New 350HD Crate Engine - Additional Parts List

Dean89 · Jun 21, 2022

I purchased a new 350HD for my 99 Tahoe that has 250k miles on the original motor. I was wondering if someone would take a look at the parts list below and see if there is anything I should add/change to it. I'm just looking for a reliable engine with similar mpg to the original. The main problem I had with the original motor was it drinking antifreeze. I would hate to know how much money I spent on antifreeze over the past 23 years. I replaced the intake gaskets twice, the second time w/felpro. It's probably going to cost me 10K. Now I am thinking I should have gotten this whole package for less than 15K! https://www.gmperformancemotor.com/parts/CPSLS3EROD6L80E.html

My main questions:
What do I have to do to have a reliable engine that doesn't drink antifreeze?
Is there a better reman transmission than the ATK for similar pricing?
It is my understanding ACDelco no longer makes the Lower Intake Manifold or the Fuel Injection Conversion Kit. What options do I have? I'm going to try to use the original Lower Intake Manifold if possible. Whats the best Fuel Injection available?

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https://www.gmperformancemotor.com/parts/19432779.html

JOHNGAAA1 · Jun 21, 2022

Change the front seal on the transmission while you are in there!!!!

stutaeng · Jun 21, 2022

Dean89 said:
Is there a better reman transmission than the ATK for similar pricing?

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$2125 for a remanufactured 4L60e doesn't sound like a bad deal at all, but then again, seems a bit too cheap?...Are you doing all the work yourself? Or are you paying someone to drop all of this for you? Check for a local shop that can rebuild your unit and give you a warranty. That way if it breaks you can go to them for work under the warranty period. They usually do a 12 month/12,000 warranty, I think.

If you are doing the work yourself, look into doing a 4L80e swap. Those units are more robust/reliable "out-of-the-box." However, it requires modifications (tune reflash, flexplate swap, crossmember modification, yoke swap), which may or may not be of interest to you. Swap may be cheaper (plenty of guys are running around with $600-800 junkyard or part-out special 4L80e swapped units, like me

) or more expensive (remanufactured 4L80e units are a little more expensive than equivalent 4L60e), depending on where or how you get the transmission.

Schurkey · Jun 21, 2022

1. Why did you buy the 350HD engine, instead of the regular Vortec 350? If you don't have a "HD" truck, you've thrown away most of the GM warranty.

2. Doesn't the engine come with a flexplate?

3. Doesn't the new distributor come with a cam sensor?

4. I would TEST the crank sensor, EGR, MAP sensor, Coolant temp sensor, Idle Air Control, and Ignition coil before I bought new ones. Same for the knock sensor(s).

5. EXPECT to have to haul those Dorman exhaust manifolds to the machine shop to have them planed flat before you install them. When it's me, I have the machinist throw 'em in the parts-cleaning oven to bake them so they heat-cycle at least once before planing the gasket surface. Not only are the Dorman manifolds not flat when you pull them out of the box, the machining they do perform is too rough. They look like some Chinese dude kicked 'em across a concrete floor a few times to "plane" them.

6. Do you actually need a new coolant overflow bottle, and a radiator shroud? OTOH, consider adding a new radiator--possibly larger than OEM. For example, a rad from a 454 or Diesel, perhaps.

7. I don't see oil, filter, ATF, antifreeze + distilled water, PS fluid, PS hoses (as required) engine oil cooler hoses (as required), air filter, fuel filter, serpentine belt, tensioner/pulley, heater hose(s), O2 sensors, or starter on your list. The belt, tensioner, and starter could be checked to see if your existing units can be re-used. 02 sensors are essentially a wear-item, at least the ones in front of the catalyst. The ones behind the catalyst are "somewhat" less-critical.

JOHNGAAA1 said:
Change the front seal on the transmission while you are in there!!!!

Why? He's buying a rebuilt transmission.

Mind you, I wouldn't touch an ATK rebuild...I'd have it done locally. And don't forget to FLUSH THE TRANS COOLER(s).

Dean89 · Jun 21, 2022

stutaeng said:
$2125 for a remanufactured 4L60e doesn't sound like a bad deal at all, but then again, seems a bit too cheap?...Are you doing all the work yourself? Or are you paying someone to drop all of this for you? Check for a local shop that can rebuild your unit and give you a warranty. That way if it breaks you can go to them for work under the warranty period. They usually do a 12 month/12,000 warranty, I think.

If you are doing the work yourself, look into doing a 4L80e swap. Those units are more robust/reliable "out-of-the-box." However, it requires modifications (tune reflash, flexplate swap, crossmember modification, yoke swap), which may or may not be of interest to you. Swap may be cheaper (plenty of guys are running around with $600-800 junkyard or part-out special 4L80e swapped units, like me ) or more expensive (remanufactured 4L80e units are a little T**************************more expensive than equivalent 4L60e), depending on where or how you get the transmission.

stutaeng said:
$2125 for a remanufactured 4L60e doesn't sound like a bad deal at all, but then again, seems a bit too cheap?...Are you doing all the work yourself? Or are you paying someone to drop all of this for you? Check for a local shop that can rebuild your unit and give you a warranty. That way if it breaks you can go to them for work under the warranty period. They usually do a 12 month/12,000 warranty, I think.

If you are doing the work yourself, look into doing a 4L80e swap. Those units are more robust/reliable "out-of-the-box." However, it requires modifications (tune reflash, flexplate swap, crossmember modification, yoke swap), which may or may not be of interest to you. Swap may be cheaper (plenty of guys are running around with $600-800 junkyard or part-out special 4L80e swapped units, like me ) or more expensive (remanufactured 4L80e units are a little more expensive than equivalent 4L60e), depending on where or how you get the transmission.

Thanks for all the info! I'm planning on doing the work myself. I will look into a reman 4L80 and what all is involved...I believe I had read somewhere that the 4L80e would give me worse gas mileage, than the 4L60e is why I hadn't considered it...but maybe that isn't the case.
Thank You!

Dean89 · Jun 21, 2022

Schurkey said:
1. Why did you buy the 350HD engine, instead of the regular Vortec 350? If you don't have a "HD" truck, you've thrown away most of the GM warranty.

2. Doesn't the engine come with a flexplate?

3. Doesn't the new distributor come with a cam sensor?

4. I would TEST the crank sensor, EGR, MAP sensor, Coolant temp sensor, Idle Air Control, and Ignition coil before I bought new ones. Same for the knock sensor(s).

5. EXPECT to have to haul those Dorman exhaust manifolds to the machine shop to have them planed flat before you install them. When it's me, I have the machinist throw 'em in the parts-cleaning oven to bake them so they heat-cycle at least once before planing the gasket surface. Not only are the Dorman manifolds not flat when you pull them out of the box, the machining they do perform is too rough. They look like some Chinese dude kicked 'em across a concrete floor a few times to "plane" them.

6. Do you actually need a new coolant overflow bottle, and a radiator shroud? OTOH, consider adding a new radiator--possibly larger than OEM. For example, a rad from a 454 or Diesel, perhaps.

7. I don't see oil, filter, ATF, antifreeze + distilled water, PS fluid, PS hoses (as required) engine oil cooler hoses (as required), air filter, fuel filter, serpentine belt, tensioner/pulley, heater hose(s), O2 sensors, or starter on your list. The belt, tensioner, and starter could be checked to see if your existing units can be re-used. 02 sensors are essentially a wear-item, at least the ones in front of the catalyst. The ones behind the catalyst are "somewhat" less-critical.

Why? He's buying a rebuilt transmission.

Mind you, I wouldn't touch an ATK rebuild...I'd have it done locally. And don't forget to FLUSH THE TRANS COOLER(s).

1. The regular 350 has been out of stock since like December on the Gm Performance website...I called them and was told there were hundreds of 350s on back order. So when the HD became available I bought it this week. I figured since I am doing the work myself there probably wasn't a warranty anyway.

2. Thank you for bringing that up, I will check it out.

3. I am not sure. I will check that out.

4. I really want a reliable engine that I can drive anywhere, so I figured a 23 year old vehicle would be good time to replace some of these original sensors. I think if I can find ACDelco sensors I will buy them as it seems that ACDelco is not making things for this engine anymore, i.e. fuel injectors, etc.

5. Thanks for the info on the Dorman Headers!!!! I will look into something else.

6. My radiator shroud is in bad shape with sections missing. Will consider a larger radiator!

7. Thank you for all the items you mentioned here! I think I was seeing how much this is going to cost and quit putting things on my list!

stutaeng · Jun 21, 2022

Dean89 said:
Thanks for all the info! I'm planning on doing the work myself. I will look into a reman 4L80 and what all is involved...I believe I had read somewhere that the 4L80e would give me worse gas mileage, than the 4L60e is why I hadn't considered it...but maybe that isn't the case.
Thank You!

I didn't see any difference in my swap. If there's any difference, it's probably within rounding error.

df2x4 · Jun 22, 2022

stutaeng said:
I didn't see any difference in my swap. If there's any difference, it's probably within rounding error.

Same here, and mine went into a V6 truck. The gas mileage difference between 4L60E and 4L80E is negligible IMO.

454cid · Jun 22, 2022

Schurkey said:
6. Do you actually need a new coolant overflow bottle, and a radiator shroud? OTOH, consider adding a new radiator--possibly larger than OEM. For example, a rad from a 454 or Diesel, perhaps.

A diesel radiator would be an interesting swap. I beleive adapters would need to be used on the hoses. However it would allow the use of the sealed and pressurized coolant bottle and move the cap there. This is a better setup for modern coolants, especially Dexcool. At one point I was looking to do this, but never followed through..... I did have the diesel coolant bottle I picked up from the salavge yard, but it ended up cracking while sitting in my garage.

Schurkey · Jun 22, 2022

I stay the hell away from Diesels. I didn't realize that the Diesels used a surge tank instead of a recovery bottle.

New 350HD Crate Engine - Additional Parts List

Dean89

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JOHNGAAA1

I'm Awesome

stutaeng

I'm Awesome

Schurkey

Supporting Member

Dean89

Newbie

Dean89

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stutaeng

I'm Awesome

df2x4

4L60E Destroyer

454cid

Sooper Pooper

Schurkey

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