0331 head change results

[winterbeater]

Casting molds always have different "mold numbers" on them. If we could look at a pile of bad ones, we could figure it out. Someone (who used to work) at Chrysler knows, but they took a buyout and agreed never to divulge this information. Personally, I'd get an older one with the better exhaust flow.

 

[Talyn]

Makes some sense - I know the exhaust ports were reduced in size for the 0331 casting, to "improve catalyst light-off" (keep gasses hotter until they get to the cat, and get the cat up to op-temp faster.) Still, it would seem that making the ports smaller into the larger tubes should not cause any significant trouble - I didn't think they'd moved them as well.

They moved the position of the ports on the 0331 head. I have a pic of the two head side by side as well as a pic of the 0331 manifold gasket on a 0630 head that shows teh problem pretty well. PM me your email addy and I will send the pics to you later tonight.

-Chris

 

[5-90]

They moved the position of the ports on the 0331 head. I have a pic of the two head side by side as well as a pic of the 0331 manifold gasket on a 0630 head that shows teh problem pretty well. PM me your email addy and I will send the pics to you later tonight.

-Chris

5-90 AT naxja DOT org will do - that's where I've been trying to route all my "Jeep tech" traffic.

Thanks!

 

[Talyn]

Sent

 

[bigalpha]

They moved the position of the ports on the 0331 head. I have a pic of the two head side by side as well as a pic of the 0331 manifold gasket on a 0630 head that shows teh problem pretty well. PM me your email addy and I will send the pics to you later tonight.

-Chris

Could you post that up here too?

 

[Talyn]

I am going to take some better pics this weekend and post them all up.

 

[Talyn]

Ok.. details... i did a rubbing of each head, scanned them and overlayed them, 0630 in red:

I also took some measurements of each head.. and did a very rough drawing.
0331:

0630:

 

[winterbeater]

I think my 0331 is cracked too although it still drives good, it uses coolant and the oil cap on the valve cover is milky. My Crown Vic cap is clean, so I am worried. Is the 0630, the best head to get for replacement? I've seen heads for as low as $50 around here on Craigslist. What years had the 0630?

As far as that aftermarket aluminum head goes, I would never put an aluminum head on a cast iron block. Escorts always had an issue with it and manufacturers had to develop special gaskets and weird surface finishes for the mating surfaces to make them work. We did the prototype machinings for the Ford modular engines and 3.8/4.2's when they went to aluminum heads and surface finishes were critical (computerized profilometer, etc.) It should be intuitive that you want the block and head to expand from heat at the same rate if you have a critical sealing surface between them. Yes, you can seal between aluminum and iron, but why? If you want aluminum, get an aluminum block too.

 

[winterbeater]

Talyn's dimensional comparison of the heads makes me wonder............Could the 0331 heads be cracking because the exhaust ports get so hot because they are only 2/3 the size of the 0630 head? Can the 0331 heads be ported out to 0630 dimensions to let the heat flow away better?

 

[92DripCherokee]

It's those back-to-back exhaust valves at 3 and 4. Awful hot there, with those narrowed exhaust ports.

If you did port a 0331, you'll have coil rail bosses, and 91-99 exhaust manifolds would fit...but that's a ton of grinding through nickel steel.

 

[ehall]

I wouldn't blame it on the exhaust ports exclusively--the '99 head uses the same manifold gasket, and it doesn't have the same problem.

 

[ehall]

Here are the fel-pro gaskets for 96

and 00

pretty big difference

 

[92DripCherokee]

ah yes, and the 99 head does'nt have the split, cast iron manifolds, it mixes the revised intake with the older, tubular exhaust manifold.
The 00 and newer intake manifold has a huge plenum, shadowing right over the hot spot at cylinders 3 and 4. The cast iron exhaust manifolds split there, and create thermal stress.

 

[ehall]

so it could just be the headers... that sucks

 

[92DripCherokee]

An infrared thermometer could prove if there's a serious hotspot at 3 and 4.

The so called "debris shield" recall for 00-01 was fishy. The "shield" is really an insulator. this thing is aluminized glass cloth. It probably prevents the vapor lock on injector 3, but likely makes the hot spot even worse.

A real debris shield would be a sheet of aluminum or something, like on the renix engines.

 

[tbburg]

Might have been covered elsewhere, but has anyone used a LATER model head? Rather then going '99-down, why not go '02 up?('say out of a TJ)

 

[5-90]

Might have been covered elsewhere, but has anyone used a LATER model head? Rather then going '99-down, why not go '02 up?('say out of a TJ)

Or a WJ/WK.

It would be a straight swap, and the general consensus is that the "Club" is comprised of heads from 1999, 2000, and early 2001 - so it would make sense to use a 2002-up TJ/WK head. But, how many of those are in boneyards right now?

 

[tbburg]

Ok, so it's a matter of supply.(or lack of,...)

 

[badron]

But, how many of those are in boneyards right now?
=======================================
They are just starting to show up. but are very pricey. They don't really want to pull them. They want to sell the entire engine from anything that new.

 

[75SV1]

I bought an '03 engine about 4 years ago. I used the block and sold the head to be used on an '00 with a cracked head. The head fit and had no problems, from what I heard. My neihbor did the work at a local dealership. I might have pictures of the ports from a Renix, '95 and the '03. I had heard somewhere that I was not sandblasting off the casting residue before the heat treament of the heads.
Tom