Valve / seat height concern

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Valve / seat height concern

Post by Schurkey »

Having problems with my TBI Chevy 5.7L. I think I spun a rod bearing, as it knocks quite badly. If I'm going to open the engine, I want to replace the swirl-port heads for (hopefully) more power. I figure if the bearing is as bad as the knock indicates, the piston probably smacked the valves on overlap. I don't see any point to putting money into swirl-port heads.

I ordered a pair of EngineQuest heads having the Vortec chamber and an exhaust crossover (so I retain EGR and manifold heat) along with the TBI-style intake bolt pattern with the center two bolts at the goofy angle.

Upon receiving the heads, I notice that the intake valves seem to be sunk deeply into the throat, which causes the intake valve tips stick up higher than the exhaust valve tips. The four intake valves per head all seem to be at an even height, the four exhaust valves seem to be all at an even height, but the intake and exhaust valves aren't at the SAME height. The intakes are about 0.035 higher than the exhausts. The valve installed height will also be 0.035 more than the exhausts, since I don't see any valve spring shims under the springs.

Image
Intake valve sunk into the throat

Image
Intake valve deep in the casting, with a bevel cut around it. Exhaust valve prominent.

Image
About 0.035 gap between center pair of exhaust valves compared to the intakes. Other exhaust valves similar.

For those of you who perform valve jobs, what is your tolerance for valve tip height differences, and valve spring installed-height on a stud-mounted rocker system on a fairly low-performance "daily driver"? Is .035 worth of difference something I should be concerned about? Possibly needing a difference in pushrod length between intake and exhaust to compensate?

This is going to get a mild cam--the TBI system won't tolerate much for camshafts without "tuning" the PROM chip, and I've got no plans to burn chips. It might get the same cam that's in it now--stock extremely-mild 5.7L 1992 Caprice roller cam, or it might get a stock 1996 Vortec roller cam which has a bit more lift and duration but still pretty mild. The valve springs and clearances are supposed to be adequate for more lift than I'll give them. This was an early-90s "B/C Body" service-replacement "crate engine" that went into my '88 K1500. It doesn't see much in the way of high-rpm use. It's run wonderfully on the original computer tune for ~90K miles except when the O2 sensor was defective.

Do I need to pull this apart to shim the intake valve springs? I haven't measured the actual installed height yet.

Does having the exhaust valve head farther into the chamber than the intake valve head create problems on overlap?
I'm sure I read that folks were doing the opposite--recess the exhaust compared to the intake--to prevent the fresh fuel-air charge from going right out the exhaust on overlap.

I don't know if this difference in valve height is a "real" problem or if I'm over-thinking the situation. I don't know of any way to correct the valve heights except to install intake valve seat inserts, which is not something I can do, and I'll avoid it if possible.

Any other thoughts are welcome.

I have contacted the seller of these heads, but not heard back from them yet.
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Re: Valve / seat height concern

Post by ProPower engines »

Any stock type builds we do i limit the tip height variance to +/- .005". There is no excuse for doing shity work.
The heads you got I never install as purchased heads regardless of where they come from. And if the tip height difference is cause for concern as either the exhaust may actually be wrong. I recently had that exact issue with those heads a customer purchased and bolted on. Spring bind was the result so my best advice to you is take them apart and check them and correct what needs to be corrected.
If you got the heads from EQ they will make it right :D
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Re: Valve / seat height concern

Post by Walter R. Malik »

It is an adjustable valve train so, that alone will not be an issue with engine assembly.
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Re: Valve / seat height concern

Post by pamotorman »

i have seen brand new chevy OEM heads like this.
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Re: Valve / seat height concern

Post by modok »

If the intake lift is .070 more than the exhaust then it would make sense, use all same length pushrods.
Yeah check the spring travel. Better safe then sorry
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Re: Valve / seat height concern

Post by cpmotors »

I'd be taking those apart and fixing the valve job myself. I wouldn't be suprised if the exhaust seat isn't anywhere near the OD of the valve.
I try to keep Intake/Exhaust tips within .005" total.
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Re: Valve / seat height concern

Post by Schurkey »

Sent MULTIPLE e-mails to the seller via the eBay mail system. Never got a reply.

They were advertised as including the head bolts; my shipping manifest shows they didn't include them. It wasn't that they were forgotten, they never intended to send 'em.

Valve spring installed height wasn't right even on the exhausts. Closer to 1.8 than the advertised 1.7.

I put 'em back in the boxes, they'll be shipped tomorrow. I had high hopes for these heads. I hate to see 'em go. If they'd been machined properly, I'd have kept 'em.

I'm very reluctant to use the OEM swirl-port jobs, but the cost of the Vortec-TBI conversion manifold is insane. Summit has "Summit-brand" (made by TFS) aluminum heads with a heat crossover and the goofy angle on the center two intake bolts. I'm debating on trying them.
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Re: Valve / seat height concern

Post by Keith Morganstein »

Those are good heads and a good choice.

You purchased them from the wrong place, eBay.

Have someone reputable assemble a set from bare castings and you'll be happy.
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Re: Valve / seat height concern

Post by groberts101 »

I know ebay is full of blems and chinese crap and some sellers are less than reputable in the way they do business.. BUT.. the way it's set up is to protect the consumer. And when using paypal you also get another layer of protection. I never buy anything from there without it.

So having said that.. I would send another email to prove you're used due diligence on your part and then simultaneously file a complaint(don't wait for his email response he already blew you off once let ebay know ASAP he's stiffing you) and ask the seller assume return charges for selling parts that are defective and also not completely including what was listed(bolts) in the sale. If used for purchase, Paypal could help you out here as well.

The typical scenario is that the seller will offer a partial reimbursement. I have gotten to the point that I do not accept anything other than what I though I should be getting or leave feedback until the seller has made things right. And as a result I have gotten MANY partial refunds through the years, some as much as 50%! The seller rating is what most build their business on in that venue so USE IT to your advantage! That partial refund will help cover some but not all the cost for sending them out to a local machine shop to correct some of these issues. Which IMO are very minor considering as Walter already mentioned that you have an adjustable valvetrain. Not saying I would run them that way cause I'm picky as hell.. but .035" on a small lobe with 1.5 rockers ain't shit. Tons of junk running around with far worse than that if you catch my drift here.

The other bigger benefit is the ability for the machine shop to do a minor bowl hog cut to relieve the crappy lower cut that comes in many of the production type valvejobs these days. Sure you spend more cash.. but you also get a better cylinder head with slightly better flow out of the deal too. Cleaner ports make better power even onthe lo-po type stuff. Just a thought and good luck with it all.
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Re: Valve / seat height concern

Post by Frankshaft »

Like walter said, its not a big deal. Measure overall valve length. I bet they are slightly different lengths. The other thing, the margin thickness is different, which effects overall length as well, so, if an ex valve is slightly shorter, or even the same length, because of the margin thickness, it won't "stick out" as far on the spring side, from the pics, the ex valves have a thicker margin. The important thing, is all the seats are close to the same depth. I see this all the time. If you use a valve seat height gauge off of seat to deck, they are the same. So, because the valve lengths are slightly different, the combo of the thick margin, why would you sink the seats that much so the tips are the same heights? That's just being ocd for no reason. If its .035, its not a big deal. They also make pushrods different lengths for a reason. Now, if all the heights were all over the board, some low, some tall, etc, then I would fix it.

If you go sinking the ex seat to match the tip heights on the other side, now you just dug a big hole for the ex gasses to get thru, killing ex flow, then, you need to at least blend the top cut into chamber and around the valve. I see a big can of worms being opened up for someone, that isn't needed. It has an adjustable valve train, just get the appropriate pushrod length for the intake and exhaust. But, on the flip side, I would be pulling those apart anyhow, to make sure the valve seats are even runnable. My guess, is the intake seats will have reasonable runout, but I bet the ex seats are out to lunch. For some reason, the only head manufactures that can cut a concentric seat are the chinese #-o. As far as installed heights being off, they make valve spring shims for that.
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Re: Valve / seat height concern

Post by Frankshaft »

I just measured 2 ferrea 6000 series sbc .100 long valves. 2.055 intake, 5.010, 1.6 ex, 5 .010 long. Margin thickness, .060 intake, .090 ex. That would make the ex valves .030 lower on spring side. The set of heads I am doing, seat depths between 2 are different by .010. exhaust seats are cut .010 deeper. I stopped cutting when the seat/top cut came in how I wanted. These heads have .020 difference in installed heights. The intake springs got a .015 shim under the .060 id locator to achieve the desired 1.90 installed height. The ex with just the .060 id locator measure exactly 1.90. They are dead on within a thou.

Should I sink the ex seats .020 to match tip heights? Plow into the chamber and ruin that transition and then have to re port it all? Does that make me a hack? You need a .020 shorter ex pushrod. BFD. I am not recutting the ex seats for that difference and screwing up the chamber/seat transition.

Not to mention, .020 would be what, 2-3 valve job freshens? Needless, pointless and the wrong thing to do.
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Re: Valve / seat height concern

Post by Schurkey »

Just to be clear...based on seeing the intake valve deep into the chamber casting, I don't think the exhaust tips are too low, I think the intake tips are too high. The valve spring installed height is especially tall on the intakes, a little tall on the exhausts.

I dropped 'em off at FedEx early this morning. Based on the most-recent postings, maybe that was a mistake. It's done now. Not getting any communication from A&A was a big part of my decision to cut my losses.

I thought A&A Midwest were "the" folks for Enginequest castings.
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Re: Valve / seat height concern

Post by Frankshaft »

Schurkey wrote: Thu Mar 22, 2018 1:38 pm Just to be clear...based on seeing the intake valve deep into the chamber casting, I don't think the exhaust tips are too low, I think the intake tips are too high. The valve spring installed height is especially tall on the intakes, a little tall on the exhausts.

I dropped 'em off at FedEx early this morning. Based on the most-recent postings, maybe that was a mistake. It's done now. Not getting any communication from A&A was a big part of my decision to cut my losses.

I thought A&A Midwest were "the" folks for Enginequest castings.
Your right, it's a mute point now, as you sent them back. I was trying to point out though, even if the in and exhaust seats are cut the same depth, as measured from seat to deck, the above valves in my example, because of the margin thickness difference, it would appear that the intake valve is "sunk" compared to the exhaust. But they are the same depth. Its an optical illusion. And also, because of the margin thickness difference, the ex valves wouldn't"stick out as far on the spring side. Not a dig or criticism, but are you following what I am explaining?
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Re: Valve / seat height concern

Post by Keith Morganstein »

Schurkey wrote: Thu Mar 22, 2018 1:38 pm I thought A&A Midwest were "the" folks for Enginequest castings.
They are the importer/distributor of the castings. I didn’t know they offered complete assembled heads or who is assembling them.
I use the castings, but buy them bare and they need prep before assembly. Often the guides are too big (I.D) and I put liners in, then a valve job.
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Re: Valve / seat height concern

Post by pdq67 »

Who actually casts EQ heads?

And do they machine them for sale/resale in house or the raw castings sold to shops that machine them??

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