High Performance Big Block Cadillacs
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Author Topic: camshafts and the cadillac  (Read 37353 times)
cadracer
C1
*
Posts: 10



« Reply #45 on: January 17, 2012, 09:57:48 PM »

Im chiming in on this cam selection as i have done the same tried many different combinations. I have also done one solid lifter setup and it did good till i ate on lobe due to either improper breakin oil  ZDP not added. Motor had an excellent exahust note and seem to have nice throttle reponce till lobe went completely away.I am running that 12.5 1 compression motor also. I do like this setup on the motor and it made some good power on the dyno but due to niagra secondaries the motor went to fat to to pull past 2500. Think it still made 460 ftlbs tq and 250 hp. Hoping this snow doesnt stick around because i want to do so street tunning on these setups.
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519 cubes with twin turbos what will it do?
gfinishline
C1
*
Posts: 6



« Reply #46 on: March 07, 2012, 11:01:57 PM »

I'm brand new here and I am trying to learn what is going on, but if you guys want your motors to 'pull up' with torque, why such wide lobe centers on all the cams ?  Why would you not use "shorter duration" with 110 or 108 lobe centers ? (small ports with rapid velocity)  IMHO the RPM band is somewhat narrow, so why not use a cam profile that matches the flow of the heads ? I am going to build a couple of turbo Cads and I am just getting into your whole world.
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"There are old racers and there are bold racers, but there are no old bold racers".
dave brode
C5
*****
Posts: 1074


Best of 11.66, 113.96, 1.59 sixty


« Reply #47 on: March 14, 2012, 05:40:14 AM »

I'm brand new here and I am trying to learn what is going on, but if you guys want your motors to 'pull up' with torque, why such wide lobe centers on all the cams ?  Why would you not use "shorter duration" with 110 or 108 lobe centers ? (small ports with rapid velocity)  IMHO the RPM band is somewhat narrow, so why not use a cam profile that matches the flow of the heads ? I am going to build a couple of turbo Cads and I am just getting into your whole world.

First, imo, your use of the term "lobe centers" may be confusing to some. You may know, but: lobe seperation angle can't be changed once cam is ground. A cam ground on 110* LSA, installed at 110/110 also has 110* "centers". However, if you advance or retard it, the LSA is still 110*, but the centers change.

--
That said, the generally accepted opinion is:

Wide LSA = smoother idle, broad power range. Narrow LSA = rougher idle, a bit more narrow power range.

---

Although it is most common to grind Caddy cams wide, some on as tight as 108* LSA have been used with good results.
 
A turbo engine generally uses a wide LSA, as tighter LSA = more overlap, which can be bad on a turbo'd deal. Most experts will say that 112-116* is better for turbo'd, although I did see one turbo'd 383 chev with a rumpity cam on a 108* LSA that ran VERY well.

Some experts also claim that if an engine is "cylinder flow limited", a tight LSA will work very well. Some reading on the subject;

http://www.speedtalk.com/forum/viewtopic.php?f=1&t=938&sid=3906f20c01cad071983932d8d9466434

Dave
« Last Edit: June 12, 2012, 02:29:05 PM by dave brode » Logged

3960 lb '71 C-10. 11.7-1 CR 514". PEP I beam rods floating MTS 18cc dish Probes, Elgin solid cam, home ported heads, MTS 2.19/1.84", Potter/Probe shaft rockers, edel 2115, 4781 850. Switch-pitch TH400, 12" 1800/3200 Tri-Shield convertor, 4.30 gears. Best so far of 11.66, 114.8 mph and 1.59 sixty
gfinishline
C1
*
Posts: 6



« Reply #48 on: March 18, 2012, 12:33:23 PM »

Thanks. I agree 'most often' turbo cams use 'wide lobe center angles' (ground into them), but many very high performance engine shops do not. I agree, advancing or retarding the cam grind will effect the 'lobe center angles' relative to the crankshaft timing, but IMHO closing up the 'lobe center angles' (ground into the cam) will amplify and pinpoint the powerband. (short track cars) As far as US V8 turbo cams I remember back in the 70's when I got started with building turbo motors. At that time Engle was the NAME for turbo cams and their grinds would 'spool up' those old stone aged turbos. (better than the other brands) Many builders have worked with Engle to improve/test new designs (including me). I see that a few people here are building turbo Cads and I am wondering what kind of cam grinds they are using. Is there a place to view (on line) Cad cylinder head flow charts? (stock and modified) I also wonder about how much power the stock crank with aftermarket rods will endure. I really like working with turbo motors, I still have my (original owner) 1979 Chevy Dually work truck. I ordered it specifically to turbo, and do a Super Chevy Magazine spread about the install. It took me 3 months to 're-engineer' a "professional kit" system, to make it work correctly. The totally STOCK 454 motor went 221,000 miles, until the timing chain cut a hole it it's tin cover. The truck has been parked a few years now because the 'long block I built' with Arias pistons..etc (1991) has only taken it to 497,000 and it really needs valve springs and seals. I'm looking at first doing a mild (7 to 10 lbs) turbo Cad 500 for a V-drive boat. I would like to have power from 2500 to 6000 so that I would not need a 'multispeed' transmission. I expect to run this on 'pump gas' possably with 'water injection', using the factory iron heads. Thanks for any/all replies. I read the cylinder head info offered here, I just wondered if anyone else had more info. Thanks.
« Last Edit: March 20, 2012, 09:13:29 PM by gfinishline » Logged

"There are old racers and there are bold racers, but there are no old bold racers".
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