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Topic Review (Newest First)
05-24-2019 08:17 AM
55_327 And if you want a thinner oil for better protection on cold starts, and less power-robbing:

Mobil 1 Formula M
5w-40
Phosphorus: 1000 ppm
Zinc: 1100 ppm

That's 25%-30% more than most modern oils.

https://mobiloil.com/~/media/amer/us...pecs-guide.pdf
05-24-2019 06:03 AM
75gmck25 Many contributors to the board have their favorite choice for high zinc and phosphorus motor oils; however, some are racing oils or special purpose blends that are harder to find and sometimes more expensive.

For several years I've been using Mobil 1 15w50 synthetic, since it has 1200 phosphorus and 1300 zinc, and I can get it at Walmart and most auto parts stores. It also goes on sale frequently as part of store promotions. YMMV.

Another weird option for oil purchase is to buy it on Amazon. I was looking online for an oil filter for my BMW and Amazon popped up with an option to buy oil also. They had no issue with free shipping of a five quart bottle of oil.

Bruce
05-23-2019 10:15 PM
BogiesAnnex1
Quote:
Originally Posted by scotty57406 View Post
i was tuning my sbc engine and after checking timing,float level and adjusting carb i set my idle rpm to 750 in neutral since it is a stick car, being that the flat tappet cams lobes are only oil splash lubricated i got to wondering if a cam with stronger springs need more idle rpm to ensure adequate oiling, i know the older cars had about 600 rpm in gear but the cams and springs were somewhat lighter
and lower lifts were used than we use now, any thoughts ?
scotty
Its a good idea to keep the idle up especially if this is a modern cam with short ramps and high rates of lift, the latter includes using higher than stock 1.5 rocker ratios as these magnify the force between lifter and lobe.

The SBC has a mostly closed valley floor, most drain back is on the ends and that mostly at the rear since most installations tip the engine and trans slighly down at the rear. So the cam and lifters are almost completly dependent on crank throwoff for lubrication. The short solution is to use EDM solids, these are drilled in the base to supply pressure oil on the contact point with the lobe.

By inspection with the engine running it's a good idea to verify the flat tappet lifters rotate in their bore. Sliding on the lobe without rotation is an invitation to sudden death for these parts.

Bogie
05-23-2019 10:06 PM
55_327 Just use some good oil with high zinc & phosphorus levels such as Driven Hot Rod oil, or even Valvoline VR1 Racing oil in the silver jar. Don't use the jar (blue, I think) that's labelled "Not Street Legal". It has fewer, if any, detergent additives, and must be changed frequently. https://www.jegs.com/p/Valvoline-Rac...gin|0||P_SKU|0
05-23-2019 01:55 PM
techinspector1 Scotty, the main difference between "older" motors and today's motors is the motor oil. Back before catalytic converters, the oil manufacturers added zinc and other minerals to the oil to serve as "extreme pressure" lubricants to protect that little pencil point of contact between the cam lobe and the lifter face (roughly 250,000 lbs per square inch, depending on springs used). Later, when catalytic converters were introduced, the auto makers found themselves with an excess of warranty claims from the extreme lubricants finding their way into the converters and rendering them useless for cleaning up the exhaust. So, the auto makers put pressure on the oil makers to cease and desist adding the extreme pressure lubes to engine oils. Realizing that the flat tappet camshaft design being used at the time would not survive without extreme pressure lubes, the auto makers converted their manufacturing process to use roller tappet hydraulic cams instead of flat tappet hydraulic cams and all was right with the world. But wait, what about the hot rodders who wanted to continue to use flat tappet cams? Well, one fix was to add the extreme pressure lubricants to off-the-shelf motor oils and that's pretty much how it's done today. Adding enough chemicals to the oil to make a 1200 parts per million mix will generally protect the lobes and lifter faces on a flat tappet cam. MORE IS NOT BETTER. 1200 works fine. This tutorial may help you and others reading this post to understand.........
https://www.crankshaftcoalition.com/...ips_and_tricks
05-23-2019 11:08 AM
chasracer No. There's plenty of oil raining down on the cam from the valley area.
05-23-2019 08:55 AM
scotty57406
minimum idle rpms

i was tuning my sbc engine and after checking timing,float level and adjusting carb i set my idle rpm to 750 in neutral since it is a stick car, being that the flat tappet cams lobes are only oil splash lubricated i got to wondering if a cam with stronger springs need more idle rpm to ensure adequate oiling, i know the older cars had about 600 rpm in gear but the cams and springs were somewhat lighter
and lower lifts were used than we use now, any thoughts ?
scotty

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