Gasket matching cylinder head

Looking for a little guidance gasket matching my reman cylinder head. I have a 89 xj 4.0 auto. I am using a fel-pro gasket and ther is a lot of meat to chew off the exhaust ports, should I open them up to the size of the gasket??All the intake ports have very little material to remove. Just seems like a lot to take off.thanks

I would suggest asking a race shop with experience on that particular head. It would suck to remove too much and cause a hot spot or get into a water jacket or oil galley. You may be better off to just smooth it out, maybe even polish it.

o you have the old head? if you do take an inside measurement of the port with a caliper. And use the measurements from each port against the other port. Then Start porting the old head keep track of the amount of material that you remove. Once you know what you can remove take a machinist rule and mark the new head ports with some machinist dye and start grinding away.

Intake ports can usually stand to be cleaned up - be sure to make it a more gradual taper going into the head (usually, if I have to clean 1/16" off at the gasket surface, I'll make the blend go in at least 3/16" inch - so 3:1) Also, cleaning up the surface of the intake port can be a help, but do not change the shape of the port! If you don't have a flowbench, you'll have no idea when (not "if," when) you start working against yourself.

Similar rules for the exhaust port, with the following strong notes:
1) Do not change the shape of the port or runner!
2) Leave the "step" there - it will help to prevent exhaust gas reversion (BTDT.)
3) The only work you can do effectively without a flowbench is just cleaning up the surface to reduce gas turbulence. Reducing turbulence will help with laminar airflow - which will help with flow efficiency. You don't want a mirror-smooth surface tho - just clean it up until you can barely feel the sand-cast texture. Ditto the intake port and runner.

The AMC242 manifold is "dry" (no fuel running through it,) so you've got rather more lattitude with port work and such than you'd have with a carburetted engine. Search up the side for Cratex Abrasives - they have an excellent DIY article that I plan to ask them if I can mirror one of these days. Their abrasive kits are relatively inexpensive and rather effective as well.

ok now time to get this done! From all the input I have rec'd from many differnt sources I will smooth but not polish the exhaut ports leaving the size and "step" alone. The gasket almost perfectly matches the intake ports, so a little fine tuning and chamferring will be done,as well as smoothing and polishing.I also plan on smoothing and polishing the combustion chambers. any input,feedback?

I took a little off the head and polished it a bit but ended up taking a lot more off the 2005 intake...

Nice! notice any difference?

Yes!
But I went from a tired 230,000 mile 4.0 Litre running on five cylinders to a brand new 4.7. :looney:

on a differnt note: I went here:http://www.geocities.com/JeepI6Power/screws.html
to get the head stud and nut size, it states either brass or bronze hardware why? Do you threadlock them in? Jeep wants $36 bucks perstud (idiots,everything I price I end up getting at the jobber) also what to torque these too?

nevermind cant source any brass/bronze ones anywhere up here, figures!

bcmaxx said:

on a differnt note: I went here:http://www.geocities.com/JeepI6Power/screws.html
to get the head stud and nut size, it states either brass or bronze hardware why? Do you threadlock them in? Jeep wants $36 bucks perstud (idiots,everything I price I end up getting at the jobber) also what to torque these too?

Click to expand...

Copper-based alloys won't seize against iron like steel will. Also, copper-based alloys will get incrementally stronger when heat-soaked and allowed to cool, vice getting incrementally weaker (like steels. Steel can be annealed at temperatures as low a 500*F.)

I use silicon bronze for manifold hardware, and I'll use brass nuts everywhere else. If you do have to use steel hardware, use SAE Grade 5, as it's a bit less sensitive to heat-cycles and annealing (due to not being heat-treated as extensively.) I have verified this experimentally - using heat-treatment ovens and test instruments available at school.

The same torque value may be used for brass or bronze as for steel - 19-21 pound-feet. I would suggest you go closer to 19 pound-feet and turn the screws slowly, as brass or bronze isn't as hard as mild steel (although quality silicon bronze can come close.) I've also found that a thin coat of RTV Copper on both sides of the manifold gasket doesn't go awry, and can help things all around. If you want to treat the threads, use LocTite #272 (or equivalent) or nothing. You don't really need "never-seez" on those threads, and they can work loose without help. Lubricating the threads can be counter-productive.

The studs aren't strictly necessary - they're a convenience. They give you something to hang the manifolds on while you start screws. You can cut them from brass or steel threaded rod (most steel threaded rod is HT to SAE3 or SAE5 anyhow) and get rod threaded 3/8"-16. Yes, the OEM studs have a coarse pitch on one end and a fine pitch on the other - there is a sound reason for doing so, but it doesn't really apply here. Making studs with all one thread will work just fine (I've done it a few times.) You'll only need two or three - both ends, and I've sometimes seen a stud in the centre top hole as well.

Are head studs a Renix thing? My Mopar block(s) all use steel bolts.
I went with ARP bolts for the new engine.