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Hello. I!m wondering if anyone has any experience with a cracked head on the 170 ohv 6 cyl.

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  • Engine: Hello. I!m wondering if anyone has any experience with a cracked head on the 170 ohv 6 cyl.

    I!ve got a 64 commander that used quite a bit of oil. THe oil pressure is quite high i thought 60 lbs plus at operating speed. So my mechanic and i decided to do a valve job on it. Well we discovered cracks in the head. Took it to the machine shop and they pressure tested it and said there were no leaks. The valve seals were bad.THe shop man said the guides were!nt bad. They did the valve job and surfaced the head. So we got it back together and it runs fine but stills smokes when its first started. My mechanic said the shop should have knurled the guides. Just wondering if anyone has run the 6 cyl with cracks in the head like i am. Can i expext the cracks to expand. And would a block and cyl head sealer work on the cracks.

  • #2
    Almost EVERYONE with a 170 ohv 6 will have experience with cracks in the head. They were famous for cracks, even back in the day. Cheaper and easier to swap in a 259 and kiss your troubles goodbye. More power AND better gas mileage. And way more fun to drive.
    Last edited by sals54; 06-15-2016, 03:34 PM.
    sals54

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    • #3
      Hi Jim and welcome to the Forum,
      For what its worth, here’s what I experienced on my engine.
      I completely rebuilt, my OHV 6 in 2010-2011 and my car runs regularly since 2012. I recently completed a +600 miles trip to the European Meeting without any problems.
      My head was pressure tested during the rebuilt and no leaks were signaled. New guides and seats were installed.
      Ever since, I noticed a lot of condensation coming out of the tailpipe, of course especially by cold or damp weather. This stops when the engine is fully warmed.
      So far, I have used two different block testers to see if there was a problem with the cylinder head. None of them indicated leaks and the coolant level is stable.
      So, I decided to use the car normally and stop worrying. As your symptoms look the same, I’d suggest you do the same too.
      I took a glance at the block sealers . If you want to use one, just make sure it is specifically designed for iron. If you do, I’d be glad to hear the results.
      Nice day to all.
      Last edited by christophe; 06-16-2016, 11:23 PM.
      sigpic

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      • #4
        Welcome Jim. OHV 6 heads had massive core shift making deck surface super thick and hard to cool evenly. they all seem to crack through the intake seat across to the plug hole. eventually you will burn a valve on the intake side. that puff of smoke on startup indicates worn guides,knurling will help but is a band aid and positive stem seals would go with that. you can drive that OHV 6 for a lot of miles or go the V8 route either way have fun driving it! Luck Doofus

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        • #5
          The old OHV6 in my truck has about 75,000 miles on it and ran fine, no evidence of coolant leaks, though it was not off to look for any cracking. The new one, which is modified with a 185 crank has about 8,000 miles on it. The head was checked and clear of cracks. Most of the really bad heads are gone, those that aren't cracked now are the better ones of them all and less likely to be a problem.
          Ron Dame
          '63 Champ

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          • #6
            I have seen a lot of heads with guides that were smooth, but real loose.
            Knurling is a cheap, short term, alternative.
            Installing a bronze liner and reaming to fit is better.
            Installing bronze guides is best.
            A sloppy guide will allow a lot of oil through and smoke (mostly in high vacuum situations).
            HTIH (Hope The Info Helps)

            Jeff


            Get your facts first, and then you can distort them as much as you please. Mark Twain



            Note: SDC# 070190 (and earlier...)

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            • #7
              I agree with Christophe . I just rebuilt my first OHV six and have driven it a few hundred miles and next week it will be driven to Warwick if I can find a parking space for a few days ? Anyway I find it fun to drive and plan on enjoying it and the Champ truck its in

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              • #8
                Originally posted by christophe View Post
                Hi Jim and welcome to the Forum,
                For what its worth, here’s what I experienced on my engine.
                I completely rebuilt, my OHV 6 in 2010-2011 and my car runs regularly since 2012. I recently completed a +600 miles trip to the European Meeting without any problems.
                My head was pressure tested during the rebuilt and no leaks were signaled. New guides and seats were installed.
                Ever since, I noticed a lot of condensation coming out of the tailpipe, of course especially by cold or damp weather. This stops when the engine is fully warmed.
                So far, I have used two different block testers to see if there was a problem with the cylinder head. None of them indicated leaks and the coolant level is stable.
                So, I decided to use the car normally and stop worrying. As your symptoms look the same, I’d suggest you do the same too.
                I took a glance at the block sealers . If you want to use one, just make sure it is specifically designed for iron. If you do, I’d be glad to hear the results.
                Nice day to all.
                Thanks everyone for the replies. Think I!ll just drive the car as is. Wife wonders what head is cracked? Mine or the cars. On another note, does anyone know of a different carb i could put on this motor? The stock one runs fine at higher rpm but at lower speeds stutters and chugs a bit

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                • #9
                  Hi If it is a RBS carb set the float height by measuring it at the knobs at the end of the float worked for me , ED

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                  • #10
                    I replaced my RBS with a AS from a '62. It was a huge improvement.
                    Ron Dame
                    '63 Champ

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                    • #11
                      The 32 RBS has a bad reputation but I managed to make mine working properly after performing all the requested adjustments noted in the shop manual. You should look if there is a shot of gasoline into the carb when you move the throttle. There is a very tiny passage in the jet and it could be clogged. If you need the technical data and the adjustement procedures, I can send them to you.
                      Nice day to all.
                      sigpic

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                      • #12

                        A little too much boost.

                        And we didn't just crack the head either:

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                        • #13
                          Ah, famous engines: The Chrysler "Firepower" Hemi, The Chebby "small block", The Ford SOHC "cammer", The Studebaker "crackhead 6".

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                          • #14
                            Originally posted by BobWaitz View Post

                            A little too much boost.

                            And we didn't just crack the head either:
                            Dang, Bob... just how much boost were you pushin through that little motor??? We got away with 14lbs, but just for a short time.
                            sals54

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                            • #15
                              Up to 17. Eventually we got an NOS block from SASCO and Greg had a steel head fabricated with a larger water jacket. That setup is now in his roadster running on LP.

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