Carb'ed vortec looking for info and opinions

[SirRobyn0]

Ok so here's the deal. If you know me, you know I like to have a plan in place. With my square it is heavily relied on, as it is the primary hauling and towing vehicle for the farm. I know it's old and one day the tranny will go. Now I've got a plan in place when that time comes. I should have plan in place for if / when the motor goes. Currently it has a healthy 305 under the hood, and even though it's slower than I'd like at times when towing, it still gets the job done, so I'm unlikely to ditch it until it needs a rebuild. but when that happens I'd like to have a plan in place.

I've thought about just rebuilding the 305, which I do like that it'll hit almost 17 on the highway empty if driven at moderate speeds, but that's about it. I've thought about going to a 454 and in some ways I think I'd be best served by a 454 when towing or hauling heavy loads, but it requires a fair bit of work, and will result in 454 gas mileage empty or loaded. I know I've mentioned gas mileage twice now, so go ahead and roll your eyes. I know a square isn't likely to break any MPG records and I'm not looking for it to. But this truck does feed runs for the farm (and other runs) and when on a 100 mile journey one way to get feed and fuel usage is one factor. Ability to pull hills is another factor, as I live in an area with lots of hills, and there are mountain passes to the east and south of me. I don't do the east one often but the southern one quite often, and coming back loaded.

So recently I've been thinking about going the vortec route, when the time comes, whatever I do I'll need to keep it economical in price, and as quick as possible so the truck isn't down for to long. To that end I would be carbureting it. If I could find a good used one at the time I needed it that I thought had a good amount of life left in it I would absolutely go that route, but in all likely hood I'd probably have to buy a pre-built long block motor / crate engine.

What I know:
Will need to buy carb'ed intake manifold
Will need to install electric fuel pump
Can reuse my distributor and carb

What I'd like to know:
Will I be able to reuse my, exhaust manifolds, motor mounts, flexplate and think but do not know that the belt driven accessories, alt, WP, PS ect and brackets bolt up to the vortec (looks like it).

As said before this truck is relied on for 100 mile runs, so this needs to be a set up I can depend on both loaded and empty.

If your running a carb'ed vortec how do you feel about it? Would you do it again? Very open to advice and thoughts on this subject. Thanks.

 

[AyWoSch Motors]

As far as I know, if your buying a "vortec" crate 350, everything should swap over from your old engine. Same brackets, same accessory drive, etc etc, really the only thing you'd need is an carb style 4bble dual plane, that can adapt to the vortec intake bolt direction, or drill out the holes in your existing intake, and buy a set of wedge spacers. I've seen that as an easy fit for modifying a vortec. Dont know if it works.
You can use your old manifolds, they'll bolt up, but the vortec heads have a slightly bigger intake and exhaust ports, so you'd be choking it a tiny bit with stock 305 log manifolds.
And vortec blocks still have the hole with the place to put a mechanical pump. You'd just need a push rod a new pump, and a block off plate with a hole in it.
Mounts will be the same, have been the same almost forever for a SBC in a truck.
Flex plate will swap over.
Factory vortecs have a totally different accessory drive bracketry, but I think the bolt holes are there to run an older style setup.

Everything should swap over just fine.
The vortec isn't much different from a normal small block. Really the only that changed was the heads, the blocks are almost identical.

 

[SirRobyn0]

As far as I know, if your buying a "vortec" crate 350, everything should swap over from your old engine. Same brackets, same accessory drive, etc etc, really the only thing you'd need is an carb style 4bble dual plane, that can adapt to the vortec intake bolt direction, or drill out the holes in your existing intake, and buy a set of wedge spacers. I've seen that as an easy fit for modifying a vortec. Dont know if it works.
You can use your old manifolds, they'll bolt up, but the vortec heads have a slightly bigger intake and exhaust ports, so you'd be choking it a tiny bit with stock 305 log manifolds.
And vortec blocks still have the hole with the place to put a mechanical pump. You'd just need a push rod a new pump, and a block off plate with a hole in it.
Mounts will be the same, have been the same almost forever for a SBC in a truck.
Flex plate will swap over.
Factory vortecs have a totally different accessory drive bracketry, but I think the bolt holes are there to run an older style setup.

Everything should swap over just fine.
The vortec isn't much different from a normal small block. Really the only that changed was the heads, the blocks are almost identical.

Ok thanks you pretty much answered everything right there. Though in my understanding production vortec's do not have lobe on the cam, or hole in the block for fuel pump rod.

Good point on the exhaust manifolds. I still have the factory style single exhaust though it's larger pipes than factory, and enough for the 305, it's still probably insufficient, and like you said will probably choke it a bit, but I can't change the exhaust down the road.

 

[AyWoSch Motors]

Ok thanks you pretty much answered everything right there. Though in my understanding production vortec's do not have lobe on the cam, or hole in the block for fuel pump rod.

Good point on the exhaust manifolds. I still have the factory style single exhaust though it's larger pipes than factory, and enough for the 305, it's still probably insufficient, and like you said will probably choke it a bit, but I can't change the exhaust down the road.

Your welcome, glad that helped. I'm not an expert on them, in sure theres someone here that knows more, but I've worked on a bunch of vortecs.

You're right about the cam, that would have to be changed, but I do believe there is a hole the block for the pushrod. I can go out and check, I have a vortec block on the stand in the shop right now.
The exhaust I dont think would be a big deal, if your exhaust is bigger than factory small block, it should be close to the newer style. It wasnt that much larger. As long as you used the bigger manifolds.
I'm running vortec manifold right now on my 78 small block 350, works great. Only thing with that, is on some vortecs, they had a special EGR tube that came from the exhaust manifold, so you'd have to block that off if you used that style. If you get a set from a 3500 or work truck, you won't have to.

 

[Doppleganger]

Just went through this with a 97 motor - the castings were all there but there was no hole for the mechanical pump. Have seen some of the later blocks where there was a plate/cap and some that the casting itself was the "plate" look.

Then there's the carb-vortec heads issue where they dont run very well in colder climates. FI isn't cheap but as crap as fuel is anymore, might be a more reliable setup in the long run.

 

[Midnightmoon]

Absolute wrong side of the country for you, but there is a carbed Vortec 350 on our local Craigslist for cheap. But, shipping would be 3x more than it is worth.

 

[SirRobyn0]

@AyWoSch Motors Thanks, Yea I've worked on a lot of vortec's at the shop, but they have always been in the vehicle they came in with factory fuel injection so confirming the stuff you did was just what I needed.

@Doppleganger FI is out. They is simply to much upfront cost involved, if it is decided that a carb'ed vortec would have runablity issues in cold weather then I'd pick to swap to some other engine. We don't get a lot of cold here. There are plenty of mornings where it is below freezing in the upper 20's but that's about it, with the exception of when I have to run over the pass so there is that to consider. From what I've been told, and perhaps you can help me out here, the cold runabilty issues come from a lack of exhaust crossover, or even hot oil being able to to heat the intake manifold. Some people seem to think that running an factory style air cleaner housing with a themac, that pulls warm air from around the exhaust manifold helps. Sounds like you know a fair bit more about this than I do. Will a carb'ed vortec be likely to be ok in 20F weather?

@Midnightmoon Shipping especially on big parts has gotten crazy expensive.

 

[Doppleganger]

I only know what I have read on it. For a while I had considered a new Edelbrock intake and carb + nice Vortec heads I had on the original block. Then started to hear of issues (there is a long thread on here somewhere about it) here and abroad, and there was so much more wrong with the truck, so went FI.

I do believe it was the lack of the exhaust crossover, but no idea what you have in mind fixes it or not. I would think if it did, that would be a known easy fix.

FI wasn't cheap but neither has anything else been on this 'project'. lol

 

[SirRobyn0]

@Doppleganger I'll look for that thread and see if I can find it.

What I've heard, and frankly if someone on this forum confirms it as being helpful, I'd be much more inclined to believe it vs folks on a message board I've never interacted with. Anyhow what I've heard. At least one of the edelbrock intakes has provisions to run coolant under the carb. and as I mentioned before a themac might help. I'll look around, but hopefully someone will with this combo will see this thread. Thanks again.

 

[bucket]

@77 K20 has been down this road with carb on vortec heads in cold weather.

 

[SirRobyn0]

@77 K20 has been down this road with carb on vortec heads in cold weather.

I didn't know, he'd be just the guy I'd wanna hear from then on this then, though he sees much colder temps than I do.

 

[Doppleganger]

I didn't know, he'd be just the guy I'd wanna hear from then on this then, though he sees much colder temps than I do.

Do a search for vortec with him as the poster......there's a library of info.

 

[CalSgt]

I believe some 305 exhaust manifolds on the passenger side have the rear bolt hole further back, Vortec heads don't have that hole drilled and tapped. I guess it's possible not all 305 manifolds used the extra hole but I'm not sure.

Most other SBC heads have two holes drilled back there to work with both sets of manifolds. A decent used set of 350 manifolds should be cheap though if needed.

Top image is 906 casting Vortec head with only one manifold bolt hole & bottom is some random SBC head with two manifold bolt holes at the rear on passenger side.

You must be registered for see images attach

You must be registered for see images attach

 

[SquareRoot]

Dude. I've been down this path. I've learned some valuable lessons. These are my experiences.
1. FORGET putting 1 cent into a 305. You can build a 350 for the exact same price for a much better result.
2. If you don't have a 350 to begin with, just get an LS. Complete running engines are available for like $1200.
3. I put new Vortec heads on a crate Goodwrench 350. I wouldn't do it again. Get an LS.
4. You want a truck that's reliable, drives like a new vehicle and gets good gas milage? I spent $1200 for a Edelbrock pro Flo EFI. It's nice reliable and drives like a new truck.
5. Gas milage! Lol, it's a square body, ain't gonna happen. Would I do it again? Nope. Wished I'd spent that $1200 on an LS. Hopefully I made my point.

 

[SirRobyn0]

Do a search for vortec with him as the poster......there's a library of info.

In progress, currently reading about his intake manifold travesties with coolant leaking and poor cold weather running. This maybe be the stop point on this idea, but will continue reading.

I believe some 305 exhaust manifolds on the passenger side have the rear bolt hole further back, Vortec heads don't have that hole drilled and tapped. I guess it's possible not all 305 manifolds used the extra hole but I'm not sure.

Most other SBC heads have two holes drilled back there to work with both sets of manifolds. A decent used set of 350 manifolds should be cheap though if needed.

Top image is 906 casting Vortec head with only one manifold bolt hole & bottom is some random SBC head with two manifold bolt holes at the rear on passenger side.

Thanks for that info, but looks like it could be over come.