Gx390 Oil Amount
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mikelavite#72
Member
I run Valvoline VR-1 straight 50wt 24oz the engine at racing rpm will spit out what it dont want ...... it works for me but may not be what others do
I have to laugh at that mike. I have always said a engine will get rid of what it don't want. It's like somone telling me I over filled the coolant resivor. Um nooo. It will puke out what is to much! thats why we run catch cans on our engines! Catch cans will catch the oil. On edit. there is a point were to much oil is to much. Obiously you don't fill your car to the top of the valve cover. But just a tad over won't hurt anything.
BigBoreDinosaur
New member
I run 32oz. of 62R in mine. I barely get enough oil in the breather lines to turn them pink.
mikelavite#72
Member
OP is on a 15* mount, you're setting him up for a seizure at 24oz. 32oz is one quart, recommended factory fill on a flat mount. I'm also on a 15* mount with my 420cc predator and I can keep about 44oz in the engine. Still having good luck with the Maxima 4T synthetic blend 5w-30 motorcycle oil, passed 6 hours of hard asphalt sprint racing on this motor so far and have done nothing but change the oil every race day.
mikelavite#72
Member
i have been racing Big Block OHV Engines for over 2 years now . i also use 15 deg. mount have always ran 24-26oz of oil and never had a issue with seizure of a engine .
Just because it is a saying that I use often. No harm met. I just got a chuckle out of it cause after I read the OP post I was going to say something along the lines that you said. Easy killer. Not laughing at the oz of oil you use. Just the get rid of what it don't want part. I really say that alot. Like I said. Can you really over fill a coolant resivor? Yes! Does it hurt anything to over fill a coolant resivor? NO. Apple to oranges but hopefully you see what im getting at.
mikelavite#72
Member
jsstump#70
Member
Good question. The ring manufacturers typically reccomend .004 per inch of bore. Thats roughly .014 on these 390s and 420s. Thats way on the large size for most builders. Ive heard some of the 196 clone guys going as low as .002. Thats a little tight IMO. If I have oversized rings and need to gap them, I shoot for.008 or so. Im sure many have gotten by on less but I dont feel the performance gains are substantial doing so. Problem is, one must buy oversized rings typically to be able to have enough "ring" to grind down to what you want. In doing so, you greatly increase the ring tension and drag, so the gains of a super small gap are offset by this. Thats why many heat and de-tension them. Good luck
A lot of it's probably my application, I'm on a 18 turn asphalt track that is right hand turn dominant and one portion of the track is taken as one big sweeping RH turn for 8-9 seconds. Pulling well over 1G cornering forces the oil was getting pinned up against the side cover and running the rod dry. We had problems with Clones Honda's WF's. The 1st year the track ran 4-stroke someone was losing an engine every race day until we figured it out, almost to the demise of the class as the 2-cycle racers and the track owner were getting tired of the track getting oiled down. We're all running as much oil as we can keep in them now, with much better results. The excess purges into the catch can, doesn't hurt anything. In fact if you put in say 50oz, and you measure 6oz in the can after a race, you know the engine will keep about 44oz.
Unfortunately our 4-cycle racers collectively have over a dozen motors with big holes blown in them due to advice to run only 12-14oz of oil
chris41936
New member
Good question here. I'm new to a 390 my self the guy I got it from told me to keep 28-32oz in it. I only race oval dirt tracks, does that sound correct?
mikelavite#72
Member
its could spit some out at you . i run 24oz and do fine