348 Head Gaskets

bubbletop61

Well Known Member
I was wondering if anyone has a source of steel Head Gaskets
for the 348, and whether they are available in various thicknesses?

Also would like to know what Cam CPG would recommend for
a high horse 348. He said I could ask this question...LOL:D

I want to stay down below 10:1. Engine will be a 3x2 built in a lo-horse block with 1147 heads. Will use stock 2 1/2" Exh. Manifolds. Haven't decided yet whether to stroke or not. I'm sure somebody has some ideas for the recipe for this engine?:D
 
Ask ME what cam ????!!!

Camashaft ?
Me ?
I dunno:rolleyes: ;)

Well....
Depends if you ARE going to stroke it ( hope so:cheers )

My recommendation:

First.... YES, stroke it. 409 crank... about 377-382 cubes

10.25:1 forged pistons. ( about 10:1 with a composition gasket )
For use with a 6.135" BBC rod. Bore .030" - .060"

I have an order in with Ross right now. They are making pistons custom designed to my request. Getting a good deal too !
And yes, one of the sets is an NHRA legal stock .060.
Anyhow, the big thing is the outside of the dome. Their production piston does not have the factory piston's rounded outer edge ( belville ). The ones they are doing for me will have this. Provides better distribution of combustion pressure... avoiding the side-loading caused by the angled deck/part of the piston head.
This conmpression works fine with 92 octane pump premium.

Heads... minor port work. Raising the roof of the intake, opening the exhaust, blending the bowls, polishing the combustion chamber ( around the plug to eliminate hot spots )... original 2.06" / 1.72" valve size.

Port match your intake to the heads

Use the Belanger/Wilson 1 3/4' headers

How's that ?

Oh... the cam;) ....

Mechanical...
.570" - .590" lift
280 - 288 adv duration
242-250 duration @ .050"
110-108 centre line sep.
1.75 roller rockers
130 lb @ seat dual valve springs.

Will run HARD from about 2800 - 6200
375 - 400 HP ( depending on exactly what cam and compression ):deal :cheers :D :p
 

bubbletop61

Well Known Member
wazzup, what cam?

Bob and Aubrey
Thanks for the recipe guys. Bob from the sounds of this... did Aubrey of the True North Strong and Free build your engine? Aubrey I know from our conversation that you love road trips, but...:D Pottsville and Hanna are a pretty good cruise apart. Well yeah, with enough time you can hit a lot of good junk yards( soooorry...wreckers yards) along the way, but its still a bit of a run.

Bob are you happy with the recipe and performance, the fact that the cost is behind you, or that the much anticipated wait is over...
I assume all three?

Aubrey I may be interested in jumping in on your order for the pistons and it may help your cost a little. Are you having only +.060" produced or are you doing any .020 0r .030. I don't want to take any more life out of the block than I have to, but the pistons sound like a good bet.

Thanks again for the info guys and sorry to have taken so long to post on again.

Cheers:cheers :cheers
Gar
 

bobs409

 
Administrator
No, I was just kidding. Aubrey's reply went right over my head. :D

I didn't even know Aubrey when mine was being built. In fact, I didn't even have a computer then. :) But I am glad it's over. Mine was in the shop for about 11 years! (don't ask) :cuss

Aubrey's the guy to deal with. He'll set things straight for ya.
 
Thank YOU, Bob:D

Isn't it amazing how much we got done, even without computers ?:rolleyes: ;)

No, Gar, I didn't do Bob's.... there's LOTS of people between these oceans who can do it..... I just like talking about it 'cause it lets me "dream" these combinations:p !

.030" ? Absolutely... It's good to not bore more than you have to.
I have two (2) sets of .030's, two (2) sets of .060's, and a set of .125" on the way. One stock stroke, three in 3.76" ( 427 ), and one in 4" ( 454 ). These are all 409 pistons, but same design for 348.

Hey Gar... with our improved $$, now would be a good time

:cheers :deal :D
 

bubbletop61

Well Known Member
11 years

Wow I thought I was bad with gettin on with things...11 years
is right up to my standard....but raising a family can sometimes
"help" with these situations LOL:confused:

I was put on to a guy in NJ last week that has done a lot of W heads for another NJ ( Chev 61-64) restorer that I have a lot of respect for. He was pretty confident with his experience at putting stellite exhaust valve seats into these heads, which I think is one of the most difficult parts of this project. Admittedly, he warned that when cutting for the seats, there is an occasional breakthrough into the water jacket, and he wouldn't gaurantee against this, because the heads vary so much in material thickness in this area.

Interesting though that he said that he had actually used JB wels a couplke of times to close the hole at the time he pressed the seats in....and it held the seal. He has seen service life of more than five years out of this fix.

Aubrey, you mentioned JB WELD for fixing my head surface problem. If it will do this fix around the seat where the temp is so high, it should be fine to fill the pits on the face of the head. Thanks
Gar
 

bubbletop61

Well Known Member
To stroke or not to stroke

Aubrey I have never done a stroker project before so I am not familiar with the effect it has on the piston design. Is the location of the wrist pin moved lower in the piston to give higher compression?
It would be great to know the details on this is if you have a minute to explain. Takin' my bride, and the progeny out for Mothers Day Brunch now, but will be back on later.
Thanks Again
Gar
 
Pin Height

Gar... yes, pin height is higher in the piston.... by .125" ( to compensate for the stroke... but if using a steel shim gasket, that will be reduced by .010" because of the slightly longer BBC rod.
If you use the compostion gasket, then go the full .125" longer... yes, your piston, at TDC, will actualy come out above the deck of the block by about .004" ( hey, my "Stocker" is .012" ! )

As for the final compression ratio... that's the proportion of cylinder volume to combustion chamber volume. In this case, because we're increasing the cylinder volume ( 348 to 377 CID ), we need more combustion chamber volume in order to keep the ratio down. This is done through varying the dome height of the piston.
 

bubbletop61

Well Known Member
.oo4 - .012" out of the block?

Aubrey
Thanks for the info. but there is something I don't get:confused:

On my heads there is virtually nowhere for a piston to go outside the block. There is no combustion chamber in the head at all. The area where the head intersects the block is flat straight across the deck of the block. I think this is normal but maybe my heads were shaved already?

Now I know that the W engine uses the area between the top of the piston and the head as its combustion chamber, and that they varied the compression ratio be "scalloping" the cylinder walls in the area where the rings did not contact. So my conclusion from all this is that either we would be depending on the thickness of the Head Gasket to provide the clearance for the piston to protrude, or we cut a groove in the head, or we modify the head of the piston to obtain the required clearance. :confused:

(Oh ,stupid me, is the protrusion above the deck of the block at the edge of the piston, or at the center crown?)

Now another question....ta daaah!

Compression ratio??? On the W engines is the cylinder area considered to be the area below the highest point of travel of the top piston ring? So the combustion chamber would be from this point up to the bottom of the head, plus the little 'as cast' bit around the valve heads? Or is it just considered from the top of the piston?

Ciao and thanks
Gar
 

dq409

Well Known Member
Supporting Member 3
Aubrey did my engine and,,,,,until last night I didn`t REALLY know how strong and fast it is!!!!

Too bad I have a full face helmet,,,,YOU COULD HAVE SEEN THE BIG SMILE ON MY FACE FROM HANNA !!!!

Open headers,,,,,100 feet of rubber,,,,,needn`t say anymore!
 
Gar... The only part of the piston that would extend out of the block would be the part that is at the same angle as the block deck. This is only by about .004" - .0012". Compensates for the .040" thick head gasket as compared to the original .018-.020 gasket.

The compresion ratio is calculated from:
Cylinder volume + the volume of the area in the block above the pistone when it is at TDC + the volume of the combustion chamber in the head + the volume between the two that the head gasket creates.
 
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