354 heads on a 331 block - locating pins

Discussion of the 331-354-392 HEMIs.

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scootermcrad
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354 heads on a 331 block - locating pins

Post by scootermcrad »

Puting 354 heads on my 331. What do I need to do to the heads? These are industrial/marine/truck heads. 57-58. See previous thread for identification of the heads.

My big concern is the locating pins. They're bigger than the holes in the heads. Should I bore them out? If so, how much tolerance do I want on the pins? Need to know how much to go over. Should I just have stepped pins made or can I buy them? How do I get the old pins out of the block?

Not too worried about the intake. will be running a Weiand Drag Star and I believe it has the provisions for water outlets built in.

Besides the pins, what else do I need to look at?
TrWaters
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Post by TrWaters »

The best way to get the dowel pins out is with a dowel puller. You will find that once you get the dowels out that they are stepped, and the holes in the block are the smaller diameter which you need. At that point you can have either new dowels made, or the ones that you removed turned down.
Approximately .308 I believe.
Early hemi to late sb Mopar trans adapters. Precision billet parts for early hemis.
Bailiesdad
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Post by Bailiesdad »

Use 2 studs to use as locating pins, put gasket on, put head over gasket, put the rocker arms on, put the head bolts in, remove the studs and there you go...

Then figure what or how you are going to seal the large rectangular port in the middle of both heads on the intake side.
firefly

Post by firefly »

The dowel pins are what locate the head NOT the bolts. You need them.
Listen to TRwaters .
Bailiesdad
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Post by Bailiesdad »

firefly wrote:The dowel pins are what locate the head NOT the bolts. You need them.
Listen to TRwaters .
I remove every dowel pin in the deck of a block when I assemble any engine, be it 331-354-392-426-MP perfor or KB aluminum. Studs are longer, stronger, and better for locating the head over the bores of a block.

Listen to whomever you want then compare the methods. :roll:
firefly

Post by firefly »

Yes studs are better than bolts, but the dowel pins are what locate the head. Not the studs or bolts just like with the trans. If you remove the dowel pins from the back of the block and only use the bolts you will crack the flexplate. The bolts or studs clamp the head to the block they DO NOT locate it.
scootermcrad
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Post by scootermcrad »

I'm sorry I have to agree with those saying the dowel pins need to be there. I may not know everything about every engine in the world, but I do know engineering practices and these are there for a reason.

Let's use a hypothetical case here for a second. Let's say you have something you're locating and it needs to be +/- .0010 concentric at it's center axis to it's mating axis. We'll say that this thing is mounted with four bolts around the parameter of it's circumference. If each of those holes has a tolerance of +/- .0050 and the diameter of the stud/bolt used to mount the item is +/-.0020 and each hole is located +/- .0010 you could ultimately be off as much as .0080 just in tolerance, not including hole fit gap so you can actually get a bolt or stud through.

I don't know what the tolerances are for the mounting bolt holes of a Hemi Head are, but one thing is for sure, in the 50's, methods for measuring and accurately drilling those holes couldn't have been better than .0030 for location AND diameter. That would give you the possibility of being .0060 off bore concnetric right there. I think that's even a fluffed number.

So, let's bring up the question of how close the block bore and the diameter of the cumbustion chamber need to be. I'm guessing they need to be pretty darn close to avoid valve interference. To me, locating a head using pins is ideal.

So give us some numbers balliesdad:
- What is the diameter of the studs you are using and the tolerance of those studs?
- What are the diameters of the the holes in the head and what are there tolerances?
- do you re-locate each hole with a precision CNC machine assuring placement of each hole AND diameter?

Holes (threaded in block and holes in head as well as the core bores themselves) will have a placement tolerance and a diameter/thread tolerance. The reason dowel pins are used is so only a couple spots will have to be of high tolerance during the manufacturing process. If EVERY hole had to be of high tolerance then the manufacturing process would be expensive and slow.

Not trying to lash out or make it seem like I'm talking down to you balliesdad, just puting that out there and wondering what your reasoning is. If you know something about studs and bolts in relationship to the holes and threads put there by the Chrysler Corporation, PLEASE share what you know. Give us some reasons why you mount your heads the way you do. You seem to have built several this way and I (as well as others) would like to know why exactly.

Thanks!
Scooter
scootermcrad
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Post by scootermcrad »

Bailiesdad wrote: Then figure what or how you are going to seal the large rectangular port in the middle of both heads on the intake side.
Also, does anyone have any thoughts on this? Not sure if the Weiand Drag Star 6x2 will block things off or not.
scootermcrad
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Post by scootermcrad »

Looks like the ports on the head will line up with the intake just fine...

The intake (not mine)
Image
My heads:
Image
Looks like blocking it off won't be required, unless I'm missing something here.
TrWaters
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Post by TrWaters »

The truck heads have a taller center port than the car heads, and most car intakes do not have enough material to cover that hole. You may be ok with your set-up.
Early hemi to late sb Mopar trans adapters. Precision billet parts for early hemis.
Bailiesdad
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Post by Bailiesdad »

" I (as well as others) would like to know why exactly."

It is easier, faster, and does the exact same thing.

You can also use a couple of cutoff head, long head bolts for the econo challanged.

I have a set of studs with one end ground to a semi round tip to slide everythng on. Just like on pro head work stands.

I learned about this when using copper head gaskets when the dowel pin holes were undersized from the manufacturer and had to be drilled open, my method eliminated that problem forever.....and any other alignment problems.

As to the flexplate problem/cracking problem I have never installed a flexplate any where near a head so I do not know..

If you donot get a gasket to cover the entire center port you will blow the head gasket, you have to seal the entire gasket around the port. Add some material to the bottom of the manifolds center ports..
scootermcrad
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Post by scootermcrad »

TrWaters.... yeah, I'm seeing this now. I didn't realize it until you pointed it out. I'm thinking that welding some material in the head to make the hole smaller might be good. Then have it faced. What's the normal port size? Maybe I can make it closer to square also, by taking some material out from the sides; if I can that is...

Is that port for water or something else?

Sorry Balliesdad, I'm still not seeing how studs are going to locate the heads better than the pins that were designed by an engineer to be there. I'm in no rush to get heads on. I'm not racing or doing head gasket swaps everytime I go for a drive. I guess you could say the "If it aint broke" theory aplies here. I still just do not see how studs would locate the heads better than two precision dowel pins precisely located in the block, but I guess you just have your methods. Not saying its wrong, just don't see any proof that it works better. I'm not hearing any hard numbers either to tell me otherwise. I think I'll stick to what I know was engineered to work. No offense.
Bailiesdad
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Post by Bailiesdad »

" What's the normal port size?"
Use a gasket as a template and fill the head if you are going to do it that way. The holes are heat exchangers meant to heat up/equalize temp in the bottom of the intake manifold.

The Chrysler Factory used a "head jig" with long pointed studs to slide the heads/gaskets onto the pins and block.

The pins are there for ease of service in a vechicle. All they do is keep
the head from sliding.
Last edited by Bailiesdad on Thu Oct 12, 2006 9:59 pm, edited 1 time in total.
TrWaters
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Post by TrWaters »

Bailiesdad wrote:" What's the normal port size?"
Use an exhaust gasket as a template and fill the head if you are going to do it that way.
Intake gasket :wink:
Early hemi to late sb Mopar trans adapters. Precision billet parts for early hemis.
Bailiesdad
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Post by Bailiesdad »

TrWaters wrote:
Bailiesdad wrote:" What's the normal port size?"
Use an exhaust gasket as a template and fill the head if you are going to do it that way.
Intake gasket :wink:

Gee thanks for pointing that out, if he gets truck/marine gaskets he will have to add to the manifolds.
johnny5
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Post by johnny5 »

The most reliable way to fix the problem is to use an aluminum intake manifold that already has the humps cast in to cover the center ports (ie Weiand 2x4bbl) or have them welded in and resurface the faces to ensure a smooth gasket mating surface. You'll have to use a remote t-stat. I'm not a big fan of welding up the head. Cast iron is tricky. Not enough people know how to do it properly.
firepower354

Post by firepower354 »

The dowels are likely stepped now. The small end is in the block. You'd just need a set of straight ones. You could open up the head holes with the right drill bit (pin size plus a couple thousandths) on a mill or even drill press if you can center it up with a bit the size of the existing hole and clamp it down.

Several aftermarket manifolds have enough stock to cover the larger water hole. If not: With a two piece manifold, you can make some 1/4"(or whatever thickness you want) aluminum manifold spacer plates big enough to cover and use longer bolts. The spacers for running low deck heads on a 392 would work great if you don't have the tools to make some. You'll have to drill water outlet holes in the plates and install fittings where the manifold has plugs to get the water out. You can run the hoses to a remote thermostat or to the radiator, sprint car style. Truck gasket on the head side, car on the other, or home made on both.

Re: Head studs as only locating device: GD&T studies on the location of hemi block and head head bolt holes on file? No pushrod binding? One piece intake manifold sealing issues? Block decks get counterbored so gaskets are locating on the shank rather than threads of the studs? Difference in stud diameter and "street" gasket through holes for those of us mortals not building blown fuelers every afternoon? Any reason NOT to use the "locating pins" to locate things?"

If you donot get a gasket to cover the entire center port you will blow the head gasket"???
"Exhaust gasket as a template" (pre-edit)? Maybe THAT'S why no pins, he bolts them on backwards?!?! Enlighten us!
mart
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Post by mart »

[quote="scootermcrad"]TrWaters.... yeah, I'm seeing this now. I didn't realize it until you pointed it out. I'm thinking that welding some material in the head to make the hole smaller might be good. Then have it faced. What's the normal port size? Maybe I can make it closer to square also, by taking some material out from the sides; if I can that is...

Is that port for water or something else?
=====================
Would you settle for blocking the
heat riser holes off entirely, rather
than just making them the same
size and shape as the heat risers
in the passenger car heads? If
so, there's a better-easier-cheaper
alternative to welding them up
with cast iron. You can cut a
couple of block-off plates out
of sheet metal, tap them into the
heat riser holes with a hammer
and then braze them in place
useing an oxy-acetyline torch
and some brass brazing rod. If
you braze the plates into the ports
so they are actually inside the port
and below the gasket surface,
rather than flush with it, there will
be no need for any resurfacing
work. Also, compared to cast-iron
welding, brazing imparts much less
heat into the head so there is no
danger of cracking or warping or
any need to pre-heat the whole
casting.

mart
========================
DblAdigger
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Post by DblAdigger »

If anyone thinks that dowels and locating sleves are not needed...because bolts do the same thing, try leaving out the sleve in the rear main cap. Please report back on how that works.
Chuck Stevens
Some people can break a cannon ball, in a sand box, with their bare hands.
Bailiesdad
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Post by Bailiesdad »

The origional question dealt with the head to block dowel pins, nothing else. You or anyone else does not need those pins.

Some times when using 331 or 354 heads, or after market heads, on a 392 block they wil not even line up, when there. When one or both are cut they sometimes will not fit period.

Here are a few more people who know the answer.

http://board.moparts.org/ubbthreads/sho ... ost3038341

The sleeve in the rear main cap is to protect the intermediate shaft.

The bellhousing dowels are always there to dial in the centerline of the crankshaft with the centerline of the transmission input shaft.
TrWaters
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Post by TrWaters »

The original post asked about the size of the dowels, not if they are needed or not.

The only way the dowels will not line up once the heads or deck is cut is if they are cut on an angle. :roll:

The Moparts post deals with BB Mopar, not early hemis.

The main cap dowel is just that, a locating dowel so that the hole for the intermediate shaft is true between the block and main cap.

I do not foresee any other usefull information coming from this post.
Early hemi to late sb Mopar trans adapters. Precision billet parts for early hemis.
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