AFR Cylinder head issue???

Discussion in 'PSI Superchargers Tech Questions' started by MKR-588, Feb 8, 2020.

  1. MKR-588

    MKR-588 Member

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    Hi guys, recently changed a set of the 357cnc BBC heads due to a valve head dropping with a new set of there 385cnc heads. We also set back the 1471 blower an extra 2 1/2 inches to even up the nozzles. It is for boat racing similar to your K Boats.

    We did a few laps on testing and then did 1 meeting with 2 races. After the meet we pulled the engine for a check over and I noticed when removing the short head studs they came out bent. It looked like the nut spot facing wasn't parallel with the deck face on the head. A couple of the bolt holes in the head had also become elongated by the bent studs. All 4 outer holes were sunken down towards the outer side or the unsupported side. This was the same with the outer middle studs as well. The center holes seemed to be sunken in around .020" all around.

    I had to send the heads to AFR's warranty guy in Australia and after 2 months of calls with them and the AFR gurus they tell me it's not there problem, the head is trying to lift. I told them that we ran the 357 heads for 14 + years with no issue and after 1 meeting we end up with this issue with the new heads. We ran 7800 rpm, 33 lbs boost and 32-33 degrees timing with the 357 heads but only ran 7500 rpm, 26 lbs boost, 30 timing with the 385 heads. We were only creeping up on the tune and power with the new heads and blower setback.

    The heads were tested for hardness and the warranty guy tells AFR they are fine there fore we get nothing out of AFR. Has any one any idea what could be the issue and what could have caused this?
    I don't want the same thing happening with the repaired heads as it cost me just under a thousand to get stepped bushes fitted to all holes.
    Originally they asked me what torque I was giving the stud/ nuts. Cant see that being the issue as I would have thought the suds would strip before it would collapse the bolt boss on the head.

    Thanks for any help/advice
     
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  2. TOL

    TOL Active Member

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    You are using a hardened ground steel washer under the nuts, correct?

    What were your torques and torque sequences?

    Any signs of detonation and/or head gasket distress? Overheating signs?

    How was the performance when you did run the new heads? Did it seem normal, or as expected, or did it seem "Off" ?

    These new heads were truly new, and not used by someone else before?

    Myself I would be leaning toward soft heads and I would be having an independent firm testing them in various locations. To bend studs and elongate (I assume you mean ovalize) stud holes is really weird IMO.
     
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  3. jay70cuda

    jay70cuda Active Member

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    I've seen that with afr heads the head holes aren't exactly in the right place. I had my engine builder reface the holes and that helped but. It's some of the casting as well being soft.
     
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  4. MKR-588

    MKR-588 Member

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    Yes TOL, heads were brand new in sealed boxes from the distributor.
    Supplied hardened washers used with ARP 235-4703 stud kit torqued to 80lbs with Detroit diesel lube [ peanut butter] Torqued to around 35 lbs first from inside nuts to outside . Then in increments to final torque working from the outside to the center.
    Head gaskets [ copper SCE with O ring wire in block & receiver grooves in heads ] were sealing reasonable, they did have minor "choofing" towards the exhaust side and minor darker spots between some of the cylinders but you would expect something like that , if not more if the heads have the washers sinking into the castings and the studs bending but why??????????.
    Performance was pretty good as it was starting to get better each time we tested. We ended up qualifying in third position for the major race that weekend.
    We also had an issue with the oiling as we were loosing 2-3 liters of oil out the breathers each race but I think that is the issue with the synthetic Redline oil we were using.
    I dont think the owner ran the valvoline racing mineral long enough for ring bed in. That was the main reason of pulling the engine for a re ring / hone to stop the breathing issue.
    AFR couldn't give me any reason why but only said that its no problem of the heads but would not send them back for examination due to the cost in freight.
    They are willing to send the heads here to sell but there life time casting warranty is limited to suit themselves. Not happy and have been using them for the last 16 years. Time to change I thing with that sort of support.
    I think I will send them to get hardness tested to my local shop and see for myself.
     
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  5. TOL

    TOL Active Member

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    If it was me, I think I would challenge AFR a bit. They say "It's not our fault..........". You say "Then explain why or how this has happened with your product..........". Somewhere within that process there may be a glimmer of enlightenment for either side.

    Two more questions that I thought of, are both of your heads exhibiting the same problems to the same degree? Did you do any machining on them out of the box before install?
     
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    Last edited: Feb 11, 2020
  6. MKR-588

    MKR-588 Member

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    TOL, both heads are similar, and machining we did was a seat job as we replaced all the AFR valves, springs etc with quality stuff and the heads had a lite face as we had receiver grooves machined. They can't explain why but they are relying on there warranty guys in Australia to be there eyes. They won't send them back for warranty as it isn't worth the effort & costs according to them, but doesn't help me. It really pisses me off that they cant stand by there product and at least give the customer the benefit of the doubt, especially if they cant see an issue that i did to cause the problem. The more I think about it ,it seems as if it must have something to do with the material or heat treatment. How else can you sink the washers into the head by .020' - .030". If they say the head is lifting under the 26 lbs boost, how can the gasket etc still be in reasonable condition and do no other damage. these engines are definitely not that forgiving. Surely a pair of bare casting wouldn't send them broke. I feel like giving them another ring but don't know what else to say, not happy.
     
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