oil restrictor kit

As an addition to the above, the book I have states that two of the restrictors go into No5 main.

Am I right in thinking No 1 is left out and the other restrictors go into 2,3,4. If so whats the reason.

Horace

Google is your friend

Perfect thanks

Not so fast, sir! Adding oil restrictors to a block with ANY kind of hydraulic lifters will certainly cause annoying rattling noises at low rpms from oil starvation. I installed them along with a hydraulic flat-tappet SVO cam, and one 'expert' told others that my engine had a solid lifter cam in it from the ticking noises at idle. On my flat-tappet cam, the noise is still apparent after 40,000 miles/20 years but seems to have not caused any extra wear. However rollers are known to be sensitive to impacts so I can't say your rollers will last with restrictors, too. You need another opinion or two before adding those setscrews. Or simply play it safe and do NOT add the one at the #5 main that restricts oil to the left-side-only lifters. Good luck!

quote:

Not so fast, sir! Adding oil restrictors to a block with ANY kind of hydraulic lifters will certainly cause annoying rattling noises at low rpms from oil starvation. I installed them along with a hydraulic flat-tappet SVO cam, and one 'expert' told others that my engine had a solid lifter cam in it from the ticking noises at idle. On my flat-tappet cam, the noise is still apparent after 40,000 miles/20 years but seems to have not caused any extra wear. However rollers are known to be sensitive to impacts so I can't say your rollers will last with restrictors, too. You need another opinion or two before adding those setscrews. Or simply play it safe and do NOT add the one at the #5 main that restricts oil to the left-side-only lifters. Good luck!

FWIW, my engine builder said not to use a restrictor kit with a hydraulic roller cam and lifers for the same reasons Jack cites.

I installed the restrictors in my engine I recall purchasing two kits and not installing some of the restrictors. Hopefully George will chime in as I followed his recommendations the engine runs well with no unusual noises etc.

Thanks,good info and food for thought. Will have another good read of Georges stickys to see if he recommends anything on this.

However on my last engine I fitted the full restrictor kit with the two in number 5. I also had the lifter bores bushed for the smaller oil outlet which was highly recommended at the time. It gave superb oil pressure and I was running a Hyd flat tappet cam on that engine.

Fortunately I didnt experience any of the noise problems mentioned above.

I would like to fit this engine with Hyd roller cam. Never fitted this to a 351C before but I like these cams having had good results with them on my 302s.

OK the 302s don't have the oil delivery issues we are discussing on the 351c but is the thinking to leave the oil system alone if fitting this type of cam and lifter setupto a 351c.

What about the lifter bores and the std large oil outlet, is it best practice to leave these alone also and not to bush with the roller hyd setup.

Cheers
Horace

Folks have been installing cam bearing oil passage restrictors in Ford engines with the same scheme as the 351C (cam bearings fed by supply to main bearings) since I can remember. I am not aware of one person ever having a problem with their "tappets" after installing 0.060" restrictions in the oil passages supplying the cam bearings. As far as I can reason that is physically impossible.

So open up your restrictor kit. You'll find 4 small restrictors and one larger one. Toss the larger one away right now so you won't be tempted to install it, and so it won't confuse you. You're left with the 4 smaller restrictors. They have 0.060" orifices in them. I know this because I measured them back in the 1970s. The instructions say to install them in the cam bearing passages at journals 2 through 5. Groovy, do that. Back at the #5 journal that is the smaller, middle passage.

Pay close attention to Moroso's instructions to clean the passages as best as possible after tapping the passages.

In the aftermath of this installation you've possibly helped your engine's lubrication system a little. That's groovy too. It can use the help. BUT ... the cam bearing passage that needs restriction the most, the one that would help the most to restrict, is the one they left out; the passage to cam bearing number 1.

I'll continue in the next post.

The need for the oil restriction at cam bearing 1 is not as obvious, since it is does not share a main bearing lubrication passage in the same way cam bearings 2 through 5 do. Think of cam bearing number 1 as a very large tappet bore diverting oil from the entire main oil passage.

If you decide to restrict the #1 cam bearing passage you'll need another small restrictor. You may find a mate that has some extras laying around, or you may have to buy a second package. If you buy that second package .... throw the large restrictor away again, so you won't be tempted to install it.

The restriction for cam bearing #1 must be installed in the cam bearing number #1 oil passage mid-way between the main bearing journal and the cam bearing journal, just above the oil crossover (horizontal) passage. Where the red dot is in the picture at the bottom. If you install the restrictor below that cross-over passage you'd be restricting oil to the #1 MAIN BEARING, not the #1 cam bearing. This would not be a favorable thing to do.

(1) Installation of this cam bearing restriction requires partial enlargement of the oil passage between the first main bearing journal and the cam bearing journal with a 5/16” drill; the oil passage is drilled out until the crossover passage across the front of the block is reached. This creates clearance for a 5/16" tap, enabling you to tap the oil passage deeper within the block.

(2) Above the portion of the passage you enlarged, tap the smaller part of the same passage with a 5/16" tap. You're going to need a long tap with a reduced shank to do this.

(3) Screw the restriction into the threaded passage. The red dot shows about where that restriction will be located within the passage after it is installed. The red dot does not infer you are supposed to drill a hole there.

The picture below is of the front of the block, the oil passages are indicated by the yellow lines.

The cam bearing oil passage restrictions only help a little. Installation of tappet bore bushings with 0.060" orifices remedies 90% of the lubrication system's problems. Now the tappet bore bushings are the items that could possibly interfere with the operation of the tappets. But not to worry, based on personal experience and the experience of many others the bushings are perfectly safe for use with hydraulic tappets ... so long as the bushings are installed in all 16 tappet bores and the big restrictor is not used. Thus modified the performance of the lubrication system improves tremendously regardless of which type of valve train is chosen. A comment I hear repeatedly after someone installs the bushings is they'll never build another 351C without them.

Back in the late 1970s I decided I needed more horsepower, so I installed a solid tappet camshaft in my daily driver (1971 Mach 1 Mustang, 351C 4V, 4 speed top-loader, 3.91:1 gears). Installation of tappet bore bushings went hand in hand with installation of the solid tappet cam. My methodology deviated from the norm back then in that I installed bushings in all 16 tappet bores. After a few months I realized I had made a bad choice. I didn't like driving the car daily with that rough idling cam in it, so I reinstalled the hydraulic cam .... and a set of new Johnson HT900 hydraulic tappets went back into the tappet bores which had been modified with bushings. Nobody I knew had ever done this, so I had no idea if it would work or not. I had a spare engine standing by if it didn't. But as it turned out, the hydraulic tappets worked just fine with the bushings in place. All the way to 7000 rpm, which that engine could pull even with hydraulic tappets. No ill effects. The engine had over 200,000 miles on it in the early 1990s when one of my son's took the car for a joy ride that ended in disaster.

cheers Mike

Thanks once again George.

As mentioned, my previous 351c engine ran both the restrictors and the tappet bore bushings with a hyd flat tappet cam and thankfully with no ill effects for many years and miles. The benefits of good constant oil pressure made it worth it for me so thats the way I think I will go again.

Unfortunately the work to restrict no 1 is way beyond my capabilities but I will have a chat with the machine shop that will be doing my tappet bushings and check with them.

Cheers