Help With Blower Cam.
 

Will the following cam increase HP in a Gen V 502 465hp crate motor with a 871 blower or is it best left as is?Merc part 485-816709.Used in the 500 Bulldogs.
Intake lobe H240/329,
300*@.0042
240*@.050
148*@.200
.559"lift@ 1.7
Ex lobe H250/340
310*@.0042
250*@.050
158*@.200
.578"lift @ 1.7.
Also will a Gen IV 525 SC cam fit a Gen V?
Any help greatly greatly appreciated.

Re: Help With Blower Cam.
 

The cams will interchange, you will need adjustable rockers, and check the clearence between the retainers and guide. Probably a better spring to match the cam. I like the bigger cams, I would run a 112 lobe separation for blower application, I would degree it in at 108 center.

Re: Help With Blower Cam.
 

Do you think the 500 Bulldog cam would be a benefit?This cam was used between 1990-94.Is that Gen V?

Re: Help With Blower Cam.
 

I don't use any factory cams, I believe the Gen V motor was introduced in 1995. I would look for a cam with the biggest .200 numbers staying with your .050 numbers it would make the most power.

Re: Help With Blower Cam.
 

I had stock cams in two 465's put Weiand 177 blowers with 31/2 lbs on them and both camshafts broke! :mad:

Re: Help With Blower Cam.
 

Crane Part Number: 139741 Grind Number: HR-296-2S-12 IG
Engine Identification:
Start Yr. End Yr. Make Cyl Description
1967 Up CHEVROLET 8 ROUGH IDLE, PERFORMANCE USAGE, GOOD MID AND UPPER RPM TORQUE AND HP, MILD BRACKET RACING, AUTO TRANS W/ 3000+ CONVERTER, 3400-3800 CRUISE RPM, 10.0 TO 11.5 COMPRESSION RATIO ADVISED. BASIC RPM 3000-6500
Engine Size Configuration
396-454 C.I. V

Valve Setting: Intake .000 Exhaust .000 HOT

Lift: Intake @Cam 359 @Valve 610 All Lifts are based
on zero lash and theoretical rocker arm ratios.
Exhaust @ Cam 372 @Valve 632
Rocker Arm Ratio 1.70

Cam Timing: TAPPET @.004
Lift: Opens Closes ADV Duration
Intake 37 BTDC 79 ABDC 296 °
Exhaust 85 BBDC 39 ATDC 304 °

Spring Requirements: Triple Dual Outer Inner
Part Number 99896
Loads Closed 132 LBS @ 1.906 or 1 29/32
Open 414 LBS @ 1.306
Recommended RPM range with matching components
Minimum RPM 3000
Maximum RPM 6500
Valve Float 6800

Cam Timing: TAPPET @.050
Lift: Opens Closes Max Lift Duration
Intake 10 BTDC 44 ABDC 107 234 °
Exhaust 58 BBDC 4 ATDC 117 242 °

Re: Help With Blower Cam.
 

Holy shirt,you are the man Comanche.This won't work with my GenV unless i change my rockers.Is that correct?

Re: Help With Blower Cam.
 

GPM.Thanks for your advice.I don't want to muck with the rockers so can you suggest a cam that will go straight in and work better than stock with a blower?

Re: Help With Blower Cam.
 

direction

Re: Help With Blower Cam.
 

sorry, I misunderstood.

Re: Help With Blower Cam.
 

You wont need that much duration. All it will do is raise the powerband to the upper rpm range and not make useable power. . .IE Narrow power band. Lift is to small. Blower like to get the air in and out quick. A lobe with a more aggressive lifter velocity would be a better choice.

Chris

Re: Help With Blower Cam.
 

Fastlane40,
Because the 2 cams you listed are Hyd-Flat, do you intend on staying with the flats or converting to roller?
GPM,
What would be the advantage to running the 3299/3295 lobes in this application?
They are the Cheater HR Lift Rule Competition family, which are extremely aggressive competition profiles that are clearly categorized as a "Race Only". They were designed for "lift rule" racing with very fast opening rates and clearly present a durability issue in a marine engine.
Bob

Re: Help With Blower Cam.
 

I think the Crane 741 would work well. It's been a proven favorite.

Re: Help With Blower Cam.
 

Over the last 15 years or so I found better power with the "Race Only" cams, I've had no durability issues when matched with the proper componants. I would rather see more lift, but I don't know if this application will alow it, the above cam may already be to big. It was only an option, the same as the Crane. Staying with the flat tappet hydraulic would be much cheaper. How much lift can he run in stock condition?
What's your recommendation Bob ?

Re: Help With Blower Cam.
 

Some suggestions for a blower Cam.
A wide lobe separation (112*-115*) to reduce overlap and blow through.
Blower engines need less (2*-4*) advance. An early IVO is unnecessary. The intake column is pressurized and early openings increasing overlap. A 110*/112* ICL on a 114* Lobe sep would work well.
Increased exhaust volume requires blower cams to have additional ex duration to rid the cylinder of spent gasses. This is dependant upon the efficiency of your exhaust port. 8*-10* spread is a baseline reference.
Stock exhaust ports need an earlier EVO to blow down the cylinder. The negative of and early exhaust valve opening is the loss of some of the increased cylinder pressure. The negative of a late EVO is increased pumping losses. Optimizing your exhaust port will help, allowing you to delay the EVO, negating the pumping losses.
If you choose to go with a custom profile you need to determine your head flow and mechanical parameters, your peak torque/HP range, and then the cam can be calculated. I agree, staying in stock configuration with a flat tappet will limit lift
If not, (2) proven OTS flat tappet cams that provide reliable power(peak@ approx 5500 RPM) with moderate boost, valve train stability, and durability:

Lunati 02005
302*/308*…224*/234*….534”/.559”…114* LSA
2°BTDC 42°ABDC /
55°BBDC -1°ATDC

Crane 132561 H-228/312-2S-14 T1.2 (525 SC)
298*/306*…..228*/236*……530”/.551”…..114*LSA
5°BTDC 43°ABDC /
57°BBDC -1°ATDC

Re: Help With Blower Cam.
 

GPM and Rmbuilder.Thanks for taking the time and helping me out.Will the 525SC cam fit in a 502HO GenV crate motor?If it will fit will it provide benefits over the standard cam?

Re: Help With Blower Cam.
 

RM, I went with the next step up from that Lunati cam in my 580" motors we are building. I believe it was 234*/244* and .557/.595 with a 114* LSA or something close to that. Don't have the cam card in front of me but I think it's going to work out well.

Re: Help With Blower Cam.
 

Look at the cam and the power MESA is getting out of a blown 383 small block, does it tell you anything.

Re: Help With Blower Cam.
 

That its not a 502 crate motor
Bob

Re: Help With Blower Cam.
 

I'm not saying to go as big as the 383, but a 502 crate motor with forged crank, rods, and pistons, 1/4 more stroke, 119 more cubic inch can take a decent size cam and make good power in a useable power range. I disagree with the 114 lobe separtion, from what I've seen on the dyno,they may idle just a bit smoother, they do extend the power range a 100 or so rpm but they cost low and mid-range torque, vrs a 112.

Re: Help With Blower Cam.
 

GPM
No, the lobes in the blown 383, are CamMotion not Comp, and not even close to the lobes in this thread.
The “Race Only” designation for the lobes 3299/3295 recommended in post #11 is actually Comp Cams designation for the lobe. By referencing page 246 of the Comp Catalog at this page the specified lobes are clearly marked in bold print as Race Only.
http://www.compcams.com/Technical/Ca...ML/JPG/246.jpg
Also on page 15 the print version of the 2005 Comp Cams Master Lobe Profile Catalog they issue additional information.
“These lobes are very aggressive and are “race only” designed lobes”
I posted this information because anyone who would seriously consider having the “Cheater HR Lift Rule Competition Hydraulic Rollers” lobe ground on a BBC core, for a marine application, should be aware that some extensive valve train tweaking would be necessary to have any reasonable expectation of any durability. My question was to you the advantage of the “restricted rule”(their design is essentially a compromise) lobes over all of the other lobe profiles available.
Bob

Re: Help With Blower Cam.
 

I actually meant the duration, BOB, It's probably the biggest cam I've seen on OSO.
Back to the Comp cam, It was only a suggestion, the shorter seat timing would idle better, the bigger .200 duration would make more hp. and maybe the low lift would actually work without hitting retainers to guides. That would have to be checked. My
suggestion would be see what fits before making the decision.

Re: Help With Blower Cam.
 

GPM,
It is not a good idea to use those lobes in a marine application. Some of those lobes require the changing of valve springs after a weekend of racing. They also require "modified" hyd roller lifters and the use of restrictor pushrods. Your thinking is going in the right direction but the "liveability of the engine" would be greatly sacrificed for the gain.

Chris

Re: Help With Blower Cam.
 

Chris, you and Bob are probably right, I shouldn't have even mentioned that kind of cam on here. I've had good luck with the aggresive solid rollers, they make excellent power, but you do have to keep an eye on the valve train. I haven't broke a valve spring since I quite useing Ultradyne cams. We definatly drifted away from the original thread, I believe the question was about a hydraulic flat tappet cam in a Gen V 502.

Re: Help With Blower Cam.
 

Flat Tappets:
I would strongly suggest upgrading to hyd roller if you can. In my industry lifter production of flat tappets was greatly affected when 1 company was closed due to financial reasons and one company just quit producing flat tappets. This coincided with the gov. mandating that since OEM's weren't producing cars that needed harmful additives that reduced wear in flat tappet applications that the oil companies were banned from putting these additives in except for oil to be used in AG vehicles. And last but not least the parkariztion of lifter faces had become so expensive it had to be dropped. . .critical in initial cam lifter break in.

Since this the amount of cams going flat has gone through the roof with cams getting blamed. Well it is not their fault. The lifters are to blame. The crown on some lifters is none existant to minimal. The reduction in the amount of crown reduces the lifters spinning motion which it must do to work.

Now lifters from China are entering the country through sub par sources. Although some of the stuff from over there is good quality when QC is inforced, some of the stuff is copy cat.

If you half to use flat tappets here's what I would suggest:

1. Get some GM EOS (engine oil suppliment). This is a must when breaking the cam in.
2. Buy lifters from the camshaft mfg. Most now will do nothing if you mix lifters with their cams.
3. Use light break in springs and don't let the engine go below 2000 rpm for the first 30 minutes.

4. Use a straight 30 oil during break in.

5. Some engine builders over fill the crank case by 5 or 6 qts. This won't hurt anything at low rpm below 3000, but what it will do is allow the crank and rods to splash and throw oil on the cam for extra lube. Once cam is broke in, fill pan with correct amount of oil.

6. Last but not least cross your fingers.



Chris

Re: Help With Blower Cam.
 

I think a post may have been lost during maintenance where fastlane40 said he wanted to keep the non-adjustable rockers also. If that is the case, it limits the options available.
Bob

Re: Help With Blower Cam.
 

Would that be somewhere around .540 max lift and the same size base circle as he is running now?

Re: Help With Blower Cam.
 

GPM
Yes, thats max.
Bob

Re: Help With Blower Cam.
 

Bob, have you ever run the old Ultradyne 231/ 239 @ .050 .531 lift hydraulic?

Re: Help With Blower Cam.
 

Several friends of mine and I have run the 288/296 (231*/239*) Ultradyne flat tappet hydraulic cam. However, the lift specs I recall used to be something more like .550"/.558" and then later it was changed to .550"/.575".

Merc used it in their 454cid 440hp Cyclone engines back in the 1980's. It is a little too large for a 454 in my opinion. I believe Merc also used the same exact cam in their 482cid 460hp engine if that tells you anything. Merc ran both of these engines with a GIL exhaust system. I think you especially needed to at least run the GIL's with that cam in the 454 just to get it to work properly. I saw some guys use this cam while upgrading their 454cid 365hp Merc engines and while still retaining the stock Merc cast iron exhaust manifolds (very crude) and they were disappointed. Back then they didn't have GPS available to really see any gains. With the stock Merc cast iron exhaust they did happen to notice more torque...in the middle, but the cam needs to breath better, especially in a 454 and the GIL's helped a lot, but some guys couldn't afford to go out and by aftermarket exhausts. As time went on some were able to afford the GIL's or Stainless Marine exhausts and once they bolted them on they noticed much better performance and were much happier. I always liked that cam, but from what I know today I wouldn't recommend it any longer for a 454cid marine application---it's a bit too large.

By the way, my cousin still has one of those cams brand new in the box if anyone is interested.

Re: Help With Blower Cam.
 

I'm sorry , I was going from memory not the cam card, I was looking for a cam that would work in a basically stock rectangular port 454. I used the 282/ 290. 233/ 241@ .050 it was .530 lift. it ran great for what it was. I would be curious how it would run in a 502 blower application.