I have been having issues with a 460 build for almost 2 years now and I can't seem to get anywhere. the builder says he will fix it but it still pours oil out of the rear main and is kind of sorry for a built up big block. there is a ton of info on the build in previous posts and the thing has headers now (L&L) and a 670 holley truck avenger carb. It rips if it revs to around 4000 and up but absolutely no low end torque im taking it back to the builder for the third time to get his input but the thing can't even get rolling with a trailer or in a snow drift or in a mudhole. once spooled up its fine but what good is power at 40 mph in a truck when you need to get through an uphill snowdrift? 5000 rpm aint the answer. I was on one last attempt to get the input from whoever will give it to me. Is this a low compression problem, is that the standard behavior of the x4270H cam? I am not sure at this point if there is a problem with the engine or if it was a bad choice in parts. cranking compression is around 150 psi at 6000 ft elevation. Next is if this is what the big block behaves like then I need a low rpm cam and low rpm intake instead of the performer RPM intake. Also after the install of the headers I lost some lowend torque and gained a lot of high end acceleration I didn't have the low end torque to lose to start with either. I liked the power of the motor with manifolds better than I do with headers. I have one more question : I think I am going to start over and have good D3VEA2A heads ported out, milled, and big valves installed, guide plates, roller rockers, and studs. what would be a good piston/cam combo with these heads for a 350-450 horse 460 factory ignition, performer rpm intake holley 670TA 2000 rpm stall converter, C6 L&L Headers or manifolds, I can do either one. My Heads should handle most hyd. cams with adjustable rockers and tall springs. The heads are milled .010 block I think is a d1ve milled .010 My brother built a 10:1 390 with stock heads, springs, and a mild cam factory 4bbl intake and cr@ppy manifolds and from stop light to stop light I think he could take my "500 horsepower gentle giant" with the same truck, c6, 354 gears I have 410 gears, and he has a 1200 torque converter. I want my engine to run like his. I'll keep you posted if I learn anything more and all the help so far is appreciated.

 

generally speaking 460s are torque monsters and make lots of power down low. leaning maybe towards cam timing, how was the cam installed?

 

Hows your distributor set up ? initial, total centrifugal, advance rate, etc. Are you running a vacuum advance ? Was the voltage verified going to the dizzy ? Was the cam degreed in ? Was the valve train geometry set up right ? What do the spark plugs look like ? How much fuel psi is it holding ? Any strange characteristics you can think of no matter how insignificant ? Back fire, running too hot, etc. How is the exhaust set up ? pipe size, duals, is there a cat on it. ?
Was your block align bored or align honed ? A rear main leak could be caused by excessive align boring/honing. If it was and not caught and no one ordered a special short chain to compensate you will have a rear main leak and a loose timing chain causing a retarded cam with no power. I've seen some cranks that the slashes ground into it that direct the oil back in were worn out. Are you sure the seal is installed right ? Is there a pcv valve on your engine ? Are you sure it's the rear main? One time in a panic/hurry engine swap I actually forgot to put the cams expansion plug in a 400 I built and it only dripped enough to be just a little annoying, even with the high psi/volume oil pump it had in it carrying 60 psi of pressure. I was all set to replace the seal, then when cleaning up I found the plug sitting on the bench covered with stuff left over from the job.

 

The dizzy is @ 12* and about 38* total with vacuum advance motocraft stocker ignition. I installed the mr gasket recurve kit in the dizzy and that caused some bad high rpm detonation at around like 50* of advance so that got swapped out for a new stocker. Cam timing I haven't verified the builder says he's verified it twice and its "straight up" but I don't know how much faith to put into that. The block was align bored and align honed it has 2.5 inch pipe with 40 series flowmasters Voltage isn't verified since the plugs are golden brown when I check them I assume that the ignition is working but correct me if I'm wrong. that would be easy to check I assume. Fuel psi I haven't checked but if it builds power with higher revs then fuel delivery is adequate right? I don't know if that is totally true but I definitely gained with the holley over the edelbrock due to the bigger float bowls I assume. I will check though. exhaust is dual, no crossover, and with uncorked headers I think is loses some power. Sounds strange, but I think I felt a power gain with the exhaust hooked up. Valve train geometry I have no Idea it has 1.73:1 comp roller rockers and guige plates with some pretty knarly looking valve springs and it will rev pretty high, but thats all I know. Rear main, I can't verify anything other than that it is the rear main I watched the plugs being put into the engine as the finishing assembly was being done and i assume it was the rear main and I am running a pcv vave and a vented oil cap Also at extremely high rpm doing a mean burnout it pops through the carb I think it might be leaning out on the secondaries on top but I haven't ran it enough above 6500 rpm to check plugs and verify. It could be floating the valves, but the builder claimed that there would be no valve float with that engine until it had a 900 or larger carb he also claimed it would be 500 HP and I think he might have lied about that. Thanks I will get to work and see how I can update this. With enough advice, I'm sure I can fix it. I will keep trying.