69 mach1 351w Roller rocker recommendation
#1
I have my heads off my 1969 mach 1 351w to replace piston rings on valve 5 & 6. While the heads are off I am thinking of installing roller rockers with probably a 1.7 ratio. Can I by scorpion pedestal mounted and use my stock lifters? I need some advise on best roller rockers to use and what exactly i have to buy.

The engine is all stock with a mild carb. I plan to use it for light street use.
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#2
Scorpion rockers arms are about the best in their price range. I use their Platinum series and am very happy with them. I don't know if that series is still available.

Are your heads 1969 castings? For 69 351W heads you need a stud mount rocker arm. For that you need to have the heads machined for screw in studs and guide plates. The only concern with a 1.7 ratio is if you ever do a cam swap there are very few cams made to work with a 1.7 ratio rocker arm. Most cams are for a 1.6 ratio and the lift can get to be too high with the 1.7 ratio rocker arm. I'd consider the 1.6 ratio and later a cam swap if you cannot do a cam swap now. A cam swap is not much more work from where you are now. You will also need hardened push rods when using guide plates. And the push rods may need to be a different length. You can check with Scorpion for the length or try one of yours for length and measure for a new length if needed.

To summarize: Scorpion rocker arms are good. You also need screw in studs, guide plates, and hardened push rods of maybe a different length. Consider 1.6 ratio and a cam swap instead of 1.7 ratio. Since a 7/16 stud and rocker setup is the same price as a 3/8 setup, go with a 7/16 setup because it is a little stronger. Also, a cam swap usually requires different valve springs so its easiest to do it when the cylinder heads are at a machine shop.

Best Regards,
Mike
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#3
I will switch to 1.6. Can I use my stock lifters or do i need the lifters scorpion sells ( i think they call it dog bone).
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#4
When you mention dog-bone, those are probably retrofit style hydraulic roller lifters for use in older non-hydraulic roller lifter compatible blocks. For the 351W that is anything older than 1995. The dog-bone portion of the retrofit hydraulic roller lifter is a tie bar connecting two lifters together to eliminate and lifter rotation.

If you motor is still stock it will have flat tappet hydraulic lifters. So, unless they are bad, you do not need any new lifters.

And truthfully, by nature of a flat tappet lifter and camshaft, it is not a good idea to replace only lifters or even mix them up. The reason is because on a flat tappet style cam and lifter setup each lobe on the camshaft is ground with a slight taper and the bottom of each lifter is slightly convex ( a small crown). This forces the lifter to spin while it travels up and down. If a flat tappet lifter doesn't spin the cam lobe will quickly grind through the bottom of the lifter. Under normal operation, after time a lifter and its corresponding cam lobe seat together which is why flat tappet lifters shouldn't be mixed up and only replaced of they are bad.

If you search "roller vs. flat tappet camshafts" or go to manufacturers websites like www.compcams.com you can find information and illustrations on the differences between flat tappet lifter and hydraulic roller lifter setups.

FYI: on your motor, you should use a high ZDDP content oil such as Valvoline VR1 Racing Oil or use a ZDDP additive. Otherwise there is a high risk of damaging a lifter or cam lobe on a flat tappet lifter setup. The ZDDP was removed from most oils several years ago.

Hopefully you're not further confused.

Best Regards,
Mike
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#5
Thanks for all the info. Since a few of the studs already turn and are loose then I will find a machine shop that can screw in new studs 7/16. Preferably the ones from scorpoin. Do you know what a machine shop might charge?
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#6
Am I correct in understanding that a few of the original press in studs are loose and turn? Or has a previous owner already installed screw in studs and a few of them are loose?

If Scorpion also has rocker arm studs, they should be fine. But for engine fasteners, including rocker arm studs, ARP is know as the industry leader. http://www.arp-bolts.com/kits/Product.ph...et1_page=1 Its a matter of selecting the correct length. Might need to contact ARP support for that. The machine shop might know.

Are you purchasing Scorpions rocker arms designed to fit under stock valve covers? Or do you plan on purchasing taller than stock valve covers? Most roller rocker arms don't fit under stock valve covers. The baffles around the oil fill hole and PCV valve usually interfere.

I don't know what a shop would charge. It's been a long time for me and my friend I've known for about 45 years owns the machine shop. They have to cut down the height of the boss to compensate for the hex thickness of the screw in rocker arm stud and the thickness of the guide plate, then thread the hole.

Best Regards,
Mike
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#7
The pressed in studs are loose and turn. I thought the scorption rockers would fit under existing valve cover if its 1.6 ratio. I'll have to research that to check
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#8
Yeah, look into it. I believe Scorpion Endurance series are advertised as fitting under stock height valve covers. I've heard some people modify the baffles if they interfere.

http://www.scorpioncheckout.com/Small_Bl..._s/197.htm

National Parts Depot sells stock height aluminum valve covers with baffles designed to clear roller rocker arms. They're actually nice looking period correct valve covers and still have the tab on top for the spark plug wire retainer.

Best Regards,
Mike
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#9
Mike can I use 1.6 all around?
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#10
I think you are referring to the rocker arm ratio of 1.6? If so, then yes. All the rocker arms typically have the same ratio. Actually, 1.6 is the stock ratio for 351W motors. In some race applications or a rare OEM application will there be different intake and exhaust valve rocker arm ratios. But small block Fords have always had a 1.6 ratio on both intake and exhaust valves from the factory.

Best Regards,
Mike
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