should I be upset or happy??

Post by **oneowner71** » Thu Apr 15, 2004 11:21 pm

Got to chatting the other night and had a few questions raised, so I decided to play around and answer them.... I think it was Trey that did the asking. As far as the rear diff ratio, the tag say 3.23, so the 3000rpm at 75 must be due to something else. As far as compression goes, I am not sure what is the correct values, but this is what I ended up with on mine (LA318)

Motor Rear

140 psi o o 131-135

140 o o 130

141 o o 140

135-140 o o 105-110

If I had to guess, I want 140 psi, in which case I am exstatic, except for the one low cylinder.... any ideas on what would cause that (ran test 5 separate times, first and last of the 8 cyls)?? Feed me, I am a blank slate.

Post by **cowboy** » Fri Apr 16, 2004 7:39 am

clint frist things frist, are you sure , grand dad did.nt change the rear gears ? second how many miles do you have on your truck ? 140 is a good presure to have & one cyl a little low is not that bad , could be a few things weak rings ( will smoke a little) weak valve guide, or weak valve it self all will cause a little smoke if only on one cyclender(sp)
8)

Website · Post by **wideblock** » Fri Apr 16, 2004 8:23 am

id bet on worn or dirty valve seats. one way to check rings wear is to pump a few sqirts of 30 weight into the cylinder thru the plug hole and retest the compression. if it goes up on that cylinder, then its rings, if it doesnt, its the heads. if it is the heads, run a good cleaner thru the gas. valvoline makes a good carb and system cleaner thats added to the gas, or a can of marvel mystery oil. then recheck the compression a few days down the road. if its dirty valves, full of deposits, this will change the reading, if it does, run a couple cans thru it and it might just clear up.

Post by **oneowner71** » Fri Apr 16, 2004 4:17 pm

Dave, to answer your questions... I have about 125K miles on it, give or take a thousand due to a dirty speedo. As far as switching the rear, the tag on the pumpkin said 3.23, and the best part about this truck is that for all but the first few years of its life, all of the mechanic work done on it was done by my father at his shop, and he doesn't remember ever doing a rear end swap... he did go through a motor rebuild at about 80,000 miles, but didn't put in new seats, as this was while leaded gas was still available. About the only smoke I get is at startup, but it comes out both banks, so it's not just the one cylinder. When driving, I only get that wonderful cloud of rich black smoke. When I get the urge again, I'll run the compr test with the oil and see if that helps. As far as the running rich thing, I'm just gonna wait till I get saved up for the 4bbl and hopefully that will fix the vacuum problem.

MountainMoparRobin · Post by **MountainMoparRobin** » Fri Apr 16, 2004 9:48 pm

Clint
3:23 sounds right, I also have 3:23 and at that speed the rpm's sound to be exactly the same. 3000 for the 440 is about ideal, and now my red line is 6500rpm's. small blocks get their power in higher rpm's, big blocks win races with the low rpm and high torque, actually, now that I think about it the 440 before cam@ 75 was 2800rpm, 440's have a longer stroke.

scoutski · Post by **scoutski** » Sat Apr 17, 2004 6:02 am

Clint, Just a thought, Did you have the throttle on the carb blocked open? The smoke on startup is certainly worn valve guides, this could cause the valves to be slightly off when they try to seat especially at a higher rpm.

Post by **oneowner71** » Sun Apr 18, 2004 2:19 pm

Scout, yeah, I had the carb wide open (handy little directions with the tester or I would have never done that). I figure at some point it would be good to get a little head work done on it, but its gonna wait. Do you still have that truck for sale??

scoutski · Post by **scoutski** » Sun Apr 18, 2004 9:19 pm

Yep, still have it. I'll let it go for $150.00 and throw in a nother 68 frame that has springs but no axles. Haven't advertised it again but I need to clear out some of my inventory.
Bill