Started putting new engine together

Discussion in ''Da Nailhead' started by Aussie V8, Jun 29, 2017.

  1. Aussie V8

    Aussie V8 Well-Known Member

    So I'm now at the stage of re-building fresh engine. I've had the crankshaft re-ground and before I install, need to decide on which rear seal to use ----- rope or neoprene. Trouble is the seal surface is far from perfect with rust pitting from sitting. The engine machinist was able to polish the surface but it's still not perfect. Russ Martin recommends using the rope seal in such circumstances and I'm asking for opinions here please. I realize the rope seal is possibly going to leak somewhat, is the neoprene going to leak more / or less ?

    Also in regards to the rear camshaft snap ring ---- I got a new replacement from Russ Martin but it does not have a rounded side like original. Is that going to be any drama ?

    IMG_7210.JPG
     
    Donuts & Peelouts likes this.
  2. 8ad-f85

    8ad-f85 Well-Known Member

    Many engines using rope seals don't have the best tolerances held as far as concentricity to the main line (if there's even a call out on the print)...so that can be a risk. The rope conforms in that case.
    If there's any issue there I machine it true (somehow and depending on the engine type) and pass that on to the customer.
    I can't speak for the pitting, if I can't polish it my crank guy gets it if he can get a wheel in there.
    The newer rope seals aren't as good as the old asbestos seals, but I've not used one in a long time.
    So, how far out of alignment is it?
    Do you have a seal in mind and a plan?
    Don't guess, come up with a plan.
     
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  3. gsgtx

    gsgtx Silver Level contributor

    neoprene seem to leak. 3 different engine builders too. the last one just finished leaks the least. had machinist cut 2 small lines in the rear main bearing, going from the oil hole, to the side away from the seal.looks like a V shape from the oil hole
     
  4. telriv

    telriv Well-Known Member

    I haven't had ANY PROBLEMS with leaking rear modern seals, even doing them in the car.
     
  5. Stevem

    Stevem Well-Known Member

    With pitting like that use which ever seal provides the wides contact pattern as that's your best hope, been there done that, but I would really try to get the customer to go for Choming that seal surface otherwise it's gonna weep or leak to some degree depending on the Crankcase pressure I promis you!
     
  6. Aussie V8

    Aussie V8 Well-Known Member

    By meaning out of alignment = out of round ? I don't think it is. The machinist polished it but was unable to get a narrow enough grinding wheel in there. I have both types of seal here, so my plan is to use which ever will provide the best method of keeping the oil in. Obviously I want to do it right the first time,
    so I have consulted the experts ( you ) ;)
    The machinist recommended the rope seal. I might have him take another look. Possibly get it metal sprayed but that's going to cost $$
     
  7. 8ad-f85

    8ad-f85 Well-Known Member

    Out of alignment meaning the circles wouldn't overlay evenly, sometimes the groove for the rope seal isn't true to the centerline of the block's main line.
    Pontiacs for example are notoriously bad, causing issues with modern seals leaking.
    Some Olds builders machine out the back of the block to fit a seal adapter...think sbc 1 pc seal housing or Ford windsor 1 pc for inspiration on this fix.
    A grinding wheel mounted on a lathe would allow options for your crank.
    Industrial rebuilders often are equipped to weld up or machine cranks beyond the scope of the automotive overhauling world.
    The few nailheads I've done with modern seals haven't had problems.
    I'm guessing that there aren't numerous nailhead cranks near you to simply start with another?
     
  8. wkillgs

    wkillgs Gold Level Contributor

    Cam snap ring....
    They are stamped from a flat sheet, so there's one side with a slightly rounded edge and the other side has a sharper edge.
    It's preferred to have the sharp edge out so it bites into the surface better. With rounded edge out, it's possible the snap ring could deform a little more and more easily push out.
    But it takes a lot of force to make that snap ring fail, it's very unlikely it will fail either way it is installed. Just make sure the side facing the cam is free of burrs.
     
  9. Aussie V8

    Aussie V8 Well-Known Member

    No, definitely no spare Nailhead cranks around here. I'm stuck with what I've got, leaks or no leaks.
    I will have a look at that snap ring and dress the side that rubs on the cam.
    Tom you got any tips please on neoprene seal installation to achieve the best result possible.
    Also, I have a new BEST gasket kit here that has some rubber seals that I'm not quite sure where they go.
    IMG_7220.JPG

    The ones on the left, there is 16 in the packet --- are they some sort of valve guide seal ?
    There's 6 of the one on the right.
     
  10. telriv

    telriv Well-Known Member

    Yes, 16 are supposed to be valve seals. I wouldn't use them. 6 are the seals that go under the valve & valley cover bolts.
     
  11. Aussie V8

    Aussie V8 Well-Known Member

    Thankyou. I thought that was the case, just double checking.
    I'm going to put proper intake valve seals on the guides.
     
  12. gsgtx

    gsgtx Silver Level contributor

    the reasons my rear seals would start leaking is running the motor many times to 5500-6000 rpms, then would start leaking, but what your doing they should be fine.
     
  13. dual-quadism

    dual-quadism Black on Black

    It is important to clock the rear seal about 1/8in off from the cap surface so that the sealing surfaces are not all in line. Also, add RTV(ultra black) on the ends and put the whole thing together. Also, there is a front/rear to the seal, the Best kit comes with instructions. Lastly, I have seen some builders not put the end cap rubber blocks in or put them in wrong also. If you do it all right, it last a long time even with a crank with light pitting. GSGTX, if yours is blowing oil after a topend run, you probably have a ventilation issue where it's building a lot of pressure at high rpm and is trying to find a way out. Venting through the valve covers may not be enough at high rpm as the oil flow coming back down the pushrod tubes may be just enough to seal the crankcase. Maybe vent throught the valley cover, worth a shot.
     
  14. 8ad-f85

    8ad-f85 Well-Known Member

    Hmmm, losing ring seal at high rpm? Not broken in yet?
     
  15. gsgtx

    gsgtx Silver Level contributor

    could need more venting, the dip stick tube does not pop out. rings are sealing. always run semi syn oil maybe that will make it leak. its a very small leak.
     
  16. dual-quadism

    dual-quadism Black on Black

    Dont go by just the "dipstick tube" test. It happens on some extreme cases, but usually it takes a lot to blow that out. Stick a breather in the valley cover and see what happens. I doubt the rings are losing seal. The semi syn oil will not "make" it leak either. Good luck!
     
  17. Aussie V8

    Aussie V8 Well-Known Member

    Anybody used ARP head bolts on their engine ? I got a set off TA Performance and the long bolt with their supplied washer is nearly 1/4" shorter than original.
    Any thoughts please. IMG_7241.JPG
     
  18. 8ad-f85

    8ad-f85 Well-Known Member

    Regarding ring seal and rear main leakage...when people were first really getting worried about cam break in and zinc additives, I was seeing engines with STP or whatever added seemingly cause rear leakage and preventing rings from seating. That changed with an oil change.
    I know this isn't exactly what was described to but thought this might be helpful in this thread.
     
  19. gsgtx

    gsgtx Silver Level contributor

    never used them but am sure there fine. T A builds motors there, they should know.
     
  20. gsgtx

    gsgtx Silver Level contributor

    you might have something there i always add a moly additive which i think its like stp
     

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