vortec heads

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tayto

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I have seen some weird stuff in 87 as well. The 87 G20 I have was a very early build. The stock TBI 305 had 187 heads with the port walls milled between intake ports like the 4.3 heads with stainless steel clips pressed over them. Some of those clips had actually broken and the ends were missing on them, I am assuming the engine injested them although it ran fine.

I also discovered despite having a catalytic converter, it was an open loop TBI system with no provision for an 02 sensor and no EGR valve. The intake manifold was cast shut where the EGR went. It also had an OE roller cam and torx bit valve cover bolts.

That being said almost every TBI engine I have been into had self-aligning factory rocker arms.

My parents 1980 C10s 305 had the lifter bore machining messed up from the factory. Several of the lifter bores were factory sleeved. When that engine got up over 100K the sleeves pushed out and the oil pressure dropped. Our mechanic at the time, shoved them back into place and tack welded them to the block. That repair worked a good number of years until dad had a low mileage 350 swapped into the truck.
ya very weird. I tried looking up pictures of the weird lifter bore but i think i lost them.i did find my engine all torn apart at the machine shop which would have been the same day. we removed oil pan and rigged up a hose to a junk pickup tube ran to 5 gal pale with oil in it. then primed the engine and saw right away that the valley was filling up with oil.
 

L31MaxExpress

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This is one of the oddball 187s. Found one for sale on Ebay a while back since nobody believed they existed. The center port divider starts well behind the intake face. The clips were a nice idea but must not have worked out or been a failure point given the unmolested 87 305 ate parts of them at some point. The gasket went on the head and the clips went over the top, holding the gaskets in place.

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Schurkey

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ended up tearing the block down and found it had this REALLY weird counter bore machined into the lifter bores. worked fine on flat tappet but for roller lifters the oil band would go into this counter bore and bleed off the oil pressure into the lifter valley.
You're the second person I've known that had the counterbored lifter bores. His is the same story--put an engine together for his own use, no oil pressure, discovers the lifter bores have been vandalized apparently by GM, so that they hemorage oil when used with roller lifters.

This guy runs his own machine shop in Maryland; well-known on various forums including Speedtalk. A top-flight guy in all respects.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

www.enginerepairshop.com

My own favorite machinist claims he's never seen this. I hope he's looking for it now...
 

tayto

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You're the second person I've known that had the counterbored lifter bores. His is the same story--put an engine together for his own use, no oil pressure, discovers the lifter bores have been vandalized apparently by GM, so that they hemorage oil when used with roller lifters.

This guy runs his own machine shop in Maryland; well-known on various forums including Speedtalk. A top-flight guy in all respects.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

www.enginerepairshop.com

My own favorite machinist claims he's never seen this. I hope he's looking for it now...
IIRC I found some obscure post on hotrodders.com forum. this was after hours of searching. my engine builder called his old boss from 20+ years ago, who was retired and asked him about the lumina lifters and apparently he found paper work from GM detailing what the fix was, though i never saw the paper work. this was well after the engine was removed, disassembled and a new block machined. had it been a more known repair, I would have just thrown the Lumina lifters in and carried on. i suspect this was a rare, 1 year only thing.
 

L31MaxExpress

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IIRC I found some obscure post on hotrodders.com forum. this was after hours of searching. my engine builder called his old boss from 20+ years ago, who was retired and asked him about the lumina lifters and apparently he found paper work from GM detailing what the fix was, though i never saw the paper work. this was well after the engine was removed, disassembled and a new block machined. had it been a more known repair, I would have just thrown the Lumina lifters in and carried on. i suspect this was a rare, 1 year only thing.

That is kind of how I suspect the intake gasket clips are as well. I have never seen reference to them in parts diagrams, although they are referenced in the intake R&R procedure without illustration. I pulled the factory intake off, one popped off into the lifter valley and I was like, what the heck are these. I have heard of using the 3.1L lifters in some roller cam SBCs before. In fact I have heard some early Vettes and F-cars used them from the factory, but no proof there.
 

Pro439

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Here in Central NY it is very common for exhaust manifold bolts to break off and not just Chevys they break off on everything. I’m sure it has to do with the crap they put on the roads in the winter and the temperature swings. And I have been outta the loop on the self aligning rockers I had no idea they started them then as that’s kinda when I went a different direction. I do know you can put inserts in the lifter bores as I have done race engines but I don’t remember if I’ve ever came across a block with them like that it almost seems as if I have and that’s what we did with it. The rust and the way things rust here is just unbelievable. I just bought a truck from Jersey and it is rusty but if it were here it would have been long gone. Trying to figure out what works best to prevent rust is something entirely different and it’s pretty obvious that nobody wants to do anything about it as no one has developed and released a product yet or it’s being suppressed. I do remember my fathers truck having a 350 that smoked and that didn’t have self aligning rockers just the regular old style. It had a mark an inch long in #1 cylinder from the factory 150,000 miles later it broke a short head bolt and broke exhaust manifold bolts taking it apart. Even with copper neverseize they still barely want to come out if you have to go back into it and forget the silver. L31 I can see you have stayed into these. I’m just getting back into them and learn something new every time we get talking about them and all the stuff gm has done. I think of that single chain as what they ran in the old days when they would stretch so bad they would jump teeth that’s why I wouldn’t use 1. I don’t have any interest in going through that catastrophe again
 
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