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Discussion Starter · #1 ·
I bought an 87 k15 with a decent running 350 2 bolt main but after seeing some janky wiring and oil/trans leaks I decided to do a frame off. The block was already bored .030 over and showed some light pitting in the 7th cylinder. The block is a 010 casting and my machine shop assured me that it was a good candidate for .060 over (shop has a great rep ran by a couple of old school hotrodders). I have an Edelbrock AVS2 650 carb, Edelbrock intake, comp cams xtreme energy 4x4 cam kit with springs and lifters, 250-258 tappet lift, .432-.453 valve lift, 111 lobe separation, long tube headers and a 7qt oil pan. I’m rebuilding a th400 to put behind it and will be running 4.11 or 4.56 gears. Unfortunately I’ll be running 882 heads because they’re in pretty good shape to save some cash. Any idea what kind of TQ/HP numbers I should see out of this setup? Also any ideas on what stall speed I should run for a new torque converter? This will be used primarily for street, no strip. Thanks for your time.
 

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Well, your .250/.258 cam lift with 1.5 rockers doesn't equal the .432/.453 valve lift numbers so something's up with that information. Making the assumption that .432/.453 is correct, and assuming that we're around 9.5 C/R, but then killing it with the 882 heads, I am thinking somewhere around 175-185 HP and 280-290 TQ. I would lean on the 4.56 gears as your moving about 6000 pounds. Downside is that you're probably looking 10-12 MPG at best. The TH400 is durable but also consumes more power, torque convertor for the street I would keep under 2500.
 

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Explain the cam the the 250/258 I think you meant as degrees not lobe lift, but I could be wrong.

Pushing the assumption that 250/258 are degrees the next question is are these at zero or are they at .050 lift. The former fairly mild the latter pretty aggressive.

882’s not the best but with some pocket porting and covering flat top pistons depending on cam and exhaust answers will deliver between 350 ft.lbs./260hp to 377/340 to/hp.

Bogie
 

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Discussion Starter · #4 ·
Well, your .250/.258 cam lift with 1.5 rockers doesn't equal the .432/.453 valve lift numbers so something's up with that information. Making the assumption that .432/.453 is correct, and assuming that we're around 9.5 C/R, but then killing it with the 882 heads, I am thinking somewhere around 175-185 HP and 280-290 TQ. I would lean on the 4.56 gears as your moving about 6000 pounds. Downside is that you're probably looking 10-12 MPG at best. The TH400 is durable but also consumes more power, torque convertor for the street I would keep under 2500.
It appears that I have read the cam card incorrectly so I updated the post. It's listed on summit as duration 250/258, lift .432/.453 , 111 lobe separation. I bought hypereutectic dish pistons for the build, hopefully I didnt get the wrong type, I've already dropped one off at the machine shop. Gas mileage isn't a big deal for me as it will not be my primary. I was thinking that the 4.56 gears might be the better option, I'll be running 35s with a 6" suspension. Thanks for your time, I appreciate all the help I can get.
 

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Discussion Starter · #5 ·
Explain the cam the the 250/258 I think you meant as degrees not lobe lift, but I could be wrong.

Pushing the assumption that 250/258 are degrees the next question is are these at zero or are they at .050 lift. The former fairly mild the latter pretty aggressive.

882’s not the best but with some pocket porting and covering flat top pistons depending on cam and exhaust answers will deliver between 350 ft.lbs./260hp to 377/340 to/hp.

Bogie
Hi Bogie,
Thanks for the reply. It looks like I goofed up when reading the cam card It's listed on summit as duration 250/258, lift .432/.453 , 111 lobe separation. I bought sealed power hypereutectic dish pistons for the build with molly rings, hopefully I didnt get the wrong type, I've already dropped one off at the machine shop. I'll be running long tube headers with either an x or y pipe with flowmaster 40s most likely with 2.5" pipe. It came with the headers with 3" pipe to flowmaster 10s dumped just behind the cab and it was terrible.
 

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Discussion Starter · #8 ·
I think this is the cam he is looking at.

I think this is the cam he is looking at.

Yep that’s the one.
 

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Discussion Starter · #9 ·

This is the cam and kit I have. I might entertain budget heads. I’ve been keeping an eye out on FB marketplace and Craigslist for a set of used heads. The cats been out of the bag for to long now so vortec heads are hard to find. The guy at the machine shop said to stay away from vortec heads made before 1996 and make sure that they are made in Mexico if I find some because they’re less prone to cracking.
 

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It appears that I have read the cam card incorrectly so I updated the post. It's listed on summit as duration 250/258, lift .432/.453 , 111 lobe separation. I bought hypereutectic dish pistons for the build, hopefully I didnt get the wrong type, I've already dropped one off at the machine shop. Gas mileage isn't a big deal for me as it will not be my primary. I was thinking that the 4.56 gears might be the better option, I'll be running 35s with a 6" suspension. Thanks for your time, I appreciate all the help I can get.


Figured it might be and I have now looked at the cam - it's a bit like the old RV cams - great torque numbers but HP not so much - this one is listed as running out of steam in the mid-4000 rpm range. For your truck, I think it's a good choice and if you already have it then go with it.
 

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If this is the Comp 12-231-2 cam that is roughly equivalent to the old Chevy 916 cam. With 882 head’s and round dish pistons that builds a 350 right around 350 ft lbs torque and 260-270 hp.

There is nothing wrong with 96 up Gen I made in Mexico or USA. Yeah they are easy to crack but all GM head’s from about 1974 forward are thin wall castings and are rather delicate, that includes your 882’s. GM attaches the name Vortec to a bunch of things, when we here talk Vortec head’s we mean the 1996 up through 2000 or 2001 factory production 350 engines designated by the GM option number L31. The 350 head’s from 1995 back to 1987 were also named “Vortec” but these are the Swirl Port head’s on option LO5 engines. Neither of these head’s will fit your existing intake in spite of the common bolt count and location of the LO5 head the angle of incidence to the head alongside the plenum changes from the 90 degrees to the intake face of the head (common to all bolts prior to 87) to a 72 degree angle. The L31 head changes all lots to 45 degrees incidence and reduces their number to 4 per side. So using factory L31 head’s requires a very specific intake which has to be cost added to the factory head’s. Your existing intake can be modded to fit the 87-95 LO5 head but they flow for crap and that cannot be changed. The aftermarket is a better place to shop head’s as you can get modern L31 Ricardo style chambers and better porting on head’s that can be had in iron or aluminum. Iron is simpler for gasket thickness and casting material reasons than aluminum. But either can be made to work. There are some very good budget head’s out there that can be had off ebay or Amazon for not a lot more than the cost of rebuilding your 882’s. These as with the GM iron L31 with your chosen cam are an easy 300 to 330 hp build with about 40-50 more ft pounds of torque to boot compared to your 882’s. That’s mostly in the greatly improved chamber design that gets a lot more power out of the mixture for a lot of technical reasons I harked on for years, just look up my responses.

Your factory style piston choice leaves some to be desired but they work OK. More power and torque is available with D dishes using a 64ish cc chamber or going to flat tops with a modern aftermarket 74ish cc chamber. These are nothing like the chambers on your 882 head’s in spite of their size, they follow the Ricardo heart shape chamber like the L31 they’re just 10 ccs bigger. Your 882’s were designed back in the day for the express purpose of reducing NOx emissions as converter technology did not yet exist to address this emissions issue, since NOx is a temperature issue the chambers were simpled to reduce compression ratio and slow the burn time. The L31 and similar aftermarket head’s is a full return to the Ricardo chamber which was used in a less complex design by Chevy and the SBF Windsor to skate around paying royalties to Ricardo for their patented chamber. Reducing emissions while improving fuel mileage and power as a combination of government mandate and advertising advantage finally forced the industry to embrace the Ricardo wedge chamber, roller cams, and EFI, stuff that’s been sitting on the shelf since the 1930’s for the chamber and the 1950’s for EFI.

Bogie
 

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Discussion Starter · #12 ·
Bogie,
Thanks for all your help. Based on your responses you obviously have a vast knowledge of engine building. I’d be grateful for any advice on a set of heads for a $1000 budget for dish and flat top pistons. I’ll stop by the machine shop in the morning, hopefully they haven’t had the chance to start on my block. I’d be okay with 91 octane for some extra power but I’d like to avoid 93 octane. I live in South Georgia if that helps for atmospheric purposes. Elevation is 200’ AGL and the truck will stay local.
Thanks again

-J011YGR33N
 

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Bang for the buck, it's hard to beat Vortecs, although they do require the specific intake.

For heads, buy some aftermarket re-casts. As it was explained to me, the ones from Summit like this are $360 each and cast with a different alloy of iron and are supposedly far less likely to crack. Good match for the cam, although I would personally do flat-tops for 9.5:1. The efficiency of the Vortec heads means you need less ignition lead and lower octane than with traditional chambers. 9.5:1 with 87 octane is very attainable.

For the intake, don't stress about buying a $350 specialty intake. Look to boat junkyards. Millions of Vortec 350 I/O motors came with carbs. Call up a boat salvage yard near the coast and ask for one. Chances are, they are going to be a re-casting of the very good GM intake that comes on crate Vortec motors, but it might say "volvo" or "mercruiser" on it. I used to have dozens of them that I got for $20-50, but I either used them on projects or sold them off.
 

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Just some added informaton...the Summit house brand Vortec head Curtis73 posted a link to in the previous post is made by Dart.

It is the Dart Iron Eagle S/S Vortec with the Dart name removed from the casting.

Nice chamber, decent Vortec level flow on the intake side(232cfm @.500" lift), but it could use a bowl blend on the exhaust side because flow numbers there are pretty average (138cfm @.500" lift, but that does match a stock Vortec) and the lip left behind by the exhaust seat cutter is really obvious and easy to remove if you've got the ability.

If you decide you want to spend a little more and get aluminum, the Summit house brand versions are made by Trick Flow.
Excellent head, and would eliminate the need for a Vortec pattern specific intake manifold to save you some of the $350 price difference. $1099/pair vs $730/pair for the iron
 

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Discussion Starter · #15 ·
Just some added informaton...the Summit house brand Vortec head Curtis73 posted a link to in the previous post is made by Dart.

It is the Dart Iron Eagle S/S Vortec with the Dart name removed from the casting.

Nice chamber, decent Vortec level flow on the intake side(232cfm @.500" lift), but it could use a bowl blend on the exhaust side because flow numbers there are pretty average (138cfm @.500" lift, but that does match a stock Vortec) and the lip left behind by the exhaust seat cutter is really obvious and easy to remove if you've got the ability.

If you decide you want to spend a little more and get aluminum, the Summit house brand versions are made by Trick Flow.
Excellent head, and would eliminate the need for a Vortec pattern specific intake manifold to save you some of the $350 price difference. $1099/pair vs $730/pair for the iron
That’s good to know, I don’t need to advertise a brand under my hood anyway!
 

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Discussion Starter · #16 ·
Bang for the buck, it's hard to beat Vortecs, although they do require the specific intake.

For heads, buy some aftermarket re-casts. As it was explained to me, the ones from Summit like this are $360 each and cast with a different alloy of iron and are supposedly far less likely to crack. Good match for the cam, although I would personally do flat-tops for 9.5:1. The efficiency of the Vortec heads means you need less ignition lead and lower octane than with traditional chambers. 9.5:1 with 87 octane is very attainable.

For the intake, don't stress about buying a $350 specialty intake. Look to boat junkyards. Millions of Vortec 350 I/O motors came with carbs. Call up a boat salvage yard near the coast and ask for one. Chances are, they are going to be a re-casting of the very good GM intake that comes on crate Vortec motors, but it might say "volvo" or "mercruiser" on it. I used to have dozens of them that I got for $20-50, but I either used them on projects or sold them off.
Lots of good info, thanks for taking the time to respond to my questions. I’m not far from the coast so I may have see what I can find.
 

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The modern Iron Eagle has a lot to be said for it. There are several brands domestic and import that got into these iron heads since many race venues agreed to accept a more or less stock port head with L31 Vortec chambers using the original 6 bolt per side intake pattern.

Again some of these are in the 72 to 74 cc chamber volume while using the modern chamber shape so we’re not talking an open chamber like the 882 and it’s SMOG cousins. And some brands do offer a 62 to 64 cc chamber so you need to be alert to the chamber volume and how that impacts any piston crown volumes with respect to compression ratio.

These aftermarket head’s are more robust than the production 062 or 901 Vortec. They accept high valve lifts without modification to the upper guides and of course regular intakes with the 55 through 86 bolt patten just drop on. They may include an exhaust heat cross over which will feed a manifold with this OEM feature.

Bogie
 
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