84 K10 305 to 350 swap

[Ewhitaker0020]

Is there anything I need to know about swapping out my factory 305 engine for a 350? I have an 84 Chevy K10. Is there anything I have to change to do the swap? Is it worth doing? I'm thinking about pulling my engine to redo some of the seals, and I'm kind of inclined to just swap it out with a 350 because the 305 is so under powered.

My transmission is a 700r4 that I just had rebuilt, so I would like to keep that transmission in the truck. I'm not looking for a super powerhouse engine, just something that has a little more umph to it.

 

[78C10BigTen]

Im gunna say you wont need anything special, its almost direct but dont quote me. Someone smarter will chime in.

 

[Shorty81]

Im gunna say you wont need anything special, its almost direct but dont quote me. Someone smarter will chime in.

X2. Direct bolt in.

 

[RoryH19]

Agreed, should be able to use same motor mounts and accessories.
700r4 will bolt up, no issue.
What carb do you have? Assuming around 600 CFM? If so, that will be enough.
Just need to verify, reset the TV cable when you move to the new engine.

 

[75gmck25]

Where are you getting the 350 and what combination is it?

If you have to buy a newly rebuilt engine or a crate engine, the best bang for the buck is a Vortec 350 ('95 and up). The Vortec heads flow better than any of the older heads, and its already set up for a roller cam. You can buy it as an L31 crate from GM, or you can look for something in the junkyard. You will have to switch to a Vortec intake manifold, but the other external accessories from your old engine will work fine. Most factory Vortecs are also serpentine drive with a reverse rotation water pump, but that's not mandatory.

Just the Vortec heads alone are good for 35-40 horsepower vs. the older 350 heads, and with a roller cam setup you won't have to worry about wiped lobes if you want more cam.

Bruce

 

[Ewhitaker0020]

Agreed, should be able to use same motor mounts and accessories.
700r4 will bolt up, no issue.
What carb do you have? Assuming around 600 CFM? If so, that will be enough.
Just need to verify, reset the TV cable when you move to the new engine.

I have an Edelbrock 600.cfm carb. So I have to change the tv cable adjustment on the new engine? Is it not the same outside dimensions as the 350?

 

[Ewhitaker0020]

Where are you getting the 350 and what combination is it?

If you have to buy a newly rebuilt engine or a crate engine, the best bang for the buck is a Vortec 350 ('95 and up). The Vortec heads flow better than any of the older heads, and its already set up for a roller cam. You can buy it as an L31 crate from GM, or you can look for something in the junkyard. You will have to switch to a Vortec intake manifold, but the other external accessories from your old engine will work fine. Most factory Vortecs are also serpentine drive with a reverse rotation water pump, but that's not mandatory.

Just the Vortec heads alone are good for 35-40 horsepower vs. the older 350 heads, and with a roller cam setup you won't have to worry about wiped lobes if you want more cam.

Bruce

So, if I wanted to go with a vortec engine swap... Can I keep the engine simple? I'm not wanting to go to fuel injection. I want a nice simple clean engine. But, if at the same time I can get a better performing engine that uses a serpentine belt set up, that would be nice.

Also I would rather not use a computer, but I'm guessing with an engine that new I would have to?

 

[RoryH19]

I have an Edelbrock 600.cfm carb. So I have to change the tv cable adjustment on the new engine? Is it not the same outside dimensions as the 350?

Ok on the carb.
For the TV cable, since you have to pull the carb when you replace the engine just want to make sure the trans shifts properly. You don't want to burn it up if the adjustment is off.

 

[75gmck25]

'95 and up Vortec 350 crate engines will be a direct replacement for older 350s, with only a few complications.
- Vortec blocks are not machined for a mechanical fuel pump, so you need an electric pump.
- Vortec heads use a different intake manifold bolt pattern than older heads, so your intake must be for a Vortec 350. Edelbrock and others sell a variety of Vortec intakes.
- Vortec engines used a factory roller cam, which significantly reduces cam wear. You can swap cams without changing lifters.
- Factory Vortec heads are limited for maximum valve lift and would have to be machined if you want to use a high lift cam. This is usually not a problem for cams that put you in the 325-350 HP range.
- Vortec blocks have a one piece rear main seal, which uses a different flex plate. However, it is much less likely to leak than the older two piece RMS.
- Although the stock GM Vortec engine used a serpentine belt system, accessories (alternator, PS Pump, etc.) from an older block will bolt right on. You can use either serpentine or V belts.
- There is no need to use a computer or any other electronics just because you swap in a Vortec engine.

Bruce

 

[Ewhitaker0020]

'95 and up Vortec 350 crate engines will be a direct replacement for older 350s, with only a few complications.
- Vortec blocks are not machined for a mechanical fuel pump, so you need an electric pump.
- Vortec heads use a different intake manifold bolt pattern than older heads, so your intake must be for a Vortec 350. Edelbrock and others sell a variety of Vortec intakes.
- Vortec engines used a factory roller cam, which significantly reduces cam wear. You can swap cams without changing lifters.
- Factory Vortec heads are limited for maximum valve lift and would have to be machined if you want to use a high lift cam. This is usually not a problem for cams that put you in the 325-350 HP range.
- Vortec blocks have a one piece rear main seal, which uses a different flex plate. However, it is much less likely to leak than the older two piece RMS.
- Although the stock GM Vortec engine used a serpentine belt system, accessories (alternator, PS Pump, etc.) from an older block will bolt right on. You can use either serpentine or V belts.
- There is no need to use a computer or any other electronics just because you swap in a Vortec engine.

Bruce

Man, I really appreciate all the good advice you've given me. You talked about a crate engine, would everything you've told me still apply to a used 95 and up vortec engine that I could pull out of a truck? Is there anything different about getting a used one?

Is there a certain year that would work best?

 

[1987 GMC Jimmy]

Man, I really appreciate all the good advice you've given me. You talked about a crate engine, would everything you've told me still apply to a used 95 and up vortec engine that I could pull out of a truck? Is there anything different about getting a used one?

Is there a certain year that would work best?

I’ll just go ahead and chime in. Answering your questions, respectively, yes, yes, and no. The big thing to look for in a used one besides anything common to a used engine like loss of compression, blow by, significant leakage of any kind, and/or hacky repairs is cracks in the heads. 96-99 GMT400 trucks and SUVs will have them, and 96-02/03 vans should, as well, but I don’t think there are any significant year to year changes at the end of the SBC 350 lineage. If you’re going used, I would personally go with an 87-95 engine that has a mechanical fuel pump provision. The heads are gutless and throwaway parts, but if you’re able to get it cheaper than a Vortec, you’d be able to handpick the Vortec heads used AND retain a mechanical fuel pump AND still have a roller block for around the same cost. The mechanical fuel pump is valuable to me. If I’m running a carb, I don’t want an electric fuel pump. Simplicity is supposed to be the perk of the more primitive setup, and electric gizmos chip away at that in my eyes. That’s just my opinion. Also, I think the cam lift ceiling for factory Vortec valve springs is .450, but the internet will for sure know.

So you’re going with a 350 and not a 454?

 

[Ewhitaker0020]

I’ll just go ahead and chime in. Answering your questions, respectively, yes, yes, and no. The big thing to look for in a used one besides anything common to a used engine like loss of compression, blow by, significant leakage of any kind, and/or hacky repairs is cracks in the heads. 96-99 GMT400 trucks and SUVs will have them, and 96-02/03 vans should, as well, but I don’t think there are any significant year to year changes at the end of the SBC 350 lineage. If you’re going used, I would personally go with an 87-95 engine that has a mechanical fuel pump provision. The heads are gutless and throwaway parts, but if you’re able to get it cheaper than a Vortec, you’d be able to handpick the Vortec heads used AND retain a mechanical fuel pump AND still have a roller block for around the same cost. The mechanical fuel pump is valuable to me. If I’m running a carb, I don’t want an electric fuel pump. Simplicity is supposed to be the perk of the more primitive setup, and electric gizmos chip away at that in my eyes. That’s just my opinion. Also, I think the cam lift ceiling for factory Vortec valve springs is .450, but the internet will for sure know.

So you’re going with a 350 and not a 454?

Yeah I'm going with a 350. I was joking about going with the 454. I have no interest in beefing up the rest of my truck to handle the 454 right now. Plus I don't even think my transmission could handle the BBC.

Hang on... So you're telling me I can put vortec heads on an older 350 that didn't come out with them? I know nothing about the later model SBC engines. What's the difference in the 84 Chevy engine that I have now (forget the fact it's not actually a 350) and the 87-95 SBC engine?

I've been finding some 350 engines for around $150-$300 used. There's a chance I can get one from the mid 90's for free from my uncle. I'll have to check and see if he still has anything.

 

[1987 GMC Jimmy]

Yeah I'm going with a 350. I was joking about going with the 454. I have no interest in beefing up the rest of my truck to handle the 454 right now. Plus I don't even think my transmission could handle the BBC.

Hang on... So you're telling me I can put vortec heads on an older 350 that didn't come out with them? I know nothing about the later model SBC engines. What's the difference in the 84 Chevy engine that I have now (forget the fact it's not actually a 350) and the 87-95 SBC engine?

I've been finding some 350 engines for around $150-$300 used. There's a chance I can get one from the mid 90's for free from my uncle. I'll have to check and see if he still has anything.

You can absolutely put Vortec heads on an ‘86 or older short block. You’ll still need the intake and Vortec valve covers, and you’re limited to using a flat tappet cam. For me, that’s not a deal breaker, plus you know with 100% certainty that it’ll have the fuel pump eccentric instead of maybe it does. For others, being limited to flat tappet might be a dealbreaker, but there are plenty of good hydraulic flat tappet cams out there. If you break it in properly and keep your oil level in check and changed (I do it every 3K), you’ll be golden.

The ways an ‘86 and older differ from the newer engines are perimeter bolt valve covers, 2 piece RMS, will always have a mechanical fuel pump provision, universal intake bolt pattern, come factory with a direct drive starter, the aforementioned lack of roller cam provision, and good factory heads are much better than TBI and almost as good as Vortec assuming they’re not shot, have accessory holes, have the right seats, etc. A Vortec head from the early 2000s will almost certainly have had less hardship than a double humper from the 1960s, and the Vortec chambers are a better design in theory than a double hump head. On the other hand, Vortec heads are more sensitive to excessive cam lift in stock form than double jump heads. I’d like to see dyno numbers to provide a real world example, but I’m sure the Vortecs edge the old style heads out by a few ponies.

 

[Ewhitaker0020]

You can absolutely put Vortec heads on an ‘86 or older short block. You’ll still need the intake and Vortec valve covers, and you’re limited to using a flat tappet cam. For me, that’s not a deal breaker, plus you know with 100% certainty that it’ll have the fuel pump eccentric instead of maybe it does. For others, being limited to flat tappet might be a dealbreaker, but there are plenty of good hydraulic flat tappet cams out there. If you break it in properly and keep your oil level in check and changed (I do it every 3K), you’ll be golden.

The ways an ‘86 and older differ from the newer engines are perimeter bolt valve covers, 2 piece RMS, will always have a mechanical fuel pump provision, universal intake bolt pattern, come factory with a direct drive starter, the aforementioned lack of roller cam provision, and good factory heads are much better than TBI and almost as good as Vortec assuming they’re not shot, have accessory holes, have the right seats, etc. A Vortec head from the early 2000s will almost certainly have had less hardship than a double humper from the 1960s, and the Vortec chambers are a better design in theory than a double hump head. On the other hand, Vortec heads are more sensitive to excessive cam lift in stock form than double jump heads. I’d like to see dyno numbers to provide a real world example, but I’m sure the Vortecs edge the old style heads out by a few ponies.

I watched Eric the car guy put together an engine for his dad's truck using what I believe to be an older block. (although I'm not sure). When he did the cam and lifters he had to install a guide on the top of the heads where the rockers go so he could use the roller cam and lifters. Was this so he could use roller lifters and a roller cam on an engine not designed for it?

Why would a flat tappet cam be so prone to excessive wear? Didn't all the pre 86 engines have them? I know my original engine has almost 100,000 miles and is all original. Is the flat tappet aftermarket cam a different design than original OEM cams?

 

[Ewhitaker0020]

I’ll just go ahead and chime in. Answering your questions, respectively, yes, yes, and no. The big thing to look for in a used one besides anything common to a used engine like loss of compression, blow by, significant leakage of any kind, and/or hacky repairs is cracks in the heads. 96-99 GMT400 trucks and SUVs will have them, and 96-02/03 vans should, as well, but I don’t think there are any significant year to year changes at the end of the SBC 350 lineage. If you’re going used, I would personally go with an 87-95 engine that has a mechanical fuel pump provision. The heads are gutless and throwaway parts, but if you’re able to get it cheaper than a Vortec, you’d be able to handpick the Vortec heads used AND retain a mechanical fuel pump AND still have a roller block for around the same cost. The mechanical fuel pump is valuable to me. If I’m running a carb, I don’t want an electric fuel pump. Simplicity is supposed to be the perk of the more primitive setup, and electric gizmos chip away at that in my eyes. That’s just my opinion. Also, I think the cam lift ceiling for factory Vortec valve springs is .450, but the internet will for sure know.

So you’re going with a 350 and not a 454?

Will this 89 TBI block be set up for a roller cam? I found it on Facebook for $100.

You must be registered for see images attach