Changing viscosity on an older engine?

[RagTop69]

I've got a mildly built Ford 302 that I have been operating recently in ambient temperatures of 100*+. This is a 1969 block and low end. The engine has been heating up and I've noticed that the oil pressure is dropping off as this happens. I rebuilt the engine 49K miles ago and have been using Castrol 10W-30 in it since. The pressure starts at a high level because I installed a high volume oil pump when I rebuilt it, but starts to drop off when the engine gets into the middle range of my stock Ford "L-H" temperature gauge. With the pressure slacking at higher temps I am considering raising the oil viscosity to 10W-40 or 20W-50 Castrol. Would this be a recommended step or should I be worrying about the bearing clearances at this point. I'd hate to think that the rebuild lasted less than 100K miles, but I do have lower gears in the rear end and this could contribute to a higher level of bearing wear.

 

[CT8]

Have you verified the pressure with a real gauge?

 

[Kuato]

1969? No problem going 10w40 IMO.

 

[rrounds]

If you have 10 psi of oil pressure for every 1000 rpm your good. The only way to know is with a good gauge that reads in psi. So if you have 50 psi @ 5000 rpm I wouldn't change viscosity of the oil.

ROD

 

[RagTop69]

I don't have a "real gauge" in the car because I show it in a modified/stock class at car shows and like to keep it looking as original as possible.
I suppose I could temporarily mount a real oil pressure gauge to find out i f the problem is with the gauge, the sender or what.

 

[OneEyeJack]

Test if with a real gauge.

 

[demarpaint]

No way of telling w/o readings from a real gauge. Hot idle, and 2000 rpm would tell us a lot about what's going on. Or check a shop manual for what the pressure readings should be.

 

[FCD]

Does the engine have a flat tappet or roller cam? if it has a flat tappet don't use Castrol 10w30 GTX if that's wat you're using, it has too little Zinc and phophorous.
Regarding the oil pressure move up to an oil like Shell Rotella 5w40 or 15w40 and report back

 

[BigCahuna]

Have you determined that the thermostat and radiator are doing the best that they can do?. If the motor is heating up due to one of those misbehaving, it will still get hot no matter who's oil or, weight oil you use.,,,

 

[BrocLuno]

I'd try it with Rotella 5W-40 (T6) and I'll bet you'll like the results. It's a bit thin (as HDEO's go) on the 40 end, sort of more like a 35, but it will be stable to high temps (synthetic) and is a good all around oil for older USA V8's

I've got a 302 with worn bearings that thinks T6 is the oil to have

 

[Superflop]

Oil pressure will drop as temps go up. Its hard to tell without a real gauge but a 302 in general is one tough mill. If everything went right with the rebuild and break in then it's easy to assume you are ok. I've had more 302's than I know what to do with and with the exception of the last one they all got havoline 10/30 and a fram... care to guess how many I lost?
BTW I wouldn't hesitate to run t6 in a 302 just wasn't a thing when I had them.


Hint: count the number with your fist.

 

[FCD]

You live in California so cold starts are not an issue i'd run the cheaper Rotella T5 15w40 conventional diesel oil

 

[BlueOvalFitter]

Originally Posted By: BigCahuna
Have you determined that the thermostat and radiator are doing the best that they can do?. If the motor is heating up due to one of those misbehaving, it will still get hot no matter who's oil or, weight oil you use.,,,

+1. I would be looking at the cooling system. It's very possible there could be air in the system. Or, the water pump could be cavitating. Is the fan shrouded?

 

[RagTop69]

Yes, the radiator was out of the car about six months ago because I suspected it might be clogged. The guy at the radiator shop did a flow check and a reverse flow check on it and told me it was the cleanest used radiator he'd ever seen. I was present for the flow checks and it only spewed clear water. The water pump is a new aluminum unit. I installed a fan shroud right after I bought the car 19 years ago. I just replaced the original four blade fan with a Ford 5 blade unit. I have used a Flex-A-Lite fan on the car in the past but was told by the engine rebuilder to get rid of it. I am running a 160* thermostat and some folks contend that this t-stat doesn't permit the water to stay in the radiator until it gets cooled. I figure that the stock 185* t-stat will probably be slam open at the three digit ambient temps around here and, with either unit, it's still going to be a battle between the radiator capacity and the engine's ability to generate heat. The engine is running a flat tappet hydraulic cam but it is a little more aggressive than the stock Ford unit (single profile .224 duration at .050, and .500 lift) and I have a custom curved dizzy that runs best at 14* initial. I may try the Rotella as suggested on my next oil change, but I'm really not expecting the oil to do anything for my overheating problem. I would just like to maintain more viscosity when the little sucker heats up. Oh yeah, I almost forgot, the engine is bored .040 over, which the machine shop thought was OK, but I've also been told that Ford SBs don't like more than .030 over and could develop heating problems.

 

[CT8]

What is the total timing?

 

[BrocLuno]

So your custom curved distributor has a vacuum advance right? Something on the order of at least 12*~15* ... And it's plumbed to manifold vacuum, not to carb ported vacuum?

 

[etex211]

Originally Posted By: RagTop69
Yes, the radiator was out of the car about six months ago because I suspected it might be clogged. The guy at the radiator shop did a flow check and a reverse flow check on it and told me it was the cleanest used radiator he'd ever seen. I was present for the flow checks and it only spewed clear water. The water pump is a new aluminum unit. I installed a fan shroud right after I bought the car 19 years ago. I just replaced the original four blade fan with a Ford 5 blade unit. I have used a Flex-A-Lite fan on the car in the past but was told by the engine rebuilder to get rid of it. I am running a 160* thermostat and some folks contend that this t-stat doesn't permit the water to stay in the radiator until it gets cooled. I figure that the stock 185* t-stat will probably be slam open at the three digit ambient temps around here and, with either unit, it's still going to be a battle between the radiator capacity and the engine's ability to generate heat. The engine is running a flat tappet hydraulic cam but it is a little more aggressive than the stock Ford unit (single profile .224 duration at .050, and .500 lift) and I have a custom curved dizzy that runs best at 14* initial. I may try the Rotella as suggested on my next oil change, but I'm really not expecting the oil to do anything for my overheating problem. I would just like to maintain more viscosity when the little sucker heats up. Oh yeah, I almost forgot, the engine is bored .040 over, which the machine shop thought was OK, but I've also been told that Ford SBs don't like more than .030 over and could develop heating problems.




I'll bet that original four blade fan pulled more air than that five blade fan.