That has been bored 30over. It has a 350 crank in it, but casting number is 68 block that could be any of those. So I got the build date code etc. Originally it was a 350. The crank needs turned so im just gona turn it in for a new one for 75 bucks, what should i get? stick with the 350 crank or change to 327 or 302 or for 200 bucks I can get a 400 crank to make a 383. The heads are 194's and its got flat top pistons in it.

I want 300+ hp, but wouldnt mind gettin 350
92 octane is a must, nothing more.
cam of choice is going to be
224/234 dur
.465/.488 lft
114 lsa

This is the same cam shane buss is runnin in his 355. but he has vortec heads.

I can go for 383 with a mild cam and medium heads or should is this cam enough for 300+hp.

what would you do?

btw, this is for the 69 not the 92 and eventually i will have the block tapped for a knock sensor, and throw tbi on it.

 

383!
That's what I would do.

 

A crossram 302 sounds good to me

 

Cola Crank, forged , for 383 stroker. I guess you can try the Summit one also. These are new units not reground 400 cores which are getting harder to find. Don't kill another 400 core.
6" rods, done.

When will you see the rev's needed to run a 302 on the street? By the time you hit 9000 grand the race is over and you lost to a bigger lower revving motor.

GM made bigger engines for a reason More cubes = more power, = less revs = longer engine life.


You never heard an old timer tell you "the bigger an engine the longer it lasts"


It's mechanics. HP is a function of torque over time.

expressed as HP = Torque * RPM / 5252

A big engine makes more torque down low hence less revs.

A smaller engine makes less torque BUT Revs higher.

I would much rather have a high torque lower revving engine, you will see more usable power on the street and track.

 

There's no replacement...

 

I dont think that tbi will be able to rev to 7500 which is where my dad used to shift his 69 Z28/RS 302.

 

unless you have the small journal block, a 302 crank is out.

 

Well the block is '68 so it should be a large journal; so he could pick up a 307 crank then to make a 302!

 

mmmmmmmmmm......ttttooooorrrrrqqqquuuuueeeee......
Go 383 man!

 

307 crank is the same as a 327. '68 is a transition year. My friends '68 Camaro ended up with the large journal 327.

 

I thought it was a 283 crank?

 

nope, a 307 is a 283 block and 327 crank.

 

Whoops I just noticed my mishap. I apologize for my wrong information!

 

how much can you bore those old engines out? maybe .125 over with a 400 style crank?

 

262 = 3.671" x 3.10" (5.7" rod)
265 = 3.750" x 3.00" ('55-'57 Gen.I 5.7" rod)
265 = 3.750" x 3.00" ('94-'96 Gen.II 4.3 liter V-8 "L99" 5.94" rod)
267 = 3.500" x 3.48" (5.7" rod)
283 = 3.875" x 3.00" (5.7" rod)
293 = 3.780" x 3.27" ('99-later "LR4" 4.8 Liter Vortec)
302 = 4.000" x 3.00" (5.7" rod)
305 = 3.740" x 3.48" (5.7" rod)
307 = 3.875" x 3.25" (5.7" rod)
325 = 3.780" x 3.62" ('99-later "LM7" 5.3 Liter Vortec)
327 = 4.000" x 3.25" (5.7" rod)
350 = 4.000" x 3.48" (5.7" rod)
350 = 4.000" x 3.48" ('96-'00 Vortec, 5.7" rod)
350 = 3.900" x 3.66" ('89-'95 "LT5" in "ZR1" Corvette 32-valve DOHC)
(5.74" rod)
350 = 3.900" x 3.62" ('97-later Gen.III "LS1")(6.098" rod)
(actually totals 346 cubic inches)
364 = 4.000" x 3.62" ('99-later "LQ4" 6.0 Liter Vortec)
383 = 4.000" x 3.80" ('00 "HT 383" Gen.I truck crate motor) (5.7" rod)
400 = 4.125" x 3.75" (5.565" rod)

Two common, non-factory smallblock combinations:

377 = 4.155" x 3.48" (5.7" or 6.00" rod)
400 block and a 350 crank with "spacer" main bearings
383 = 4.030" x 3.76" (5.565" or 5.7" or 6.0" rod)
350 block and a 400 crank, main bearing crank journals
cut to 350 size


does that help guys.

it is a large journal block
cast # is 3956618
casting date is aug 4th 1968
put into car = flint michigan. febuary 2nd 1968


Decided is this
staying with 350 crank

so 355.
76-78cc heads, 1.94 intake, 1.50 exhaust. slight port job with 3angle valve job
cam ~214/224 .465/4.85 114
flat top pistons with 4valve reliefs
4bbl carter afb carb i think is 650 (came with camaro)
torquer II manifold
full lenth headers, 3ft of pipe and thats it. no mufflers. for now
anybody with desktop dyno, run that by for me. i think it will hit 330+ with torque around 350+

thanks guys. ill let you know how it runs next week.

 

don't use the torker 2. The 7547 is more agressive and more suited to TBI. the plenum is about as wide as the TBI so if you grind on the squarebore ridge for clearance you're gonna be much better off. It also has bigger ports than the Torker2 (that has Performer size ports).

 

MEGA TORQUE = HAPPY GEAR JAMMER