Oil pressure problems..Help please..

[noahdallas]

I have a 350 bored .040 over with a Holley 650 douple pumper. I recently installed a new edelbrock cam/lifter set and a new timing chain. I had a couple of backfires and they have stopped thanks to working on the timing. I have some low oil pressure issues when I put the truck into drive or while idleing at a light. It starts at 40-50 psi and when I put it into gear it drops to 19-20 psi. The truck feels like it wants to die when it hits under 20 psi. Any advice would be appreciated.

[rage'nrat638]

THE BACKFIRING may have blown the power valves in your holley carb.
bad oil pressure should have nothing to do with engine wanting to die..
well unless it's ready to lock up..
check the power valves.... let us know

[noahdallas]

My carb says it has power valve protection. I had another board member tell me how to check them and they seem to be fine. I have no backfire and low pressure in gear.

I have been reading other post on the board and maybe stuck floats???

[rage'nrat638]

what rpm is your engine at in gear?

[noahdallas]

I have no idea... does that mean I have to add a tach??

[rage'nrat638]

i am thinking your idle is to low and your timing may need to be advanced.

advancing your timing will make your rpm's higher..
did you unplug your vacuum advance on the dizzy when you set your timimg with the timing light?

in gear you idle should be about 600-650,,, in park around 700-800
mark

[noahdallas]

Yes uplugged and set at 8 degrees.... and plugged back up ... if I remember think it jumped to 13.. dont quote me though.

Could please you tell me how to check the rpm's?

[junkyardjohn]

Noah... A Good Rule Of Thumb Is 10 Pounds Of Oil Pressure For Every 1000 Rpms. It's Not Unusual At All For A Motor With Any Miles On It At All To Have Less Than 15 Pounds Of Oil Pressure At Idle Once It's Warm. John

[Steelawork'n]

Is 8 degrees stock timing? If it is...your truck isn't stock any more. I always set mine with a vacuum guage. I don't even use a timing light...I don't even own one.

[jhow66]

You don't have a oil pressue problem. 19-20 lbs. if good at idle.

[70GMCer]

Mine is around 10 psi oil pressure at idle in gear. You didn't mention what the specs are on that cam. You might have a high lift, big duration on it and needs to be set at a higher RPM than stock. A big cam will act like it wants to stall at low RPM. Jusy my 2cs......

[noahdallas]

I am pretty new to all this timing issues...so I do appreciate all the feedback... Steelawork'n... could you tell me how to check timing with vacuum gauge? I was told stock was 8 but could you please give me your opinion on what it should be now....and is a vacuum gauge pretty cheap to go get? Thanks for all the help!!

Ohh... and the cam I got is an Edelbrock 2102..
Duration Advertised 278° Intake/288° Exhaust
Duration @ .050'' 204° Intake/214° Exhaust
Lift @ Valve .420'' Intake/.442'' Exhaust
Lift @ Cam .280'' Intake/.295'' Exhaust
Lobe Separation Angle 112°
Intake Centerline 107°
Intake Timing @ .050" Open 5° ATDC
Close 29° ABDC
Exhaust Timing @ .050" Open 44° BBDC
Close 10° BTDC

[jhow66]

Buy you a timing light or take it to someone and have them to set it up to about 12* BTDC. Should be alot better.

[Steelawork'n]

Yes, get a timing light, but the first time with it, also set up a vacuum guage to your system. When you adjust your timing, you're trying to achieve the high possible stable vacuum pressure (when the needle is stable), and then note that possition with your timing light. You can also set your carb adjustments the same way. It's really simple, just watch the needle and try to achieve the highest stable vacuum reading.

This method also trains your ear to the sound of a proper running engine.

I have a Holley 600 on mine and with power brakes I get around 22psi. With out the brakes I get close to 30. (Thats on a 283 bored 30 over with an RV cam).

[john]

Heres some tech tips from GMC Pauls. Scroll to bottom for vacuum tips to adjust carb with guage.

http://www.gmcpauls.com/Tech%20Tips1.htm

[noahdallas]

Thank you everyone for the help... I finally got sometime today to tinker with my timing. I am going to pick up a vacuum gauge tomorrow and do some more tinkering. I uped my timing to 12 and it seems to be running better. I am still have a small backfiring under the truck. It sounds like a spark plug fouling out? If that makes sense. Anyways I really appreciate the important info from every one responding.

[qksilver]

Another way the old timers used was to , if auto, to put it in reverse and rev against the brakes, then turn the dist until it pinged and then back it down a little.
Safety issues, use emergency brake and block the wheels and who ever is turning the dist do it from the side. Cheap and easy, but first make sure your idle mixture and speed are adjusted, then do the timing then readjust the idle speed and mixture again
Just a flat rate trick............

[Steelawork'n]

Never figured out why they did it that way. I helped my dad tune his engines all the time. The fact is, if the engine is old you can't tune it to specs any more cause it's slightly outa whack. And, if you have it rebuilt with extra improvements, it can't be tuned and the Jiffy Tune and Lube cause they tune it by the book.

Bottome line, get to know your engine and how it likes to be set. You set it a 12 degrees and it still needs a little tweaking. It's ok to tweak it a little beyond the 12 or under until it runs good.

[Steelawork'n]

I let my friend install an intake and a carb on mine a few years back and he was telling me I had valve problems cause he couldn't get it tuned properly. Well, I knew it had a cam in it so I got my Vacuum guage and adjusted the carb settings...he had it strangled.

Another thing I noticed was he install the distributor weird so the vacuum advance slapped the intake so tuning was limited. So, I pulled it and rotated it a dropped it back in so it had more freed of movement.

Needless to say, I have no idea what it was tuned at when I got done with it...it only took me 15 minutes...but it runs great. The vaccuum guage was reading around 30 psi. My friend was totally surprised at the outcome cause I didn't even pick up the timing light. Oh, gas mileage is ok if I keep my foot out of it.