Hot Idle Oil Pressure

[CV355]

We took the Mach 1 out for its maiden voyage yesterday.  All went well, no issues whatsoever.  I just drove it up to the nearby gas station to fill the tank, keeping an eye on every gauge.  When I fired it back up after filling the tank, I noticed the oil pressure was around 15psi at idle.  I believe idle is set to around 650rpm which I think is a bit low (engine smooths out nicely around 800, thinking about just leaving it there).  As soon as I put it in gear and started moving, it shot back up to between 45-55psi.  I do know that FEs are notorious for low hot idle oil pressure, but is this something I need to watch or be concerned with, or is it normal?  The other part to question is the Autometer sending unit's accuracy that low...

On a side note and somewhat related...  Let's talk cam and idle quality.  We all love the sound of a nice lopey cam, but the cause of that sound and behavior is essentially chaotic conditions in air and fuel volumes by valve motion not meant for low velocity.  There's very little load on anything at idle, and everything smooths out as load and rpm increase.  But, I have to wonder, is that aggressive cam behavior necessarily "bad" in the long run?  If I was asked that from an engineering perspective, I'd probably say "not by anything measurable," but I'd like to know your opinions. 

I have the TCP urethane motor mounts, which are pretty stiff, so the car shakes pretty violently at idle (part and parcel for having a big cam in a pony car).  However, I've had multiple other vehicles with big cams that didn't give me this sense of "everything is falling apart."  Is this just a perspective and something to get used to?  Rolling down the road at 45mph, the Mach 1 was surprisingly smooth and comfortable, but that idle is a bit wild...

[My427stang]

I would certainly idle it up a bit, the oil off the rods is beneficial for everything camshaft related with really no down side.  15 isn't too low, but I like to see more, it's a feel good thing though.  May want to put a test gauge on it and see to make sure

With the cam, it can't be that rowdy if idling at 650, but I wouldn't call it necessarily chaotic.  What you have is likely residual exhaust that can't escape and causes a poor burn due to the poor cylinder fill.  It won't hurt, but isn't efficient.  Once the RPM comes up, the negative exhaust pulse pulls that burned mixture out, and fills the cylinder more efficiently and actually more than atmospheric pressure alone at some points.  No issues, but would also clean up a little with a little more idle RPM

ON EDIT found your specs  287/295 on 110, with 9.5:1 .  That idle should not be that rowdy with 71 degrees overlap if it's idling closer to 850.  How did your tuning go?  Offer is still on the table and free to look at your global file and tweak it if you'd like.

Just takes a first class stamp on your email, always can delete and go back if you don't like it

[CV355]

I would certainly idle it up a bit, the oil off the rods is beneficial for everything camshaft related with really no down side.  15 isn't too low, but I like to see more, it's a feel good thing though.  May want to put a test gauge on it and see to make sure

With the cam, it can't be that rowdy if idling at 650, but I wouldn't call it necessarily chaotic.  What you have is likely residual exhaust that can't escape and causes a poor burn due to the poor cylinder fill.  It won't hurt, but isn't efficient.  Once the RPM comes up, the negative exhaust pulse pulls that burned mixture out, and fills the cylinder more efficiently and actually more than atmospheric pressure alone at some points.  No issues, but would also clean up a little with a little more idle RPM

ON EDIT found your specs  287/295 on 110, with 9.5:1 .  That idle should not be that rowdy with 71 degrees overlap if it's idling closer to 850.  How did your tuning go?  Offer is still on the table and free to look at your global file and tweak it if you'd like.

Just takes a first class stamp on your email, always can delete and go back if you don't like it

I took your advice on the timing and it cleaned things up to the point where I could drive the car.  Before that I was getting backfires and hesitation.  The delay from then until now was in that I had to do a lot of other "fixes" (swapped front springs for safer ride height, added a Leed vac pump for the brakes, modified the export brace, etc).  Part of the harshness was the PCV breather striking the export brace, so we re-fab'd the brace to clear it sufficiently.  I also only have about 1/16" clearance between the Cyl 5 upper header flange bolt head and the shock tower.  I cleared it out slightly but it's possible there's still contact there at times.

I'll give 850 a try and see if it clears up further.  I was still seeing 6" vac at idle, but I could see it dip as low as 12"-14" while cruising which was a good sign.  Street manners were fine overall.  It's just a matter of getting the idle a bit smoother so the engine isn't shaking the car apart.  I have no basis for comparison on what is "normal" for an FE car.  Mod motors, Coyotes, LS/LT, SBF, sure, but a big cube FE is sort of its own animal from what I'm seeing.

I think part of my issue is just being nervous about a new build and the rowdy idle shaking the car is making me second-guess all the torque values and paint dots I left along the way.  I'm obsessive but that doesn't mean I'm perfect...  I think some minor improvements to the tune and a few test drives around town will build some confidence in things.

[My427stang]

Well, there are so many obscure fields in the software, let me know, happy to help

I think there is something in there fighting you just the same, the offer stands though, it takes so little time happy to do a freebie

USe my screen name at yahoo.com if you decide to send your GCF.

BTW, here are some references to compare, both port injected EFI, but shouldn't change significantly

This is a 461 in my pickup, much less overlap at 60 degrees, but you can see the vacuum number on the handheld. 

https://www.youtube.com/watch?v=glqqIkB1POE

Here is one of my own car, this has 74 degrees overlap and 12 inches of vacuum, so a bit more rowdy but not much

https://www.youtube.com/watch?v=AtTEvZ2uQmA

[CV355]

Well, there are so many obscure fields in the software, let me know, happy to help

I think there is something in there fighting you just the same, the offer stands though, it takes so little time happy to do a freebie

USe my screen name at yahoo.com if you decide to send your GCF.

BTW, here are some references to compare, both port injected EFI, but shouldn't change significantly

This is a 461 in my pickup, much less overlap at 60 degrees, but you can see the vacuum number on the handheld. 

https://www.youtube.com/watch?v=glqqIkB1POE

Here is one of my own car, this has 74 degrees overlap and 12 inches of vacuum, so a bit more rowdy but not much

https://www.youtube.com/watch?v=AtTEvZ2uQmA

Those sound awesome! I'm tempted to take you up on the offer.  If I can't get things exactly where I like them here, I'll definitely be sending you an email.  In either case, I appreciate the advice as it has certainly helped so far!

[Stangman]

Once you get your timing right your idle shouldnt be 650 more like 850 like others have told you, even if you set it up were its 800 or so in gear.

[winr1]

Curious as to what oil pump is installed and what main/rod clearance ??

Also, upper an lower mains fully grooved or 3/4 groove ??

I rebuilt the 352 in my 65 F100 around  40 years ago, had right at 365 K on it

All 8 top rings were broken, 5 second rings were broken

Two ridges in bores, had to use a rat tail file to get the ridges out enough to run a ridge reamer through the bores

All inserts were worn to copper and thin, crank journals were worn and had deep grooves

I used a ball hone and water on the bores, sandpaper and a shoe string on the journals

Rocker shafts and rockers are grooved

Original oil pump, put a few washers to increase spring pressure

Had a never run 352 Ford donated to an Automotive school that my scrap man nicked, not sure how he got it into his station wagon

Rebuilt original 352 just to move truck around, still runs smooth today , 190 degrees, 700 idle, 27 psi at idle, 60 psi off idle

Heads are 60 and 61 with hardened intake and ex. seats.. valves are .030 with reamed guides, plain umbrella seals

Change plugs around 20 K, are clean ... points distributor

I reckon the bores may clean up at .040 over perhaps...




Ricky.