'75 W300 repair/mod project - Ol' Blue

Gasket-matching is always a bad idea--unless you're going to carry the gasket's cross-sectional area all the way from the plenum in the intake to as far as the intake ports will allow. Any less than that, and you're simply setting up an area of port stall and a corresponding dip in flow. Think about it: All you accomplish by gasket-matching is creating a bulge in the port. Greater volume means a loss velocity, which then requires the mixture to re-accelerate toward the port. Port-match the smaller port to the larger one only. Don't worry about the gasket's port cross-section unless it intrudes into the port (in which case you obviously trim the gasket away). The small gap left by the gasket not being flush to the head/intake surfaces is aerodynamically inconsequential as it's below the port flow's boundary layer.

As I noted above, a smooth finish is not desirable when porting--that includes the exhaust ports. The desired finish is not "as cast" but rather stippled, and it has nothing to do with keeping a mixture in suspension--it's about efficient airflow. The pros smooth the port, then stipple it. John Baetchel bored me to tears yammering on about it for a couple hundred pages. His book about it was so redundant I'm surprised I didn't get two copies for the cover price. :doh:
 
Well, that simplifies the task at hand. So no to gasket matching, except for the places you mentioned. Got it. :bravo: It makes sense about a bulge dropping the airflow velocity. Sounds like a bad idea on either side of the head.

One thing I know I want to avoid is going much beyond a basic port clean up. To do so would most likely shift the power higher into the RPM range while giving up some torque under the curve in the process. That's the best case scenario though. Worse case? I could fuck the porting job up so bad I'd be better off with a stock 2bbl 318 instead.:doh:
 
Stay away from the short-side radius, and if you need to stretch the port floor to match the intake, only run the blend in as far as necessary for a smooth transition. Same situation on both intake and exhaust, really. Any removal of the floor material in the transition from port floor to bowl area will kill flow unless you know exactly what you're doing. Few do, myself included, and it's the most common way people screw up cylinder heads. Bigger ain't always better!
 
Yesterday I got the rest of the valves out of the driver side head and today I got three of those broken stud holes repaired. I have one stud left to fix and then I'll be done with that headache. I'm about halfway through cleaning up all the ports and bowls on the first head so far.

I just ordered the .010 under Clevite main bearing set (#MS1277P) from RA a few minutes ago, so that should get here some time next week. I also picked up some valve lapping compound, those suction cup type valve lapping tools and some moly engine assembly lube. I'm going to lap the valves before I put them all back in the head for good. That should be the last of the parts I needed to buy to be able to put this engine back together. I hope...

EDIT: All four of the broken studs are now cleared out of the holes and all of the exhaust stud threads are now fixed. :giggedy:
 
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In regards to the head porting discussion here's a very interesting short video;

[video=youtube;aijyLKCvbU8]https://www.youtube.com/watch?v=aijyLKCvbU8[/video]
 
That video is a total crock of horsefuckery, as are most of their videos. Did you see the camshaft comparison between hydraulic flat and hydraulic lifter camshafts? "Everything is exactly the same, except of course the hydraulic roller has slightly more exhaust duration and .050" more valve lift on both." No shit it's going to make bigger numbers, assholes--that's a shit-ton of extra lift. Had the cams actually been identical, so would've been the HP and torque numbers. Probably less with the roller, actually, since the added height of the lifter exacerbates the already-bad pushrod geometry of the LA engine. But they've gotta support those sponsors pushing expensive hydraulic rollers that make no more power than hydraulic flat tappets, or there'd be no magazines or YouTube videos.

In this video, we have "home porting" by a genuine, known professional who also:

  • Moved the pushrod holes and an intake bolt hole
  • Used an aftermarket rocker-arm setup
  • Upsized the valves
  • Improved to a race valve job (that is a very big deal)
  • Had another professional port the intake manifold
Moving the pushrod/intake-bolt holes and upsizing the valves isn't within the realm of the typical home porter unless he's got some very impressive machinery. Rest assured, without those humps removed from the intake ports or the race valve job, the results would've been far less stunning. He'd have picked up 25-30HP max simply by porting the heads the way a normal home porter could.

However, one positive aspect of the video is that it reinforces what I've said time and again about max-effort, and especially stroker, LA engines:
The stock intake port is shit, and you'll get shit results using it. If you're not using an arrangement with moved intake pushrods and offset rockers so that the port is (or can be) widened, you're pissing up a rope. The inferior Magnum heads have no recourse for making real power, since there's no offset rocker arm arrangment available. You're absolutely stuck with the shitty pushrod location, as if the shitty rocker arrangement and affinity for cracking weren't enough.

There's a reason I hoard offset intake rocker arms, y'know. At last count I've got four sets of W2 intake arms, plus the correct ones for my T/A (W1) heads. :dance:
 
The main bearings showed up in the mail today, but I've still got a ways to go on the heads before I'll be ready to put them in the block. I'm currently done with the exhaust side on the first head, and about halfway done with the intakes on that same head. I haven't started on the passenger side head yet, and don't plan to until I finish the first head.


I'm going to be getting the heads milled, just enough for a cleanup cut, before I put them back on the engine. There's some pitting around the water jacket passages and the head gasket surface has a few scratches on it.
 
When it comes to porting, I better not quit my day job (retired) just yet. I'm now looking at needing to touch up the valve seats where the air die grinder chuck bumped into the seats in more than a few places. [smilie=l:

I cleaned the carbon off the valves and found some severe pitting on a few of the exhaust valves. New valves are now on the shopping list. I'll be sticking with the standard size valves rather than bumping them up in size. As big, heavy and unaerodynamic as this truck is, I'd rather keep the smaller valves and not trade any torque for upper RPM HP.

BTW, I was planning on just getting the heads skim cut to clean up the head gasket sealing surface. Would it be worth it to have them milled a bit further, say about .100, to increase the compression a little? What are the pros and cons of doing this? The 346 head casting I have is an open chamber design. Taking that much off the head would almost make it a closed chamber just by looking at it. I know the intake sealing surface would need to be milled down to compensate for the .100 (or what ever size) cut, but by how much?
 
Larger valves really won't cost you much in terms of torque provided the port leading to the bowl area is left alone. Obviously, you'd want to keep your bowl cleanup work at a minimum. However, upsizing the valves probably wouldn't be a fiscally-responsible move in this case anyhow. Not only have you got to buy bigger valves, you've got to have the seats machined out (possibly cutting through the induction hardening) and a completely-new valve job done. It all adds up, and while not hideously expensive I don't think you'd get much bang for your bank. Your porting work is a good idea with the 346 heads, which are widely regarded as the worst open-chamber big-block head extant. Ironically, the later heads flowed not only better than the 346, but also better than the vaunted 906. Regardless, they'll work well for your project so don't let that get you down. You're building torque here, not a high-strung drag engine. Mild porting (especially following the MP templates) goes a long way.

I've mentioned it elsewhere, but without CCing your cylinder heads it's impossible to know how much is a "safe" cut. "Nominal" chamber volumes are just that; your 346s may be listed as having a certain chamber volume, but it could be several CC in either direction. A .100" cut could be perfectly safe or it could whet the engine's appetite for head gaskets. Only your burette knows for sure. The old MP guidelines for minimum chamber volumes didn't account for core shift during the casting process, they simply went off the design parameters. I'd probably maintain a CC or two above their listed minimum volume for safety's sake unless you're going to sonic-test the deck surface. If you're not going to CC your heads, I don't know that I'd recommend cutting them beyond maybe .070" or so. Run the MP or Mr. Gasket .028" head gaskets for a little extra CR.

As far as your actual CR, it's probably considerably lower than advertised. Don't be surprised if after CCing the heads and getting a "down the bore" measurement with a piston @ TDC, you find out that your engine was/is actually only 7.6:1 or thereabouts. It's a lot more common than you think, due to production variances and Chrysler's optimistic printed specs.
 
Honestly I probably won't CC these heads. I'm more likely to follow the safer number, .070 in this case, and just run with whatever CR that gives me. IF I decide to go back into the engine at a (much) later date and beef it up, then I'l look into getting some better heads for it. Maybe those Stealth aluminum heads from 440 Source, or something similar to them.

BTW, how much should the intake surface be milled to compensate for the .070 to be removed from the bottom of the head?
 
The first head is finally done, except for the milling, and I may have lucked out on the valve seats. I did all the porting work with the head still dirty so I could see where I was hitting with the carbide bits easier. The few places I contacted the valve seats with the air die grinder chuck were either below or above the 3 angle area ground into the seats. There were two places I hit the ground angles on the seats, but apparently those hits were only light enough to remove the carbon from the surface. When I sand blasted the head after all the porting was done I couldn't find the places the marks were. I'm still going to replace all the exhaust valves with stock sized ones, and all the valves will be lapped to their seats when I put everything back together.

After sandblasting, I went over the head with the air nozzle blowing everything out of all the ports bolt holes and water jackets. I'm sure there's still some blast media left in there, so I'll be pulling the freeze plugs and washing it inside and out with mineral spirits and then repainting the heads when I get them back from the machine shop.

Speaking of paint, the blue paint on the head was all messed up from rolling and flipping the head on the bench during porting. The sand blasting also hit enough of it that it wasn't worth trying to save any of it. It all got stripped down with the blaster, as much as possible anyway. Whatever bits of paint that were still left over were removed with a wire cup brush in the cordless drill.

The factory casting flash on the outside ends of the heads was catching on the wire brush a lot so I let my OCD take over and I did something about it. I broke out the angle grinder with a thin cut off wheel and nibbled away at the casting flash everywhere I found it. A few rough places got hand filed smooth, and then the carbide bit in the air die grinder went over everything afterwards. The carbide made the finish look more like the untouched cast surfaces around it, and the wire wheel blended it in even further. The net result is decent, but it's all in the looks department. There aren't any performance benefits from doing all of this external cleanup work that I'm aware of.
 
I took a break from the head porting today and did a little basic clean up on more of the truck. The throw out fork, it's threaded pushrod and the rubber boot are now clean and the fork and pushrod got painted satin black. I also cleaned the driver side frame rail from the engine cross member forward, as well as the steering gear box. It to quite a while to get all the built up dirt, oil and crud from between the gear box mount and the box itself. Even with using the purple degreaser, I still needed to spray some carb cleaner around to lift the stubborn stuff in a few hard to reach areas. That entire area got sprayed satin black as well, but I ran out of paint before I could get to the wheel well side of the steering gear box. It was already dark by the time I was done, so I'll get some pics up tomorrow.
 
What does everyone use for photo hosting? Looks like Photobucket recently went "full retard". :wtf:
 
the next solution right now will be IMGUR

just an FYI photobucket is still functional for viewing and using HOWEVER any external linking to SHOW a pic instead of a directlink will result in showing that stupid image of "buy our 400$ a year service"

i use "dropbox" to move things from my phone to PC seemlessly , and am looking into my OWN photo hosting on my own server since...the server itself is built and going thru testing and final tweaks..for the rest of everyone right now all i can say is wait and hope bucket pulls their collective heads from their asses..or move over to imgur

i do belive this site has its own internal hosting of pics as well right?
 
Thanks for the tip 69.5.:bravo: I'll look into Imgur and most likely sign up there so I can start posting pics again. Going back and fixing all the PB inks might take a while longer though.

Anyway, I'm almost done with the pass side head now. I've got the exterior all cleaned up and all the intake and exhaust ports done. All I have left is the bowl work to finish and then I'll be able to take both heads to the machine shop.

BTW, all the intake valves were fine so I'm reusing all of those. The exhaust valves were a different story, so I ordered 8 new ones from RA. The guides were all in good shape with no wobble in the stems. When I get the heads back and lap in all the valves, I'll almost be over the hump. Everything will get a final clean up and then I can start on the reassembly.
 
wish i had your uh lets go with ability...to get stuff done, no bellhousing pretty much stops my engine swap dead in the water
 
C'mon 69.5, you can say what you really mean. It's more like blindly stupid determination in my case. :D

BTW, I never could get a hold of that guy in Butte for the flywheel. Did you ever find one yet? I can check with those two Mopar guys in my neighborhood for a BB truck bell housing. Do you have a particular part number(s) you want me to look for? Any idea on what you'd be willing to spend for one if I can find one?

I'll shoot a PM off to you with my phone number in case you don't want to discuss numbers in public.
 
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It's a little past 2AM here and the passenger side head is finally finished. Tomorrow (today?) they're both getting dropped off at the machine shop and then I'll start working on cleaning up the rotating assembly parts while I wait to get the heads back.

I'm way past burned out, so I'm going to bed now.:shifty:
 
I got to the machine shop too late today and they had already closed. I'll have to try again on Wednesday.
 
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