Best mods to make a 253 go harder

[A-TEAM AUTOMOTIVE]

hey i just wanted to know if there are any mods that would make a 253 go better. all i have on my 253 right now is exhaust n extractors and a holley 600 double pumper. wat else could be done? i was told the 253 revs harder than a 308, is this true?

 

[Boonz]

well a nice big cam for a start to make use of those revs... and yes the do rev harder due to the shorter stroke.... the 600 dp is a good choice but what manifold do you ahve??? thats the biggest thing that affects the amount of power they can make

 

[A-TEAM AUTOMOTIVE]

ive got a standard bloody manifold. i have been looking into buying a high rise manifold but i wouldnt know where to look. it isnt very good off the mark tho, i think its due to the old trimatic, and i had to use the 202s 308 salisbury diff which is really really worn out now. if i was to put another diff would it get off the mark abit or alot quicker?

 

[greenfoam]

Firstly it will go much better with a quadrajet on it that the 600dp, that's a bit too much carby for a 253 and your bottom end and mid range will be pretty sad. We had a 253 with a 650dp on it one and it was a steamer everywhere but the very top end. The standard 4 barrel manifold is ok, the L34 race motor made 400hp with one so it can't be that bad .

I'd go for some ported heads a quadrajet and a mild/medium cam and the thing will scream

 

[253@7k]

So far on my HZ ive got:

253 with acl pistons
cleaned heads (no real porting, just a quick tidy up)
Good cam (hydraulic, @.050 int=214, exh=226, 112ls)
tri y extractors, twin 2.5' with modified mufflers
torker manifold (Port matched to head)
600 vac seconds
earls fuel lines (stock pump, new one soon)
msd pro billet dizzy, msd coil, msd 6al box
+other usual bits, oil pump, twin row timing chain, etc.
backed up by a supra 5 speed and a 3.08 lsd.

Bit slow down low but between 3500 and 6500rpm it goes very hard.

in your case a good cam, heads and elec dizzy should get her moving fairly well. Keep the 600 though imo quaddies are too big for 253's.

 

[stroke it]

Thought i'd toss my two cents in as ive had stinking hot 253's. You need compression to get the 253 to boogie.
Bore the 253 to 60 thou over, they actually have quite thick bores so 60 thou wont be a problem.
Youll end up with around 261 CI.
Use ACL Duralites and go for 10.5:1
Deck the block 0.025 to square the face with the crank tunnel.
Use VN V8 rods (now it has to be rebalanced)
Good camshaft is a solid 237 degrees at 0.050 duration on intake and exhaust, 0.525 lift 108 centres.
1.65:1 roller rockers.
Yeah, give the heads a mild port, 1.85 inlet/1.50 exhaust.
Dont worry about Edelbrock performers, use a standard HQ 308 valley cover.
465 to 500cfm carb Carter or Holley
HEI dizzy regraphed to give 38 degrees full advance/all in by 3800rpm on 15 degrees static.
Extractors 1 1/2 inch primary, 3 inch collector four into 1 pipe.
3.45 diff.
get it all together on a dyno.
Should pull like crazy to 7000rpm and pretty close to kissing 250Kw.
I'd run it on around 105 octane though.