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#1
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BOP 1 piece vs 2 piece seal
Which one am I gonna have better luck getting not to leak? Which one are you guys using? I need success and failure stories, do's and donts, that kinda thing. I am buying the one piece pan gasket.
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468/TKO600 Ford thru bolt equipped 64 Tempest Custom. Custom Nocturne Blue with black interior. |
#2
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the one piece pan gasket will not work with an IA2 just fyi
if you have a factory 455 N crank, i am a fan of 'the best rope seal' they seem to work real well. On my IA2 i have used KRE and BOP 2 piece seals successfully. I usually put the seam where it does not fall at the parting lines, however others seem to have success with normal installations
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1969 carousel red firebird 455, richmond 5 speed 1964 540 gto 1971 lemans sport convertible 1972 Maverick under slow construction |
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#3
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If you are replacing a seal in an assembled engine then you use the two-piece seal, otherwise use the one-piece. The one-piece has one less joint to leak and it is also at the top of the groove which helps. The one-piece also has two lips as opposed to the single lip on the two-piece seal. Follow the included instructions and if you have any questions call them. We had a machine shop bore into the block .027" in cleaning up the mains. Obviously operator error on the machinist part, but we were stuck with the results. Through Wade's guidance we matched the seal to the new journal height and it's been a year without leaking.
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Mick Batson 1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 2+2 survivor AC auto -- 1965 Catalina Safari Wagon. |
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#4
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Ive had better luck with a 1 piece on my 455, 2 piece and graphite seal both leaked on that engine. On the 389 2 piece was fine.
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Illinois Outlaw Gassers 6.27@107 9.97@131 |
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#5
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I have factory 455 block & crank. Used Best graphite seal. Pretty pleased. Been together a long time. Seal will leave a little spot when it sits over the winter. When the car gets driven, no problem.
Murf |
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#6
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I replaced a leaking new rope seal on my 428 with the 2 piece seal. I followed directions carefully and it leaked less than the rope seal but it does leak some.
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The Following User Says Thank You to Goatracer1 For This Useful Post: | ||
#7
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I've been fighting this on my stroker build. I thought a one piece would be an easy deal but during the "tip test", the one piece seal leaked so I installed a two piece meticulously - which is also leaking. Butler and BOP tell me not to worry about the tip test as the crank serrations will have some leakage when the block is tipped. When I have the block at a less extreme angle there's no leakage at all.
Debating giving the graphite seal a shot, but I've heard the serrations on aftermarket cranks can eat them up.
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Ken '68 GTO - 464 - Ram Air II heads - 236/242 roller - 9.5” TSP converter - Moser 3.55 Truetrac (build thread | walk around) '95 Comp T/A #6 M6 - bone stock (pics) |
#8
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posted many times.Im 100% with the BOP 1pc seal,100% with the Bestgasket rope seal and 50/50 with the BOP 2 pc seal.FWIW,Tom
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The Following User Says Thank You to tom s For This Useful Post: | ||
#9
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I've used both the 1 piece and 2 piece seals but prefer the 1 piece since there's one less parting line. The key, by far, to getting them to seal is proper measuring and installation. You absolutely have to measure the seal grove diameter, and then whether the groove is equally deep in the block and the cap, as measured from the parting line surface of the block. If any of these measurements are out of specification, then you need to take material off the backside of the seal to adjust. I use A TON of these in Pontiac engines and have very few to no issues when properly installed.
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62' Lemans, Nostalgia Super Stock, 541 CI, IA2 block, billet 4.5" crank, Ross, Wide port Edelbrocks, Gustram intake, 2 4150 style BLP carbs, 2.10 Turbo 400, 9" w/4:30 gears, 8.76 @153, 3100lbs |
#10
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I bit the bullet on the two-piece BOP this summer and my buddy put it in for me...still leaking but I'm getting used to it...it's a pontipig lol
Gouged me for shipping too...ah well...built in oil change Stock block/crank. Good luck! |
#11
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Quote:
I read that also, that the BOP one piece pan gasket doesn't work with the IA2. Well I made it work and so far it's been great. I made a metal spacer for the front area of the Canton 15-452 pan. Been 2 seasons and it's held up very well. I had to use the right stuff in the front and rear to help seal it up. No leaks to date.
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68 Firebird. IA2 block, 505 cu in, SD Performance E-head, Solid roller 3600 weight. Reid TH400 4:11 gear. 29" slick. Best so far 9.95@134 mph. 1.43 60 ft. 76 Trans am, TKX .81 o/d, 3.73 Moser rearend, 468 with KRE D-ports, Doug headers, 3" Exh. |
#12
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Quote:
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#13
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I installed the 2 piece BOP seal this spring, measured 3 times, assembled with torque. Took it apart again, measuerd and installed again.
Hooked engine up in hoist and adjusted tillt on levler til i had a heavy angle backwards, and filled 5 quarts of oil. Let it hang for a day, not a drop, turned the motor over , still not a drop. 1 week after i got the engine in and have been driving it was leaking. Dont know what black magic i have to to do to make it seal up.
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Murphy's law - "Anything that can go wrong will go wrong". -469 ,Butler 310+ Eheads, Hurricane intake portmatched by butler, Butler roller 230/236 @0.50 112 LSA, Johnson lifters, pypes 2 1/2" exhaust, 3.42 yukon duragrip lsd, holley sniper efi, hyperfuel efi tank +++ |
#14
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1 piece seal here .... no leak during the tilt test, few hours of run time so far, not a drop yet.
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I'm World's Best Hyperbolist !! |
#15
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Quote:
The Viton seals require some checking and then corrective work if necessary as slowbird says. The old way of cutting some material off the end of the seal to allow the lip to not curl isn't recommended by BOP anymore. Guess sort of a live-and-learn adjustment. Now they recommend sanding the exterior of the seal on the shallow end so the seal ends up concentric with the journal. New method requires measuring from the flat of the journal to the bottom of the groove for both the block and cap and sanding the seal where needed. The seal used in the deep cut block I mentioned above had to be sanded to where the metal support was showing to center the seal. No fun, but is leak free after over a year.
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Mick Batson 1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 2+2 survivor AC auto -- 1965 Catalina Safari Wagon. |
#16
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Have done 3 with the 2 piece BOP seal, now it is 12-15 years later on each engine and still no leaks, have done one 1-piece BOP about 8 years ago and it started weeping in the first year of service. It passed the tilt test.
I never tested the other 3. The asbestos rope seal I installed in my '65 GTO 41 years ago is still leak free. The new rope seals in the overhaul kits do not seal well at all. I hear good stuff about BestGasket square rope seals. Never used one, though.
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Jeff |
#17
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Does an NOS asbestos seal have a shelf life?
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Will Rivera '69 Firebird 400/461, 290+ E D-Ports, HR 230/236, 4l80E, 8.5 Rear, 3.55 gears ‘66 Lemans, 455, KRE D-Ports, TH350, 12 bolt 3.90 gears '69 LeMans Vert, 350, #47 heads: work in progress |
#18
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I would not think so.
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1968 Firebird 400 RAII M21, 3.31 12 bolt, Mayfair Maize. 1977 Trans Am W72 400, TH350, 3.23 T Top Everyone you will ever meet knows something you don't. Bill Nye. |
#19
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Also, any way to tell them from later seals? I've got bags of seals all mixed together and bet than there are some older ones in there. Unfortunately all the old unmarked bags look the same.
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Mick Batson 1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 2+2 survivor AC auto -- 1965 Catalina Safari Wagon. |
#20
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I did the dance with the 2 piece neoprene seals (pre-BOP) twice and failed both times. First time was with a Ford 460 neoprene seal and the second time was with the '63-'67 Cadillac neoprene seal which I believe the current BOP one is based on.
On the first build, I trimmed the ends .010" proud of the block dry, set it in silicone clocked with the ends away from the block/cap interface. Leaked like a sieve. When I removed the seal, it looked like the crank never even touched the seal even though it took noticeably more torque to rotate the crank after installing indicating it was sealing. On the second build I used the Cadillac neoprene seal per the late Jim Taylor's (Pontiac Guru not the forumite) recommendations. I hand-cut radial anti-rotation slits in the block groove for retention, installed the top and bottom seal in separate operations, trimmed meticulously, meticulously set it in silicone making sure to fill the retention holes in the block first and siliconing the ends and out across the caps before torquing. Looked perfect, tilted with no leakage overnight and then leaked like a sieve within hours of running. I pulled the motor, installed a graphite Best Seal and never had another leak.
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Triple Black 1971 GTO |
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