7120 for 0630

[brokenujoint]

I have a 97 0630 head and my vehicle is due for a valve job. I've also been building a stroker that has a 7120 head thats already rebuilt and ready. I'm wondering if the 0630 is a direct swap?

[604rail_king]

2nd post

http://www.jeepstrokers.com/forum/viewt ... f=34&t=241

[5-90]

I have a 97 0630 head and my vehicle is due for a valve job. I've also been building a stroker that has a 7120 head thats already rebuilt and ready. I'm wondering if the 0630 is a direct swap?

Mechanically? Mostly.

You'll need to fabricate an adapter plate to put the 7120 in place of the 0630 - or figure out how to fit the earlier exhaust manifold. The exhaust ports in the 7120 are larger than the 0630, and they won't necessarily be covered by the 0630 exhaust manifold

Get the manifold gaskets for both heads, fit them to a steel plate (something reasonably thick - I wouldn't go less than 12ga.) Fit the 7120 gasket to one side, drill holes to locate and drop bolts through.

Flip the assembly over, drop the 0630 gasket onto the other side. Drop flat washers onto the bolts, finger-tighten nuts onto the bolts to fix the gaskets in place. Scribe the outlines of the 0630 ports onto the steel sheet. Also, scribe the outline of the gasket (either one) onto the sheet.

Remove the gaskets, cut out the ports you've scribed. Cut out the outline of the plate. Dress all cut edges, using a fine stone drum in a Dremel or a fine file.

Install the 7120 gasket to the head, then the adapter plate, then the 0630 gasket, then the exhaust manifold. I would suggest using a thin layer of RTV copper on BOTH sides of BOTH gaskets - you've made a relatively complex joint there, and it won't go amiss (I know RTV copper works on exhaust gaskets, I've been doing it for 25-30 years without negative effect.) Keep the layer thin and even.

Since the 6-242 is a side-draught head using a common manifold gasket, a single sheet is best. If you go with something THICKER than 12ga sheet, get longer screws (don't leave out the dish-shaped washers, unless you're going to replace them with proper Bellevilles. They're there for a reason!) IIRC, the OEM screws are 1.75" long under the head - so if you use 1/4" sheet, use 2.00" screws. If you use 1/8" sheet, you'll probably want 2.00" screws - but get a handful of flat washers to take up some slack if you need to (flat washers are usually 0.060" thick, so use two. Put them between the head and the bowl washer or Belleville - whichever you use.)