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Thread: 6.2 Redblock Theory

  1. #21
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    Chainsaws are hoarded as well
    As a crossover tie in, i have a diesel powered chainsaw...
    And a few other rarities in the chainsaw world.
    Like i said "way out there"
    90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews

  2. #22
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    Quote Originally Posted by Yukon6.2 View Post
    I will watch to see what you end up doing
    I have 3 in my yard
    1 is ventelated
    2 is burnt
    3 is running in a 2wd rustbucket
    The burnt one still rolled over,had antifreeze in the block and is out of the weather
    I contacted a lab…
    https://www.metengr.com
    1. I need 1-5grams of 6.2 Redblock Drill Shavings.

    2. Grind the block surface clean to bare block material.

    3. Use clean/new drill bit and get 1-5 grams, 5 grams preferred.

    4. Place the shavings in a sanitized container.

    5. Post pictures of motor, date code and sample location.

    6. Ship the sample to my home and I will reimburse you for time, materials and shipping.

    How soon can you giterdun?

  3. #23
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    Once you get the test results....please post the data....This will be very interesting stuff.....
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2007 Chevy Avalanche
    THIS IS BOW TIE COUNTRY

  4. #24
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    Yukon6.2 NVM on the samples. I just found a crack free 1981 660 cast Redblock.


    Quote Originally Posted by Robyn View Post
    Once you get the test results....please post the data....This will be very interesting stuff.....
    For you Robyn, Anything ;-)

    The lab is going to charge me $300 per test. I am going to test 3 motors.

    1. 1981 6.2 Redblock
    2. 1985 6.2 Block
    3. 2003 6.5 NAVSTAR Optimizer Block.

    All data will be posted on every Diesel Forum.

  5. #25
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    Montana
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    Some random thoughts came to mind..

    So it was not mainly the heat that cracks the heads of the redblock but lack of material from the bigger exhaust valves.

    So with brass tubing between the valves, that pretty much solves the cracked head problem yeah?

    And with bigger exhaust valves, that would be a better candidate for a turbo because it dissipates the heat and exhaust better and faster yeah?

    And I read that the 6.2 Redblock heads came with an extra coolant passage that caused premature head gasket failure. There was a recall I read that GM fixed this issue by putting a freeze Plug type cap on that extra passage to fix the problem. Anyone know more info or got pics of this?

    So new Theory…

    Bigger exhaust valves=Faster spooling, more boost, less heat, lower egts and more efficiency? Sound correct?

    So in theory, the redblock heads should be lock n stitched and taken to a machine shop, cleaned, cap off the extra coolant port per Gm recall, shaved and valve job done and would be considered the best 6.2 heads yeah?

    Or drop the cash for new smaller valve heads?
    Last edited by 2INSANE; 05-24-2022 at 18:56.

  6. #26
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    The heads on the early 6.2 did have issues.....

    Best choice for heads......Get a set of the AMG 6.5 heads.

    Better castings, ZERO duty cycles.....A proven winner

    The brass sleeves between the valves was a BANDAID....The castings are still cracked and will eventually erode and fail...

    IMHO....Why spend a dime on old cracked junk.....

    ONE EXCEPTION

    A classic car with an all stock engine, matching numbers...A rig that is a show car and must pass inspection to place in the show......NOT DRIVEN MUCH.

    Your 6.2 project will likely be used a lot.
    Why start with broken junk and try to patch it up.

    The AMG heads are the best iron available......Best design of precups....
    Just be sure you get "Pickup heads" The HMMWV/VAN heads have the 60 degree intake manifold bolt angle.....

    Back in the early days when we were all trying to keep our 6.2/6.5 on the road the game was much different...We did not have a good source of available parts other than Ma General....$$$$$$$$$$$$$$$$$$$$$$$$$$

    40 years on the Red engines now.....

    Just my thoughts..
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2007 Chevy Avalanche
    THIS IS BOW TIE COUNTRY

  7. #27
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    Another thing to consider is the Red Heads are limited to what you can do to the injectors.
    there never was a different option to the ones that were designed for the red heads originally.
    For all other heads the 6.5 injector will fit.
    Plus the red heads may not have all the bolt holes required to bolt on the serpentine system.That happened on my Burb engin.
    The heads that came off the donor were missing a bolt hole which i did not notice till i was installing the alternator/air pump mount.At that point i was not going backwards so i just went with one bolt not installed.
    90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews

  8. #28
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    Montana
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    Quote Originally Posted by Robyn View Post
    The heads on the early 6.2 did have issues.....

    Best choice for heads......Get a set of the AMG 6.5 heads.

    Better castings, ZERO duty cycles.....A proven winner

    The brass sleeves between the valves was a BANDAID....The castings are still cracked and will eventually erode and fail...

    IMHO....Why spend a dime on old cracked junk.....

    ONE EXCEPTION

    A classic car with an all stock engine, matching numbers...A rig that is a show car and must pass inspection to place in the show......NOT DRIVEN MUCH.

    Your 6.2 project will likely be used a lot.
    Why start with broken junk and try to patch it up.

    The AMG heads are the best iron available......Best design of precups....
    Just be sure you get "Pickup heads" The HMMWV/VAN heads have the 60 degree intake manifold bolt angle.....

    Back in the early days when we were all trying to keep our 6.2/6.5 on the road the game was much different...We did not have a good source of available parts other than Ma General....$$$$$$$$$$$$$$$$$$$$$$$$$$

    40 years on the Red engines now.....

    Just my thoughts..


    Quote Originally Posted by Yukon6.2 View Post
    Another thing to consider is the Red Heads are limited to what you can do to the injectors.
    there never was a different option to the ones that were designed for the red heads originally.
    For all other heads the 6.5 injector will fit.
    Plus the red heads may not have all the bolt holes required to bolt on the serpentine system.That happened on my Burb engin.
    The heads that came off the donor were missing a bolt hole which i did not notice till i was installing the alternator/air pump mount.At that point i was not going backwards so i just went with one bolt not installed.
    Awesome info! AMG heads it will be!

    So the Redblock I though I found that was crack free has some bad pitting in the cylinders even after it had been honed. Greg the Machinist said to check for one locally to reduce costs. I’ll post some ads. I’m back to searching for another one.

  9. #29
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    Jim, you know of any hoarders here in Montana?

  10. #30
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    No consideration for sleeves? (not that I would, just tossing it out there)
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  11. #31
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    Quote Originally Posted by DmaxMaverick View Post
    No consideration for sleeves? (not that I would, just tossing it out there)
    Idk. I have never researched sleeving a 6.2 before.

  12. #32
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    It seems nothing else is off the table. It's been done, and I know of a few locally. If the block is sound otherwise, why not?
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  13. #33
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    Quote Originally Posted by DmaxMaverick View Post
    It seems nothing else is off the table. It's been done, and I know of a few locally. If the block is sound otherwise, why not?
    Definitely an option worth considering! But first need to find a Redblock to get the chemical testing done or else this theory will remain a theory…

    Yukon6.2 are you willing to donate 5 grams of Redblock material for this cause? Would even pay you for your time and postage!

  14. #34
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    Pull your sample from the red block you have. The bell housing boss is a benign area between the bolt holes. A few 1/4" divots won't weaken the block. Be sure to use a clean, new, dry bit for each block (no lube or coolant), careful to not cross-contaminate the samples. Drill slowly over a magnet to capture the chips. Too fast and the chips will fly away. Invert a sandwich bag over the magnet so you can get away clean. Start the drilling with a larger bit to "clean" the sample area (just enough to break the surface), then drill/collect the sample from within that divot. That will isolate your sample from any surface contamination and paint. Don't use a center-punch, grinder, or metal brush. The metallurgic differences may be only a fraction of a %, so any of the above may skew the result.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  15. #35
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    Quote Originally Posted by DmaxMaverick View Post
    Pull your sample from the red block you have. The bell housing boss is a benign area between the bolt holes. A few 1/4" divots won't weaken the block. Be sure to use a clean, new, dry bit for each block (no lube or coolant), careful to not cross-contaminate the samples. Drill slowly over a magnet to capture the chips. Too fast and the chips will fly away. Invert a sandwich bag over the magnet so you can get away clean. Start the drilling with a larger bit to "clean" the sample area (just enough to break the surface), then drill/collect the sample from within that divot. That will isolate your sample from any surface contamination and paint. Don't use a center-punch, grinder, or metal brush. The metallurgic differences may be only a fraction of a %, so any of the above may skew the result.
    I do not have a red block to get a sample! Lol! Thought I explained that. Or you talking to Yukon6.2?

  16. #36
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    Quote Originally Posted by 2INSANE View Post
    I do not have a red block to get a sample! Lol! Thought I explained that. Or you talking to Yukon6.2?
    Thought you said you had one, but the bores were pitted. Even with pits, they may not be too deep to bore. If they are too deep, sleeves are next. At any rate, the procedure should apply to anyone pulling a sample from the blocks.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  17. #37
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    Quote Originally Posted by DmaxMaverick View Post
    Thought you said you had one, but the bores were pitted. Even with pits, they may not be too deep to bore. If they are too deep, sleeves are next. At any rate, the procedure should apply to anyone pulling a sample from the blocks.
    Wish I had a good one for sure! lol

  18. #38
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    I found another potential redblock 6.2 in Idaho. I plan on making the 6hr round trip drive either today or tomorrow. It was taken out fresh 2 months ago and all ports have been kept closed. PO said they pulled it because they think the injection pump is bad.

  19. #39
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    Good luck in the quest for a good one
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2007 Chevy Avalanche
    THIS IS BOW TIE COUNTRY

  20. #40
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    Quote Originally Posted by Robyn View Post
    Good luck in the quest for a good one
    Thanks! I am more excited about finally getting to do some chemical testing!

    When I inspect the Redblock, I will see if the crank turns, remove oil pan and check for cracks in the mains Pre purchase.

    Photo bucket is getting expensive so does anyone know of any good way I can share pictures free?

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