Aaron Klein

Hey guys

I'll start with I'll have to do my searching all over again to find the exact model but months back I had been thinking in my head how cool it would be to have roller lifters in the 4.0 as well as roller rockers (which I'm aware there's a kit for) when I looked I couldn't find a set of roller lifters for the 4.0.

In my searching what I did find however was that there was an AMC built V8 that shared the same standard lifters with the 4.0 and said V8 did indeed have a roller lifter setup available as a drop in replacement.

MY question is theoretically since they both take the same standard lifters would it be possible to install 6 of the 8 corresponding roller lifters in the 4.0? Would there be other issues I simply am not foreseeing?

third coast

What is your end objective? Are you creating a high horse power race engine where every last bit of intake and exhaust flow improvement count and money is not a consideration? Even if they fit the following should be considered: the engine will need stiffer valve springs to accommodate the faster and harsher response that a roller gives you; stiffer springs demand better rocker studs so that they are not ripped out of the head; a new cam with more aggressive, higher lift lobes will likely be on tap to take advantage of the faster responding lifter, standard cam bearings benefit from enhancement to accommodate higher loads, roller rockers to go along with it often require a higher valve cover, larger valves and head porting for improved flow, etc. Someone will probably say they just put in roller rockers and experienced significant HP improvement. I would be interested in seeing before and after dyno data.

Aaron Klein

Well you've given me something to think about. I wasn't trying to build anything super powerful rather free up and wasted friction energy that may be present. I did know they could lower the friction in the valvetrain but I can't say I was fully aware of the "harsher" response you're warning me about. Is this do to the a lack of hydraulic dampening? The fact they're solid?

even of it's a route that isn't worth it for me in the end the discussion can easily go on in case someone with big power in mind come around searching.

I'd still love to know if the idea is sound even if I don't wind up doing it myself. Remember were talking theoretically here for the time being.

s346k

ive given this a lot of thought, myself. the conclusion i drew is it would not be worth the effort to convert unless one had a purpose built race engine. i believe the roller design is better in all aspects. however, i don’t think the inefficiency in the engine lies in the flat tappet lifters and small cam profile. cool idea but you had better know what you’re doing as many small things will need attention to survive.

Aaron Klein

Well thank you very much! Not to worry even IF I ever go that deep into the mods on my jeep that isn't something super high on my list. As I said it's just something I've thought of several times in the past and I'm truly sure it probably isn't one of the things wasting noticeable energy.

I'll probably post another question regarding it in more detail but I'll say that one of my main objectives with the jeep has to do mainly with the fact I'm blessed with at least somewhat better mileage then most people locally seem to have with the same model. Ever since I've noticed this I've always been interested in mods that aren't particularlyaimed at producing more power but rather doing more with it's stock fuel consumption. I.e. I'm planning on upgrading from the stock single hole injectors to the newer 12 holes. I'll be likely to install a better flowing muffler a new cat and a better air filter setup to reduce a little bit of pumping losses and on the table also is possibly installing the 99+ intake manifold one day as well as soon as I can find some more concrete evidence that it really helps with low end. So far I've only read posts filled with conjecture on that subject. And possibly an exhaust header instead of the current manifold but one of stock diameter so I can keep velocities up (and who doesn't like that sound). Obviously I'm not against any of the small power gains the combination of mods could all accumulate to but I was never planning on going crazy.

third coast

Some time ago there was a good article on what works and what does not to improve horsepower on the Jeep 4.0 engine. It is interesting to see how little HP gain many of the mods provide. When you look at in dollars and effort per HP many engine performance mods don’t make much sense for a Jeep application. Jeeps were designed primarily for utility and off road capability, not to go fast. Also realize that the HP gains typically only come at a narrow band of conditions such as RPM, so you will not consistently achieve that HP gain in typical use. I prefer to trust data, in this case dynamometer results. Here is a link to the article. Spend your money wisely.
http://www.fourwheeler.com/how-to/en...ing-true-lies/

Aaron Klein

Thank you that was really straight forward and critical for me. It actually confirmed a lot of what I suspected as well. I never really thought any of those would add a ton of power but as a combination they can all help a little bit. Which is all I was really looking for honestly. And not even so much for maximum power but to boost up those mileage numbers.

according to the article most of the mods I've mentioned would work well together minus the intake manifold. Which is both a surprise and not a surprise at the same time. I'm not surprised because of course the older style has a lesser volume keeping intake velocities up and promoting better air fuel mixture at low end (which is what I'd prefer) but at the same time I'm surprised that the manufacturer would make the decision to do this is if only hurts performance. (One wonders if the writers in fact put the ecu in fast learn nlmode so it might take advantage of it) ehh they're probably smart enough for that. But regardless I didn't want to buy one if I didn't have to. Cold air intake was a plus and it's also not expensive really. I was always gonna do a custom setup using a hood louver to feed a short ram intake for that quicker response mentioned. That should be really nice along with the injectors. I was also surprised that a throttle body spacer helped even the tiny bit that it did I had never considered that. I don't expect to punish the pavement with the jeep at all but by the time it all adds up it should at least be noticeably more fun to drive and still better on gas then currently.

I should also mention that if I am interested in improving any rpm band it would be the low end more. But that said I'll restate I'm not going for much nor am I expecting a lot either.

It may take some time but I can do it all one project at a time and it should be entertaining at the same time. Thanks again for the link to that article. Most enlightening.