dont know where to start...

[ccautoupholstery]

So I have a 67 c10 that originally had the straight 6 and 4 on the floor, they were pulled out and a 305 with i think a TH350 (came out of a 78 camaro) just got put in today...well most of the way. I dont know where to start as far as the wiring harness, is the original one useable? should i look into a new harness?
Also I know absolutely nothing about rear ends, when it ran with the straight 6 i wouldnt dare take it above 60 bc it would be screaming at that point, i dont know if that was bc of the motor or the rear. Will i need a new rear end? Any help is much appreciated

[Mmorgan32]

You can modify the wiring. I've never had a straight 6 truck but my nova was before I put a crate engine in it. classic industries makes stock style replacements tho. I did my old gmc with them. There is other places I'm sure to get them too. As far as the gearing it's probably a combination of the trans and the rear end. If you count the ring gear teeth you can figure out your ratio or look up what ratios came in your truck. Lmc truck catalogs have a lot of vin and other number info in the front of the book

[LockDoc]

Originally Posted by ccautoupholstery

So I have a 67 c10 that originally had the straight 6 and 4 on the floor, they were pulled out and a 305 with i think a TH350 (came out of a 78 camaro) just got put in today...well most of the way. I dont know where to start as far as the wiring harness, is the original one useable? should i look into a new harness?
Also I know absolutely nothing about rear ends, when it ran with the straight 6 i wouldnt dare take it above 60 bc it would be screaming at that point, i dont know if that was bc of the motor or the rear. Will i need a new rear end? Any help is much appreciated

Welcome to the board. Check the original harness over good for brittle or broken wires. Usually the wires that go around the back of the engine and down to the starter are bad because of the heat. And sometimes the alternator wires have problems too. If everything checks out OK you can use them. I have replaced sections of the wire loom that were bad by cutting out the bad sections and splicing in new pieces. Just be sure and solder the wires together and use heat shrink tubing on them. If it is bad enough that you are concerned about it just replace it.

You probably have a low geared rear end (probably a 4.11 or 4.56:1) so you would have to get a higher geared rear for it like a 3.73:1 or put an overdrive transmission in it, maybe a 2004r or 700r4.

LockDoc

[ccautoupholstery]

Thanks guys. Is there a link on here anywhere that would have a wiring diagram for a 305 engine/cab? I'm having a hard time navigating the site on my phone and its my only way to get on here :/

[Mmorgan32]

Use the search box at the top u might find something

[LockDoc]

Originally Posted by ccautoupholstery

Thanks guys. Is there a link on here anywhere that would have a wiring diagram for a 305 engine/cab? I'm having a hard time navigating the site on my phone and its my only way to get on here :/

http://67-72chevytrucks.com/vboard/s...d.php?t=185856

LockDoc

[midniteblues]

If you need a place to start. There is a decision to make.
The truck came with a points distributer.im sure your new er
Engine either has or had hei distributer.
The wiring would need to be changed based on Your decision.
It is very simple to do.

Pics of your trucks engine bay and your new er engine would be very helpfull and does it have a 3 or 7 hole instrument panel?

A 6 cly harness will work on a v8 but some wires need to be moved around such as the oil pressure sender(if it has one) wire,temp sender wire and the Coil wire.

Other things to consider is your alternater(should/will)be on the other side of the engine bay with your replacement motor so those wires would need extended.

I don't think much needs done in the cab if it wasn't touched.
It's easy to get overwhelmed when looking at wires. But these trucks have the most basic wireing you could get and pretty easy if you take your time.

[ccautoupholstery]

Thanks! I'll try to get a pic in a day or so. I know I'm capable of doing whatever wiring work is needed but like you say, it's overwhelming when looking in at them.

[ccautoupholstery]

so here are a few pictures of the engine and the wiring harness. I did stop by auto zone and got the correct connector for the alternator but im not sure which wire on the truck would go to the red wire for the new connector. I tried to get the connector for the distributor at the same time but they said they arent able to get it...any help with what needs to be done would be greatly appreciated.

[ccautoupholstery]

They wouldn't upload :/

[midniteblues]

Try uploading one pic at a time.
Pic a pic up load it.
Pic another pic upload it.
Don't upload 2,3,4,5 at a time.
That's how I do it. And I'm puter dum.
But I'm becoming phone fart.....smart

[cericd]

If you are uploading them from an iPhone or iPad you can only upload one per post.

[ccautoupholstery]

Try again

[ccautoupholstery]

And

[Mmorgan32]

Originally Posted by ccautoupholstery

And

Your alternator is on the wrong side of your wiring. You can either get a different bracket and move it to the driver side or add some wire to move your wires over to the passenger side. Also make sure you have the right alternator for your set up or the correct wires for the alternator you are using. U can buy a little conversion let of wires to modify your harness to work with the modern alternators. Same with hei. They make kits to add the wires for hei. That's how I did it

The wires you have on you passenger side are for you starter and something else maybe temp or oil sensors. I would loose the flex fan and get a clutch fan and a fan shroud too

[ccautoupholstery]

I have the correct pigtail for the alternator but haven't been able to find one for the hei, where did you get yours?

[Mmorgan32]

Summit racing but o'reillys or autozone might have it. U can just call summit and tell them u need to modify your harness for hei and they will hook u up, comes with instructions too, if u want to change it all classic industries has new engine harnesses with hei on them

[Mmorgan32]

http://m.summitracing.com/search?keyword=Hei%20harness

[midniteblues]

Ok one at a time. in your first pic you have alt. Wires but the alt is a internally regulated alt and your truck has a external regulater.

On your passenger side there is a thick purple wire that one routs down behind the engine to the inner small post on the starter.

There is also a smaller yellow wire you may see two yellows but it's the same wire. Tape them up not needed.

You didn't tell us about your gauges 3 or 7 hole in your dash
This will tell us if you need the oil sending wire ore if it has a mechanical guage.

[midniteblues]

Also down on the starter don't forget the big red battery cable it goes too the big post.
The yellow wires turn into a cloth/braided wire that goes into the bulkhead.
You are gonna need to find it and swap it out.
This is gonna require the correct connector.(
In my pic is a thick red wire on the left this is what you need to do. its in the same location as the cloth wire you need to pull. You need to unbolt the bulkhead separate the two halves find that wire and pinch an pull that wire out and replace it with a 12ga. Or bigger wire. I included pics of the other side of this wire that plugs into the distributer pics for referance.

Of course you could take the easy way and plug your distribution wire it the fuse box. I never did it that way but you could.

[midniteblues]

Some where on your pass side wires you might have a double wire with a roundish plug.this would be reverse lights.
Not sure on what you need too do with them. Are you automatic or stick shift?

Then there is another single wire on the pass side.
for a 6cly harness it will be pretty long it's either green,gray or cloth covered ( being color blind its hard for me too tell) this one is your tempature sending wire. Most times it will connect too the thing between the front two spark plugs on the Dr side. It could look like this one.

[midniteblues]

Gotta go for now but that should keep ya busy for awhile.
Hopefully others will give sugestions

[ccautoupholstery]

Sorry I forgot the about the gauges. It definitely gives me a good start! I appreciate all the help. With the alternator, what do I need to do as far as the truck having an external regulator and the new alt being internally? Do I just bypass external regulator?

[ccautoupholstery]

So I got the new 12 gauge wire ran in the bulkhead for the distributor, couldn't locate the temp sensor wire. I'm thinking oil sensor is mechanical, there is a hard line that coils near the end with a flanged nut that I'm thinking is it? I got the purple ran to starter small terminal...slowly making progress also I'm pretty sure it is electric choke, do I need to run a wire for it? Oh and in original wiring harness there are 2 wires, a dark and a light green..any idea what for?

[midniteblues]

The green wire is it a double wire and long? If so it's the reverse lights.
Since you doing a auto it needs to go too a neutral safety switch on your shifter or colum or a toggle switch too turn the reverse lites on.
Good call on the oil sending unit wire you don't need it with the tube it connects under the distributer but you need too remove the one that's there allready.