Time for a crate engine. Suggestions?

[RecklessWOT]

EFI is good, but you can get the same horsepower with a carburetor if you know how to tune it. However, EFI means it will start and run every time, even when your spouse/brother/son/daughter is driving it, and regardless of the weather. If its a DD, then EFI is a good choice.

It's not my DD anymore, but it was for a few years and I'd really like to get it back to that point. It gets quite cold here in the winter, EFI is awesome when it's 20 below zero and you're out there in the dark at 5:30 in the morning getting ready to go to work. My wife usually does not drive the Suurban but has in the past if she needs to pick up something big or if I have her car for the day and there's an emergency (it's the only other vehicle in the driveway that isn't standard, and she has some mental block which prevents her from driving stick even though I've seen her do it and know she can...)
I'm not afraid of a carb, but that's not what I'm going for in this truck. Hah, I got used to the EFI and now I've gone soft.

 

[Old77]

That's basically what I'm thinking too. I could build my engine but after all that time and money it would be so much easier to just toss a crate engine in there, and a warranty is freaking sweet (not that I don't trust my own mechanical abilities but it's nice to have that reassurance). I wonder how it works though because I would be putting the engine in myself, most warranties only cover if a shop does the work. How do they verify the mileage? Also I do like the sound of the 350/350, I've heard of that from other people too

Just gotta figure out what to do about the fuel injection, not sure if I would pass enough fuel for that. Probably some bigger injectors would be fine

You register the engine along with the odometer reading and I guess they trust you from there lol

 

[RecklessWOT]

with your fuel injection on the truck I would look at gm crate engine 12681431 or 12530283 brand new with a warranty and would work well with your 700R.

That looks like a no ******** engine, and the price is pretty agreeable too...

 

[RecklessWOT]

You register the engine along with the odometer reading and I guess they trust you from there lol

Hah, well until I change out the gear the speedo/odo read 10% low, so hell I will even send them some pictures if they want, sounds like an extra 3,600 miles under warranty

 

[chappy78]

It's not my DD anymore, but it was for a few years and I'd really like to get it back to that point. It gets quite cold here in the winter, EFI is awesome when it's 20 below zero and you're out there in the dark at 5:30 in the morning getting ready to go to work. My wife usually does not drive the Suurban but has in the past if she needs to pick up something big or if I have her car for the day and there's an emergency (it's the only other vehicle in the driveway that isn't standard, and she has some mental block which prevents her from driving stick even though I've seen her do it and know she can...)
I'm not afraid of a carb, but that's not what I'm going for in this truck. Hah, I got used to the EFI and now I've gone soft.

Hi Kevin,

I'm in the process of installing a Chevrolet Performance L31R Vortec 350 in my K20. You can read about my project here:

https://www.gmsquarebody.com/thread...a-1978-chevrolet-k20-intro.27765/#post-531430

https://www.gmsquarebody.com/threads/1978-chevrolet-k20-build-and-l31r-vortec-engine-swap.27832/

Chappy78

 

[Frankenchevy]

What’s your budget?

my new l31-r long block from Chevy was $1800 to my door. Factory roller is nice with today’s oils. They make a tbi intake manifold with Vortec bolt pattern I believe.

 

[DoubleDingo]

What’s your budget?

my new l31-r long block from Chevy was $1800 to my door. Factory roller is nice with today’s oils. They make a tbi intake manifold with Vortec bolt pattern I believe.

Not bad at all

 

[77 K20]

I'll throw my 2 cents in here. I bought a GM crate engine- the HT 383. Loved it all summer. Once it got cold it would start right up then sputter and cough for the next 15 minutes or so. "Upgraded" to an Edelbrock throttlebody EFI unit. Still would start right up then sputter and cough for 15 minutes.
Turns out the one thing that no one mentions about vortec heads is that GM designed them for a dry manifold (for multiport fuel injection). The intake manifold has no provisions for heat in it. The exhaust crossover tube that was below the carb/TBI is gone.
When fuel gets atomized and then has to suddenly change direction 90 degrees the fuel will drop out of suspension. This then causes a puddle of gas to form. It then gets chugged down into the nearest cylinder after a bit.
The GM performance manifold that came with the engine had a completely smooth bottom of the plenum. This was "strike 2". Most manifolds have either a washboard pattern or a waffle pattern to them. This is designed to help puddling. The puddle will move and hit the top of the ridge where the air will cause it to break free and try to be back up in the airstream. Of course this works MUCH better if the manifold is heated. The gas will evaporate also.
I found ONE manifold from Edelbrock that had a plenum under the carb/TBI. They said this could be plumbed for an exhaust or a coolant plenum for some heat. Didn't know how to do the exhaust way- so instead plumbed it up as a coolant bypass. (GM also says any engine with Vortec heads will need a coolant bypass because some coolant passageways are not there anymore).
I installed the Edelbrock manifold and coolant bypass and then coolant kept going "missing". Found the manifold was porus and after you shut it off there would be a small puddle under the carb/TBI. Edelbrock said BS- that can't be. Like an idiot I bought a second one and installed it. SAME THING!!! So I dumped a tube of alumniseal in the coolant and dropped to a lesser pound radiator cap. Been running like that for about 3 years now.
So with this setup it still coughs and sputters but only for maybe 5 minutes tops. The coolant bypass is right out of the block back to a return on the water pump. It bypasses the radiator.
I noticed the issue of it sputtering at temps of mid 30s and below.
If I ever get rich I guess my plan is to get rid of the manifold and TBI and go with a true multiport setup.

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[Frankenchevy]

I'll throw my 2 cents in here. I bought a GM crate engine- the HT 383. Loved it all summer. Once it got cold it would start right up then sputter and cough for the next 15 minutes or so. "Upgraded" to an Edelbrock throttlebody EFI unit. Still would start right up then sputter and cough for 15 minutes.
Turns out the one thing that no one mentions about vortec heads is that GM designed them for a dry manifold (for multiport fuel injection). The intake manifold has no provisions for heat in it. The exhaust crossover tube that was below the carb/TBI is gone.
When fuel gets atomized and then has to suddenly change direction 90 degrees the fuel will drop out of suspension. This then causes a puddle of gas to form. It then gets chugged down into the nearest cylinder after a bit.
The GM performance manifold that came with the engine had a completely smooth bottom of the plenum. This was "strike 2". Most manifolds have either a washboard pattern or a waffle pattern to them. This is designed to help puddling. The puddle will move and hit the top of the ridge where the air will cause it to break free and try to be back up in the airstream. Of course this works MUCH better if the manifold is heated. The gas will evaporate also.
I found ONE manifold from Edelbrock that had a plenum under the carb/TBI. They said this could be plumbed for an exhaust or a coolant plenum for some heat. Didn't know how to do the exhaust way- so instead plumbed it up as a coolant bypass. (GM also says any engine with Vortec heads will need a coolant bypass because some coolant passageways are not there anymore).
I installed the Edelbrock manifold and coolant bypass and then coolant kept going "missing". Found the manifold was porus and after you shut it off there would be a small puddle under the carb/TBI. Edelbrock said BS- that can't be. Like an idiot I bought a second one and installed it. SAME THING!!! So I dumped a tube of alumniseal in the coolant and dropped to a lesser pound radiator cap. Been running like that for about 3 years now.
So with this setup it still coughs and sputters but only for maybe 5 minutes tops. The coolant bypass is right out of the block back to a return on the water pump. It bypasses the radiator.
I noticed the issue of it sputtering at temps of mid 30s and below.
If I ever get rich I guess my plan is to get rid of the manifold and TBI and go with a true multiport setup.

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There must be a point temp wise where this becomes an issue. This hasn’t ever happened with my truck on a sniper setup, but the coldest temps it has seen are ~25*F.

 

[RecklessWOT]

I'll throw my 2 cents in here. I bought a GM crate engine- the HT 383. Loved it all summer. Once it got cold it would start right up then sputter and cough for the next 15 minutes or so. "Upgraded" to an Edelbrock throttlebody EFI unit. Still would start right up then sputter and cough for 15 minutes.
Turns out the one thing that no one mentions about vortec heads is that GM designed them for a dry manifold (for multiport fuel injection). The intake manifold has no provisions for heat in it. The exhaust crossover tube that was below the carb/TBI is gone.
When fuel gets atomized and then has to suddenly change direction 90 degrees the fuel will drop out of suspension. This then causes a puddle of gas to form. It then gets chugged down into the nearest cylinder after a bit.
The GM performance manifold that came with the engine had a completely smooth bottom of the plenum. This was "strike 2". Most manifolds have either a washboard pattern or a waffle pattern to them. This is designed to help puddling. The puddle will move and hit the top of the ridge where the air will cause it to break free and try to be back up in the airstream. Of course this works MUCH better if the manifold is heated. The gas will evaporate also.
I found ONE manifold from Edelbrock that had a plenum under the carb/TBI. They said this could be plumbed for an exhaust or a coolant plenum for some heat. Didn't know how to do the exhaust way- so instead plumbed it up as a coolant bypass. (GM also says any engine with Vortec heads will need a coolant bypass because some coolant passageways are not there anymore).
I installed the Edelbrock manifold and coolant bypass and then coolant kept going "missing". Found the manifold was porus and after you shut it off there would be a small puddle under the carb/TBI. Edelbrock said BS- that can't be. Like an idiot I bought a second one and installed it. SAME THING!!! So I dumped a tube of alumniseal in the coolant and dropped to a lesser pound radiator cap. Been running like that for about 3 years now.
So with this setup it still coughs and sputters but only for maybe 5 minutes tops. The coolant bypass is right out of the block back to a return on the water pump. It bypasses the radiator.
I noticed the issue of it sputtering at temps of mid 30s and below.
If I ever get rich I guess my plan is to get rid of the manifold and TBI and go with a true multiport setup.

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That's a little concerning because it does get pretty cold here in the winter. I've never heard anyone else mention it before, I wonder how common of an issue that is? I like the idea of getting Vortec heads but not if I have to switch it over to tpi or something. Sure that would make a better engine but once again that's even more hassle when I'm just trying to get this thing streetable again. Did it really run that bad or was it just a little rough till it warmed up? I can live with it being a little rough for a few minutes, but if it makes the truck un-driveable then I would want to steer clear of that option.

 

[77 K20]

The colder it gets the worse it is. It was better when I ran a carb- as it had a high idle when it is cold. My Edelbrock TBI has no high idle speed for when its cold. On a cold day it will fire right up instantly then within about 10 seconds it will die. I have to use the throttle to keep it running.
Once in gear it sputters and I need to put my foot in it a bit to clear it out- then once driving at higer RPM it feels fine.
When I did all my research into a replacement engine it seemed like most lived somewhere warm and so never had any issues.
I do really like the extra power of the engine design and the roller cam-

 

[77 K20]

There must be a point temp wise where this becomes an issue. This hasn’t ever happened with my truck on a sniper setup, but the coldest temps it has seen are ~25*F.

Does the sniper have a high idle speed for when it is cold? Does your engine have a high vacuum at idle? Seems like when you have an aftermarket performance cam with less vacuum it can run better when cold.

The temperature of air drops even more when entering a vacuum.

 

[Overland Suburban]

I've never tried one but West Coast Engines seems to have great reviews and a good warrantee. They have a 300 hp 370 ft lbs of torque 350 they build that your stock tbi works with and they give you a new chip to calibrate. Comes with roller Cam and 50,000 mile 5 year warrantee. Apparently it's a great build for fuel economy also if there is such a thing with a square body suburban

 

[Frankenchevy]

Does the sniper have a high idle speed for when it is cold? Does your engine have a high vacuum at idle? Seems like when you have an aftermarket performance cam with less vacuum it can run better when cold.

The temperature of air drops even more when entering a vacuum.

Yes, high idle when cold. It looks at CTS, MAT, etc. My cam is stock Vortec(engine is a factory crate L31R). Vacuum is really high. It idles at 26-27kPa, which is over 22inHg.

edit: fuel enrichment is accomplished by a number of parameters like CTS, MAT, etc. timing is also computer controlled and adjusted by these and many other parameters. One of the other tunable features is after start enrichment, decay rate thereof; there are a multitude of adjustments possible in the software. I’d assumed there would be similar tunability in the edelbrock software, but I don’t know much about it. There’s enough involved with learning the depth of features of the Holley software. It’s actually quite incredible how tunable they are.

 

[Tjm1534]

Radley Chevrolet,I have bought 2 crate 350s from them.100,000 mile factory warranty’s.My last one was 3 years ago .Cost free freight Tmd was less than 1500.00.They ship fast and are the largest gm engine seller.