Ford 300 rockers on 4.0

[kro10000]

So I remember this being mentioned in another thread, but did we ever determine if these rockers would work, and if they achieve higher lift?

 

I did some crossreferencing at work and found all the applications for these particular rockers:

85-96 anything with the 300

86 sable with 4cyl

86-90 taurus with 4cyl

84-94 tempo/topaz

 

I'm going to try to order a couple next saturday to measure, but I was wondering if anyone had any info

[Eagle]

I'm guessing the answer is no.

 

A lot of engines have a rocker ratio of 1.5:1, and increasing that to 1.6:1 produces a bit more lift. AFAIK AMC engines have always used 1.6:1 rockers, so there's nothing there to be gained.

[kro10000]

I'm guessing the answer is no.

 

A lot of engines have a rocker ratio of 1.5:1, and increasing that to 1.6:1 produces a bit more lift. AFAIK AMC engines have always used 1.6:1 rockers, so there's nothing there to be gained.

Well then I'll take some measurements of both Saturday and I will post my findings. It would be interesting to find an inexpensive way to get our engines to breathe better on the cheap. If you buy all the parts new it will be somewhere about $110, or if you find some at the junkyard in good condition, very cheap.

[kro10000]

AFAIK the Ford uses a 1.6:1 ratio, however it seems to me that it would still be possible for a rocker to establish a higher ratio in one head over another due to design differences. If in the Ford head the rocker pivot point is closer to the valvestem than in the 4.0 head, than that same 1.6:1 rocker on the Ford could be a 1.75:1 on the 4.0. Obviously there would have to be other coincidental specs on the rockers as well, like the distance for the pushrod tip to seat would also have to be correct, or close.

 

Anyway this is based on my own thoughts, so please correct me if my logic is wrong. :typing:

[dasbulliwagen]

:popcorn:

[SubSonic]

Yes, I too was upset that there was no follow up on the original thread. So I will be very, very interested to see the results. :D

[jeepcoma]

In addition to "specified" ratio of the rockers, there's an issue of quality control as well. In the LT1 world it's a popular upgrade the stamped "1.5" rockers with roller rockers (either full or tip) in 1.6 ratio. Beyond the stated improvement of +0.1 in the ratio (and better tip design), it's been found that QC was lacking in the stock stamped rockers. They could vary as much as -0.7, meaning you'd really be running a 1.43 ratio rocker, or even down to 1.40 if there is enough clearance and flex throughout the valvetrain (which explains why some respond so much more drastically to the upgrade).

 

I don't know if it's an issue with the Jeep motors, but it'd be worth measuring at least! :cheers: It's a shame Chrysler hated the 4.0 so much and made only minor changes over the years, I think there's a lot of potential for improvements with more modern components (especially since the 4.0 HO was so cutting edge at the time of it's release, and then basically left alone thereafter).