Over boring 348's

[DIV1RACER-2]

Some time ago & also just recenty there has been speculation of whether or not the 655 truck block can be bored to standard 409 or not. The question in my case has been answered, Courosity finally got the best of me !!

I took a 65 production date block to the machine shop & had it sonic checked. Every block is different , some have core shift worse than others, this is how my block ck'd .

Each cyl. was ck'd in 4 places with a low # on only 1 cyl. of .199 & a max of .309. The bore on this block is pretty well centered & is uniform top to bottom . My conclusion is it won't go standard 409 unless you want to see a good block wasted no1:

As an alternative i put some #s together & this is what i would or will do w/ this block / + .090 with a 4 in stroke & comes out to 446 cubes

Chevy people are spoiled w/ big bores & short strokes that will in stock form RPM very well . Other manufactures use long stokes & smaller bores that run very well Okay maybe they run okay ?????

Some of you guys may differ in opinion , so let's hear your opinions.

BTW for a $25.00 charge ?? for a sonic test it's money well spent.


Happy holidays

 

[Tom Kochtanek]

Empirical evidence

Denny, thanks for the detailed analysis of your "655" block. I believe this is the same 348 truck block that TomO has, and I will be interested to see how his turns out.

Now that the word is out there's going to be a "run" on 348 truck blocks, right?

Good work!

regards,
TomK

 

[Va348]

Hi Denny

My thouht's on Bore ver Stroke is, If the heads or manifold do not have great flow and your are not going to rev much over 7000 rpm STROKE is the way to go I think.

If the heads and manifold will not flow but say 250 you have 2 choices Pull on them longer with Stroke and DO Not waste any of what you have. The best way
that I have to bet bad air flow is with CR .It's A Big balancing act. When you rev past tq peak CR is dropping like a rock.

And allways degree Cam where you have about 9.1 to 9.5 race 7.75 to 8.25 street. at intake closing at the Valve rocker arm on, lash set Take head off and measure stroke and fig CR right there.

You Made need 15.1 stactic just depend on what Cam.


Denny I need you to Call Me, I lost your Ph #


Dale

 

[DIV1RACER-2]

Dale


Good to hear from you !!!! Been going to call ya. time factor , i'll call this week.


An additional e-mail i have is feightyfour@aol.com

Couldn't sleep last nite so i did some posting !!!!

Happy Holidays

 

[SS425HP]

email address

Denny, you forgot to tell me to SPELL 84. I was sending to f84@aol.com No wonder it didn't get to you, but I never got anything back saying it wasn't delivered.????

Fred

 

[TomO]

Denny - Thanks for the info - it always helps to have real numbers than speculative. As Tom K mentioned I do have a 65' 348 truck block (thanks to Tom K!). I have been pondering how much the block could safely be bored and still leave some material for additional hone if needed down the road. The block that I have does seem to be well centered if the cam bore to cam face on the casting is any indicator. I know that every block is different so I will have to get mine tested before I go very far in making up my mind how to proceed. I still need to knock out a couple of pistons before I take it to the machine shop for testing. I have gotten side tracked over the past couple of months - happens to everyone.

Is there a specific area in the cylinder that I should take the measurements?

I would like to hear more thoughts on the bore to stroke for a 817/333 headed 348 stoked engine. The heads/intake flow is going to dictate how the engine is built. When it comes to engine building I am all theory and not much hands on expereice.


TomO