How to make power in a carbed 2.8?

[cardana24]

I have a 1985 Jeep Cherokee, and with the 2.8 it is soooooo slow. I know this will never be a fast vehicle but I would like to not feel in danger when merging on to the highway. What can I do with out boosting it to make a little more power? I like this Jeep and the engine runs well and only has 100k miles on it, so I would like to give it a little more pep. Thanks for any advice.

[geoffinbc]

People like to add the Weber conversion kit. It really wakes the motor up. A new cam and headers will also make a difference. Headers are usually considered the best bang for the buck.

[montess408]

i would got with headers and dual exhaust and then a edelbrock intake with a 390cfm holley carb for starters and if you wanna tear in to it a cam would defenety wake it up

[cardana24]

People like to add the Weber conversion kit. It really wakes the motor up. A new cam and headers will also make a difference. Headers are usually considered the best bang for the buck.

where can I find a set of headers? I am really having trouble finding any thing at all as far as performance parts for this engine in a jeep platform.

Also how much will a Holley 390 cfm and a torquer II intake manifold add? Is there a noticible power difference? Has any one ever done a dyno compairson on the stock set up compaired to the Holley and torquer II set up?

[geoffinbc]

Well the best fit headers I can advise are S-10 headers. They may need some work to drop in. Or maybe they will drop in fine.

I cannot say how much power the Edelbrock intake and carb package offers. Maybe ask the Edelbrock techs how much the 2.8L power package they sell will gain you.

[IXLR8]

well to make a lil more power out of that old engine try this and tell me what you think.... most ppl are gonna think im crazy but i did it to my truck and it seems to make a nice lil difference.... take your old PCV valve and grind the end off of it to get the lilttle valve out... then stick it back in its original spot.... this will cause a vacuum to be created in the crankcase, should make a lil difference... try it out... if you dont like it your out what $2.00.... im getting a nice 3mpg more out of my blazer from doing this... the engine runs noticeable smoother at idle......

[Guest]

well to make a lil more power out of that old engine try this and tell me what you think.... most ppl are gonna think im crazy but i did it to my truck and it seems to make a nice lil difference.... take your old PCV valve and grind the end off of it to get the lilttle valve out... then stick it back in its original spot.... this will cause a vacuum to be created in the crankcase, should make a lil difference... try it out... if you dont like it your out what $2.00.... im getting a nice 3mpg more out of my blazer from doing this... the engine runs noticeable smoother at idle......

What do you think the PCV is supposed to do?

You'rs was probably clogged.

[cardana24]

so has any one dynoed any of the mods, or does anyone have time slips from before these mods and after mods?

[IXLR8]

mine was not clogged it was brand new i was just messing around with stuff... and the pcv valve normaly does cause vacuum in the crankcase but the one way valve limits it. when you take the one way valve out it creates alot more... its really hard to pull the oil cap off while the truck is running... The main reason i did this is because I have Chrome valve covers, and they leaked. now that i have modified the pcv valve i have not had a leak anywhere on this motor... the rear main seal quit leaking as well.

[CNCguy]

A year ago I would have laughed about opening up the PCV valve. But not so much now since I found that the LZ9 doesn't use one. It has a straight hose into the valve cover with no valve. I have never seen that before but it would make sense that it would keep the crankcase under vacuum.

[IXLR8]

It works quite nice try it out......

[Ray Hamilton]

On the LZ9 where does the hose come from that goes to the valve cover? Full manifold vacuum or ported? Or to the air cleaner? With after market covers you can put a push in breather in each cover and block the vacuum line. That makes it like the old time engines that just had a pipe running out of the block for ventilation. However, when the engine cooled it drew moisture into the block. Just like when the master cylinder was under the floorboard, drew in moisture and ruined the brake system. Early 50's it was moved to the firewall.
http://en.wikipedia.org/wiki/PCV_valve. You can't run full manifold vacuum from one side of the engine to the other, it'll cause a full vacuum leak and the vacuum from the source will suck the oil out, making it smoke at the least. About not being able to get your fill cap off, do you have a hose on the other side of your engine going into the air cleaner?

[IXLR8]

well i have had mine like this for about 30,000miles and havent had a problem with it.. No I dont its completly sealed off because the valve covers leak

[CNCguy]

On the LZ9 where does the hose come from that goes to the valve cover? Full manifold vacuum or ported? Or to the air cleaner? With after market covers you can put a push in breather in each cover and block the vacuum line. That makes it like the old time engines that just had a pipe running out of the block for ventilation. However, when the engine cooled it drew moisture into the block. Just like when the master cylinder was under the floorboard, drew in moisture and ruined the brake system. Early 50's it was moved to the firewall.
http://en.wikipedia.org/wiki/PCV_valve. You can't run full manifold vacuum from one side of the engine to the other, it'll cause a full vacuum leak and the vacuum from the source will suck the oil out, making it smoke at the least. About not being able to get your fill cap off, do you have a hose on the other side of your engine going into the air cleaner?

It has full vacuum to the front cover and a vent line from the rear cover to just ahead of the TB. The front line is restricted to around 3/16" diameter to limit air flow. The whole arrangement surprised me. I guess there is a reason for it but wonder how it will work when the engine starts getting some blowby.

Another odd thing about it was the size of the connector on the valve cover. It is the same size and configuration as the fuel rail connector and is around 4" away from it. It would be really bad to hook your fuel supply line up to the valve cover. You can see the fittings in this pic. http://60degreev6.com/gallery/files/...7_original.jpg

[cardana24]

So does anyone have any dyno proof or track times to show that there were substantial power gains from any of the mods that have been listed? Does anyone have a link to a set of headers I can buy? I think my PCV is working fine so I would rather not cut it. Would a cat back exaust help at all? What is the optimal size for these engines? 2 1/4"? Thanks for any help.