HO cams wont raise compression, if anything it will lower it a bit. The higher lift and duration a cam has, the more time the valves will spend off seat, or slightly open. Valve to piston collisions are more common with high lift cams, but the HO's are designed to work with stock internals, so it will not be an issue with these cams.

 

Well airram has the cams on back order so i will have to wait a little longer.

Hey horseapples i was thinking the same thing you said but when i mentioned to my dad he said he was not talking about copression ratio. He was saying that the new cam would increase cylinder head pressure and inturn when the intake valve open the more air entering the cylinder would cause more pressure in the cylinder itself.
So lets say at right now i have a cylinder at 160psi the new cam would with a larger lift and longer duration would cause that same piston to suck more air in and increase the pressure on that same cylinder to 180psi (hypothetically). He was saying that the increase of pressure in the cylinder could cause the piston rings to unseat, but now that i have confirmation people that have changed the cams with the about the same milage i do i am not worried anymore.

Thanks again everyone for the replies and i will keep yall posted on progress, it might take a couple of months cause i also have to get my house preped for sale.

 

im not a mechanic for any means, however I am trying to grasp on how your father says a cam will increase compression. The pistons, block, and heads are all still the same. the only thing that is changing is the cam lobes. Does anyone think like me, or am i still in engines 101??

 

I don't know what Air Ram is getting for them, although I know his prices are usually excellent, but Mopar Parts America usually has them in stock.

Even though many swap just the cam with no other modifications, Chrysler suggests going from the stock 6.69 coil, 4.28 diameter springs to the H.O. 7.30 coil, 4.77 diameter springs with that cam. They can't cost much from, even from the dealer.
I'm going to use the stronger Hemi 6.1 SRT springs when I do my cam swap in the Hemi to the KRC 210, and even those springs are only a little over $4 a piece from my local dealer. I doubt 4.7 H.O. springs would even be that much. Small price to pay for peace of mind, since you are going to have to be in there anyway, IMO...

 

I beleive what is he trying to get at is that the new cam will have a larger lift and a longer duration holding the intake valve more open than before and for a longer time. That means when the piston is on its down stroke it will suck in more volume of air than before. With a larger volume of air when the piston comes back up for the compression stroke it will have to compress more than beofre resulting in a higher pressure in the combustion chamber.

 

Yeah i looked up the new springs and they are not much so i am ordering them also.

BTW does anyone know the difference between the 4.7 and the H.O. heads themselves. I found a place the sells the heads without valves, cams, or anything and the part number is the same for both the regular and the H.O. heads. This got me curious and looked up the intake and exhaust valves and they are different part numbers between the two dioff heads. I figured if the vlaves wre differnt the heard would be also to account for the dieffernt seat or diameter. Anybody know more about this.

 

Heads are different. Here is a comparison chart between the 4.7 and 4.7 H.O. Engines, all modified/different parts on the H.O. are shown in red...

http://www.wjjeeps.com/engine.htm

 

I know that this thread is several months old But I couldnt resist, Ijust registered and everything here anyhow my questions are what about an engine with 100+K miles on it, Would that be Dangerous or a potential Disaster just waiting to happen? I Checked out Airram's page and asked a few questions but didnt think to ask whether or not excessive miles would be an issue, They Recommended Changing the Gear Ratio. Im fairly new to all this..It started with a few bolt ons and Ive went Hp Crazy, I always have been crazy about Mopar..Im confident enough with my mechanical skills. My other Question is They told me there that H/O cams Boost Low end hp but didnt say anything about Mid range or topend..Naturally Im assuming that I should see change throughout the Intire Powerband but a drastic change in low rpm range is that right or do they not affect top end at all?