Hello,
I'm working on a 300 engine rebuild and trying to locate rockers for and upgrade. I have read many posts discussing the use of Chevy Big Block roller rockers for the 300 six and they seem to be far more available than finding specific Ford rockers. Can anyone tell me if the following rockers will work?

Comp Cams Ultra Pro Magnum Rocker Arms
1.7 in. Chevy Big Block
7/16 studs
396-454 cid
Part # CCA-1620-16

Thanks ahead of time for any help and I already had my machinist prep the head for 7/16 studs

 

https://www.summitracing.com/parts/c...view/make/ford

These are what I used on mine. They're made for the 300, so they have the correct geometry and 1.6:1 ratio (which is what aftermarket cams will be designed for). They also come in 7/16" and 3/8" stud sizes.

The other perk is they fit underneath the stock valve cover. Usually, with the CBB rockers, you have to find a way to raise the valve cover up for clearance.







Lastly, they come in a set of 12.

 

I looked at those but really want to stick with the 1.7 range for my rebuild.

 

I don't have my own experience and I'm regurgitating things I've read, so take it with for what it's worth (basically nothing)...

My assumption is that the OP is looking for a "bolt-on" upgrade to increase lift without needing an aftermarket cam? This is where the 1.7:1 Chevy roller rockers could help, but not without additional work. As you said, valve cover clearance is often an issue, as well as push rod length. Needing slotted push rod holes or guide plate if they aren't slotted. Screw in studs if the rockers bottom out on the stock pedestals? What's the benefit of increased lift if the log exhaust is kept and is still a restriction? Same with the carb and intake? Anyway, as I said - I haven't done it so I can't say if the part number he chose would work. I'm going with an aftermarket cam and stock head, so I will get my lift from the cam.

@AbandonedBronco , didn't you at one time use the 1.7:1 rockers in your setup? I seem to remember you doing work with custom length push rods. Or, did you also need them for the HS rockers you posted above? Sorry, my memory is fuzzy.

 

Thanks Adam,
I realize other modifications will need to be made. Increasing the height of the valve cover, valve clearance, and push rod mods will be a few. I am mainly looking for options in the rockers in the 1.7 range that will fit the engine plan I am working on with my machinist. We already did a P&P and larger valves on the head, Will be upgrading the intake and going to an EFI exhaust set up. Finding quality USA made rockers that will work is somewhat of a challenge. I like the specks on the Comp Cam Pro Magnum series I'm just not sure if the particular ones I listed will work or if I need a different model type.

 

I didn't. The only rockers I've had were the stock originals, and then the 1.6:1 Harland Sharp rollers I have now. Just like, you, 81F, I got my lift from the cam.

 

I used the Comp Ultra Pro XD 1.6 ratio rockers #1826 without any problems.
https://www.dropbox.com/s/dlwsfdl82z..._0134.JPG?dl=0

What year head do you have.
Did you use the SI 1.94"/1.60" 4.810" long valves or the SBC 4.910" long valves?
Which cam are you looking at using?

 

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I used bbc 1.7 Crane roller rockers for a short time. I changed back to 1.6 when two of my rocker studs sheared off and my engine almost sucked a valve., which would have been like a gernade in one of the cylinders. What happens when you change to a 1.7 ratio is it moves the p.rod closer to the pivot point of the rocker, and it moves the p.rod closer to the opening through the head. Although I had a slotted head, the p.rod still touched. When you change the geometry a bit, it creates forces that the valve train is not designed for. In my case I was hitting 5k rpm before a shift, and boom. I can't imagine the force needed to shear off two rocker studs!

 

What's the deal with the 1.73 scorpion rockers then? They're made for the 300 specifically. I was thinking about them on my next build. They just bolt to the factory "bolt down" holes? Would the 1.73 ratio cause problems like stated above due to geometry?

https://www.summitracing.com/parts/scc-scp1059/make/ford

 

The Scorpion rockers are made for the 1985 and later heads which do not have slotted holes and may have a little more clearance.

 

I was waiting for the OP to answer but will post more info before hand.

The distance from the valve stem tip center to the rocker stud center is about 1.58" to 1.59"
The fulcrum length on a Harland Sharp Ford 300 roller rocker is about the same so the roller rocker tip sits on the center of the valve stem tip at 90 degrees.

A BBC or BBF fulcrum length is 1.65" so in order to get the roller tip pattern centered across the valve stem tip the rocker must sit lower than normal and barely get to 90 degrees at full valve lift.

There should be room to offset the hole in the rocker stud tower when drilling and tapping the 7/16 hole for the screw in studs so the rocker stud to valve stem centers are closer to 1.650" making it more compatible for the BBC roller rockers.
This also moves the pushrod towards the center of the thru hole in the head making more room for a higher ratio rocker.

 

Thank you all for the additional information. I wasn't aware that such an additional stress was placed on the rocker mount with the 1.7 change. I was looking to get a small performance upgrade without changing the cam but I guess that wasn't such a grand idea after all, lol.
I have spoke with my machinist prior to this post and discussed the scorpion rockers and he said two of his other customers were dealing with failures of there product so he didn't recommend them. That is why I posted to see if there were any better options out there.
Pmuller when you installed the Comp Ultra Pro XD 1.6 ratio rockers #1826 did you upgrade the cam from stock? I have a 1978 300 head, just got the port and polish completed and had the valve seats done. I am not opposed to upgrading the cam/valves if anyone has recommendations. I'm not looking for a race vehicle but rather a reliable daily driver that I will be putting a 5 speed ZF trans behind to help with the 70 mph highway speeds around here. The truck is a 1960 4x4 with a 3.70 ford 9 rear and a 3.73 dana 44 front that I rebuilt and swapped in from an F250.

 

Yes. The reason for the Comp 1.6 ratio roller rockers was because I was using a much larger cam with high valve lift beyond what the stock rockers can handle.
Cam specs: 232/232 .050" duration, 288/288 advertised duration. .534" valve lift, 112 LSA.
1985 CNC ported head with SBC 2.02" intake and 1.60" exhaust valves.
Quick Fuel HR 650 4 barrel carb on a Clifford intake and Hedman headers.

The Ford 300 has large 50 cu in cylinders, same as the 400 V8 with a head that has undersized ports. Even with a fully ported big valve head the port volume doesn't increase enough to effect low rpm response.
As a result the larger cams actually increase torque from an idle over the stock cam and produce a very wide power band.

On my combination the engine idles smoothly at 900 rpm and will break the tires loose at 1200 rpm in second gear (T18 tranny) and gets 18 mpg highway @ 70 mph, 2400 rpm, 15 mpg around town. 1977 2WD pickup.

Because the BBC roller rockers have a 1.65" fulcrum length and the 300 head valve stem tip center to rocker stud center is around 1.585" I had to set the rocker lower than normal to get the rocker roller tip pattern centered on the valve stem tip.
I would look at off setting the hole for the rocker stud back when the hole is drilled and tapped for the 7/16" screw in rocker stud.
If the distance between the valve stem tip center and rocker stud center can be increased closer to 1.65" the geometry will be better and the rocker tip travel across the valve tip can be decreased from .080" to .020"

 

Sounds like a great set up. Unfortunately I already had the rocker holes drilled to 7/16 so I can't offset them. Since you set the rocker lower did you need to adjust the push rod length also?