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73-87 Chevy _ GMC Trucks => 73-87 Chevy & GMC Trucks => Topic started by: 1979C20 on August 31, 2014, 04:37:38 am
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So I rebuilt the motor in my 79 about 5 years ago. The truck has been sitting for the last 2 years and I just got it going again. Ive got about 3k miles on the build. Im having quite a few issues. The a/f is set correctly with a vac gauge, the timing is at 10°btdc, with the advanced connected to manifold vacuum, im running 4qt 20w-50 and 1 qt lucas heavy duty stabilizer. My throttle response is great, its torquey, it sounds very solid. My oil pressure suddenly dropped pretty exponentially before I parked the teuck 2 years ago. It has the melling high volume pump and it used to idle warm at 30psi, accelerate it goes to 65psi and cruising 45mph was around 50psi. On a fresh oil change! Now, it idles at 7psi, accelerating is around 45psi, and cruising 45 is around 25-35psi. So I need some suggestions there.
Also, I took my truck to the 1/4mile at Firebird/Wild Horse Pass Raceway. Its a standard bore 350, 440lift 262dur int/exh cam, 8.7:1 compression with decent flowing heads, Edelbrock Performer intake, Carter 650 carb with choke wired open. Ive got headers with old cherry bombs dumped under the cab, sm465 trans with stage 2 6puck ceramic clutch, corp 14bolt with 4.10s, 235/75r16 tires on the rear. The motor casting number and vin number show 350/350 hp/tq to the flywheel factory since its a trailering special. I only ran a 17.7 at 75mph and I was quite disappointed. Does this time seem accurate for the build or does it sound like something is off?
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How much have you ran the truck since it has been parked for 2 years ? The oil pressure could be build up in the oil passages from sitting which is partially plugging the flow of oil.
Your run at the track. Really depends on how well you shot the light and changed gears. It is harder with a standard than with a automatic to get the gear changes at the right time and speed. That would be hard to determine without seeing the run.
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yeah dude there are alot of factors that come into play on a 1/4 mile time.
how well the truck hooked, what rpm you shifted at, ect.
how did you come up with the timing at 10*btdc? did you use a vaccume gauge to set the timing?
and what is the a/f? air fuel ratio? referring to the idle mixture?
im not trying to pick you apart im just trying to get some more info
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Bake, the oil pressure got lower and lower while I was still driving it. Before I parked it.
Its at 10° initial timing. Off the line I chirped and launched strong, shifted at 4800rpm and chirped second strong. Rode second to 4500rpm and hit 3rd. The engine seems fall off around 5200rpm. Yes the idle.mixture was set with a vac gauge.
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Bake, the oil pressure got lower and lower while I was still driving it. Before I parked it.
Have you looked at the heads to see if the oil passages look dirty ?
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Verify oil pressure with a mechanical test gauge. If, indeed, the pressure is low, there maybe some debris lodged in the oil pump pressure relief, a badly scored pump, AND/OR there maybe developing bearing damage.
Remove the oil filter and cut it open, inspecting for metal particles. A scrubbed cam could easily cause all of your symptoms - low engine power and damage to the oil pump, resulting in low oil pressure.
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I have not checked the heads yet. Im using a mechanical gauge and I can watch the oil in the clear plastic tube.
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Im also noticing some weird behavior with my oil pressure. Say im in second gear, if I accelerate the psi slowly raises, but when I let off the gas and the engine hold the truck back, the psi jumps way up. Then when I accelerate again it drops back down. Ive also tried adding an extra quart of oil to see if maybe the pick up tube fell but theres no difference. I dont know what to do anymore.