409 in a 1935 chevy

[jwhotrod]

Took the car down to my frontend guy this morning and had the alignment checked and AC charged. Runs good, still messing with the idle/ iac little stuff. The engine when it got hot today oil pressure at idle dropped from 43 to 30 psi (30 wght oil)I'm thinking the distributor adapter sleeve in the block is suspect so I ordered a new one from show cars this morning. More to follow.

Big Jim

 

[yellow wagon]

Big Jim, keep an eye on that oil pressure. 30psi isn't bad so don't worry. I just feel a little better when mine is 32-35psi-ish hot. Mine spikes right up to 65-70psi with a blip of the throttle. Good work on gettin some miles on it. Can always go with a tick heavier oil too or add a little Lucas oil additive.

 

[jwhotrod]

I feel sort of silly, I have been searching for this oil pressure problem for awhile now, Sunday I went back thru the whole system trying to figure out why it wouldn't build pressure beyond 30 psi with a Melling high pressure/high volume pump in it and making 85psi on the engine dyno???? Well I found it, the last time I hooked up the remote oil filter setup it was hooked up backwards (in to in/ out/to out) instead of (in to out/out to in) thus running oil backwards thru the filter/pressure relief valve. Swapped the hoses, changed oil and filter just to be safe, and no making 45-50psi at idle 75-85 psi running. All is well. Leaving Thursday for the power tour.

 

[jwhotrod]

I must ask the question here, as I said above I was concerned with the pressure and last wednesday ran the car about 30 miles, towards the end of that loop the idle pressure @ a stop sign (800-900rpm) dropped to 20 psi but ramped right back up with the throttle to about 45 psi @ 2 grand running down the highway. When I posed the question to the GM tech guys here on the power tour they didnt think it was an issue. Have you seen this and what is your opinion????

Big Jim

 

[oldskydog]

Just a general rule of thumb is 10 psi for each 1000 rpm with a minimum of 15 at idle is what I've always heard.

 

[Don Jacks]

Do you have a "temprature gun' handy,I'm wondering if you're running into oil temprature issues? All engines will drop oil pressure at idle,but not usually this much.That said,no, I dont think you have any worries at this point.

 

[Stovebolt V8]

Seems quite normal to me

 

[62impala409]

I am like Big Jim when it comes to oil pressure. I like to see about 30- 35# at idle when up to temp. My motor idles at 900 and I use 15w40 oil to achieve those numbers. I had always wondered how the newer vehicles can have the constant oil pressure and temps with very little movement until I read that they use compensators on the gauges to limit the constant variations like we see on our after market gauges. The oil pressure gauge in my GMC truck varies about 5# (45-50) between idle and driving. The temp gauge goes to 190 and stays there until I shut it down. Leo

 

[jwhotrod]

Thanks guys, I am going to do some more checking with the temp and "stuff" I am convinced that it probably ok. Had a great time on hte power tour although it was a plan "B" trip (didnt have the sedan). I will let you know what I find.

Big Jim

 

[jwhotrod]

Well, when all was said and done I left the car at home and drove my wife's Lucerne on the Hot Rod Power Tour, and I was not the only one in "plan B" as it was. Great time ready to do it again next year.it did give me a chance to talk to 3 separate GM HP drivetrain guys over the week and they all said I should not be concerned with the Oil Pressure variation I am seeing, go home and drive the car and enjoy it!!! They said a rebuilt, hand assembled engine like this that drop from cold to hot (45-20 idle and 85-45/50 running) is very typical and since I had verified that it was oiling ok and everything, I could move on. since a friend with a 70 olds 442 w30 big block says his car does the same thing. Everybody understood my concern but felt it was unfounded.

NextBig trip is Des Moines July 5,6,7 onward and upward as they say!!

Big Jim

 

[jwhotrod]

There is trouble in river city, I thought I had this under control and on short trips it has been. This morning I took the car out on the toll road and drove east to rt 47 where I could turn around and come back, it is about 15 miles each way, Going east all was well cruising 70 mph at 2400 rpms oil pressure steady at 55 psi got off at 47 idled down and oil pressure at 800 rpms 20 psi. Got back up on the toll road west bound 3miles from home oil pressure starts to decay so by the time I got to ramp at 2ooo it is at 15psi and drops to8-9 psi at idle. another 1.5 to home pulled in the shop, shut it off and pulled the dip stick out-no oil in pan. Now I had modified the stick to show me where the bottom of the pan is so I could check this after I had found no oil on the stock stick a week ago. It seems as though there is a oil return problem in this motor because there are 7 quarts in the pan and 1 in the filter, so where did the oil go? Up in the engine because if I wait 10 minutes and check again it is right up on the fill mark where it belongs. It is a stock pan Melling M55A hp standard volume pump, Brad Penn 3ow oil and as I said it is full actually with 7 quarts in the pan it is slightly over full, however there is plenty of room for it below the windage trays. I am very discouraged I just cant seem to get past this motor it is getting very close to being very expensive garage art.

Big Jim

 

[Ronnie Russell]

Jim, As you know, the problem has to be a clogged drain back passage. A simple way to diagnose would be to run the engine for a while then shut it off and pull valve covers. If the drain back holes in the heads are blocked , the valve covers would be full of oil. A very messy way to check but at least you would know if the problem is head drain back. The only other reason I can come up with would be a rag left in the lifter valley.. Sorry I can't be of more help but I'm reaching for the not so obvious.

 

[oldskydog]

Just a few things to think about:
- Do you really have a HIGH VOLUME pump and do you really need it? Theoretically, it should just bypass any excess volume and not suck the pan dry unless running consistently over about 4000 rpm. Any obstruction in drainback as Ronnie mentioned, might be just enough to unbalance the scavenge/return process.

-I'm wondering if your reverse hookup of the remote oil filter might have damaged the bypass valve causing it to stick open not to mention the possibility of collapsing the filter....especially a Fram and some others. I know you checked and changed the filter, so collapsed filter is probably not an issue.

-If your engine was built between 20o4 and 2009, could you have installed one of the inferior thin casting Melling oil pumps which had a habit of cracking/breaking at the mount. Several horror stories of loss of oil pressure and finding the pump and/or pickup tube laying in the bottom of the pan.
A cracked pump housing might explain pressure loss, but not the empty pan.
The small 5/8th pickup tube could contibute to cavitating of the oil, causing a pressure drop. GM went to a 3/4 pickup about 94 to help eliminate this problem. Lengthy discussion here:
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=20&cad=rja&ved=0CIsBEBYwCTgK&url=http://www.nastyz28.com/forum/showthread.php?t=65870&ei=n5PMUdHcFYjRigLYuYHgCw&usg=AFQjCNG-HRUfBbjF3uQDwZUzXdSPR2Pn-A&sig2=xHxkVAgWkWKyBqwZOObTlA&bvm=bv.48572450,d.cGE

-Weak or broken spring in the oil pump.

- When you replaced the failed cam, was there any damge to the distributor gear? Does the replacement roller cam have a steel gear? If so, does the distributor have a compatible gear? Damage from that previous cam failure could be showing up again from worn /incompatible parts or small pieces of metal getting into the oil pump/ bypass valve.

-Is the remote filter plumbed with hard lines or flexible lines and if flexible, are they teflon?
Teflon lines can look perfectly normal but the teflon liner can be collapsing internally.

Just a few thoughts, as I am certainly no expert.

 

[models916]

Later W blocks had a lifter galley drain drilled into the filler tube boss to drain back to the pan thru the timing cover. If it's coming apart, might just drill the hole.

 

[models916]

I remember when I used a SBC to 409 adapter, it poured a lot of oil in the lifter galley. Seemed to be too much space between the two. 10w-30 is the thickest oil for on the highway use I would use, might have drain back problems with the thicker stuff at sustained speeds.

 

[jwhotrod]

This morning I pulled the valve covers off and find the oil drain holes blocked almost completely, I thought it was the head gasket, and may well be but we think the holes in the heads / gasket and the holes in the block are mismatched by at least 1/2 the hole. We can feel the block / gasket hole above the cast hole in the head with a welding rod probing the holes. All 4 holes seem to have this condition.

 

[oldskydog]

Weird. I can't believe the factory could mis-match the castings that much......way out of production tolerance. Probably the gasket.
That certainly explains the problem.

 

[Don Jacks]

Great going Jim,you found the problem,,,,,,,,,,,,,,,,Now to fix it.

 

[jwhotrod]

this pump was installed 11-12-2012 so it is not one of the suspect ones, as to the distributor it was changed since the cam failure as well. The pump is a high pressure standard volume pump M55A 85 psi relief spring. I changed the oil, and filter when I found my reverse hookup. This is all oil up in the motor and not draining back fast enough. If it was the pump or the filter I would expect the problem would be reversed, no oilin the motor all of it in the pan. I am not lying, when I say all 7 quarts were GONE out of the pan. Shut it off wait 10 minutes and it magically appears in the pan,

 

[jim_ss409]

This morning I pulled the valve covers off and find the oil drain holes blocked almost completely, I thought it was the head gasket, and may well be but we think the holes in the heads / gasket and the holes in the block are mismatched by at least 1/2 the hole. We can feel the block / gasket hole above the cast hole in the head with a welding rod probing the holes. All 4 holes seem to have this condition.

I don't think the head gasket even touches the oil drainback holes.
I don't think the hole you see from above goes all the way to the deck. I think it only goes part way, then gets intersected by another hole that goes into the lifter valley. The result is a passage that looks something like this... \__
If the two holes don't quite line up, that would lead to a problem and of course sludge could settle into the passage over time and cause a restriction.