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#1
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Help in selecting rod & main bearings
Pontiac Guys a question: what brand and style bearing would you use for this build AND 1/2 groove or full grove and why... thanks
1967 Firebird (engine is from a 71 GTO) Street Car, 400ci +035 with Weisco Pistons 2 valve relief +2.60 Standard rod w/ ARP bolts Crank Nodular cut 10/10 Comp EX256H cam and kit (keeping it just a hair above stock) #96 Heads all redone with a tiny bit of chamber cleaning and hardened seats STOCK TH400 and converter 3:08 Posi If I run this at all it would be maybe twice a year at the NMCA West Street class. |
#2
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Federal Mogul 4040M 3/4 groove mains. Clevite rod bearings. full groove is old school and developed before the engineers fully understood the need for a good oil wedge to support the crank. I once took a P350 apart that had full groove mains and you could see the abnormal journal wear that lined up with the full groove.
Some constructive criticism- I would ditch the stock rods in favor of cheap forgings. By the time you install aftermarket bolts and have the big ends resized, its the same cost as stronger rods. XE256 is a decent cam for a P350, but not a 400. I had that cam in the same 350. XE cams have valvetrain noise in my experience with 2 different XE grinds. I'd use a slightly larger cam like a Summit 2800, a 067 copy or something with about 215 duration with 112LSA. The XE grinds are on a 110LSA so the power peaks then ends early. Those 96 heads will put the compression in the mid to high 8s, so you'll have to mill them if you want any serious power.
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I could explain all this to the girl at the parts store, but she'd probably call the asylum. White '67 LeMans 407/TH350/Ford 3.89... RIP Red '67 LeMans. 407/TH400/Ford 3.25 Last edited by chiphead; 07-24-2014 at 05:05 PM. |
#3
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Quote:
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“It takes considerable knowledge just to realize the extent of your own ignorance.” Dr. Thomas Sowell |
#4
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I am going to use full groove bearings by "King". These were recommended to and sold to me by Ace when he had PPR. I don't see why a full groove bearing wouldn't work. I am under the impression from a few different sources that King bearings are of the highest quality and I will just proceed with the belief that their engineers aren't wrong.
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Karl |
#5
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That being said, a 455 running to only 5500-5800 rpm will have a high success of living a LONG TIME. Tom Vaught
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
#6
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Quote:
In my specific case I have the following; A .030" over 400 block, obviously a 3" crank journal, Very light rods(700g), pistons are 543g, so my bob weight is 2003g. I'm figuring this engine can live many years on the STREET occasionally hitting 6000rpm using the King MB5526AM and CR815CP bearings.
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Karl |
#7
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Clevite, P series, full grove, is ok on the non cross drilled 400 factory crank.
1/2 grove on the 3.25 cranks that are cross drilled. |
#8
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A decent read. Check out the discussion further down;
Basically, 180 or 1/2 grooves give better loading without starving the rods. http://www.vandervell.co.uk/images/s...gPerforman.pdf Last edited by PunchT37; 07-24-2014 at 09:05 PM. |
#9
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I would get either 1/2 groove or 3/4 groove bearings. I don't run full groove bearings, unless that's all that's available. I've seen cranks wear the main journals pretty bad with full groove bearings. They're a no/no in my book.
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Paul Carter Carter Cryogenics www.cartercryo.com 520-409-7236 Koerner Racing Engines You killed it, We build it! 520-294-5758 64 GTO, under re-construction, 412 CID, also under construction. 87 S-10 Pickup, 321,000 miles 99Monte Carlo, 293,000 miles 86 Bronco, 218,000 miles |
#10
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Quote:
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“It takes considerable knowledge just to realize the extent of your own ignorance.” Dr. Thomas Sowell |
#11
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OK, I went an ordered the connecting rods so thats a worry gone. Now as for the Bearings I'm leaning to a 1/2 grove...
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