A few left over questions about a build plan

[metalman]

hello, I've been lurking for a bit, I've learned tons, and I ended up having a few questions still not answered after searching, thanks for taking the time to read over this.

I'm going to be building a 4.6, I'd like it to be able to run 87 octane, the goal is just low rpm torque, I'm not concerned about high revs or peak HP at all. Its going to have a manual trans, and built more for well rounded use than anything else, little towing, maybe wind up in the desert a bit, but able to get up roads where ever we'd like to go.

90 renix block
12cwt crank
probably kb944 pistons
megasquirt, COP ignition

This is where the questions start coming in

heads - I can get an 03+ 0331 for under $200, but I have renix and HO heads sitting on a shelf. I'm leaning towards an 0331 because I'd rather just build this right once and it seems like the better head despite internet hype against it, but does anyone think it would be worth it or should that money be spent elsewhere? I am curious if anyone has any information on the flow numbers with the intake and exhaust in place? i have read some people hinting that with manifolds on is where the 0331 shines, even though bare flow numbers are better on the earlier manifolds. better yet, has anyone "wet" flowed the 0331 with manifolds vs other heads? Also, does anyone have any information on what kind of polishing work the 0331 heads like, i hadn't planned on any serious porting work. I planned on putting in bigger valves since it needs single groove valves anyways, just to get a few more cc's to bump up chamber volume for the SCR.

Connecting rod - from what I can gather, hesco uses blueprinted factory rods, and they get to select the better stock, but essentially its a stock rod. The eagles are out of production, but does anyone know of an alternative? I'm not going to shell out close to 150$ each for hopped up stock rods. Also, I have the 90' rods and a set of 98' rods. I know earlier blocks are better, but does anyone have an opinion over which rod would be better or if anyone knows of a difference in metal/quality between them?

Main caps - I also have the 258 main caps, I read the garth hill thread about using 258 main caps. I know it would atleast need to be line honed after that, but does anyone else have anymore info on using them?

for the compression ratio, I have read a bunch of threads about who does and doesn't have problems with 87 octane. I figure MS might help a bit, and I planned on getting a bigger radiator, but does anyone have advice on what static and dynamic compression ratios work with 87oct at sea level? the info I have found, even on here, is all over the map.

[4.whoa]

does anyone have any information on what kind of polishing work the 0331 heads like, i hadn't planned on any serious porting work. I planned on putting in bigger valves since it needs single groove valves anyways, just to get a few more cc's to bump up chamber volume for the SCR.

Your time/money would be better spent on porting then on bigger valves. You don't need to do a "full" porting job, the pockets are where the biggest gains are, especially @ lower RPM.

I'm working on a 7120 head now (sorry don't have pics yet) and it's unreal how much extra metal is in there! I opened up my chambers slightly for better swirl (biased to the int side) but i'm not done so I can't give you chamber #"s I'm also having the valves cut for 30* seats for better low lift flow.

010.jpg

this is a pic from a chevy book, but it's the same idea.

Have you thought about notching your bores for the cc overhang? Its not a proven fact, but its a very possible hot spot in the chamber (and it hampers flow) that could help prevent detonation.

[amcinstaller]

have you read alot about the megasquirt and a distributor-less system? the last couple builds ive read have used a distributor with their megasquirt.

[metalman]

Honestly I wanted to avoid porting work so that I could keep things as "plug and play" as possible, just in case something breaks I don't want to loose time and $ in machine work. To be upfront, this is my wifes first project, i'm a chevy head, but she likes jeeps so thats what we're putting together for her, so when we're ready to put together the next engine, we'll probably be more open to putting work into the head.

I don't mind doing some work to clean up the castings, but thats really about as into it as I wanted to go. having said that, which head would you recommend for idle to 3500rpm type preformance with it just being cleaned up a bit. cam selection is wide open, but like I mentioned I haven't even found enough flow numbers to start trying to pick a cam besides following the herd with a CompCams 68-231-4 206/214

as for any reliefs into the block, I wouldn't be opposed to it, but I haven't found much information on what size of relief they are talking about when it comes up. I've known some guys who have done it in other engines to help unshroud valves, usually just putting an eyebrow into the edge of the cylinder with a die grinder, as long as they stayed above where the rings would travel they seemed fine. when you say notching for the overhang, do you mean to the front and rear of the cylinder where the outside edges of the valves are closest? it looked like the cylinder bore might be even with the combustion chamber edges, but I wasn't aware that the chamber actually hung outside the cylinder over the deck.

as for MS with the distributorless system, I know plenty of guys that use them, not any jeep guys, but I don't know of any issues from it. honestly, I might get it running with a distributor and switch later. the distributorless system had more to do with being water resistant than anything else.

[SilverXJ]

The 0331 supposedly flows better with its intake and exhaust manifolds than the other heads, especially the exhaust sides. A little casting clean up and polishing won't hurt anything and will do good. Polish the combustion chamber as well. Then, since you have the polishing tools, you can polish your connecting rods as well. Have the resized and have ARP rod bolts installed. I believe 505 performance or another company carries better rods that are stock length and use a pressed pin. Don't remember the other company though. Maybe it was bulltear. With the comp cam 68-231-4 and KB 944s you will need premium fuel. Larger valves aren't worth the money unless you need the guides redone than they can just be reamed out for the larger valve stem instead of having new guides installed. As for nothcing the bore for the head, I would luse some machinish blue and see where it over hangs, then grind.

[metalman]

seriously, thanks for pointing me towards 505 for the rods, it would have cost me almost that much just to get arp bolts for the stokers.

I've found a few long rod setups along what I'm interested in, but a lot of them sound borderline with 87 octane (ex only if its under 90 deg outside), id appreciate it if anyone has one in particular they recommend. is there a very good idea out for what the limit on dcr for 87 octane.

also, it seems like the comp.ratio for the kb944s comes in a little high for 87 octane. this has me leaning towards the bulltear pistons since I can get them with a bigger dish. is there anything else I'm missing between them? for a few extra bucks and waiting it seems worth it to run 87 octane.

[4.whoa]

as for any reliefs into the block, I wouldn't be opposed to it, but I haven't found much information on what size of relief they are talking about when it comes up. I've known some guys who have done it in other engines to help unshroud valves, usually just putting an eyebrow into the edge of the cylinder with a die grinder, as long as they stayed above where the rings would travel they seemed fine. when you say notching for the overhang, do you mean to the front and rear of the cylinder where the outside edges of the valves are closest? it looked like the cylinder bore might be even with the combustion chamber edges, but I wasn't aware that the chamber actually hung outside the cylinder over the deck.

You just need to stay above the rings and inside the gasket fire ring. The castings must have had core shift cause on mine they were all different, some int side ,some exh, some both

[metalman]

that sounds like some pretty bad core shift

[jbxx]

Please keep us informed about the use of megasquirt.
I have seen a few setups in the Chrysler section in the MS site on Jeeps.
I am very interested in putting one of these together, BUT, I want to get her up and running first.
I don't want to change too many things on the outset to make it easier to troubleshoot if I have problems.
J.B.