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Hot Rods Valves romancing pistons, problem solved

Discussion in 'The Hokey Ass Message Board' started by vtx1800, Jun 1, 2016.

  1. vtx1800
    Joined: Oct 4, 2009
    Posts: 1,378


    I've had a couple of threads on here trying to determine why I was having a driveability issue. It seemed at the time I was having a fuel issue. I was WRONG. The problem got worse so......I pulled the valve covers and found 15 pushrods. Number 16 was laying on the valley under the intake. I thought maybe I got a bad pushrod so I ordered more and after installing and driving it (with no improvement) I found four bent pushrods. Here is the specs on the engine:
    327 +.030, Speed Pro L2166N pistons
    Heads 3947041 org 1.5/1.94 valves, now has 2.02 intakes (64 cc combustion chamber)
    Head gasket is .034 I believe it is a Fel Pro
    Cam Howard Hydraulic Roller part number 110235-10 lift....intake-.485 exhaust .495, note these take shorter push rods which were installed
    Harland Sharp Roller Rockers 1.5 ratio (I think--no markings that I can see)

    You can see the scuffing on both the valves and pistons, I can have the machinist "sink" the valves a little, find a thicker head gasket, have the pistons fly cut or do it myself with a die grinder. Those are ideas I have contemplated but I am open for suggestions.
    Piston 6.jpg Valve 6.jpg
    henryj1951 likes this.
  2. How far is the piston in the hole at TDC ?
    henryj1951 likes this.
  3. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,390


    Isky still sells a piston notching tool.
    Nailhead Jason likes this.
  4. blowby
    Joined: Dec 27, 2012
    Posts: 8,054

    from Nicasio Ca

    Check your cam timing. If you retard it you'll gain intake valve clearance.
    Baldies, Russco and henryj1951 like this.

  5. squirrel
    Joined: Sep 23, 2004
    Posts: 50,261


    Do they all look like that? could be a few different things causing problems...did you check the valve to piston clearance when assembling it the first time? any sticky or tight valve guides? are the valve springs set up right? etc
    henryj1951 likes this.
  6. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 6,695

    Member Emeritus

    I was thinking "weak" valve springs being used with the roller cam, as rollers like more spring pressure. You're correct about setting up the valves/springs/retainers differently for a roller also, and it sounds like you're on top of things. I'm going with a roller cam setup, FOR THE FIRST TIME, with a BBC build I'm doing, so I'm learning as I go. The other issue I have, is my "backup" 327 I have for my Delivery has the same pistons, only in .040 oversize. My flat tappet, mechanical cam has more lift also, so now you've got me a little worried, even though that engine ran fine when in a Chevy II Wagon I used to have it in. I'll be following this thread! I am Butch/56sedandelivery.

    I've heard of the valves "kissing" the pistons, first time I've heard of it as "romancing".
    volvobrynk likes this.
  7. drtrcrV-8
    Joined: Jan 6, 2013
    Posts: 1,522


    You probably should check any valve that shows "contact" for being both straight & not cracked, & then thank the "Motor Gods" that none of them came off & took out a piston. Actually, check them all while you've got it down, then you won't wonder if you missed one. If you catch one of the 'broom-sales' from Competition Products you can usually get all 16 new valves for less than$80
    Rex_A_Lott and LostBoy like this.
  8. rocketsled59
    Joined: Mar 14, 2010
    Posts: 760


    Piston out of the bore at tdc? Are you sure of the rocker arm ratio? Use a dial indicator to see what your actual lift is. Assembled height of valve and spring assembly. Kraft cheese slice in the wrapper makes a great tool for checking your valve to piston clearance. RS59
  9. jimmy six
    Joined: Mar 21, 2006
    Posts: 10,270

    jimmy six

    Put on the head gasket, bolt on the head doesn't need to be torqued but tight after you install 2 lightweight springs you can push with your hand on one cylinder, set the valve clearance, roll the engine over until the piston on TDC is up on its overlap stroke, valves should be partially open. Push down each valve if you have a dial indicator see how much you move the valves. .100" is recommended for the exhaust and .060" for the intake. You can be closer but others will chime in. Good luck
  10. LostBoy
    Joined: Mar 16, 2016
    Posts: 217


    I'm surprised you didn't hear that. I'm also surprised you didn't bend them.

    Sent from my iPhone using Tapatalk
  11. henryj1951
    Joined: Sep 23, 2012
    Posts: 2,305

    from USA

    :cool: please let us know the FIX that you do....
    Last edited: Jun 8, 2016
  12. Rex_A_Lott
    Joined: Feb 5, 2007
    Posts: 1,019


    Double check the springs/installed heights etc. Replace the intake valves. "Eyebrow" the pistons with a made- for- that- purpose tool, and try to take a uniform amount off each one, so as not to throw the balance off. To do it right you'd really need to rebalance it all, but that might be a little more than you wanted. It sounds like a lot of work, but you're lucky its not worse.Good Luck!
  13. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,390


    I would do the clay thing to see if it's a cam or guide or spring problem.
    falcongeorge likes this.
  14. R Pope
    Joined: Jan 23, 2006
    Posts: 3,309

    R Pope

    Probably a cam duration thing, not lift. At full valve lift the piston is way down in the hole. Also springs are not the problem unless the valves are actually floating at high RPM. Grind in some clearance or go to a different cam with less duration.
    falcongeorge likes this.
  15. treb11
    Joined: Jan 21, 2006
    Posts: 3,694


    How much have the heads been milled?

    Disassemble and check everything for damage including the cam. Use a clearance tool on the pistons and reassemble.
  16. henryj1951
    Joined: Sep 23, 2012
    Posts: 2,305

    from USA

    Q: Just the one (why only one)valve to piston (look real close at the others)
    weak spring, poor guide clearance, (guide might get tight when warmed up)
    move one of those rockers off to the side( probably the one missing the push rod)
    and LQQK see where the roller was rolling... on the valve , if it appears to be in the middle,
    or forward or way back. This checking where it was rolling might be near impossible...
    as it might not have much of a wear spot .
    Q: press in rocker studs?
    (Dr.Needs more info)...:cool:
    guide -n- seal to retainer clearance ( might have came in contact with each other)
    Q stock size valve springs? 1.25?
    Last edited: Jun 2, 2016
  17. That is why you don't just screw one together. The solution is to cut the valve pocket deeper in the piston. At least any machinist worth his salt will tell you that.

    If you are zero decked you can go to a .040 gasket, ideally you want your quench to be in the .040 range ( give or take a little bit). Even at that you need to clay it and see where you are at. I like to keep .060 between the valve and the piston. I cannot tell you where that number came from, maybe decades of trying to go as fast as possible, or maybe someone told me that or both.

    Live and learn I guess.
    Mark Hinds likes this.
  18. SicSpeed
    Joined: Apr 23, 2014
    Posts: 653

    from Idaho

    That's better than this problem I had with my Boss 302
  19. I would just replace the bent valve and run it. :D
    LostBoy likes this.
  20. vtx1800
    Joined: Oct 4, 2009
    Posts: 1,378


    Virtually all of the intake valves show some "interference" fit. I didn't want to tie up too much band width with pictures of all of the cylinders. There are screw in rocker studs, I was foolish for not doing a "fit up and check" when I assembled the engine, I foolishly assumed that a fairly mild cam would not have enough lift to cause a problem.
    deck height --#1-.042, #7 .045, #2 .0345 and #8 was .0325, note that the even number side had the most interference.
    The heads were redone just prior and had new valves, the heads had enough wear that the machinist just upsized to 2.02 valves, the guides had been replaced less than a 1000 miles before. Spring height is about 1.85 inches. The valve springs were suggested by Competition Products where I purchased the cam. If the heads were milled I am unaware of when it was done. I've had them since the 80's, just never used them.
    I've contacted Harland Sharp to determine the rocker ratio, just sent pictures a few minutes ago, hoping that my guess of a 1.6 ratio could be my "problem".

    I built the first engine for this car in the 70's but used all stock pistons etc and a cam of unknown duration/lift, cut the ring ridge out (it should have been bored) new rings and bearings, virtually no problems and it would spin 7 grand. I should have learned more in the last 40 years:(

    As far as hearing the interference, I am 71 years old, hearing is not perfect and the damn thing is so loud that a radio is a useless accessory. I appreciate all of the suggestions and info, you guys are great!!

    Edit, it appears that I have 1.5 rockers. Guess I can forget that possible fix.
    Raunchy likes this.
  21. Engine man
    Joined: Jan 30, 2011
    Posts: 3,480

    Engine man
    from Wisconsin

    The intake valve should just start to open as the piston reaches top dead center. On a roller cam they can open very quickly. If all of the intake valves are hitting, it could be a cam timing issue. It might be possible that the lifter was adjusted too tightly but it still shouldn't hit the piston unless the lifters float.

    As others have said, I suspect that the valves were sticking in the guide. Since you have the heads off it's a good time to have the valves checked for straightness and make sure there's enough clearance. The valves will heat up faster than the head so they expand before the guide does. They demonstrated this in auto shop with a head in a freezer. The valve moved freely. A valve was removed, put in boiling water then attempt to put it back in the head. It wouldn't go in until the valve cooled off again.

    I don't know how good the quality control is these days. Valve stem sizes could be different or a valve stem not straight. The stem needs some clearance so enough oil can get in to lubricate the guide. They might not stick at first but too much friction could eventually make them stick.
  22. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,390


    213 -217 @ .050 on 110 LDA is not a radical cam
    Last edited: Jun 5, 2016
    falcongeorge likes this.
  23. henryj1951
    Joined: Sep 23, 2012
    Posts: 2,305

    from USA

    H380 and vtx1800 like this.
  24. Atwater Mike
    Joined: May 31, 2002
    Posts: 10,728

    Atwater Mike

    'Romancing'? I call it 'banging'.

    (That's what Betty Hargrove's Dad told me when he caught us up in the loft. I tried hard to convince him of the honorable content of my intentions, but I think he'd been down that road before. Betty's road...:p)
    shown50, vtx1800 and falcongeorge like this.
  25. I aint touchin that. :)

    Here is the deal in a perfect world the intake valve chases the piston down the hole. Now the valves are just dumb parts, not capable of thinking or rationalization. They are a lot like a dog that chases cars. I had an old Belgian Shepard once that chased cars, problem was that once in a while the old dog would catch one, now being a dog when she caught one she didn't know what to do so she would just crash into it. Its the same deal with this motor, the valve is chasing the piston down the hole, it is a dumb part and when it catches up with the piston is does not know what you do so it just bangs its head into it.
    shown50, Mark Hinds and vtx1800 like this.
  26. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    from BC

    back up and re-think that Benno. When does the intake valve come off the seat? How does running a narrower LSA, or advancing the cam affect that relationship?? The catching up part could be right, but you also need to consider which way the piston is moving when the intake valve first comes off the seat. This is why checking with the soft-spring method at TDC isnt good enough, to get an accurate picture, you need to clay it.
    I wouldn't even bother saying anything on this thread if it wasn't Benno posting.
    Raunchy and Dog_Patch like this.
  27. I am thinking that anything beyond the simple would be too much here. :rolleyes:

    I made a momentous guess on this one that the valve caught up with the piston on the way down. If it had happened in the other direction it would have made a big gaping hole in the piston and not just scuffed it.

    I was throwing a small block together for a fella in the latter part of the last century. His cam was custom ground for him from Lunati basically an L-79 cam on a 108 instead of a 112, same lift, same duration. His machinist told him to just screw it together, flat tops stockish grind cam but he asked me anyway. I clayed the pistons then took his pistons to work and relieved the tops for valve clearance. With the cam straight up tightening up the lobes made all the difference in the world. ;)
    falcongeorge likes this.
  28. vtx1800
    Joined: Oct 4, 2009
    Posts: 1,378


    For what it's worth, I called Howard Cams and asked the same question, their tech suspects that the cam needs to be moved, with the cam and piston combo there shouldn't be any interference. The first thing I will do now is pull the rest of the front clip (38 Chevy) and be thankful that I spent money on a two piece timing cover, wish I would have done more checking before bolting everything up. Wish me luck and if there are any other suggestions please throw them my way.
    34 Deluxe likes this.
  29. Old TFFdriver
    Joined: Jan 14, 2016
    Posts: 191

    Old TFFdriver
    from California

    I may of missed this part but I have to ask. ? Did you degree the cam and check TDC ?

    I do not care what cam card says or what timing marks say. I ALWAYS confirm these things and clay the cylinder just to be safe.
    Last edited: Jun 2, 2016
  30. vtx1800
    Joined: Oct 4, 2009
    Posts: 1,378


    I did have TDC set, but, foolishly did not degree the cam, I will be doing that before I reassemble and I will check the clearances with clay or cheese (never thought of that one), I assumed, a dangerous thing to do, that with a mild cam that I would have no issues. I guess we all know what "assume" means:(
    Old TFFdriver likes this.

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