Big Block vs Poly
HOLD ON! GRAND ERRORS TAKING PLACE HERE!!!!!
Big block , ply is heavy , parts are not easy to find .
No so! Major error! SOME parts is more correct. Let me list what is hard.
Cam. Few companies still have a Poly cam listing. Allow me to list the 2 worthy.
Racer Brown
Crane Cams
Gaskets, look up Detroit gaskets
Pistons may get into custom territory depending on your needs for your goal. Forged slugs are almost always a custom item. Figure on a !1,000 set of slugs if you go outside the box.
Bigger than stock valves MAY be a custom order.
No way in hell a poly will touch weighing in at BB levels,even w/aluminum heads.
You have this reversed. Even with aluminum heads and intake. The Poly has not a aluminum head. But does so on the intake.
I acquired a dual quad intake & WCFB's.
I have said intake and they will use 2 - 500 AFB/AVS - Carter or Edelbrock. 600's require intake carb pad mods.
I found some numbers on engine weight, for the Poly, LA and B Engine.
273-318-340 LA - 525lbs
360 - 550lbs
B Engine - 620 lbs
RB Engine - 670lbs
B Engine with aluminum heads, intake, water pump housing about -530lbs
Poly with LA block and aluminum intake - 530lbs
LA with aluminum head and intake - 455lbs
So with the Poly/LA hybrid, and the B engine the same weight or so, the B engine has the advantage with the extra cubic inches.
Thank you for the engine weights. The in bold text quoted from you has an issue that the OE poster MUST be made aware of.
There is no way in high heaven or the depths of hades that a LA block and Poly heads can work together OR a Poly block and LA heads work together UNLESS YOUR ONE HECK OF A GOOD WELDER AND CAN SERIOUSLY THINK OUTSIDE THE BOX.
I have in the past show the 2 blocks side by side with each of the engines heads mounted on each other's block to show why this can not be done unless, UNLESS YOU ARE ONE HECK OF A DYNOMITE WELDER AND CAN THINK OUTSIDE THE BOX TO MAKE THIS HAPPEN.
And I'd love to see this ****!
The Poly valve layout is EI EI EI EI
The L.A. valve layout is EI IE EI IE
Now think how that cam goes on each engine and let me know how you plan to work it.
LMAO!!!!!! "Z" pushrods? Drill and tube the head with pushrods in a "X" fashion?
The Poly block has a water passage inboard the engine in the valley area that feeds the intake cross ways to the otherwise of the engine.
To the OE poster, IF, IF you want to do a Poly engine, be prepped for a bigger expense than an LA. With less bang for the buck. While there is a fella CNCing Poly heads, there max flow falls short of the LA head in a similar state of work done to it.
Be in known, I personally know a Poly that has gone .060 with plenty of wall left. I have read .100 over bored. Some LA 318's have gone .090. (4.00 bore)
