimes it acts like its missing it could be the distibitor maybe or the carb i don't know any suggsetions
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First of all check the plug wires and make sure they are all good.
{check them at night to see if you have any craks in them...by doing this at night or in the dark you will be able to see sparks} also check your plugs and maybe even look for loose vaccum lines or even craked ones. only other thing I can suggest is check for leaks around the intake, also might have your timing checked out.
good luck.
 
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