Head volume queston

[mk153smaw]

Anyone know the head volume for the 1987-1989 renix?
I am trying to work some math on how much I am shaving in my bowl and I cant sem to find any stock data for the flow stuff on the head.
Also if anyone happens to know the thickness of the cast would be nice also.
I am going to reshape the areas around the sparkplug and put some bigger valves.
Yes this is for a max build of a 4.0 to a little bigger than the 5.0 I just made.

 

[majic_tech]

the renix head is supposed to be 58cc ......yeah im building a stroker so ive been through the formulas too........you want your compression heighth within .045 and do the math to get your compression back under control....i need to remove 6/7 cc from the piston dish/combustion chamber to get back to 9.5 compression........damn quench areas and pinging anyway!!!!!! and the renix head is ok till you get past 4500 to 5000 rpm then it gets wheezy.......one tip though the casting is really thin just measuring the exhaust port gasket to the deck surface then measuring from deck surface again to the inside of the casting through a coolant passage in the head tells me the exhaust cant even be gasket matched.....im just gonna polish mine.......i dont plan to run it over about 4000

 

[mk153smaw]

Thanks for the cc info. I really needed that.
As for gasket matching, yeah the exaust is very limited to pretty much polishing ans some pocket work. It is best to gasket match the intake and lift the runner a bit on its ceiling.
We are going to try and gasket match the combustion area though, hopefully gaining double digit cc's. We havent heard of this being done on the 4.0 head but I have done it to V8 heads a bunch of times for that lil bit more.
I will try to get some pics and numbers for the head work if anyone wants to copy it.
If it works nicely I will try it in the existing 5.0 block we have to see if I can push past 325hp. I scored that on the dyno without the amount of millwork I am doing now. BTW the cost is not worth the effort........ I am so lucky I have an uncle whom is a master machinist and master welder. Him and my cousin took some time away from Vance and Hines to help us lesser beings in the family tree with our toys

 

[alex22]

Have you thought about going to a newer head casting, a 7120 or a 0630?
I do have flow numbers for the intake and exhaust ports on a 0331 head.

~Alex

 

[mk153smaw]

If I didnt have a couple of heads already for free I would have gone newer. The port work makes up for the older head having some issues though.

I just finished some math. If I can get 7cc's more out of each chamber I can effectively drop the CR .6ish
That would be for the buget guys who want a fine tuned 4.6/4.7 with these specs:
89 block (I like those better, just because)
milled out to .060 (tons of pistons at this size 3.935 with pin hight@ 1.581)
have the pistons dished @24cc's (costs money but well worth it)
the stock pistons I started with, and removed, had 10cc dishes. Can anyone confirm if this is pretty much the same on all the motors?
4.2L 4wt crank (for DD use, the 12wt is for pure rockcrawler IMO) milled for the 4.0L
4.0L 6.125 rods (get them conditioned)
then use the Mopar performance 0.043 head gasket (they have an 0.055 if you need more)
this will get you under 9.0 CR if the work is done well, if not you will be right at 9.0ish.
I may go to the 0.055 gasket and drop into the 8.8 zone which would be ideal for me.
Pump gas baby, pump gas.