Oil recommendation for a 1986 L98 Corvette, please

[Finn]

Old topic revisited.

Vette has been sitting in my warm garage partially dismounted ie. engine, trans, diff unit are off. Original engine had all sorts of leaks so my idea was to put the 383 of above video in and be done with it.

The -78 Vette was going to get this Shafiroff 427 SBC I bought for it but in a brief moment of insanity I sold that one and decided to put the 383 in C3. So what to put in C4?

Rebuilding the original iron headed flat tappet engine would have cost a lot so I found this brand new 350 short block at the same builder who did my 383. All parts are new, block included. It has a funny Mutha cam in it so that has to go so this short block will get AFR 180cc L98 angled plug heads with 65cc chambers. Cam will be Comp Cams 260XFI HR12 and it will be fed with original TPI intake. I know I will leave somethin like 70...80 hp on table because of TPI but the torque... And this needs to have daily driver manners in and out of town.

Shortblock has high volume Melling oil pump which he will chenge for a std volume/pressure Melling. I think I would like to have Z28 oil pressure spring nevertheless if I decide to go with 5W30 or 10W30. All clearances are 'normal', he said.

AFR have about 4 week delivery time now so with some luck we can dyno the engine before Christmas.

Something to look for come next summer.

 

[BrocLuno]

OK, you are on your way. I like most of the build plan including the TPI for daily driven vehicle, good choice. The issue is not oil pressure. You'll have plenty no matter what pump you put in it.

I build the occasional SBC, and some to decent outputs and RPM. Last one I was involved with went 10.99 in a 48 Studebaker pick-up at Sears Point (I won't use the corp name ...). So stout is in the book.

I like to build them as droolers. That is extra oiling where it was a bit lax in the OEM config. The timing chain in these is not well served with limited splash and mist oiling. They are one of the first issues with aging motors. Yours will be fine when new, but as the miles accumulate ... I assume you will be using a roller chain... They like lots of oil.

So I drill the front lifter oiling galley plugs 0.030" each and let them squirt on the back of the cam sprocket. I also slot cut the lower boss ring on the distributor so it will drool a bit more oil on the cam gears. As the oil pump spec goes up (flow or pressure, or both) the load on the cam gear goes up too. This helps.

If you can make 50 PSI hot you will never have any oiling issues. I'd keep the HV pump and run the lowest spring pressure you can get. Yeah, I know seeing big oil pressure numbers is reassuring, but it's not the thing. High pressure saps HP unnecessarily and loads the cam gear which is not needed or wanted. Flow through the bearings is needed. And that is modest pressure and plenty of available oil. HV all the way.

20W-50 is a bit much unless you are doing back to back passes on the drag strip. You need some viscosity, but mostly you need an oil that will not shear down to lower grades easily.

You will be letting it sit for days at a time between drives, so synthetic drain-off is an issue. I'd run a good semi-syn oil in something like 10W-30 or 10W-40 (summer, track days) and call it good. 0W-30 or 40 would do too, as long as it's quiet on cold start after sitting ... Lifter clatter is OK, but no lower end noises at all on cold start.

The pan you pick is more important than the oil. You'll need a large pan and the pick-up in well baffled corner to stop oil starvation under heavy cornering. If it's mostly right hand turns, get a pan biased to load oil into the pick-up on the left side, or visa-versa. For drag racing the pan needs max rear sump. Get the pick-up within 0.10" of the bottom of the pan, and tack weld the tube in place on the pump body.

Use louvered windage tray vs a screened one. Let the crank blow the oil into the pan. Track days develop foaming issues. So the oil needs a good foam control additive. Ravenol, Motul and others make really good oils with decent foam control.

You do not need any USA oil. You have excellent choices in Europe. Anything on the Porsche A40 list will prolly do just fine

OBTW - I don't use Comp Cams for anything, but that's just me. I prefer Howards for most daily drivers. Crane for some, Schneider for others, etc. But even with a Comp, try not to use their lifters. Too many failures ...

Don't run needle bearing rollers. Use trunion rollers. Much stouter and more forgiving. One little needle comes apart and your motor will die ... I like Isky's trunion roller lifters: https://iskycams.com/cart/index.php?main_page=index&cPath=106 You can get them either solid or hydraulic. Just depends on where your upper RPM range is ...

 

[JeffKeryk]

It depends on valve spring seat pressure. It sounds like you are running a fairly mild flat tappet cam, so any good 5w30 should work. I have run Rotella 15w40 in my 68 L36 Vette (mostly stock) and original 65 4-4-2.
Going forward, one of the increased ZDDP oils makes sense.
FYI - If I ever pull one of these motors apart again, a nice roller is going in...
I like the Mobil1 15w50.
Here is a good link, from the Corvette forum:
Flat tappet oil analysis

 

[BrocLuno]

I believe his new motor is a roller ...

 

[Finn]

Yes, the new motor is with roller cam.

 

[1JZ_E46]

I’d go with an A3/B4 synthetic with the typical manufacturer approvals (LL-01, 229.5, A40). They should be readily available in your area in 5W-30 or 5W-40 and have solid additive packages.

 

[Finn]

Thanks, BrocLuno, for your advise, much appreciated.

I need to check the list what timing kit will be used - I do know that he does not use weak/bad brands and parts.

I'm fairly stuck with Comp Cams as that is what is in the country. In the 383 I have Crane billet roller cam - when I was bying a cam for that Comp Cams seemed to have too many quality issues.

I want roller rockers and, I'm afraid to say, Comp Ultra Pro Magnum is what is readily available. And I want them in steel and 1.52:1.

FWIW, a pro simulation program gives 427 lb-ft @ 3300 and 300 hp @ 4200. So it will be a steam engine.

 

[BrocLuno]

I have no beef with Comps roller steel rockers. They hold up well

Mostly I beef about their flat tappet stuff ...

Timing kit likely Cloyes ...

The thing about the TQ and HP curve you are alluding to is that it will be a hoot to drive. You will be grinning from ear to ear every time you stab it

 

[Finn]

Got the engine home today. This is what it made with GM ZZ4 intake and Demon 750 carb ie. 410 hp and 421 ft-lbs.

Cam is Comp Cams 260 XFI and heads AFR 180.

TPI manifold will cut 100 horses off the hp but the torque should be just plenty.

 

[Franz]

Any 10w40 would do a perfect Job in your engine I would use Shell Helix in the blue bottles or any other 10w40 brand! Would be good as well in winter and summer! Also oil Burning would be less than a thinner grade like 5w30! My personal recomendation would be Selenia 20K 10w40 available at eBay.de for a good Price and reliable protection for 20000kms!