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Thread: VN headed 355 blown head gasket - why?!

  1. #1
    Registered User 355LX's Avatar
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    VN headed 355 blown head gasket - why?!

    Hi guys,

    Epic (but boring) story ahead!

    Wondering if anyone has alot of experience with blown head gaskets on holden based V8's.

    Quick details:
    cast VN heads
    Crankshaft rebuilders crank
    Scat H beams
    SRP forgies
    solid roller - cannot find cam card!!
    10.5-1 comp
    VS factory clearanced block with 4 stud conversion and ARP head stud conversion
    Torque Power shigh rise dual plane with holley 750 ultra HP
    12-13 degrees intial and about 32 all up at about 3500 (IIRC)

    makes 400hp at the wheels starts to fall over at about 6800.

    Was at the track yesterday and popped head gasket at number 1 into the valley. It always seems to pump the water out into the expansion tank (20PSI cap) but doesnt recover all of it and regularly spews it into the engine bay. It holds at about 85 - 90C while on the track, but when I come in to the pits can creep up to 100 and eventually comes back to about 80. Normal driving/cruising see's about 80C.

    The head gasket is a Felpro, and it seemed to be soaked in coolant. Head stud nuts were all tight when I was undoing them. There was moisture creeping up the longer three closest to the valley. I was told you are not supposed to use the holden sealant on ARP head studs(?).

    Pics








    Any suggestions regarding head gasket selection, use of Hylomar or anything else? The car does the odd bit of circuit work, but has been primarily built for tarmac rallies.
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  2. #2
    Loving teh titties.. carcrazy's Avatar
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    Running too lean? Detonation? Bad fuel? Heads warped?
    Quote Originally Posted by Einstein
    The definition of insanity is repeating the same action and expecting a different result

  3. #3
    sack riding 10sec rx7's Avatar
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    You can still use head stud sealer no problems at all,

    From a lot of the efi 5L I do 25-27 deg timing makes the most power, you might be a little over advanced,
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    i regularly see them take 32 with no dramas. definetly put some gm sealer on the studs and get some cometics

  5. #5
    Registered User 355LX's Avatar
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    When it was on the dyno the AF ratio's were pretty good, i'm thinking about taking some timing out of it as i think it's definately a factor. I'm going to borrow a timing light off a buddy that shows a much more accurate reading of total advance.

    Fresh Ultimate in the tank. Ran a straight edge over the heads and they looks square, but going to get a poofteenth taken off them anyway to be sure.
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  6. #6
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    did they tune the timing on the dyno?

  7. #7
    are hairy dogsballs's Avatar
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    do you have to torque the head bolts in a specific sequence for these? i know some you have to do a sort of spiral starting inwards to outwards.
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  8. #8
    Registered User 355LX's Avatar
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    Yes you start from the inside and work your way out.

    And to the earlier question, yep we adjusted the timing while it was on the dyno.
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    Quote Originally Posted by dogsballs View Post
    do you have to torque the head bolts in a specific sequence for these? i know some you have to do a sort of spiral starting inwards to outwards.
    Pretty much every engine requires head torquing in the correct sequence.

  10. #10
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    -got some pics of sparkplugs?

    -If it really is making 400rwhp then 32 degrees is too much especially given its running out of steam at 6800, the grandpa spec manifold (LOL) and roller cam is probably building an arseload of cylinder pressure around peak torque.

    -piston tops look horrible, grab some pics of head chambers and ports.
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  11. #11
    Resident Oaf Jim's Avatar
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    straight edge the block and head. Especially if it's the same cylinders all the time.
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  12. #12
    Registered User TK's Avatar
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    I'm with greeny, that is det damage - prolly too much timing.
    Combustion does not look good, looks a bit oily/wet, may have been pulling oil past the rings & rattling on the oil, especially with 32 deg timing on VN heads.

    What is the deck height, static comp ratio & cam specs?

  13. #13
    Registered User 355LX's Avatar
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    0 deck height and approximately 10.5 - 1 compression. Will find cam card tonight but its not an aggressive grind. Will get as many facts together as I can.

    Thanks for all your input
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  14. #14
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    Also whip the bowls off and see what jetting is in the primary and secondary and what vac rating the PV is.

    since its apart Id be looking at the manifold to head alignment, i have a shit screen but it almost looks like theres not enough clamping on the bottom edge of the manifold, symptom of angular issues between the two and if your doing a lot of part throttle/over-run (high manifold vac) it can suck oil up from the valley.

    what did the oil look like and how old was it?

    did you leak it down before dissasembly?

    what are you doing for PCV/catch can?
    Last edited by greenhj; 08-08-11 at 10:33 AM.
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  15. #15
    Registered User 355LX's Avatar
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    I'm not running a PCV valve, I have a dash 12 hose running from the top of each rocker cover to a 3 1/2 litre catch can with two k+n breathers.

    Inlet manifold alignment is spot on, in the pic it looks funny due to the way the gasket material partially tore off on removal.

    I didn't do a leakdown test.

    Jets and powervalve are as it came out the box we just went one size smaller on the air bleeds.

    I will find cam card tonight.

    Oil less than 300km old, you can just make out a bit of silver in the, and I think a touch of moisture but I could be wrong.
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  16. #16
    Registered User 355LX's Avatar
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    I'm pretty convinced now 32 degrees is too much for my motor, so 28 might sound a little better? How much initial, still about 12?
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  17. #17
    Registered User TK's Avatar
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    I like 14-16 initial, 28 total.

    But keep looking, I'm not sure that 32 deg on 10.5:1 comp with a decent cam is enough to push out the head gaskets, methinks timing is a factor, but something else pushed it over the edge of det.

    Pity you're in perth, I'd be happy to have a look over everything & figure out what went wrong, it's almost impossible over the net.

  18. #18
    Registered User 355LX's Avatar
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    Thanks again. I'll definitely try and find my cam card, it will certainly help
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  19. #19
    Registered User 355LX's Avatar
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    After some more reading and thinking, I am starting to suspect that coolant has been leaking up the studs, and compromised the head gaskets as they were both very wet and you can see they've been leaking in other places. Then with my slightly excessive timing it has let go. There was a rumour of a bad batch of ultimate kicking around the same time I got fuel too.

    I know my engine builder used arp thread servant on them, and after some online reading a lot of people have had dramas with this stuff.


    What are peoples thoughts? I have golden sealing compound, just use that?
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  20. #20
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    ive used black silastic before with no issue.

    You only need to keep water out, its doing exactly fuck all else.
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  21. #21
    Registered User 355LX's Avatar
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    Thanks greenhj I'm going to use some ultra black.
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    Id wait for more opinions before going off my advice lol.
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  23. #23
    Registered User 355LX's Avatar
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    Hahaha Nah mate mate from what I've read and heard its the way to go. If it does go though, what's your address so I know where to send the bill?!
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  24. #24
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    FWIW mine was together 3 yrs with silastic in the studs, the studs were used for 6.
    Last edited by greenhj; 09-08-11 at 05:52 PM.
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  25. #25
    never good enough ott308's Avatar
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    too much timing?? use gm sealant on the studs and get some cometic MLS head gaskets. Follow the correct torque sequence to for the heads. In my opinion just get some genuine head bolt sealant, but i have'nt tried anything else

  26. #26
    Registered User 355LX's Avatar
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    One head on one to go. Using Ultra black, my engine builder said he does it from time to time on some engines. Hopefully it lasts for the whole of Targa weekend, it's only 2 weeks away!!


    Thanks for everyones advice, will update on outcome when I've clocked up some more km's.

    Oh and here's a quick pic of the car from a couple of weeks back. Was a very wet day but good to get an idea of how it behaves incase Targa is wet this year.



    Heading back out now to finish screwing it together, scrutineering is this Saturday!
    Last edited by 355LX; 10-08-11 at 12:43 AM.
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  27. #27
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    cool!

    Probably too late now but when i do it I just use the thinnest wipe over the top portion of the stud thread to (try and) stop silicone worms ending up every bloody where except where they should be.

    My car is just a street/strip shitter and it stayed sealed up for 3 yrs (only pulled it apart because it broke something else) so im sure youll get a weekend out of it (provided the coolant leak was the cause and not a symptom)

    Good luck with the race mate!
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  28. #28
    Torching plugs Greg Rust's Avatar
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  29. #29
    Registered User 355LX's Avatar
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    Sorry for the thread revival but I thought I would just explain the outcome of the drama's I was having.

    Basically after screwing it back together again with fresh Felpro head gaskets I slotted the the motor in and ran it up to operating temp. I thought I would have a quick look at the oil and fuck me if I didn't find water in the oil again!!

    So with about a week before Targa I was pulling the motor out again, and this time I took it down to my engine builder to look at for me, I just wanted to leave it with him and pick it up sorted. Unfortunately when I called he informed me he was neck deep with his offsider off sick and a massive backlog of work to get through. So he said bring it down anyway for a look. Once there we left it on the trailer and I simply pulled a head off for him to have a look. The head gasket was super wet and you could see that moisture had been escaping into the valley. I had used a very small fine smear of silastic around the water gallery holes on his advice. Anyway, he could not see anything visibly wrong and the heads were still dead straight. So he organised a set of graphite Larry Perkins race series gaskets instead of the Felpro's he normally uses.

    I took it home and screwed it all together exactly as I had before, did not change anything. Put the motor in Tuesday night, got her running and checked the oil again. Looked good. Went for a drive, checked oil upon return, still all good. 2 days later, Targa started and the car did not miss a beat for the full 4 days, I beat up on her as much as I wanted.

    The only cause I can come up with in the end was the Felpro head gaskets allowing water to leak into the valley. On reflection I'd had trouble with water in the oil since day one, but had not really realised it, putting it to cold moist winter mornings causing moisture build-up in the rockers covers etc. I dropped the oil once every 300-400km for the first 1000km of the engines life for various reasons and it always didn't look quite right. I was stupid for not picking up on it earlier. So anyway, now the oil after 1500km looks great, just like slightly used motor oil should, instead of the usual discoloured watery shit.

    I did also take some timing out, I think I'm sitting at about 28-29 degrees. I really wish I had an ICE system so I wouldn't have to compromise initial for total or visa versa due to the MSD dizzy adjustment style.

    Once again thanks to those who offered their advice, and hope this may help someone else one day.

    Dave
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