Race Engine Forum UK

Hi Guy and all others readers,
I'm trying to solve a lubrication problem, which I have had since I did an engine rebuild about 2 1/2 years ago.

The engine in question is a Fiat 132 2L (in a 124 Spider) which I built using instructions/suggestions from The Book (to the extent my student economy allowed). It has dual IDF40's, Pittatore 304 degree inlet cam (nominal lift 10.75 mm), original Fiat 1608 exhaust cam (both timed at 110 deg). Pistons and head (ported, using the instructions from Guy's book and homepage) from 1800 124 Coup’‚©. Everything is balanced, lightened,etc.
Original cast 4-2 manifold and downpipe, single straight through muffler, 2 1/4 inch exhaust. It also has a SAAB 9000 Turbo oil cooler (11 row I believe), and 72 deg C termostat.
You'll find some photos of it below.

It runs well, but I'm considering building a new engine to see if I can do even better the second time around.
Before doing this I'd like to solve the problems that I've had:

-I have noticed at a number of times, when I'm driving hard
on twisty roads, that the oil gauge starts to flicker, due to the pump sucking air. I have decided to build a big wing trap-door sump, according to Guy's recommendations, to solve this problem.
There are some photos in the book, but there used to be a series of very detailed photos covering this on the web page but I couldn't find them now (perhaps I'm looking in the wrong place?).
Would Guy, or anyone alse who has detailed photos of this type of conversion done to a 124 sump please consider posting them. It would be a great help to me!

-Another question I have is about oil pressure level, particularly at idle and low rpm's. When running 10W40 Shell Helix Ultra I have 10 psi / 1000 rpm on a hot engine, measured with a calibrated cap. gauge. When I switched to 20W50 it got slightly higher.
My gut feeling is that this is slightly low at low engine speeds (<2000rpm), and especially 700 rpm idle. When I searched the forum at Mirafiori.com the opinion seems to be that this is an acceptable level, and Guy's book mentions the same level. Since I built the engine I know that all measurements are well within spec, and the oil pump was brand new when fitted (unknown manufacturer however). Considering this I would expect pressure to be higher.
-Does Guy or anyone else have any suggestions on how to increase pressure, or isn't this necessary?

I couldn't reach the pricelist on gcroft.com but I noted earlier that there was an oil pump performance/overhaul kit of some sort available.. Would this be an option even if my current pump only has 10.000 km's on it? I have heard that quality of new oil pumps can be very poor.

Any suggestions/help/ideas in these matters are greatly appreciated!

Thanks to all and especially to Guy for this great forum.
Best regards,
Emil Aberg

Hi Emil

great photos and interesting post, well done;

Big wing sump design, see:

http://guy-croft.com/viewtopic.php?t=48 ... =wing+sump

I'll come to back to your other questions, but for now the price list is in the GC Virtual Workshop under Tuning.

GC

Hello Guy,
Thank you for your super quick response. The photos were just what I needed. Looking forward to read your thoughts on oil pressure.
Thanks again!
Emil

Emil,

first I'd say I would not run that motor on 40 grade oil; it is just my preference, I am not a big fan of the lower viscosity oils and never will be whatever claims are made for them. I would go to 50 or higher upper temperature viscosity. These engines have old-fashioned oil pumps and as I have said on other topics the leakage rate from the bearings could potentially exceed the pump delivery, noting of course that with a wet-sump unit the pump is delivering not pure oil but 'aerated' oil and, in cornering, maybe just air/crankcase gas.
Use the most expensive oil you can get is my advice, the oil is the hardest working component in the engine.

As for oil pressure I would not worry overmuch about low idle oil pressure, provided that the pressure jumps up when you press the throttle. That said if it drops below 10 I'd expect some crankpin/aux driveshaft/bearing or conrod big-end out-of-round problem.
10 psi per thousand rpm is OK and with an oil cooler and associated oil lines I'd be looking for a minimum of 55psi under load at higher speeds, you may not get more than that, although with the oil pressure relief valve shimmed up you can get more. Remember that the hotter the oil the lower the pressure at the gauge, try and keep it at 85-90 deg C.

I can certainly rebuild the pump and restore it to where it should be using good donor parts if required or polymer coating. You are right, there are counterfeit pumps on the market, I don't who is making them, theya re distinguishable by being milled on the mounting face rather than lathe-turned (which they are on the OE ones) and you'll never get get them to fit.

GC

GC

I was always told Guy, that the best Oil pump was the 131 Sport type. Is this true?
Good oil for these twincams are VALVOLINE 20/50 RACING OIL and CASTROL MAGNATEC 15/40 [my favorite], and oil pressure should be minimum of 10psi per thousand revs.

Andy.

It's possible to buy Shell Helix Ultra in 15W-50, but only in 20L drums in Australia. Many of the local rally teams use it. It's quite cheap per litre in that quantity and I now run it in everything I own, including the Honda whipper snipper!

For more on pumps see:

http://guy-croft.com/viewtopic.php?t=26 ... t=crescent


GC

Guy, Peter, Andy,
Thanks for your suggestions and useful tips.
I have switched to Valvoline Racing 20W50 (couldn't find the Castrol oil mentioned) and I was out driving quite a bit during this weekend. The difference is quite significant, and I now have around 15 psi/1000rpm (never less, usually slightly more). Interesting that the difference can be so great even compared to the other 20W50 oil which I have tested.

I'll stick with my current pump for now since pressure seems alright (yes, it bounces right up as soon as I increase rpm's from idle) but I might get in touch with you Guy, if I decide to switch pumps when I fit the big sump..
Can't remember if the pump was lathe-turned or milled but it fit without trouble so I suppose it was OK.

A question re. the big sump: Instead of measuring the photos and trying to figure out the measurements: Approx how much did you shorten the pickup, and how high are the "boxes"?
Thanks again!

Best regards,
Emil

I used elf 15w50 "semi"synthetic oil and it was o.k, except for long long turns, my warning light turns on at 30psi (for security reason). Starving must be the reason as it is a Beta, even with trap door and baffle tray.

I switched to mobil1 0w40 thinking of better protection: more expensive-more protection. Wrong?, i don't know.., pressure droped when oil was hot (80⼠or more) in comparison to the elf (at least 15psi less). Some peple tell me that even less pressure, still protects better. What do you say?

Emil, I just wanted to compliment the work on your car. It is very nice!
I would like to ask if modifying the head for better oil flow back to the pan would help the problem of oil starvation in turns? The reason I ask is I have heard of several owners with this concern, but I have not encountered it, even with 10W30 oil and turns at 7k rpm.

Tico, hi.
If you want to keep that nice motor in one piece get rid of the 0W/40 oil and use synthetic (or semi) with 50/55 or 60 high temp viscosity rating.

Denise, hi
No, modifying the drain-down does nothing to eliminate oil starvation, sorry. If only life was so easy. Let's put that one in the bucket with crank scrapers - what d'ya say?!

Anyone with oil starvation problems on an otherwise good motor, with baffled sump and oil grade as above - and running Gc recommended engine coolant temp 75-80 deg C and oil temp 85-90 deg C is strongly advised - by me - to fit an oil pressure accumulator. Yes, this is (in part) a plug. I keep them, see GC list in V/W and article on same if you don't know what they are. I don't brag about the lowest prices in town but I don't keep these on the shelf for show, and despite my best efforts to pursuade owners to use them for high performance driving I have sold ONE in the last year. 1.5 qt Moroso is plenty big enough unless you're doing Le Mans. They are an engine saver.

GC