I have a 1997 F-150 longbed standard cab with the 4.2 V6 and 4r70W tranny and 3:55 gears, I have recently upgraded the exhaust to the flowmaster kit 17304 which is a catback single inlet dual side outlet kit that exits behind each rear wheel, The kit has the 50 series muffler and it has a nice sound and I am happy with it, I have also fabricated my own cold air intake kit that enters thru the stock fenderwhell location but I am designing a kit that will enter thru the front bumper cutout and be close to a ram air type setup, I am considering several other upgrades to my truck and one is roller rockers which are pretty much a bolt on upgrade without having to tear the engine apart too much, after that I am considering a chip or tuner but figure to go with the rockers first, My question is what is the ratio on the stock rockers because I have found several roller rockers with ratios ranging from 1.7 to 1.83, Secondly what can I expect as far as hp/torque increase with roller rockers, I use my truck as basic transportation and also for pulling my tractor occasionally so I want to keep and possibly increase the power on the low rpm end for my truck, I figure the roller rockers will free up some hp/trqe due to friction loss but what about the gain from a rocker ratio change.

Any comments/suggestions are welcomed

Val

 

I remembered a thread from a few years back....

I believe stock is 1.73

https://www.ford-trucks.com/forums/3...r-rockers.html

 

Hi Brian and thanks for that info.
Val

 

Can anyone confirm that the 3.8 and the 4.2 use the same rocker arms, I have done several part searches and they use the same part number so I am pretty sure they do but I contacted a supplier that had a listing for 3.8 roller rockers and they advised they would not fit my 4.2 and that they were not available for my engine.

I realize that any performance gains will be very modest but if you add all the small gains up from the exhaust,CAI,Roller Rockers and later the chip then realistically the gains could add up to a 5% increase(10 +/-hp)

Again thanks for any responses.

Val

 

Here is a response I received back from a well know performance parts(roller rocker) manufacturer and this is what they had to say.



My inquiry: Hello, I am considering installing a set of your roller rockers on my 1997 Ford F-150 pickup, My truck has a 4.2 V6 with auto trans and 3:55 rear axle, Can you tell me what kind of realistic performance gains I can expect from your roller rockers, my truck is stock except for a cat back flowmaster exhaust system and a cold air intake ., I use my truck as a daily driver and am looking for improvement in the low to mid rpm range. Would the 1.73 or the 1.8 ratio rockers be better suited for my application.
Can you confirm that your S40018 and S40173 are direct bolt on replacements over OE(stock) and will not require different length pushrods or head machining

Their response: "The S40173 and the S40018 are both direct bolt-on applications and should not require any changes to the pushrods or machining of the heads. Either one will give you better performance usually around 8-10 RWHP but you will definitely notice better throttle response. The S40018 will give you about .015” more lift than the S40173"


The rockers in question sell for around $320 for the set plus shipping so it is a moderately expensed upgrade but it is an upgrade that I can do without having to tear the engine apart and it does reduce the friction load on the engines valvetrain, I think the 8-10 RWHP is probably a high estimate.

Val

 

I contacted Harland Sharp and was able to order a set from them, I got the 1.8:1 ratio and will install them as soon as they are delivered, I will update this thread when I have the rockers installed and have had a chance to see how they do, After that I plan on installing a chip or using a tuner and I will be looking for any reccommendations on what others have used on their 4.2

Val

 

The rockers came yesterday afternoon and I started to put them on around 10 am and finished by 12:30 , They went on very easily and the truck runs quieter and seems smoother, I have not taken it out of the driveway yet so I can not comment on any performance gains, I found 2 pushrods that has significant scarring on the ball tips so I went ahead and replaced the whole set, The pushrods could have been contributing to some of the valve train noise but it sure does sound quieter with the new roller rockers

Val

 

Great update!
Thanks for keeping us posted.

 

Now that I have had a chance to road test my truck with the new roller rockers, My feelings and these are only my feelings as I do not have a Dyno to make any test is that the expense and relative minor labor of installing the 1.8:1 roller rockers was a good investment on a hp per dollar basis, The truck runs smoother and quieter and has a bit more pep throughout the rpm range, I would not say that the difference was a seat of the pants grabbing experience but there is a definite difference that is noticable to me and especially during acceleration from a dead stop, I feel that the roller rockers combined with the flowmaster catback exhaust and the self modified cold air intake has made a very noticeable difference over stock, The total cost when added all together was less than $700 did not involve any major modifications to the vehicles engine or drivetrain and most important was something that I was able to do myself without having to pay someone, My estimate(again just my feelings) is that between the 3 modifications I have been able to free up/gain an additional 12-15 horsepower and probably a equal amount of torque, My primary use for my truck is hauling my 14' trailer with either my Kubota tractor with front end loader or my other smaller tractors and lawn equipment or firewood so my goal was to make any gains in the lower rpm range(idle thru 2000) which is where the primary use of the truck occurs, This I have accomplished and the truck was road tested this morning with the trailer and kubota in tow, acceleration was smooth and constant and cruising at 60-65 mph felt like I was not towing anything. I would still like to add a chip but at this point I am very happy with the performance of my truck.

Val