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#1
10-31-2001, 12:30 AM
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I have an original 68' 400 engine with 90K+ miles on it. I am having the engine pulled and some block work done to it. I have had a few opinions regarding drilling the block in order to get more oil on the crankshaft. I have been told the 400's weak link is the crankshaft at high RPM. Supposedly this will help alleviate the problem. Any articles regarding this or opinions.
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#2
10-31-2001, 12:30 AM
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I have an original 68' 400 engine with 90K+ miles on it. I am having the engine pulled and some block work done to it. I have had a few opinions regarding drilling the block in order to get more oil on the crankshaft. I have been told the 400's weak link is the crankshaft at high RPM. Supposedly this will help alleviate the problem. Any articles regarding this or opinions.
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#3
11-05-2001, 12:33 PM
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My opinion is the stock 400 crank is stronger than the 428 or 455 crank - nuff said huh. Could go one better with the cross-drilled 400 cranks.
My other opinion is the crank failures usually had a pre-amble failure in the name of a hot rod journal, spit rod, split main saddle, ineffective balancer, detonation and crossfire. Then again, I'm in the minor leagues.
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12.24/111.6MPH/1.76 60'/28"/3.54:1/SP-TH400/469 R96A/236-244-112LC/1050&TorkerI//3850Lbs//15MPG/89oct Sold 2003: 12.00/112MPH/1.61 60'/26"x3.31:1/10"/469 #48/245-255-110LSA/Q-Jet-Torker/3650Lbs//18MPG 94oct Sold 1994: 11.00/123MPH/1.50 60'/29.5"x4.10:1/10"/469 #48/245-255-110LSA/Dual600s-Wenzler/3250Lbs//94oct |
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#4
11-11-2001, 06:27 PM
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The oiling system on a 400 Pontiac sends the high pressure oil from the pump thru the filter and into the oil galley. From the Galley, the presurized oil is either consumed by the lifters or flows down and around camshaft bearings (thru special grooves cut in the bearing)and into the main journals before entering the crank shaft and lubricating the rod journals. Enlarging the cam bearing to main bearing oil passages will improve the oil flow capability of the bottom end but the oil still gets bottlenecked at the cam bearings. Race blocks fix this problem with priority main oiling systems that send oil straight to the crank.
For high RPM's out of a production block, I'd look at trying to find cam bearings that are designed to allow more oil flow to the crank (IE. bigger oil flow holes and enlarged oil flow groove in the cam bearing), use roller lifter/rockers as they require and consume less oil (not to mention the multitude of other advantages), high volume oil pump to force more oil into the galley, cross drill the crank to get more oil to the rod journals (very important), install a crank scraper to reduce parasydic losses caused by oil riding up and flinging off the crank, and get a quality front timing pieces. If you do decide to enlarge the oil passages, remember to open up the bearing holes to match otherwise you may have done more harm than good. Just my thoughts.
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1969 TA RAIII M40 Auto Cameo White/ Std Blue Int 1970 TA RAIII M21 4-spd Lucy Blue/Std Black Int 1971 TA 455 HO M22 4-Spd Lucy Blue/Deluxe White Int |
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