1.6 or 1.72 rockers whats the difference

[5.0_GT_kid]

Roller rockers are a great mod, they relieve valvetrain stress, lessen oil heating by friction, and free up horsepower. Ford used 1.6 ratio stamped rockers on our motors, so using a 1.6 roller will maintain your factory valvetrain specs. 1.72 rockers create a little more lift and duration by magnifying the lift of the cam a little more than the 1.6s This is calculated by taking the length of the highest part of a cam lobe from the center of the cam, and multiplying it by the ratio of the rocker. Basically it's either "xyz" lift x 1.6 or "xyz" lift x 1.72, where the 1.72 ratio will result in more lift. The higher ratio can be good good because it essentially "beefs up" your cam a bit, and allows your heads to breathe better. It does have a down side though. Ford engineered it's heads to run with 1.6 ratio rockers, so everything is made to those specs. running 1.7s puts a little extra stress on the valve train, and can lead to alot of valve guide wear. That might be acceptable if you want to rebuild your heads every two years, but most guys opt for 1.6s because the tradeoff isn't worth it. I myself run 1.7s on a set of prepped GT40P heads, and I love 'em. They give my cam a little more balls, and they free horsepower. I don't plan on running my heads forever anyway, so the 1.7s work for me. They were also available at the cheapest price through a friend, which helped. I have no valve clearance issues, and my combustion chambers are smaller than stock heads, I have a bigger cam, and the bigger rockers. Think about the tradeoffs- more lift vs. longevity, and decide which ratio you want. I believe stock and Ford Racing heads are pedistal mount, but I'm not sure of the thread size. Once you've figured out the numbers you want/need, pick a quality brand and go to town!

That makes sense, but aren't the rockers on the 93-95 Cobra 1.7 ratio stock?

 

[joebeez]

at the time i didn't know much about the 5.0 mustang motor. before this car i hav been a straight chevy guy. i just didn't do enough home work.

 

[astronut1885]

No, Cobras have 1.6 rollers I think, whereas we got 1.6 stamped.

Joebeez- don't worry about it. good heads are easily found. mine came from Ebay, but a local Junk Yard can get GT40Ps out of any V8 explorer SUV for cheap.

 

[5.0_GT_kid]

No, Cobras have 1.6 rollers I think, whereas we got 1.6 stamped.

Joebeez- don't worry about it. good heads are easily found. mine came from Ebay, but a local Junk Yard can get GT40Ps out of any V8 explorer SUV for cheap.

Are you sure I could have swore that Cobras had the 1.7 rockers that were made by crane. I'll double check.

 

[86Cobra]

Cobras had Crane 1.7 roller rockers.

 

[astronut1885]

My bad then. Don't forget, Cobras are made by SVT, so I don't consider them to be normal ford motors. Odds are they were designed to support the 1.7s. They also came with GT40 Iron heads, not E7s. I'd like to think that SVT would take such considerations into account when they build those sweet machines. Look at the 03/04 cobra, it has a different block and internals setup then the Mach 1, which also has a DOHC, so I don't think it's fair to compare the Cobra GT40s to the GT E7s or normal GT40 or GT40P heads. Also, many aftermarket heads are designed to support the higher lift and abuse from bigger rockers and cams, but that's brand and head specific and requires a little more homework.

 

[Michael Yount]

Astronut - Cobra GT40's = 'normal' GT40's -- there's only one GT40 iron head - those same special heads used on the Cobras came on every soccer mom's V-8 Explorer and Mountaineer from 95-early 97.

 

[monsterstang70]

Ill take 250 for them because they are brand new. The only thing I did to them was take them out the box to check them out and thats it.
http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=1583

 

[monsterstang70]

Also got a set of E7's if you want them for porting.

 

[5.0_GT_kid]

My bad then. Don't forget, Cobras are made by SVT, so I don't consider them to be normal ford motors. Odds are they were designed to support the 1.7s. They also came with GT40 Iron heads, not E7s. I'd like to think that SVT would take such considerations into account when they build those sweet machines. Look at the 03/04 cobra, it has a different block and internals setup then the Mach 1, which also has a DOHC, so I don't think it's fair to compare the Cobra GT40s to the GT E7s or normal GT40 or GT40P heads. Also, many aftermarket heads are designed to support the higher lift and abuse from bigger rockers and cams, but that's brand and head specific and requires a little more homework.

True, they were more than likely made to support that. When you made the comment about 1.7's causing stress on the valve train I though you were referring to all heads in general, not just E7's