Head Swap Options For 5.7L 350 TBI Engine

[Majoraslayer]

I can't swear to this because I'm far from an expert, but from what I've seen researching online, the 906 heads tend to have the reinforced valve seats while all of the 062 heads I've collected so far do not. Hypothetically they "should" be the same performance-wise, but despite several people asking I've not seen anyone actually do flow test comparisons between the two. It would probably work, but unless someone confirms the flow numbers are super close it might not be a good idea to mix and match them. If anyone has actually tried mixing them I'd be curious to know how it worked out.

 

[Majoraslayer]

Annnnnnd as predicted, the 906 heads were cracked too. If I've learned anything, it's to never buy anything with a factory Vortec head on it.

 

[454cid]

Where are the cracks?

 

[Majoraslayer]

The 062 heads were mostly cracked around the valve seats. The 906 heads cracked down inside the coolant passages.

Aside from a specific version of the 906 heads having reinforced exhaust valve seats, I suspect I've discovered the main difference between 062 and 906 heads is the day of the week they were mostly likely to have cracked on.

I guess the main reason for the hype around Vortec heads is that they flow well, and I can confirm it. Exhaust, intake, coolant, it all flows anywhere it wants between all the cracks.

 

[PlayingWithTBI]

Annnnnnd as predicted, the 906 heads were cracked too. If I've learned anything, it's to never buy anything with a factory Vortec head on it.

Tell us what you really think

 

[Erik the Awful]

the 906 heads tend to have the reinforced valve seats while all of the 062 heads I've collected so far do not.

As far as I've read, the standard valve seats in Vortec heads are induction hardened. Some 906s got pressed-in inconel valve seats. The induction hardened seats tend to crack, the inconels sometimes fall out. I got the engine in WCJr with a dropped valve seat. It thoroughly trashed the piston and head.

 

[Majoraslayer]

I will note the 906s I ended up with didn't have the pressed-in seats. All of the 062 heads cracked near the valves, while the 906 cracked in a coolant passage instead. From what I've read, those pressed-in seats were only used on HD trucks for more strength in lower RPM pulling applications. I would guess one would be less likely to encounter them in the wild than the heads without them. The end result for me is the same, I'll be ordering the eBay heads since all OEM Vortecs are more cracked out than Hunter. It's still interesting to document the design history though.

 

[tayto]

I will note the 906s I ended up with didn't have the pressed-in seats. All of the 062 heads cracked near the valves, while the 906 cracked in a coolant passage instead. From what I've read, those pressed-in seats were only used on HD trucks for more strength in lower RPM pulling applications. I would guess one would be less likely to encounter them in the wild than the heads without them. The end result for me is the same, I'll be ordering the eBay heads since all OEM Vortecs are more cracked out than Hunter. It's still interesting to document the design history though.

I would get them from Summitracing or something so you have a chance at a warranty. especially with your luck (no offense). a buddy of mine got the "updated" aftermarket vortecs from Summit probably about 5 years ago with no issue thus far.

 

[L31MaxExpress]

As far as I've read, the standard valve seats in Vortec heads are induction hardened. Some 906s got pressed-in inconel valve seats. The induction hardened seats tend to crack, the inconels sometimes fall out. I got the engine in WCJr with a dropped valve seat. It thoroughly trashed the piston and head.

My 97 van had 906s but they had induction hardened, wider, single angle seats. The pressed in seats I have seen were Natural Gas/Propane engines.

 

[rebelyell]

I noticed over the weekend that my truck has developed a head gasket leak (coolant in the exhaust, hard cold starts, and engine compression shooting pressure into the cooling system). Since I'm going to have everything apart anyway, I'm considering options for possible upgrades to get a little more HP out of my engine. My truck is a 1988 K1500 and uses all of the sensors/accessories for that year, but the engine block itself was pulled from a 1995 truck. There's not a LOT of difference there, but I want to mention it since some of the electronics had minor changes in 1994/1995 and the blocks were supposedly cast without provisions for a roller cam.

For reference, I'm looking at possibly following this guide for suggestions, and it's where some of my info I'll reference came from. --> https://harristuning.com/Tbi/recommended-350-tbi-mods/
I noticed they offer custom tune chips as well, so I thought I might work backwards from setups they use since I don't have a tuner shop anywhere near me for customization.

In the article above, the author recommends either swapping to Vortec heads or using a set of Summit Racing aluminum heads for better flow. I've already skimmed through the thread in this forum on swapping Vortec heads onto a TBI block, and it sounds like a pretty big headache (no pun intended) that I'd prefer not to deal with. Since Vortec heads are also prone to cracking, I'm moving them to the bottom of my list for options. I want a boost in power, but this will be a street truck and I'd prefer to make it as reliable as possible. Reliability may be a pipe dream if experience with this truck is anything to go by, but I'll do what I can anyway.

That brings me to the Summit Racing aluminum heads, which sound like a direct swap. The problem is that the Summit site lists them as Not Available, which leads me to wonder if they've been discontinued completely.

I know there are a lot of options to take here, including custom fuel systems or carb swaps, but I'm hoping to work within the confines of retaining a TBI setup. I'd prefer to keep my factory 700R4 happy without having to pull the transmission and do valve body modifications, since the TBI ECM controls TCC lockup in 3rd and 4th gear on these trucks.

I guess my opening questions are:

1) The Summit Racing heads sound perfect for what I want to do. Does anyone make a comparable alternative to the SUM-162108 heads that could accomplish the same or similar result?

2) Are there any other factory GM heads that would make for a good upgrade, without needing major block modifications to run TBI?

3) If I go the Vortec route, I may cut out the middle man and just get a complete Vortec engine instead of just swapping heads, then install one of the aftermarket TBI intakes. I know this would require swapping my chip (obviously) and my exhaust headers. What other modifications would I need to do? Will the rest of my accessories be able to work around the Vortec water pump, or would I need to run all Vortec accessories and brackets?

First, postpone "elective surgeries" until after you've saved for a complete overhaul.

Next, Do upgrade to OE type roller lifters & roller cam; Don't gamble on today's flat tappet game.

When you do bore cylinders, Don't pick cheapo pistons; instead Do choose pistons with modern thin, metric ringpak (as are L31 pistons). And pay close attention to replacement pistons' Compression Height, Your block's Deck Height and Your measured Quench Height; it all matters!