Dsm cylinder head

[blakkat]

Hey guys so I've decided to start building a second engine to drop into the talon. I picked up a 6 bolt cylinder head for $200 and it seems to have warpage of around .003 around the firing rings but everywhere else is under .002. Manual says .008 is acceptable but I'm thinking I should still get it machined completely flat, can anyone confirm this? Also I hydro tested the valves and found cylinder 1 and 4 exhaust valves to be leaking so I was thinking of doing a 5 angle valve job. Question here is do I need new valves to go with the recut valve seats? Or is this all dependent on the margin measurement ? I also found some pitting on the flats of the combustion chamber, is this ok? Or will it cause hotspots and allow some knock? Should machining get it all out? There is a small amount inside the combustion chamber bowl as well, can I just grind it out ? And lastly the previous owner ran the bottom center exhaust stud in pretty far , and I'm not sure if it's in far enough to actually cause issues with the oil return. Thanks guys here are some pictures

 

[guamboyeli]

you dont want to chance it... just have the machine shop resurface it... as long as the valves are not too bad you should be fine...

 

[blakkat]

Well they seem to be leaking , would a 5 angle valve job and some lapping on those stock valves be enough to get them to seal? I've never done this before so sorry for the noob questions

 

[mean4g]

depends on what is wrong with the valves. If they just have a bad seal on the seats, than a standard lap would work just fine with compound, or have the machine shop cut a 5-angle to unshroud the valves a little bit. However if they are bent you are done. Need to pull them out and take a closer look.

 

[blakkat]

Alright will do, I need to see it Snapon stocks a spring compressor when I get back to work so I can dissasemble it all. Also is the pitting and stud ok? The stud looks like it goes in a bit far.....

 

[mercaholik]

Yes you should def have the head decked, but first polish out those pits. I really think they will cause hotspots, that at certain point the edges of those may cause pre ignition. I'm no expert on the matter but I have my head off and I polished the heck out of my cc's. For both best heat reflection and eliminate any hotspots in the chambers. Just don't go to deep and you'll have to cc each chamber to keep them all within .5cc of each other.

 

[bduran1220]

When I replaced my HG on my 7 bolt a few weeks ago its was completely flat I measured it with a straight edge and mill shop confirmed it too but i wanted a clean surface to. id measure the head from the timing belt side to head surface and water pump outlet side to head surface for head cylinder hight be sure to make the head bolts to make them wider to they need drilling & 6 bolt head bolts are needed....oilport mod can be handy at this point before milling as for the valves id have everything replaced 6 bolt heads probably seen better days at this point

 

[blakkat]

Well I'm running a 6bolt block, so I would still need my bolts drilled over ? I'm a little confused about the oil supply hole the tear drop one, when the head is resurfaced you have to change the size of it to get the same oil flow?

 

[mercaholik]

Yes, effectively the passage is made more shallow after the head has been milled. Bogus svo has a great write up about, but basically it's a little shallow to begin with, so after you take material off the head it's even more shallow.

 

[blakkat]

Ok I'm a little confused here, do I just need to do the oil port mod? I'm bolting a 6 bolt head to a 6 bolt block. Why would I need to drill the holes larger , if the bolts I'm installing are the normal 12mm 6 bolt headbolts

 

[bduran1220]

The oil port mod is taking rotary to the tear drop on the head, making the tear incline for better oil flow thus making zero lifter tick HLA (LIFTERS). The oil port mod is not a need its gonna be totally up to you if want to do this mortification or not. It does have it benefits but its your choice. I posted pic of my oil port before and after to give you the idea of course it was a pic before my job valve. As for the drilling part I thought you were putting a 6 bolt head on 7 bolt block so disregard that part. You should be good with 6 bolt ARPs.

 

[mercaholik]

Yes that's correct except it's the 2g head on a 1g block that needs the head bolt holes enlarged. There was a 1g 7 bolt that would still have the larger head bolts. But like bduran said its up to you not necessary but a good idea imo, I did it and bogus svo is a smart and talented machinist so take it for what it's worth.

 

[blakkat]

Ok cool so even though I'll be having the block and head resurfaced I just need to do the oil port mod. Any word on that exhaust stud ? And also I found one of the vc bolts was drilled over and filled with jb weld then helicoiled, wonder if a machine shop could weld it shut and re drill and tap it.

 

[bduran1220]

The oil port mod needs to be done before milling/resurfacing. And the VC "fix" that the last owner did....why did they do that??? I personally wouldnt have welded, drill and re tap it. That sounds like a very dangerous job to perform. Maybe just making it a little bigger with the next size up for taping you should fine & just get grade 4 bolt or better with only 2.2ftlbs on the VC BOLTS!!! Too much you could crack the Valve Cover.

 

[blakkat]

Because I'm finding out more and more that Dsm owners for the most part ghetto rig the shit out of everything. I'm gonna see it a machine shop can weld it shut, and retap it , he drilled it pretty large , like maybe big enough to accept a 10 mm bolt...... When I was first checking out the head I thought it was just rtv in the hole because a lot of people use rtv on those gaskets but I guess not...

 

[mercaholik]

That sucks man, that exhaust stud is a little far in but it blocks about 3/4 of the passage anyway iirc. I would replace all the ex manifold studs with new ones, I'm going with arp, and use a high temp rtv on that stud or it will leak. Just put the stud in till it hits the back then back it out a little bit? I don't think it's gonna make to much of a difference.

 

[bduran1220]

You should ask the machine shop to see your opitions are about the valve cover fix the last owner did. And the exhaust stub removal fairly simple but i still hate them!!!!!!!!!!!! I used a set of Irwin bolt grip to remove my old ones.....& work like a charm. And use hi temp oil resistant RTV on that exhaust stud that breached the oil return gallery.