Offy 6x2 for Hemi 331! H2O flow concern...

So I scored an NOS Offy 6x2 this weekend for my 331 Hemi. I haven't taken any pictures of it yet, but here's some picture of another one just like it.





Disregard the block off plates.

I have a conern about water flow. I'm going to be running 354 industrial heads on the 331 and as you know, 354 Industial heads don't have water outlets in the front... well the intake doesn't seem to have provisions for water EITHER! UH OH! The area of the manifold that covers the water jackets on the heads leads right into the mix area of the manifold, so it doesn't appear as if I'll be able to tap into the manifold. Looks like I'll be tapping into the heads instead.

The other makes of 6x2 log-type manifolds have provisions for water flow consisting of a pipe thread or the likes. Here's a Drag star for comparison... (can't remember if this was Hemi or not, I think it is)




So what the hell do I do? Any suggestions on where to drill the heads? Should I drill for a cross-over at the rear of the heads too, or will the front be sufficient while running a remote thermostat housing? I guess the good news is that drilling and tapping the heads will keep the top of the engine pretty neat and clean, keeping all the water flow up front.

While I'm asking questions about this manifold... what should I use for the cross-over tubes? Will heater hose or something similar work fine for the application?

Also, what do I use for manifold bolts on this? I was guessing that stock 331 manifold bolts wouldn't work since some of the bolts actually mount from inside the manifold body (access through carb ports). So what do I use and where should I look for them??

Let me know what you guys think about my little cooling dillema and stuff.

Thanks!

Scooter

 

Why not make some thick spacer plates (between the intake and head) and put your water fittings there??

 

Hmmm... I hadn't thought of doing that. I would need some pretty thick plate for that. Smells like big bucks. 3/4" aluminum stock might do the trick water jetted to fit. I wonder how that would effect the flow characteristics of the manifold? I think the physical placement relative to the dizzy or anything else would be fine with a spacer like that, but maybe not. Never looked at the log manifolds close enough to know how close the drivers side log comes to the distributor. Anyone know? I know some of you have 6x2 logs on here. Do tell.

Wouldn't I need about a 1/2" pipe fitting or larger to get proper water circulation from head to head?

Here's the remote thermostat housing I plan on using no matter what I do:

 

Looking at that manifold, you best bet maybe putting fittings in the front of the heads. The 55s & up dont have a rear crossover, so I wouldn't worry about it.

 

Drill into the heads. My pops did it on his 331 Industrial w/ standard 331 heads. It didn't seem too difficult.

 

I've seen heads drilled all day long. Doesn't seem to be that big of a deal. Would be pretty clean too. The only thing I would like is the "modern" looking fittings coming out of the heads. Anyone recomend some nice looking fittings that won't stand out too much?

Just a thought. What if I drilled about a 1/2" diameter hole, milled the front head suface down, drilled and tapped mounting holes for a water crossover like this at the front of the heads? Anyone tried this? Is it even possible?

More work (if it's even possible), but would look nice.

 

The pipe plugs in the intake are 1/2 NPT so if you drill and tap the front of the heads for the 1/2 NPT you should get the flow you want since the housing you are using has 1/2 NPT ports into it.

 

I Think the crossover you are talking about using is the 392 so it would be too wide for your application. I don't know if there would be enough water jacket in that area to take up the lenth difference between the 331 and 392 heads? Maybe Bob Walker would know at hotheads.

 

Now that I think about this idea, it's probably wouldn't work because of where the ports would have to be drilled. The tube probably wouldn't be long enough. 392 cross-over might do it, but would probably come up short.

 

(talking to myself again...)
Looking at the heads, maybe I WOULD be okay adapting a cross-over tube somehow...





Maybe I should shut up and just follow the KISS theory. Just anal about this thing looking right when it's done. I don't want that braided hose crap going all over the place if I can help it.

Can someone point out about where I need to drill without drilling into something I shouldn't drill into??

 

I hear that. That's one thing I hate about all the Hot Heads stuff my pops is using. They make everything real easy, but then it looks so modern and "bolt-onish".

 

YES!!! You and I are on the same plane here, brotha'! Can't stand all those anodized blue/red fittings all over the place. I could maybe deal with black anodized since my engine will be pretty well blacked out with mostly aluminum accents here and there, but I don't need anything to stand out. Brass would be a viable option I suppose. I would shape each fitting so they didn't look like I stole them off the kitchen sink or something though. I wonder if I hardlined with copper tubing and brass DOT compression fittings how that would work out... might be cool. I guess I would use refridgerant (copper) tubing or something? Do those remote thermostat housings have a set of mounting holes or something so it can be solidly mounted??

 

Can someone please post some pics of drilled, tapped and plumbed heads like we're describing?

 

If you take the W/P off a 55/56 the OEM 392 crossover will bolt right up. Wasn't you gonna use a Chevy W/P anyway? It looks like your heads are already machined for it, just drill the openings. The bottom bolts are apx. 11" apart, & the top just over 14" apart.

 

what do you plan to do with the heat riser port in the middle of that industrial head? on car heads, exhaust gas is used to warm the intake, but on truck and industrial heads, hot coolant is used. your new intake doesn't cover the opening. you're going to have a big, wet mess when you fire it up.

 

and the dragstar is for a dodge

 

The center coolant port I believe won't quite be covered up because of the shape, so I'm going to have the machine shop close that hole in a bit to the shape of the stock 331 heat riser port... at least that's the plan thus far. I've been told it's not a big deal to close that gap so the manifold will cover it. Excellent point and thank you for reminding me that needed to be done. That had slipped my mind for a minute.

Yes, swaping to a SBC pump and snub nosed 354 cam. I need to get the down pins out of the 331 block so I can mock up the heads and see where things measure and also have some mock-up fun with the intake. Can't wait to lay it all out with the 94's on top!!

Oh yeah.. the pads you see on the front of the heads with the two bolt holes are to the exhaust side of the head. I don't think I want to drill that low, do I?? The funny shaped extrusion on the front of the head closer to the intake side is where the normal port would be on other heads with crossovers out the front. I don't think I can utilize that area.

 

Scooter - you may very well get by with something thinner than that. Keep in mind you do not HAVE to make it so your fitting will bolt in - you could fabricate a bung ,weld it in and since you're fabbing it you could make it FLAT (oval) to keep the profile down where it connects to your spacer plate.

These plates were common in 1/2" - they are still readily avilable. Another thing to consider is your angle of attack - if you made a spacer with a slight "wing" on it - you can effectively get a size thicker than your actual plate thickness.

BTW there are other log manifolds that are plumbed for a fitting over the water jacket. See pic - it's not a good angle, but if you look close you can see it - circled it.

 

Drill and tap 1/2"NPT in head, about an inch in from intake manifold face, up about an inch from head gasket face (these measurements are to the centre of hole), and use that thermostat module. the wall thickness isn't that great, but is sufficient to do the job. If you're nervous, do a 1/4" pilot hole to make sure you hit the water jacket, and if it all looks bad you can easily plug it back up, I say that because there are a number of variations of the heads, so please tread wearily, it won't hurt to make the effort.

As for intakes....see the attached pics, the 'Dragstar' and Edelbrock log manifolds have a drilled and tapped section above each water port. These are the 'preffered' units, for the above reason.

Keep an eye out for the above listed intakes, or a set of 354 heads if you're too nervouse about using fittings and drilling your existing heads.

Cheers,

Drewfus

 

Thanks for the location tip. Seems like it's going to be hard to get a good square hole on that radius though. How far am I actually going until I reach the jacket? Is it just right on the other side of that face? I don't want to find myself in a port. I need to stare at these heads a little closer.

I should also ask, where in the hell am I going to plumb a water temperature sensor? Would it be better just to use an existing hole in the block somewhere to get an accurate water temp reading or should I be considering a Tee junction in this cross-over somewhere?

I really do wish the offy manifold had the luxury of having threaded ports already, but it doesn't and I really want to make it work. I also got a very reasonable deal on it for being an NOS product. I really like the idea that I'm the first person to ever bolt this manifold to something. I've seen heads drilled all the time, so I'm going to go for it. I'm having the hardest time finding pictures of heads that are drilled though. I've seen them at shows and on the internet, but can't seem to find the pics again.

 

my bet would be to find a set of tripple 5 heads.it´s an additional cost,sure,but I´d think it´d pay off in the end.

 

Thank you for the word of caution Jeff. I really do appreciate it. I don't claim to be an expert on fuel systems, so I am always open to a work of caution and respect people's input.... especially with the words "fire" and "exploded" are used in relationship to a fuel system I would like to run.

I do plan on running all six carbs. Not big on going with something just for looks. I will however being running the Holleys progressively with idle running the two centers and all six dumping at full foot. And yes, only a street car. I have no intentions of doing much more than driving the hell out of it around town and on road trips. No strip action is predicted for this car.

Again, I appreciate the comment brotha'! Maybe Littleman or someone can comment on safety and fire prevention related to log manifolds.

Swedester... yes, good idea on finding the tripple nickle heads... for simplicity sake, but not only are Hemi heads getting hard to find they're heavy as HELL which makes them expensive to ship when you do find them. I'm pretty partial to just making what I have work. If things really get bad, I'll just see if I can get a swap for an Edelbrock or Weiand that has the threaded ports already.

 

After learning to dial in a over carbureated motor the FIRST thing I can tell you is to get yourself a GOOD IGNITION system. Fouling plugs out while trying to learn how to set up your carbs is not only dangerous but makes things twice as hard to figure out as well. An MSD is a must IMHO.


An MSD will "cover up" a world of carbureator mistakes and allow you the run time to tweak things where they need to be (or not - depending on how much time you are willing to devote).

 

YES! I agree!! Fouling plugs SUCKS too!! I'll definitely be converting to something new. Was actually thinking of one of those "mag-looking" self contained distributors that Hot Heads and Speedway sells. Nice neat little package.

The tips are good. Keep 'em coming! Still would like to see some pics of tapped 331 and 354 industrial heads too! Don't leave me hangin'! Also, would still like to know about location possibilities for H20 temp sensor.

 

New day... any new thoughts out there? Anyone come up with a picture? I still can't seem to find any showing the tapped and plumbed heads.

 

Anyone ever find a picture of drilled/plumbed heads?

 

Okay... I'm bumping this back up because I STILL haven't seen any pictures of drilled and tapped heads and I can't find the one, single picture I have somewhere at home of tapped heads. Please! I'm begging! Someone show me the way!

 

Scotter,

I think the ultimate solution may be to give up and sale the car to me.
hehehe. I am trying to so some research for ya.

Love ya,

Nate

 

I had this same problem...
thought about drilling the heads.
but put an ad in the classifieds and traded my NOS Eldebrock for a polished Drag Star with the water provisions.

That is the K.I.S.S. solution.