95 Burb 5.7 TBI rattle when warm under load at specific rpm

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Gramps

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So my mechanic said it was $1100 for labor to swap heads. I'm going to do it myself. I want to learn how.
I started to order a set of heads for $585, but he had a set of GM performance TBI heads with aluminum valve covers complete that he said he'd sell me for $500.
I'm ordering this plus exhaust gaskets and new exhaust manifold bolts(currently have one busted in the old heads). I'm trying to fix this right and so it'll last. Do my parts look ok? I'm going to have some help adjusting the valves. I figure since I have to take the heads off I might as well fix the minor exhaust leak. The burnt or dead valve is on the opposite side of the motor as my exhaust leak.
What other parts do I need? Oh and my hot water heater in my house busted today. Pretty expensive day!
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Is this a budget cruncher or have you got dough to blow?
I’d skip those aluminum heads....I may be wrong but there’s not much for “performance” tbi heads out there let alone aluminum ones. I’d guess he’s either got tpi or lt1 heads. Either way they won’t work or won’t work without modifications to your intake so better triple check before forking over money. No need to over complicate this, and it seems shurkey beat me to the punch in the parts list.
 

Erik the Awful

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If you want minimum down time and good reliability on a budget, get a TBI head from the junkyard. Before you buy it, inspect it carefully for cracks between the valve seats, and between the valve seats and spark plug boss. When you get it home, clean it thoroughly and inspect it again. Check the deck surface for flatness, and check to see if any of the valves have side-to-side slop - this will determine if it needs any machine work. Take the valves out, clean them carefully on a wire wheel - grab 'em tight because the wire wheel will try and rip them out of your hand, eat 'em, and bend 'em. Lap the newly cleaned valves to their seats. Clean the head again. Install the valves with new valve seals and springs. Boom! You're ready to swap the head on at your convenience.
 

PlayingWithTBI

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And when it comes to flat washers--like those included with the ARP head bolts, you'd lube the underside of the bolt head where they touch the washers, but NO lube applied to the WASHERS. Lubing the underside of the washer leads to over-torquing and fastener failure. Remember to adjust the torque specs based on the lube on the threads and under-side of the bolt head. The more-slippery the lube, the lower the torque used.
A lot of great info here! One thing I would add is, get a set of thread chasers and use them on any application where you need to torque the bolts, especially head bolts which all (IIRC) go into the water jacket. You may be able to get away with a set of taps but, you're running the risk of wiping the threads out and losing proper torque.

You can save a couple bucks with these head bolts if you insist. I did since I went to aluminum heads - just because :biggrin:

www.summitracing.com/parts/sum-910200
 

moondog1

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1. Your parts list is...interesting. Ten dollars each for two tubes of ARP sealer? You will not be able to use one entire tube on a two-cylinder-head replacement job. IF (big IF) your existing head bolts are in good condition--not stretched or corroded, for example--REUSE THEM, using that ARP sealer on the threads and some oil or other lube under the heads. Save a hundred dollars. GM head bolts are fine-quality items. Your choice of head gaskets is not optimum. Bore size larger than it has to be, no telling what the thickness is, 'cause it's not listed. Your stock engine has the pistons "in the hole" about .025 already, maybe more. (You should verify.) Mine were about .028. Ideally, a .015 head gasket (thin steel shim gasket) would give you near-perfect quench/squish IF (big IF) the block doesn't need to be decked. If it turns out you need to deck the block, the very thin head gaskets won't work. About the best you can hope for is
as long as the gasket clears the combustion chamber--I'm sure it will. These steel-shim gaskets have a rubbery coating on them, no sealer needed.
Add a container of anti-seize. ANY brand, ANY kind is better than "none". I'm currently favoring Loctite/Permatex "Copper", but I've used 'em all over the previous decades. They all work.

I would also add a tube of engine assembly lube. Every automotive company on Earth sells their brand of assembly lube. Lubriplate "105 Motor Assembly Grease" is the industry standard. I have a mostly-used-up tube of that in my shop right now.
However, I also bought a tube of Sta-Lube Moly-fortified engine assembly lube, which I'll begin using when my 105 runs out. And there are liquid assembly lubes, too--but I prefer a grease so it stays where I put it.
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You'd put a dab of assembly lube on each end of the pushrods, on the rocker-arm pivot balls, on each valve tip where it touches the rocker arm--anywhere there's moving parts making contact that you've disturbed in the process of replacing cylinder heads.

Any fastener that doesn't get oil or moly-based thread lube, or threadlocker, or sealer, gets anti-seize. NO FASTENER gets assembled "dry". And when it comes to flat washers--like those included with the ARP head bolts, you'd lube the underside of the bolt head where they touch the washers, but NO lube applied to the WASHERS. Lubing the underside of the washer leads to over-torquing and fastener failure. Remember to adjust the torque specs based on the lube on the threads and under-side of the bolt head. The more-slippery the lube, the lower the torque used.
I can't think of anything this job requires that needs threadlocker. You'll probably want a gasket dressing although it's not absolutely essential. My favorite is Gasgacinch; but there's thirty brands and types, and they all work just fine except one. DO NOT use RTV Silicone spread onto a gasket to "seal" it. RTV Silicone is for use ONLY where you aren't using a gasket at all--the cured silicone IS the gasket; or when there's a seam between two gaskets, or between a gasket and a seal. Then a "dot" of RTV Silicone is used only at the seam. For the record, Fel-Pro is likely to include some silicone sealer with the gasket set, if needed. And Permatex "The Right Stuff" is the best silicone-type sealer I've ever used. I'm not sure it's actually silicone. I've heard it's Polyurethane but never been able to confirm.

2. $200 is not going to get you headers that will make any difference. Might as well use the stock manifolds IF (big IF) they don't have (obvious or hidden) cracks, and they're not so distorted you can't get them bolted-up again. They actually make manifold spreader tools that you wedge into place, so when the manifold bolts come out of the head, the manifold doesn't warp. And the manifolds will likely need to be planed flat again, too. If the manifolds are smooth and flat, and the exhaust manifold surface of the head is smooth and flat--DON'T USE GASKETS. Bolt the manifold DIRECTLY to the head. Improves heat transfer, manifold runs a little bit cooler. When it was me, I bought shorty headers that connect to the stock exhaust--but that was more than twenty years ago, and they were WAY more than $200 even then. And--truth to be told--they didn't make much difference.

3. Might as well budget for new rocker arms. The ones you have are probably worn-out by now. You can play games with more rocker ratio, with roller tips, and full-roller rockers, but none of that is genuinely needed. The existing rocker arms are "guided" or "self-aligning". Make sure the replacements are, too. Possible you could get by with the existing pushrods, but inspect them carefully for wear and for straightness.
If your new "Performance" heads have steel pushrod guideplates, you MUST buy hardened pushrods, the stock pushrods will be eaten alive, and you MUST NOT use self-aligning rocker arms.

4. Do these "performance" heads have the correct intake manifold bolt angles? The center two on each head need to be at a steeper angle than the front and rear pairs.

5. CONFIRM that the valves on these "performance" heads actually seal. There's various hobby-style solutions that generally involve some sort of solvent poured on one side of the valve, and then you look for solvent traces on the other side. An actual machine shop is likely vacuum-testing the valve seal. A vacuum machine is attached to each intake and exhaust port in turn, and the gauge on the vacuum tester shows how close to "perfect" vacuum the machine can generate. There's always some minor leakage past the valve guide, so you'll never see 100% sealing. But 70 percent and better should be fine.
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Vacuum tester connected to Lumina 3.4L DOHC cylinder head exhaust port, showing 87% perfect vacuum.

The VALVE can be worn-out, burnt, pitted on the valve face, or taper wear on the valve stem, or both. The valve SEAT can be burnt/pitted/eroded, and the valve GUIDE can be worn out. Any one--but it's usually a combination--can lead to poor valve seal. Slapping new valves into worn seats and guides is a short-term "fix".

6. When the intake and heads are off the short-block, pull ONE LIFTER AT A TIME to check for lifter bottom wear. The bottom of "flat tappet" lifters like TBI engines use, is very slightly crowned, like the outside of a contact lens. It should rock slightly on a piece of glass, or a truly flat benchtop (glass preferred.) If the lifter has "indented" wear, like the eyeball side of a contact lens, IT'S JUNK, and SO IS THE CAMSHAFT.

7. Before I pulled the intake manifold off, I'd pop the distributor cap so I could watch the rotor. Turn the crank to TDC in the normal direction of rotation. Then turn it BACKWARDS, as slowly and steadily as you can, while watching the rotor. You'll turn the crank a degree or two before the rotor moves. The instant the rotor turns, stop moving the crankshaft, look on the timing indicator for how many degrees it's turned. 5 degrees or less is good, 10 degrees or more means the timing chain/gears; or the distributor gear is wiped-out. When the distributor comes out, look at the gear--if it's worn excessively (not just "polished"), you need a new one, and if it isn't, you need a new timing set. Between 5 and 10 degrees is kind of a grey area...you "probably" need a new timing set. If you need a timing set, be sure to "degree" the camshaft.

8. As an newbie to engine work, confirm EVERYTHING you do with the Genuine GM service manual; but adjust torque specs as needed based on your choice of thread lubes compared to what GM suggests.
I didn't get a notification for this. Thank you. I'm reading through it now. I really appreciate your time!
 

moondog1

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Update! We are back up and running! Lots of new parts! So I put the aluminum heads on, which do not fit the TBI intake correctly. The center 4 bolts that connect the TBI intake to the heads are different on the aluminum heads, it's the angle. Had to machine the holes to a different angle and finally got it to work.

Also, turns out, I didn't burn up a valve. The head gasket let go between cylinders 4 and 6. So got lead down several wrong roads and but we're up and running. I seemed to have picked up 1 mpg. I got 12.1 on my last half tank test. Such an efficient vehicle lol.

The 4 intake bolts that didn't angle up right with the new head, power steering pully, and after my manifold spreader broke getting the passenger manifold back on, those were the 3 hardest parts about changing heads.
 

moondog1

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Good to hear you got it fixed. :waytogo: Which aluminum heads did you get? The 162108 ones from Summit Racing I got fit perfectly.
I bought them used for $500 from the mechanic who said I had a burned up valve. It was just a head gasket let go between cylinders 4 and 6. He assured me they would fit exactly, turns out they did not! But he's a nice guy. Also had to leave one bolt out of the compressor mount on the front because the bolt pattern was different.
I believe what he said they are GM performance 604 heads, but what I google comes up a little bit different looking. I have no idea. I'm happy it's back together.
 

Schurkey

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he had a set of GM performance TBI heads with aluminum valve covers complete that he said he'd sell me for $500.
These are iron heads, with aluminum valve covers...right?
4. Do these "performance" heads have the correct intake manifold bolt angles? The center two on each head need to be at a steeper angle than the front and rear pairs.
You were warned.
I put the aluminum heads on, which do not fit the TBI intake correctly. The center 4 bolts that connect the TBI intake to the heads are different on the aluminum heads, it's the angle. Had to machine the holes to a different angle and finally got it to work.
Aluminum heads? Not iron?
Also, turns out, I didn't burn up a valve. The head gasket let go between cylinders 4 and 6.

I bought them used for $500 from the mechanic who said I had a burned up valve. It was just a head gasket let go between cylinders 4 and 6. He assured me they would fit exactly, turns out they did not!
You need a different "mechanic". Did he refund your diagnosis money due to his botched diagnosis? Did he adjust the price of the heads based on needing to rework the manifold?

Also had to leave one bolt out of the compressor mount on the front because the bolt pattern was different.
That surprises me. WHICH "bolt pattern" are you talking about--the one on the head, or on the compressor mount?

I believe what he said they are GM performance 604 heads, but what I google comes up a little bit different looking. I have no idea. I'm happy it's back together.
Photos (in-focus, nicely-cropped) of the heads you bought?
 
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moondog1

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These are iron heads, with aluminum valve covers...right?

You were warned.

Aluminum heads? Not iron?
They are Aluminum heads, definitely not iron.
You need a different "mechanic". Did he refund your diagnosis money due to his botched diagnosis? Did he adjust the price of the heads based on needing to rework the manifold?
Nope, but I'm not going back. He said I through him off the trail by telling him everything I had replaced and done so far. lol. Whatever, I have a one year old and a 50-60 hour week job. If I had more time I'd go back there, but small town, word gets around, so it'll work out.
That surprises me. WHICH "bolt pattern" are you talking about--the one on the head, or on the compressor mount?


Photos (in-focus, nicely-cropped) of the heads you bought?
I'll see if I have some photo's of the heads I bought. They are missing one bolt hole for the compressor mount, that bolts on to the head with two bolts. I only have one in there right now.
4. Do these "performance" heads have the correct intake manifold bolt angles? The center two on each head need to be at a steeper angle than the front and rear pairs.
You were warned.

You're dang right I was and I appreciate it. This whole thing was such a learning curve. I appreciate all of y'alls help.
Sorry I've quoted these post strangely.
 
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