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Discussion Starter #1
I am gonna be installing a new cam here shortly hopefully. I will also be installing new mopar performance roller lifters, valve springs, retainers, keepers, and seals. I was wandering since I will have all of this stuff apart would it be a good idea to go ahead and pull the heads to replace the head gaskets and also to port and polish the heads? I have a exhasut manifold bolt broke on the driver side head so I think that I will for sure pull that one to get that bolt out. I tryed getting it out when I installed my header but no luck. Also what exzactly is port and polish? Is that something that I can do myself or do I need to bring the heads somewhere? I would also like to do my intake manifold. Anything else that I should do while I am there and replace?? I already have the 1.7 RR's.
 

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Just a couple ideas for you. If the heads are off you can have a magnaflux test to see if any cracks exist. A shop could perform a valve job and install the parts. Porting is the removing of head material to install larger valves or enlarge the combustion chamber or I/E tracts. Not a good idea to do this yourself. Polishing is smoothing the surface for better air flow. A shop can do this or you can use a buff wheel on a dremmel. A popular spot to smooth out is the intake tracts.

Did the 1.7 RR's help w/ low end power? Good Luck!!
 

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I took my heads off and gave them to Napa and a guy there ported/polished them both for about 175.00 cause he has never seen a V-10 with it done and he did an awesome job only took two days. So take them to a machine shop and they will do them right.
 

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I believe westwood makes a set of porting and polishing bits, but like it has been said, let a pro do it or get some junk heads from a machine shop to practice on first. Take off too much material and you can screw things up. Usually they make the openings match the size on the gaskets. Have em do a 3 angle valve job while they are at it.
 

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You don't want to port and polish your heads if you don't know what your doing. Even with the templates it is a real bitch. Send them to someone that knows Mopar heads if your going to have it done.
 

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:withstupid: There's a science to porting heads. Most people will just gasket match them and send them down the road with very little or no gain in performance. A true port and polish job will cost you some serious money. Porting and polishing is for high RPM applications. Now if you're gonna run 6-7k rpm all the time then id say go for it.
 

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Discussion Starter #8
Ok then I will just save my money then. Thanks.
 

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It's pretty hard to screw up gasket matching, you'd have to either be drunk of retarded to screw that up..

You could do a little bowl work and not screw things up.. But anything else it's wise to have a flow bench.. You could grind out casting flash, smooth ridges ( but not changing the shape ). You can smooth the port bends slightly ( but not polish, keep it rough ).. Smooth up the bowls a little and smooth down machine grooves ( the grooves that are made when they cut when they (re)grind valve seats )... There is plently to do just in that stuff. Just as long as you dont change port shapes and sizes ( you can with gasket matching, but ONLY go into the port a 1/4 inch to blend it to the port ), leave the port floors alone, and dont do much with the exhaust side you'll be alright..

You dont really gain that much from doing it, but the way I look at it is it's free power ( if you own the stuff to do it )... Just remember that it can change your power curve, even more so when your working in the exhaust ports..

Polishing the ports is a very bad idea.. Unless you have a engine that lives around 4-8K RPM, you'd be hurting yourself badly.. If ya deside to do it hollar at me and I'll show ya some pics of a set of heads I've been working on... It's really not that hard, grab a old head to practice on is the main thing, even if you know what your doing it's good to have to "warm up" with.. Paying someone to do it for you ( a performance machine shop would be the only people I'd let touch them ), you'll looking at some bucks.. A few hundred bucks, and even more to have them stuck on a flowbench.. To me, if I had a race engine I'd do it in a heartbeat, but for a street vehicle with stock cast heads I wouldnt..

They also say that with Magnum heads, it's not wise to port them... They are prone to cracking... But from research I've done, and all the pics of cracked heads I've seen, they crack between the exhaust and intake valves in the combustion chamber.. You wont be messing around in there, so I dont see why they say it's not a good idea. Plus that, any casting flash you take out is just one less spot for a crack to begin. Myself, if I had to pull the heads on my 318 for any reason, I'd port them while they were off and have a valve job done..
 

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If you are going to have the heads and the intake off, have them both milled the same amount.
Milling the heads will locate them closer to the block, and increase your compression ratio slightly. Plus it will ensure you have a truely flat mating surface.
If you decide to do this, make sure you mill the heads AND the intake the SAME amount. If you don't they won't match up.
 

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Discussion Starter #11
On 2005-12-13 13:43, chizzle1 wrote:
If you are going to have the heads and the intake off, have them both milled the same amount.
Milling the heads will locate them closer to the block, and increase your compression ratio slightly. Plus it will ensure you have a truely flat mating surface.
If you decide to do this, make sure you mill the heads AND the intake the SAME amount. If you don't they won't match up.

Will milling them cause problems with a custom comp cam? I will be installing one when I tear this apart.
 

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it shouldn't. If any play was to occur from the minute amount they are moved it should be taken up by the hydrolic lifters.
Only talking about .020" or .030" max. Any more than that and you would have to fly cut your pistons to avoid contact interference (sp?).
 

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There have been several articles in recent Mopar Muscle magazines about porting on Magnum heads. I have read too many post about antifreeze leaks, which usually led to cracked heads. Even if your heads magnaflux out fine, I would be very hesitant to put any money in the stock heads. I would save up for a set of R/T heads or the Edelbrock aluminum heads. This way, you know you have a good set of heads that are not prone to cracking.
 

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If you mill them you'll have to get different lenth pushrods.. But you should check them when installing a cam or putting new rockers on anyways.. If you deck the block, basicly doing anything to change valvetrain geometry...


I wouldnt mess with milling though, unless the heads are gasket etched, warped or something ( remember though, if the heads are warped, and your not rebuilding the engine and cant check the deck, think hard about doing anything, because the head could be warped to the conture of the block deck and cause more probs than it solves and can lead to cracked heads! ), even then I'd only do it enough to take out the etching.. If I remember right, the compression ratio on 318's and 360's stock is 9:7.1, which is plently high.. Unless you like running high octane fuel, and possibly even having to add octane booster.. Part of the reason our trucks detonate so bad is the compression ratio.. Other vehicles ( take some Ford engines for example ) have knock sensors to adjust timing when they detonate, our trucks dont.. You could move the crank sensor back to decrease ignition timing 3-4 degree's though..

As far as aftermarket heads, always a good upgrade.. For me, if I had a set of stock heads that just needed a valve job and all the SIMPLE stuff, I'd put a little extra money in them.. When it comes to adding guides, valves, and all that jazz, I look into new heads. If I have the money to spend then I dont even think about messing with stock heads. Ofcourse unless it's a junker that I dont care about, just toss the stockers back on.. And while the heads are off, taken apart and clean, I always try to find the time to gasket match and knock the casting flash out.. Just like deburring a engine block, I do it just to prevent cracking or the possibilty of it breaking off and sending casting sand through the sys...

If it was my truck, I'd try porting them.. Even if they might crack. I would do it now too, but this engine has to many miles on it to even screw with, might be just fine, or it may open up a can of worms. Think about it, these heads STOCK are prone to cracking.. It's just a matter of time, with any head really.. I just wonder if it's the stress of being loosed back up, then torqued back down thats causing them to crack. Think about it, where the head bolts are, they do cause those area's stress, as with every engine. I dont know, but where these heads are cracking I dont see how slight port work will cause them to crack, simply because if you do it right your really not in the area where they are cracking, between the intake and exhaust valves.. I have seen a few heads crack in that area before, and it was because they ported them to far, far enough that it was hurting performance rather than improving it. Some so far they left nothing but paper thin material between the exhaust port and a water port, then cracking or busting out from pressure and heat then pumping water in the exhaust port ( or intake ). If anyone has any info proving me wrong tell me, cuz this is just how I see it and my experience, I dont mind being corrected.... Didnt mean for this post to be so long, just trying mention what I know on the subject..
 
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