General Category > Quadrajet Carb Talk and Tips

512 cad 230/236/110LSA

(1/3) > >>

512 cad:
Hey, great info in the book!  Nice parts kits too.  I'm kinda new to carb tuning(built one last month for a nearly stock towing motor and worked out great) and my combination isn't very close to anything in the book or posts I've read, so...where to start.  Here's what I've got:
carb-17080226
4,000 feet elev.
5,000-5,500 pound coupe deville for cruisin/kicks/chicks
512 caddy mtr
10.1 : 1 compression
comp cam Hyd. Flat tappet 230/236/110LSA
.5232 valve lift
2.19/1.84 valves
mildly ported heads
intake plenum divider removed/smoothed
1"carb spacer
2.5"dual exhaust, no headers(probably later)
TH400 trans(stock converter for now)
2.94:1 gears(want 3.23:1 or so)

Cliff Ruggles:
I'd use recipe #3 from our book, on the lower end of it.  Considering the size of the engine and 10 to 1 compression, it should idle pretty good, even with a 230/236/110LSA cam in it.

I'm really surprised Comp grinds cams on 110LSA's for the Caddy engines.  They are big cid/low rpm "tractor" engines.  I would have expected 112-114LSA for them?......Cliff

512 cad:
Thanks Cliff!
Would Nitrous like 110 LSA?  I ordered that cam from Maximum Torque Specialties.  Comp says it is a custom grind.  I told Al that I may get a little greedy down the road and spray it(really doubt it though, not enough tire and it should be all the fun I can handle anyhow).
512 cad

Cliff Ruggles:
Not sure if it matters much. 

My experience with big CID long stroke engines has kept me away from any cams that have short seat timing, less overlap, and tight LSA's.

Big engines, as a general rule, will like a lot of off seat timing, lots of overlap, later intake closing point(s), and wide LSA's.

We've been going out to 114LSA with a few recent Pontiac 455 builds, with EXCELLENT results at every level.

Idle quality is greatly improved, torque curve is broader, and more top end charge as well.

IMHO, those "tight" LSA grinds are fine for little low compression engines, but don't help out engines that are already trying to make all their power early and in the mid-range right to start with........Cliff

512 cad:
Just to clarify, 68-75 cad motors really aren't "long stroke" motors, at least not IMHO.  Stock bore is 4.300" on both 472's and 500's, and a 500 crank moves 4.304".  Mine is .040" overbore, so I guess I should be calling it 509.  The folks at comp returned my message today and said this cam should pull 13" vac. @ 800 and 16" @ 1,000.  It idled better than I expected it to before I moved and put it in storage.  I was pressed for time, and  so I just bolted on a small primary Q-jet that was set to factory specs for a 454.
       

Navigation

[0] Message Index

[#] Next page