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Author Topic: Planning on HG replacement, need advice...  (Read 95 times)
bronz truck
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« on: July 11, 2017, 01:24:59 AM »

I am planning on a HG replacement - I need some advice...

My engine was overhauled by someone else.  It only lasted ~25K, then it blew the HG again. My assumptions are that something was done wrong...

I was beginning the process to purchas parts.  MLS HG, obviously.  But how do I know the needed HG thickness?

The pistons were purchased on them being 8:1 (~stock compression), the block was "used" (mine was cracked), new-old block was surfaced just to make it had the required RA finish needed for the MLS HG (I used another already purchased HG at that time), the new-old block was already 20-over and required boring to 30-over (no other blocks were available), and the head has been resurfaced twice.  It has ARP head bolts.  This is what I paid for.  Assuming I got what I paid for.  What HG thickness should I get (and 95mm is OEM, correct), I am aiming for more or less stock compression.  My boost is ~7 PSI (Stock)...

How do I know the pistons were made correctly?
How do I measure the block deck height in the truck with common tools?

Thoughts (I am not a mechinest or mechanic - keep it simple.  The block is in the truck)...
« Last Edit: July 11, 2017, 01:33:25 AM by bronz truck » Logged

1987 Extra Cab, 4x4,  SR-5, 22RTE; ~10K miles on second rebuild, ARP studs, LCE Head - DOA parts, 30-over and ~8.0:1 CR - custom pistons. TEC Turbo. 9-10 PSI. 2.5in Exhaust. A Duel purpose Vehicle - My main HAM Vehicle - 14 Antenna's...
ReelDeal
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« Reply #1 on: July 11, 2017, 05:36:54 AM »

Bronz, I am not an expert by any means, but I build a few engines and know some really good people. First, a couple of clarifications, 95mm (3.740") is the bore diameter, not the HG thickness and the stock compression is 7.5:1. I also assume that when you stated ARP head bolts that you meant ARP head studs. Did you every take a compression reading when your engine was running? Most importantly, BUY A NEW CYLINDER HEAD! If you have the stock 22RTE dished pistons, but a 22RE head. That will give you a CR of 8-8.5:1. I wouldn't bother with a MLS Hg if it were mine. The RA is just too critical. I would use an OEM HG, or better yet, find a complete Corteco set on eBay. Don't worry about the deck height with a new head.

Ok, you are probably wondering how to tell what pistons you have. The only true way is to pull the oil pan, pop out a piston  and have a machine shop cc it. The dish should measure 22cc's for a stock 22RTE piston. Then again, If I were going to that much effort, I would pull all of the pistons, hone the cylinders, install new bearings and rings and re-install everything in situ. That is an extra days labor and probably another $200, but you would have a fresh motor. The whole job done correctly can be done for under $1,000.

T
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bronz truck
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« Reply #2 on: July 11, 2017, 04:27:59 PM »

I appreciate your input.

However if my bill estimate comes to $1K the truck is totaled.

I knew the bore diam was 95 not the HG its thickness.

From the factory manual the compression is 7.95.  IE 8.0.  I know its highly disputed.

Yes, ARP Studs.

The head was meant for a 22RTE.

Being that it was not pinging before, I assume the CR is OK.  What I don't know is, how thick of a HG, I needed.  I was hoping for something I COULD do.  I have the time because I just lost my job. So I have more free time.  So my budget is limited.

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1987 Extra Cab, 4x4,  SR-5, 22RTE; ~10K miles on second rebuild, ARP studs, LCE Head - DOA parts, 30-over and ~8.0:1 CR - custom pistons. TEC Turbo. 9-10 PSI. 2.5in Exhaust. A Duel purpose Vehicle - My main HAM Vehicle - 14 Antenna's...
ReelDeal
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« Reply #3 on: July 11, 2017, 05:36:50 PM »

Sorry about the job. Have you had the current head checked at a machine shop, valves etc.? The factory does not recommend surfacing the head and yours has been surfaced twice. It is not wise to use it again as it is probably warped anyway. If by chance it is usable, then have them measure the thickness to find out how much material has been removed compared to a stock head and use a shim or extra thick gasket. I will measure a stock gasket later today and post the dimension. It this is the path you choose, then be prepared to do the job again sooner than you would like. Again, I would use an OEM gasket if I were you.

Good luck,
T

ok, I measured a stock HG @ about 1 1/2 mm or 1/16". I am guessing that you will needs at least an .080" (2mm) thick HG.
« Last Edit: July 11, 2017, 08:24:15 PM by ReelDeal » Logged
jrunner
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« Reply #4 on: August 01, 2017, 04:07:38 AM »

Hello guys I too use to blow head gaskets 5-8000 miles. Then I bought one of those new heads from Mexico or China and used a cometic gasket couldn't tell you what thickness but also have the arp studs and am going on over 40,000 Miles on last rebuild. I did buy used heads a couple times before and had them rebuilt always with the same results blown.
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bronz truck
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« Reply #5 on: August 11, 2017, 06:49:52 PM »

An update...

The head is off any being worked on.  
The good news:  Its straight.  And still thick.
The bad news:
The valve job done was done poorly, ~25K miles ago.  
--  The guilds are iron.  They weren't done exactly correctly.  The valves were not put in square (straight), and the valves weren't lapped, so the exhaust valves weren't sealing 100%.  Requiring new valve job.
--  Some how the steam ports were made bigger that normal.  This is impinged into the sealing area near the fire ring*.  I will be using a Cometic, this should elevate this problem.
The HG was leaking in several areas slightly, this led to the head being pitting in those areas.  This, requiring minor surfacing.

More to come as its known...

* I'll place the new HG down on top of the head to see how close the steam port really are.
« Last Edit: August 18, 2017, 12:05:57 AM by bronz truck » Logged

1987 Extra Cab, 4x4,  SR-5, 22RTE; ~10K miles on second rebuild, ARP studs, LCE Head - DOA parts, 30-over and ~8.0:1 CR - custom pistons. TEC Turbo. 9-10 PSI. 2.5in Exhaust. A Duel purpose Vehicle - My main HAM Vehicle - 14 Antenna's...
ReelDeal
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« Reply #6 on: August 13, 2017, 05:14:13 PM »

Bronz, relatively good news. Everything can be fixed. I still think it is a mistake to go with the MLS HG though.

Good luck and keep us posted.

T
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