Recommended Oil

[Zanzer]

John -

The clearance numbers you're quoting are from Haynes and the numbers I gave you are from Mitchell, which also correspond to the Chilton numbers. Who published your Festiva manual? (just curious)


Haynes specs .0007-.0014 oil clearance. Oil pressure = 28-43 psi @ 10000 RPM/43-57 psi @ 3000 RPM (hot). This is for both the Festiva and Aspire. The B series in both models are the same engine other than the cam and roller rockers used in the Aspire B3.

Both Mitchell and Chilton specs .0009-.0017 oil clearance and oil pressure at 50-64 psi @ 3000 PRM hot (no spec for 1000 PRM)

If I had the access code for my AllData discs I'd look it up on there. It would be interesting to see what they have just for giggles.


When it comes to the .0002 variance in oil clearance I think we're just splitting hairs. The 7 psi pressure difference between specs is a little larger, but still marginal when looking at the big picture.




Brian-

I agree. Anyone who goes through life just driving nothing but Ferraris and never experiences the awesomeness of a Festiva is truly missing out. Poor guy

Also, I like the 10psi/1000PRM theory. Sounds like a good "rule of thumb" and I'll be sure to remember it for future reference :thumbup:

[JohnGunn]

John -

The clearance numbers you're quoting are from Haynes and the numbers I gave you are from Mitchell, which also correspond to the Chilton numbers. Who published your Festiva manual? (just curious)


Haynes specs .0007-.0014 oil clearance. Oil pressure = 28-43 psi @ 10000 RPM/43-57 psi @ 3000 RPM (hot). This is for both the Festiva and Aspire. The B series in both models are the same engine other than the cam and roller rockers used in the Aspire B3.

Both Mitchell and Chilton specs .0009-.0017 oil clearance and oil pressure at 50-64 psi @ 3000 PRM hot (no spec for 1000 PRM)

If I had the access code for my AllData discs I'd look it up on there. It would be interesting to see what they have just for giggles.


When it comes to the .0002 variance in oil clearance I think we're just splitting hairs. The 7 psi pressure difference between specs is a little larger, but still marginal when looking at the big picture.

I've got four manuals. Here is a list with the information they contain about crankcase-to-journal clearance and oil pressure.

1. Ford 1990 Festiva Car Shop Manual
   • 0.0009-0.0017 inch
   • (HOT@3000 rpm) 50-64 psi
2. Ford 1992 Festiva Service Manual
   • 0.0009-0.0017 inch
   • (HOT@3000 rpm) 50-64 psi
3. Ford 1994 Aspire Service Manual
   • 0.0007-0.0014 inch
   • -
   • (These two lines appear in the Oil Pressure Testing instructions.)
   • 28-43 at 1000 rpm
   • 43-57 at 3000 rpm
   • -
   • (HOT@4000 rpm) 50-64 psi (Looks like it should be 3000 rpm.)
   • (HOT@3000 rpm) 50-64 psi
4. Haynes Ford Festiva and Aspire Repair Manual
   • 0.0007-0.0014 inch
   • 28-43 at 1000 rpm
   • 43-57 at 3000 rpm

Came across this post at www.mazdaforum.com which explains the 50-64 number. At the time of the post the writer was a senior member with 2,751 posts to his credit, so maybe he knows what he's talking about when he refers to that range as the "maximum pump relief pressure". I'm guessing a relief valve opens in that range and stops the pressure from going any higher. Please correct me if I'm wrong.

Something doesn't seem right about these pressure numbers. Since the pump is directly driven by the crankshaft shouldn't the pressure it provides be directly related to the rpm of the engine? For example, the pressure at 2000 rpm should be roughly twice that at 1000 and the pressure at 3000 should be three times the pressure at 1000. That seems to be confirmed by a change in oil pressure spec between the 1993 and 1994 Miata. The 1993 numbers were the same as the Festiva/Aspire numbers we have, but in 1994 they changed to

Oil Pressure at 1,000 rpm 15-28 psi
Oil Pressure at 3,000 rpm 43-56 psi.

And 15 times 3 is 45 which is very close to 43. Now, 28 times 3 is 84, not close to 56, but at that speed the oil pump relief valve may have started to open and stop further pressure increase.

Is it possible a mistake of this magnitude could go uncorrected over so many years?