2.3L engine higher oil temp than expected, jetting?

[mskala]

Trying to make this short and uncomplicated as possible. What AFR should
you shoot for on these air-cooled engines while cruising? I suspect I don't
have it right as my oil temp is going eventually to 230F after 20minutes or
so when it's 80F outside.

I had the O2 sensor hooked up after the build but was doing only the full-throttle
graphs.

Configuration:
short stroke crank with 86mm JE pistons, DC30 cams, 2.3L. Heads are 72 911T
but with those small ports opened up.
Weber IDA:
32 venturis
55 idle jets
135 main jets
170 air corrector
F26 tubes with 2 of the 4 topmost holes soldered up

This is in a 914-6 so no external cooler stuff. My gauges have been working
fine and last year when engine was 2.2L temps were better.

I don't have real data for cruise AFR, but it was below 14.7 or I would have
noticed.

Would like to make a change in the jetting that mainly affects low throttle
at highway rpms without messing up the full-throttle high rpm mixture that
I already like (attaching graph FYI)


Thanks,
Mark S.

[Trackrash]

I'm surprised you can get the 55 idle jets to run. I have to use 65 idles on my 2,5. My carbs are setup the same as yours otherwise. My oil temps would never go over 200 on the street.

[mskala]

Haven't heard of needed 65 idles in such a small engine before.

[mskala]

Also, I checked that thermostat was really open (only thing easier on 914 vs. 911).

[1QuickS]

Jetting looks OK. Be sure your Webers are IDA and not IDTP1 which were OEM for 914/6. The IDTP1 Webers have a different progression circuit design from IDA Webers and behave differently at transition/cruise than IDA Webers.

Typically main jets used with F26 E-tubes are larger than when F3 tubes are used but since you soldered two top holes shut the main circuit should come on a bit earlier and possibly be a bit richer through main circuit operation. If you wanted to affect transition mixture then I suggest adjusting idle air bleed jet size, these are not typically a tune-able item but they can easily become a tuning option. They adjust progression mixture just like the main air correction jets adjust main circuit mixture...larger jet size results in leaner fuel mixture curve with advancing engine RPM and conversely.

Double check cooling air paths on you engine for heat issue: fins on cylinders, air diverter plates attached to cylinders (there was a modification for these to help cooling efficiency), thermostat operation (you have performed this but check to see it opens at 180 degrees or whatever it should do) and radiator fins of oil cooler mounted to engine. Did you have your oil cooler cleaned/flushed when building your engine? Also check distributor for timing and smoothness of operation, spark plug selection for your engine. Check air flow balance of Webers at 3000 RPM.

[mskala]

Thanks Paul.
Unless I broke something, the majority of the engine is same as before as I went
from 84 to 86mm pistons/cyl but kept the rest. The engine was fine beforehand.

I do have IDA webers. I did the cutouts on the tin around the cylinders per Wayne's
book. The distributor is the same. Thermostat found to be fully open when I
stopped the car at this high temp but later I can confirm opening at 183. Oil cooler
is same one. New spark plugs this year are NGK 7 temp rather than 8 as used
before. Last month they didn't look bad, I will check them again for any signs.
I found some manifolds that were ported larger.

I had noticed the occasional lean pop at about 2800 at very low throttle, and
that's when I plugged the 2 holes of the F26, but I don't think it worked to fix that.
It's hard to guess when the display was changing all the time, but at steady
driving it's plenty rich at 2000, maybe 14's above 3000 on highway. Unless my
sensor was bad.

[1QuickS]

A little lean at cruise is fine. You can try opening the idle mixture screws a bit to see if that helps or perform "Lean Best" adjustment at 1500 RPM to help get idle mixture right when throttles opened up a bit. You want enough richness so that when you apply throttle at very low RPM the engine will take it and not hesitate.

I had 52's (!) for idle jets in my 2.3 with S cams but it is twin plugged. I now have 60s but I'm trying new throttle plates with thinning near the edges that sweep past the progression holes; this allows more air into the mixture than with when using constant thickness plates. I think 55s should be good for you.

I still do not understand the heating issue, I would expect a constant 180 temp in 80 degree ambient air during street driving.

[moneymanager]

Like Paul, I don't get the heating issue. Your carbs are close enough to normal that I can't imagine they are the problem. I'd look to a restriction somewhere.

[mskala]

Thanks guys.

Here's the latest experiment, we had co-operating weather here.

With everything else the same, I drove for 30+ minutes on highway to see
where the needle ended up stable.

Yesterday it was 55F outside, and the temp is approx 197.
Today it was 81 outside, and the temp is approx 229 (vertical needle).

The 914-6 gauge only has a few numbers, hidden, but especially vertical is
right on one of them.

So, I think that cooler must be blocked or something.

[mskala]

I think I'll start a new thread on coolers.

Possible relevant thing is last year I had a substantial leak that turned out to
be breather hose. Can the fins have enough oil on them that it doesn't cool?
I didn't steam clean it but it was not blocked by anything.

[1QuickS]

Hate to suggest but unless more sage advice follows I would pull the cooler and flush to see that what goes in comes out easily. Also, check your pressure relief valves and galleries in the block from the pump to the cooler, etc. I think there is something in there that shouldn't be. Perhaps a Gremlin dropped a surprise someplace during your build that is now manifesting itself.

[NICE 69 S]

Pacific Oil Coolers, 1677 Curtiss Court, La Verne, Ca. 91750
800 866-7335
Bob B

[mskala]

It may come to that soon

[mskala]

Update:
I can't afford too much downtime, so went with new cooler from stoddard and will
send my old one out for cleaning at my leisure, probably sell it.

Anyway, new oil cooler is in and temp was 80F again today, and where before I
was eventually getting fully vertical needle (helpful that that is one of the few
markings), now it is at most 1 needle's width to the left (colder). So, I went from
~229F to ~221F, not really even conclusive as different day, etc. Also I had my
sump plate on 'wrong', but because it's the aluminum Mainely Custom one I don't
think it mattered. Fixed that anyway.

So, definitely time to look at the relief springs/pistons.

Mark S.

[porschetub]

Presume you have rechecked your timing,you could try retarding it slightly and see what happens?,are your cooling tin seals in good condition....theres a lot of hot air to be drawn up past these seals if they are bad.
No chance your fan belt is slipping? it could be one thing causing the higher running temp or a number of smaller issues ,good luck

[mskala]

I did try retarding the timing way back at the beginning without effect.
All my tin is freshly painted and in good shape, but I don't use the heater
hoses so there are 2 holes where those would go. I didn't think of plugging
those as it is the same as last year, but it would be worth doing anyway. I
believe the 914 configuration is supposed to run slightly hotter than 911
configuration, but keyword would be 'slightly'.

[porschetub]

Originally Posted by mskala

I did try retarding the timing way back at the beginning without effect.
All my tin is freshly painted and in good shape, but I don't use the heater
hoses so there are 2 holes where those would go. I didn't think of plugging
those as it is the same as last year, but it would be worth doing anyway. I
believe the 914 configuration is supposed to run slightly hotter than 911
configuration, but keyword would be 'slightly'.

.

Plugging them will make quite a differance,I custom built some f/glass ones using the steel ones as patterns,not a job I want to do again as getting the fit right is a hassle,read once that correctly blocked off they can improve cooling around the cylinders.....don't really know however as my motors not in yet.

[mskala]

I removed both pressure and safety valves. Confirmed both are 70mm spring
and have the pistons with holes. Pistons and springs look good, seemed to slide
in the bore fine. I assume it's correct that the safety one requires you to compress
the spring about 1/2 inch before the threads on the cap engage?

I found a piece of something stuck in the pressure valve spring, just big enough
to be caught up in it. Looking under a microscope, it's a piece of paper towel or
similar. hmm. I'm sure that it was not blocking anything right there, but don't know
how it could get there. (Last week when I dropped the sump cover there was
nothing like that stuck to the screen).

[red 2.7]

Check that your temp sender matches the gage. I chased a "hot engine" for months till I found out that the sender was for another vdo gage.

[mskala]

Originally Posted by red 2.7

Check that your temp sender matches the gage. I chased a "hot engine" for months till I found out that the sender was for another vdo gage.

Thanks I did that back when it was first put together as a 2.2, so I know they
are matched.