cylinder head mod question from a newbie

[blacktj44]

Im in the process of my first motor build and its a 4.7l stroker for my rock crawler. Its going into a 2000 tj with stock intake and exhaust manifolds. The block is a 1997 xj block and the head is off of a 92 xj. My question is with a stock cam shaft in the 97 block what if any modifications should i do to the cylinder head? Is larger intake and exhaust valve a good call? And if so which ones work with a stock camshaft? Also is it money well spent to port and polish the head? Any other suggestions would be greatly appreciated. Thanks. Also im not trying to go overboard in the money department, the wife is already giving me funny looks as it is. Im budgeting arout 400.00 including machine shop labor. I can go a couple hundred over that if i had to but that is it. Thanks again for the help.

[SilverXJ]

No advantage to larger valves. With the stock shaft no modifications need to be done.

However, you might have a larger problem. You might want to check your 97 block as the 00+ TJ block is vastly different as far as engine mounts and accessory mounts.

[blacktj44]

Yes im tackling all the accessory problems now and as far as motor mounts it looks to be the same.

[biscuit]

400.00 thats the deposit. lol. keep digging, you will find all your answers for free here. the parts and labor will get ya once you figure out what you want to do. great site, keep searching and asking. i got it half figured out, and my budget is over by 150% find dino's 4.0 performance site. dig there too. a lot of low buck diy stuff there.

[bigal389]

Fwiw I ended up with about $1600 in my 4.6 stroker. That was $600 in machine work $435 for Pistons, $100 for a 4.2 crank, $120 to have it re-ground,$100 for a Rebuildable 4.0 and the rest was the rebuild kit. That does not include the throttle body or tuning.
Al

[biscuit]

i would be the same, but i went for the p&p head, oversized valves, dished pistons, new cam, and a few other details. i started on a poor mans journey, but as i saw the details, i decided to spend a little extra. i little extra everywhere, adds up to a lot. I am gonna learn on this first build. however, i'd rather spend a little more now, than a little more or a lot more later. if my time was worth 10$/hour, i have over $2000.00 in time just pouring over information.

[blacktj44]

My bottom end is all finished up. Im just running a stock cam and was getting started on the head. My 400.00 budget was just for head work ive already got a head off of a 92 block. Just looking for suggestions on what to do in the way of head work.

[Russ Pottenger]

If your going to run a stock or near stock camshaft, stock diameter valves will be fine.
My recommendation would to locate a engine machine shop close to you that builds performance engines and
have them do a good 3 angle valve job. Have them lap the valves then do a back cut angle on the back side of the valve face.
Then, (this is the where the necessary experience comes in) have them blend the bottom 55 to 60 degree angle into
the port 1.500 to 2.500. We usually refer to this as a pocket port. If done incorrectly, the port will flow worse than if you left it alone.

A important rule of thumb is, the most critical area of a cylinder head port regarding airflow, is the area closest to the
valve seat. The farther you get away from the valve/valve seat the less benefits your going to receive.

If you still have money in your budget, installing hard exhaust seats is always a good idea. Lastly, at roughly $3.00 a valve
spring it's not bad to toss a new set in while your at it.