512 cad 230/236/110LSA

[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.
       

[512 cad]

Just a little more info:
Advertised duration is 273 int./290 exh.
What's "a lot"?  I have 13 degrees overlap(I think...does that sound right?).
I was expecting a 2100-5200 powerband(motor should hang together pretty well to 5800-6000).
I might be missing out with only 1.6:1 ratio rockers, but I squueeeezzed them under stock valve covers.

[73ss]

Is this the X-Treme energy for the caddy's? I've noticed most of the 114 lsa are advertised as "Maximize nitrous, power adder, etc". I'm deciding on a 114 grind for my 454. No power adder.

[512 cad]

I don't know anything about the exteme energy series cams, but I do know mine is a custom grind that MTS has done for them.  It was manufactured by Comp Cams.  I don't have a clue why the 110 LSA was specified.  I'm sure they know more about it than me.  It beats the stock smog cam!   

[Cliff Ruggles]

How many Caddy engines do you suppose Comp Cams built and dyno tested with 110, 112, and 114 LSA camshafts.

My bet is not a single one.

Same deal with Pontiac 455 engines, their XE cams are "turds" in those engines.  Not enough seat to seat timing, not enough overlap, and LSA too tight.  

We've done WAY better using long duration (seat to seat) cams on wider LSA's in those engines.

Engines are just round pistons moving up and down in round holes.  Any big cid relatively "long" stroke engines are going to share similiar results.

Keep in mind here, I'm discussing street and street/strip engines that require good idle, good vacuum at idle, and strong low end power.  This means we're looking at smaller cams for them.

With high rpm race engines, we typically have to pull the LSA down some to get good results.  Almost the exact opposite with pump gas street engines.  We do NOT want to narrow up the power curve, and make a lot of cylinder pressure in the mid-range (detonation) using pump gas.  Much better to spread the power (torque) out as much as possible/practical...IMHO....Cliff

[512 cad]

Carbs and cams are the two parts of a car that I have not endeavered to understand until this winter...but I'm learning from you.  Thanks!

I understand what you are saying.  I don't doubt it.  I'm not saying this is the best cam choice. 

What I was trying to say is that I don't think Comp Cams came up with the specs.  They said it was a custom grind.  I don't think they sell it retail.

I think Maximum Torque Specialties came up with the specs.  I ordered it from them, they shipped it.  They do restore, race, pull, tow, cruise and dyno cadillac engines.  Only.  For sixteen years. 

I haven't asked them why they thought this was the best cam for my land yacht.  Mabey they shipped the wrong one by mistake?  I doubt it.
512 cad     

[Cliff Ruggles]

In recent years we've been going out to 112 and on to 114LSA camshafts in Pontiac 455 engines.  They have strokes from 4.21 to 4.25 and bore sizes up to 4.21".

We also tested a couple of cams on 110LSA's.  The 110LSA grinds did not make the field.  They tried to throw a lot of power at us early, idled worse, and narrowed up the power curve considerably.

The best results to date have been from the 114LSA grinds, in terms of smooth idle quality, strong "locomotive" type power over a broad rpm range, and strong top end charge......Cliff