Crossflow Engine Rebuild - tips and Help (Harrison Kotrolos)

[Harrison Kotrolos 29]

Hi All,

 

I got a worked 250 Crossflow that I must pull out and tear down.

 

I've had to replace the flywheel and harmonic balancer, and it's starting to build some harmonics above 4000rpm.

 

Everything else seems healthy, but I thought I checked with the experts.

 

It's got a new STD Mellings Oil Pump (only about 9 months old), and running 20W-50, my oil pressure will range from 320 kpa (46 PSI) to 410 kpa (59 PSI).

 

Breakdown of oil pressure:

• Cold Idle: 380 KPA/55PSI
• Hot Idle (900RPM): 315 KPA/45 PSI
• Hot RPM (5000RPM): 410KPA/59PSI

 

How do those numbers stack up? I'll be upping compression for this next rebuild, and the car is used for weekends and tracking.

 

Should I try and raise the bypass on the oil pump a little? Get the RPM pressure up some more?

 

Any advice is welcome.

 

Also, where should I make a thread to track the engine rebuild and ask any questions I might have?

 

Thanks,

Harry

[deankxf 20,292]

57 minutes ago, Harrison Kotrolos said:

Any advice is welcome.

 

Also, where should I make a thread to track the engine rebuild and ask any questions I might have?

 

Thanks,

Harry

I can't advise any oil pressure numbers, it's likely listed in the gregorys etc though, 

feel free to start a project thread to document anything you do in the build. 

i could retitle this thread as your own even if it's mostly crossflow related 

 

@SPArKy_Dave may have more info, as he does checks like this due to being more meticulous. (I've either got someone to reco a full engine or chucked in a second hand one, and that's usually not oil pressure related, just extreme wear overall)

 

[Thom 6,651]

General rule of thumb for oil pressure is 10 psi per 1000 rpm is adequate, so in that case you have plenty, you can shim the pressure relief for a little more but unless you are planning to spin it over 6k rpm there's no need, as all you are doing with higher than necessary oil pressure is putting extra load on the oil pump drive, which other than breaking the oil pump drive can cause issues like spark scatter, excessive wear on the distributor drive gear and the distributor housing, in saying all that you do want to make sure you oil pressure relief isn't stuck open and moves freely as while you do have enough oil pressure to not have any problems I've routinely seen stock oil pumps provide 80psi when cold above idle and 65-70psi warm at 4-6000rpm on a freshly rebuilt engine, but that also depends on your bearing tolerances, reading your original post if the pressure relief valve isn't stuck i wouldn't change anything

[SPArKy_Dave 8,881]

5 hours ago, Harrison Kotrolos said:

Hi All,

How do those numbers stack up?

 

4 hours ago, deankxf said:

I can't advise any oil pressure numbers,

 

I'm probably not one to advise either, tbh...

I used to run my XF wagon, with the oil light flashing at idle on hot days.

 

I just thought it must be on the worn side, till I had the bright idea to fit a new oil switch one day.

Problem solved...

 

At the same time, I tested the pressure with a manual gauge.

25psi at idle from memory.

40-50psi whilst holding revs around 3k-ish rpm.

 

 

[Harrison Kotrolos 29]

7 hours ago, deankxf said:

I can't advise any oil pressure numbers, it's likely listed in the gregorys etc though, 

feel free to start a project thread to document anything you do in the build. 

i could retitle this thread as your own even if it's mostly crossflow related 

 

@SPArKy_Dave may have more info, as he does checks like this due to being more meticulous. (I've either got someone to reco a full engine or chucked in a second hand one, and that's usually not oil pressure related, just extreme wear overall)

 

 

Would be great if you can re-title the thread, will be all Crossflow related, think some people might be really interested in what I'm doing

Title - Crossflow Engine Rebuild - Threat and Help?

 

3 hours ago, SPArKy_Dave said:

 

 

I'm probably not one to advise either, tbh...

I used to run my XF wagon, with the oil light flashing at idle on hot days.

 

I just thought it must be on the worn side, till I had the bright idea to fit a new oil switch one day.

Problem solved...

 

At the same time, I tested the pressure with a manual gauge.

25psi at idle from memory.

40-50psi whilst holding revs around 3k-ish rpm.

 

 

 

Okay, so sounds like I'm on the money, I need to fix up my shroud for my oil cooler to be more efficient, as when it get's up to 50 - 60 degrees, my oil pressure will drop down to 380-390 KPA (~55 PSI)

 

6 hours ago, Thom said:

General rule of thumb for oil pressure is 10 psi per 1000 rpm is adequate, so in that case you have plenty, you can shim the pressure relief for a little more but unless you are planning to spin it over 6k rpm there's no need, as all you are doing with higher than necessary oil pressure is putting extra load on the oil pump drive, which other than breaking the oil pump drive can cause issues like spark scatter, excessive wear on the distributor drive gear and the distributor housing, in saying all that you do want to make sure you oil pressure relief isn't stuck open and moves freely as while you do have enough oil pressure to not have any problems I've routinely seen stock oil pumps provide 80psi when cold above idle and 65-70psi warm at 4-6000rpm on a freshly rebuilt engine, but that also depends on your bearing tolerances, reading your original post if the pressure relief valve isn't stuck i wouldn't change anything

Thanks Thom, will update the thread as I pull it down and re-measure everything. Bearings are already 0.030 bigger, and to get tighter clearances would require a re-grind and jumping up to 0.04.

I'm pretty happy with the oil pressure, probably could do with a better sump though.

[Harrison Kotrolos 29]

@SPArKy_Dave

Or anyone else.

 

C2 Alloy head, what spark plugs should I be using? I'm currently running NBK BP5ES, but you can also get NGK BRE527Y-11 for XF Alloy Head.

 

The BRE527Y-11 has a longer electrode and sticks into the chamber more.

 

 

[SPArKy_Dave 8,881]

3 hours ago, Harrison Kotrolos said:

 

C2 Alloy head, what spark plugs should I be using?

 

I've always used the long electrode ones myself.