69_340_GTS
Well-Known Member
You cannot get those. Jegs and Summit don't seem to like to remove unavailable items from their catalogs.
340
- Thread starter 383Scampman
- Start date
-
AdamR
Big Member
not a surprise. mopar is great at advertising products they dont make too.
I was just looking for a new stroker crank, 4.15" to get the 426 ci I want. Scat had the kind you want for about $700/$800. Mopar has one too. $?
Molnar has some stuff *I Think*
Try Hughesengines for greater than a 4.00 stroke crank. I forget who makes (or made) the 4.25.
Try Hughesengines for greater than a 4.00 stroke crank. I forget who makes (or made) the 4.25.
gzig5
Well-Known Member
How much more work to the block is required to run the 4.15" vs the 4" crank? Obviously rods and/or pistons have to be different and will be more expensive, but I wouldn't mind hanging a 426 badge on the hood and have it be truthful.
If you need to grind away at the cylinders bottom for rod clearance, that’s about it besides the cost of the crank and pistons themselves. Rod choice can keep costs down and between the 4.00 & 4.00+ cranks, the rods can be the same. It’s piston differences that can be more money. The added stroke of .15 or .18 or .25 will need to be addressed at the piston.
I got this from a book called How to build BIG inch Mopar small blocks. I know Barnes and Nobles has it.
A 4.04in bore with a 4.25 crank will get you 435 ci. if you want as close to 426 as you can get, you need a 4.2 crank and a 4.02 bore, or a 4.15 in crank and a 4.045 in bore. A 4.1 in stroke (Seems to be the norm) and a 4.05 in bore is only 422 ci. A good cam for the street is Mopar 4876348. .501 in lift w/ 230/234 Duration. Good for about 10 sec's. Use the early 360 as it has more meat where you need it. The '75 up to the Magnums are all thin wall castings and not a good choice. Magnum's are a good choice. I'm still looking for the cylinder mod's, rod's and pistons. Bore x bore x stroke x # cyl's x .785 = C I's. for heads, use Mopar # P5007141. has 2.02" valves. W/ a good valve job you can stuff 2.08" nail head valves in them. Does this help?
skrews
Well-Known Member
SalC
Well-Known Member
I just picked up two 340 blocks, one is a '68 & the other a '73. Both stock bores. The guy I got them from got the '73 out of a boneyard in '77 so very low miles, in fact hardly a wear lip in the cylinder. Both cleaned up now and magnafluxed.
Last edited:
Did you sonic check them? Wondering if the 73 is actually a thinner wall.
nm9stheham
Well-Known Member
Look into shorter Chevy aftermarket rods for a 2.100" rod bearing, or even 2.000". You can then grind the crank journals down and even offset grind them to adjust the stroke a bit and/or piston heights. You might have to narrow up the big ends of such rods a bit.
Just for those looking for their block, what is the VIN on the 68?
-
