351c Oil system mods

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Feb 11, 2019 | 10:14 PM

Mercury100

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351c Oil system mods

Building a 351c for low end torque to move my 68 f100 for a nice cruiser.
After doing some reading I’m starting to have some doubt about the oil system.
Cam is from 1200 to 5500 rpm.
I won’t be racing or street racing.
Im thinking a good oil pump and stock clearances it will be just fine.
From what I’ve read these engines have oil starvation above 6500 rpm.

Feb 12, 2019 | 05:45 AM

Crop Duster

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From: Tri Cities, TN

Here is a link to a good article on the Cleveland. I only have oil restrictors to the cam bearings and a stock oil pump. My engine holds 60-65 lbs. of hot oil pressure at 2000 rpm, using Valvoline VR1, 20-50 oil. TMI sells a set of grooved cam bearings that look like they would be a real good idea in one of these engines. https://pantera.infopop.cc/topic/sti...ormance-tuning

Feb 13, 2019 | 11:21 AM

dogdays

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Well, hundreds of thousands of 351Cs were built and their rpm range was from idle to 5500 or in some cases higher, and most of them managed just fine with their stock oil system, at least as long as it took to wear out the engine. 400s and 351Ms had, I believe the same system and many, many more of them were built and ran without complaint, except for being low on power. My personal '77 400 is at 165,000 or more and although it did need new pistons and rings it is still holding oil pressure in the middle of the gauge during normal driving. So modify if you wish but it shouldn't make any difference in normal driving.
However, if the engine is going into a boat that will run with throttle parked at say 4500rpm for hours at a time, or if you're a drag racer and plan to rev past 5000rpm on a regular basis, then it needs the modifications. No argument.
I have a friend who "worried" himself into a new block for his racecar because he modified his oiling system according to some "Gospel truth" from an Internet Guru. Now he's back to stock and running fine.
Good Luck!
R.

Feb 13, 2019 | 07:13 PM

kopfenjager

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From: In the woods of Oregon

"The Pro stock Pinto book was adamant that 50 psi was the minimum allowable hot oil pressure for a Pro Stock motor; we applied that limit to street motors too. We didn't think it was wise to run the hot oil pressure on the ragged edge of the safe oil pressure limit either, so we relied on the 10 psi per 1000 rpm rule and made 60 to 70 psi the target hot oil pressure for our 351C street motors. Our target hot oil pressure was validated in the 1990s by Don Nicholson who was quoted in print stating 60 psi hot oil pressure that holds steady until the rev-limit was enough pressure even for Pro-Stock racing. Sixty psi could be difficult to achieve with factory components however after the crankshaft bearing clearances had been increased. There were three schools of thought regarding modifying the 351C lubrication system for hydraulic camshaft street motors:

(1) One school of thought preferred no modifications at all. Achieving 60 psi hot oil pressure with no modifications was possible only if the bearing clearances were within the range of the "desired" factory specification which was 0.0010" to 0.0015" main bearing clearance and 0.0011" to 0.0015" rod bearing clearance (the Ford manual listed two bearing clearance specifications, the "desired" specification and the "allowable" specification). We found however using the "desired" factory bearing clearances in a high performance motor resulted in bearing damage. I wouldn't recommend such tight clearances even in a motor for a "grocery getter".

(2) A second school of thought preferred following the advice given by Jack Roush in a 1976 story published in Hot Rod magazine. Jack Roush recommended a standard volume oil pump, the Moroso high pressure oil pump relief spring and the Moroso cam bearing restriction kit used in conjunction with 0.0020" to 0.0025" main bearing clearance and 0.0025" to 0.0030" rod bearing clearance. The motor's cold start oil pressure ran about 120 psi with the high pressure oil pump relief spring installed, enough to burst an oil filter canister if the driver inadvertently blipped the throttle. A Motorcraft high pressure oil filter # FL-1HP was recommended to use in conjunction with the high pressure spring.

(3) The final school of thought preferred a high volume oil pump to deliver more oil to the crankshaft bearings ground for 0.0020" to 0.0025" main bearing clearance and 0.0025" to 0.0030" rod bearing clearance. But installation of a high volume oil pump alone without taking any measures to control where the extra oil was flowing would also supply more oil to the camshaft bearings and the valve train. So to control the oil flowing to the camshaft bearings the small restrictions from the Moroso cam bearing restriction kit were installed, and push rods having restrictions in the tips were installed to control the oil flowing to the valve train. In this way the extra oil supplied by the high volume oil pump was routed as best as possible to the crankshaft bearings where the clearances had been increased. This was the lubrication scheme Ron Miller liked to use. Today we realize more oil is lost in the clearances between the lifter and the lifter bores than we imagined in the 1970s. There are also lifter compatibility issues today we didn't have back then. Today my preference is installation of lifter bore bushings in all 16 lifter bores and installation of cam bearing restrictions for all 5 cam bearings; for all 351 Cleveland's, in all applications. "

from this link,
G. Pence Nostalgia - 351C 4V Street Motors in the 1970s Aug 2011 - Classic Cleveland Tech and History - 351C.Net Clevelands Forever!

P.S. and I totally forgot about Tim Meyers oil mods witch consists of restricted cam bearings and a standard volume pump.

Feb 14, 2019 | 11:39 PM

SDDL-UP

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From: North Idaho

I would not worry too much about it. Tim Meyer makes special cam bearings to help keep oil where it's needed most, this is an excellent place to start since you'll be putting in new cam bearings anyway. I would not use a high volume oil pump in anything but a racing application. High volume pumps are tougher on the oil pump drive shaft and can fill up your valve covers if the oil drainback passages are not up to the increased capacity.

Feb 15, 2019 | 06:22 PM

mark a.

Lead Driver

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Another thing to consider is the crappy balance job the factory does. That isn't doing the main bearings any good.

Feb 17, 2019 | 04:18 AM

Crop Duster

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From: Tri Cities, TN

Balance

Quote:

Originally Posted by mark a.

Another thing to consider is the crappy balance job the factory does. That isn't doing the main bearings any good.

Boy that's the truth. The last 351C I had balanced was an original 114,000 mile engine. The machine shop called me an asked if I had any extra rods, "which I did" because one of the rods in that engine was so heavy they couldn't grind enough off of it to get it in balance.