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Old 06-15-2017, 06:03 PM
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Give up on Vortec heads?

Howdy all.
So here I am with 3 of 4 Vortec heads being scrap or cores.
1 pair of 906s and 1 pair of 062s.

Never had a problem in the past with GT40 heads being boat anchors 1 after the other but it is what it is.

1 pair came with a block that I just had squared and bored. (It's ready to go)
Another pair came on a $50 '98 L31. <--This was a great deal because now I have a "modern" serpentine assembly, powder rods + roller spider & retainer components + I'm tossing the block on CL for sale.

So now I'm on the edge of going the bare import aluminum head route.

I have an LT4 Hot Cam ready to go. (This seemed like a great choice for the cost and the application .500 (1.5 rr) or .525 (1.6 rr) for the Vortecs with a quick spring\lock\retainer mod.

The plan is to use the OEM 5.7" powdered metal rods, a stock 350 crank that has been turned\polished.

Now comes the heads that I had based the build on.
There's an online company that sells remanufactured Vortecs for $175 each shipped with no core fee up front, simply return the cracked heads via pre-paid return postage.

At this point do I trust the remanufactured heads?
What causes these things to be cracked 90% of the time?

Is it because the people overheating the engines just keep on driving them or is it an inherent design issue that's going to happen regardless over time??
Because if it's the latter, I can't see spending $350 + another $500 on springs and Vortec specific intake...

The results thus far have me disappointed.

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Old 06-15-2017, 06:43 PM
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The main reason you find them used at all is the fact that the owner drove the car/truck/SUV low on water and overheated the motor, cracking the heads.
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Old 06-15-2017, 07:06 PM
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Originally Posted by techinspector1 View Post
The main reason you find them used at all is the fact that the owner drove the car/truck/SUV low on water and overheated the motor, cracking the heads.

That and the castings are too thin in several places. Just magged three pairs Wednesday... I good head and 1 repairable one. About normal results.
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Old 06-15-2017, 07:52 PM
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Dude, that's crazy. 6 pairs and 1 good one?
I just picked up my block from the machine shop today and am trying to get my rotating assembly balanced but I need to select the pistons.

Should I go with 72cc or 64cc heads? It seems like 72cc offers 10x the options to get the compression right compared to 64cc.

Reverse dome pistons for 64s are super expensive where flat tops are much lower cost. I don't mind running "premium" pump gas but keeping it in the 10.1 or less range seems like a narrow margin for 64cc heads.
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Old 06-15-2017, 09:20 PM
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Flat tops with valve reliefs (6 cc's) will make 9.42:1 in a 350 bored +0.030 and using a Fel-Pro 1094 shim gasket. That's about the limit for iron heads on pump gas.
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Old 06-16-2017, 10:44 AM
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Originally Posted by PushrodV8 View Post
Howdy all.
So here I am with 3 of 4 Vortec heads being scrap or cores.
1 pair of 906s and 1 pair of 062s.

Never had a problem in the past with GT40 heads being boat anchors 1 after the other but it is what it is.

1 pair came with a block that I just had squared and bored. (It's ready to go)
Another pair came on a $50 '98 L31. <--This was a great deal because now I have a "modern" serpentine assembly, powder rods + roller spider & retainer components + I'm tossing the block on CL for sale.

So now I'm on the edge of going the bare import aluminum head route.

I have an LT4 Hot Cam ready to go. (This seemed like a great choice for the cost and the application .500 (1.5 rr) or .525 (1.6 rr) for the Vortecs with a quick spring\lock\retainer mod.

The plan is to use the OEM 5.7" powdered metal rods, a stock 350 crank that has been turned\polished.

Now comes the heads that I had based the build on.
There's an online company that sells remanufactured Vortecs for $175 each shipped with no core fee up front, simply return the cracked heads via pre-paid return postage.

At this point do I trust the remanufactured heads?
What causes these things to be cracked 90% of the time?

Is it because the people overheating the engines just keep on driving them or is it an inherent design issue that's going to happen regardless over time??
Because if it's the latter, I can't see spending $350 + another $500 on springs and Vortec specific intake...

The results thus far have me disappointed.

GM ran these engines much too hot from the factory the line between operating temp and fried was way too thin. Add to that the coolant Dexcool had a lot of in-service problems where it attacked the gasket material resulting in leaks that people didn't take care of that lead to a chemical failure of the coolant causing corrosion and more leakage. The end result is many of these engines were fried resulting in the cracks of a sensitive casting. These heads work well if new and the temps are carefully controlled to keep the engine around 180 degrees operating temp not 205 or 210. Use conventional coolant like Prestone used to be these days probably the closest to that formula is O'Reilly's house brand.


There are plenty of aftermarket choices in iron and aluminum that are sturdier and don't take redoing the valve guides and paying for springs that your not going to use with your cam selection. Going this route lets you select the valve train parts you need for the cam. Nice thing about aluminum is it lets you get away with more compression for the squish/quench clearance which will be a little wide with them because between an undecked block having .025 inch between the piston crown and deck along with the thinnest composite gasket these need which is the GM 10105117 or the 14096405 both being .028 gives a squish/quench of .053 which is .013 more than the ideal of .040 but an aluminum head is much more tolerant of this wider band. In fact GM ran the L98, LT1 and LT4 engines with a .053 gasket and a .025 deck for a total of .078 inch clearance.


I'm not so sure of the Vortec PM rods these had a higher than normal failure rate in these engines, not extreme to be sure but high enough that I won't use them in a built engine. Scat has some inexpensive I beam 4340 forgings available in either bolt and nut or cap screw versions that are excellent pieces for a 400 horse street 350 which are much better that the factory rods PM or forged. The cast GM crank has shown to be plenty sufficient for a 400 horse street motor and then some.


I like the LT4HOT cam for a 400 horse street motor in fact I run one with 1.6 intkae side only rockers in my Frankenmouse powered S15.


Bogie
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Old 06-16-2017, 06:28 PM
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Quote:
Originally Posted by BogiesAnnex1 View Post
I like the LT4HOT cam for a 400 horse street motor in fact I run one with 1.6 intkae side only rockers in my Frankenmouse powered S15.


Bogie
How about a couple of pictures for the interested crowd

OP - used Vortecs are rare to be found in good condition. Those engines ran too many miles and were on the edge when running correctly (as Bogie mentioned.)

JEGS Performance Products 514005: Cylinder Head SBC Vortec Cast Iron | JEGS for a guaranteed reman Vortec or add another $65/per and grab some new ones. This is the price of a well worked set of heads by a machine shop.

If the budget allows for another $300-500, then grab a set of Profilers, Jegs house brand (also Profiler), Speedway, ProMaxx, Dart, etc. aluminum.
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Old 06-16-2017, 08:14 PM
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So do I have bad information on the PM oem rods? I though I had read a good bit of information stating that they were better than previous forged oem rods? That the metallurgy was quite good and reliable?

As for CR can someone comment on the head cc size? Is 64 cc the way to go?

The bare AL heads I was considering are Dart knockoffs, 64cc, straight plug, fast burn heart shaped comb. chamber.
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Old 06-17-2017, 09:18 AM
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Quote:
Originally Posted by PushrodV8 View Post
So do I have bad information on the PM oem rods? I though I had read a good bit of information stating that they were better than previous forged oem rods? That the metallurgy was quite good and reliable?

As for CR can someone comment on the head cc size? Is 64 cc the way to go?

The bare AL heads I was considering are Dart knockoffs, 64cc, straight plug, fast burn heart shaped comb. chamber.
Head chamber size is part of the SCR equation. You need to know what piston, head gasket and deck clearance you're going to run prior to making this determination. Usually this comes down to a conglamourate of part pricing and availability.

So, with this in mind, there a ton of pistons available in cast, hyper, and forged, that will work great with a 64 cc head. If you were working ona 383, 406, or larger, then your choice would be different. You will need a 'd' shaped dish to work on a 350(355) or a piston with valve relief only with a 327(331).


Engineering the correct piston pin ht to achieve an good quench distance of .035 - .045" is much more important than worrying about a 1/2 - 1 point of compression IMO.

Send us a link to the heads that you are looking at - please.
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Old 06-19-2017, 10:35 AM
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Here's the link to the heads I was looking at -- SBC Aluminum Cylinder Head Set

Based off of what I could find on the web, they're not ProComps and that they are extremely close to a Dart casting and pretty good overall as a bare set.

The only other heads I was considering are the NKB aluminum heads.
NKB heads have multiple CC options to choose from.

Originally, I was going to do the 383 route but then that's $1k for the rotating assembly.
But if you guys are saying that I shouldn't trust the PM rods then the only thing I'll have to reuse is the machined block \ new camshaft \ roller cam retainer components.

Might as well sell everything else and start back on the path to the stroker motor.

Here are the rebuilt Vortec heads I mentioned.
For the sake of curiosity, has anyone purchased from CHI before? shop.headsonly.com << CHI -- Cylinder Heads International (Since 1968)

For about $500 I could have a set of Vortec heads with the upgraded .550 spring \ retainer kit.

I figured for about $750 I can build up those bare eBay heads completely.

And the set of NKB heads, are going to be about $850-$900 once the studs and guide plates are factored to be complete.
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Old 06-19-2017, 11:02 AM
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How about a couple of pictures for the interested crowd


I'm planning on pulling Frankenmouse down later this summer to do some maintenance and inspections on it. I'm planning on doing some detail pictures to go with a wiki submission to Crankshaft Coalition on how to modify LT1 and LT4 heads to conventional blocks. I meant to do this some years ago when it was somewhat popular before inexpensive quality import heads existed (they were available but mostly junk) so like putting modified 305 heads on 350's back in the 1980's and 90's putting modified LT1/LT4 heads on a standard block had a spate of popularity as a cheap(er) way to pump up standard SBC block power. But today especially given the cost of the GM carb intake this just isn't economical to do any more, but it is an interesting project. A sometimes contributor here SilverBack runs a set on a 305 block with good result.


But there's never been a really through published methodology with daily operating results published, YouTube has some hints from people who went in different directions but leave a lot of detail out. Some try to weld something up that lets then use a conventional manifold for coolant return, but by their own admission has some serious problems with sealing. Most others use various methods of returns from the ends of the heads both using Smokey's the side or using the vapor return on the high side. One guy from Switzerland used plumbing sized commercial over braid fittings and hose which I would think too small but he reports it works, then again the weather is a lot cooler than that found in much of the U.S. My process was to offset drill the vapor returns and tap them for 1/2 NPT threads. Then install 1/2 90 degree street elbows, this a much as anything is a space problem driven by the engine set back in the S15 (GMC version of the S10); these then rubber hose to a Weiand remote coolant return that mounts in the more or less standard Chevy location over a GMPP LT1 intake. I had to beef up the Weiand casting to put threaded holes into it in not standard locations with some welded up pads. The return hoses are 1/2 inch heater hose. The Weiand also sports a 5th tap that supplies the heater/bypass as an independent flow route, there's other ways this could have been done. The heads have some reshaping of the ports but run stock 1.94 and 1.56 valves.


Bogie
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Old 06-19-2017, 04:07 PM
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If you shop smart, between Ebay for the castings and Competition Products for the assembly parts you can end up with assembled import castings for $600 including studs and guideplates, with good enough parts for anything short of solid roller cam abuse.

I've bought that same casting from SouthCoastPerformance, it is really decent for imported, actually real nice and near identical to Dart Pro-1 Platinum 200cc.

I believe the NKB and Assault Racing are the same casting, and possibly RPC also.....if you know what to look for you can visually tell it apart from the other import castings.

I don't even bother with Vortecs anymore, too hard to find usable....and the decent import aluminum will make more power if you want it while costing only penny's more than a Vortec refurb....

I never cared for the Powdered Rods either, seen too many broken beams in performance usage.
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Old 06-19-2017, 06:33 PM
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Thank you all for the replies.

I watched a few vids on YouTube about the CHI heads. Some were really good and a few not so good. (Nature of the web naturally)

But yeah I've decided to let go of the Vortec 'dream'. I know they were a great when they were the newest thing but now I've seen 1st hand the issues (crack prone in addition to the lift limitation + specific intake and self aligning rocker arms) and all those add up to more work/risk than the return.

Once I get back to a computer I'll post up the parts list I created for those Dart repops.
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Old 06-19-2017, 06:40 PM
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Oh and to respond on the powder rods subject: Again I had read plenty about them being stronger and more reliable than pink rods and or forged rods. But I also completely understand the fact that something that withstands constant heat fluctuations, friction, harmonic vibrations, in addition to being in an unknown mileage / maintenance engine is yet another ? component that has the ability to wreck the whole assembly.

With that, I'm going with AL heads and building up a 383.

It's going to take 2 months but that's ok.
No major rush.

The 30 year old 305 and TH400 still runs great but it's a smogger slug and I just can't stand how damn gutless it is. (Coming from a Ford 302 / 351 with plenty of go fast goodies)
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Old 06-20-2017, 12:42 PM
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Quote:
Originally Posted by PushrodV8 View Post
Here's the link to the heads I was looking at -- SBC Aluminum Cylinder Head Set

Based off of what I could find on the web, they're not ProComps and that they are extremely close to a Dart casting and pretty good overall as a bare set.

The only other heads I was considering are the NKB aluminum heads.
NKB heads have multiple CC options to choose from.

Originally, I was going to do the 383 route but then that's $1k for the rotating assembly.
But if you guys are saying that I shouldn't trust the PM rods then the only thing I'll have to reuse is the machined block \ new camshaft \ roller cam retainer components.

Might as well sell everything else and start back on the path to the stroker motor.

Here are the rebuilt Vortec heads I mentioned.
For the sake of curiosity, has anyone purchased from CHI before? shop.headsonly.com << CHI -- Cylinder Heads International (Since 1968)

For about $500 I could have a set of Vortec heads with the upgraded .550 spring \ retainer kit.

I figured for about $750 I can build up those bare eBay heads completely.

And the set of NKB heads, are going to be about $850-$900 once the studs and guide plates are factored to be complete.

The Ebay heads are from the same Asian supplier as ProComp and many other sellers. They have become as decent in terms of quality over the past several years as any other in the market. As you found the bare head costs another 500 bucks to outfit with valves and supporting characters. Keep in mind that these heads as with most aluminum heads require a valve with .1 inch more stem length and that drives back on the push rod length. If you're building a moderate performance street engine where special valves and valve train parts aren't necessary it's more cost effective to buy the heads populated.


Bogie
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