[Cliff R]

Some comments on the Crower 60919 camshaft and selecting a cam for a 455 in general.

Dating clear back to 1999 all the 60919 cams I've installed here were 304/316, 231/240 @ .050" and on a 113LSA, ICL at 109.

The last one we used was about 7-8 years ago and it was this version.

All that time the Crower website clearly stated that the cam was 112LSA with the ICL at 108.

ALL of the 60919 cams I installed came in much closer to 112-113ICL and had to be advanced to get them to 109ICL as stated on the cam card. I truly believe to this day that Crower was either re-boxing SPC-8 cams or grinding them at or very close to the original RAIV specifications.

They may have started actually grinding them to the specs shown on their website recently. I personally haven't seen this version but haven't used a flat cam in quite a while in one of these engines. If you go to their website right now the cam card still states 304/316, 231/240 and 112LSA.

That's what it has always stated nearly as I can remember but the cam they are currently selling may be what Jay describes above.

Anyhow, I've been around 455 Pontiac street engines for a good many years now. They are a HUGE engine and require a pretty hefty cam if you want to make great power from them. They also love larger cams on wider LSA's. Doesn't mean you have to go that direction but for sure you can smooth out the idle, improve throttle response, clean up stinky exhaust and make great power with a big cam on a wide LSA. You do NOT need a lot of compression either, but it is always your friend with these things as high static compression ratios offset negatives from more overlap and longer duration.

Some cam companies will tell you flat out that LSA doesn't matter. Not going to argue LSA but keep in mind that tighter LSA INCREASES overlap all else being equal, and in almost all cases those cams are ground for advanced ICL and earlier intake closing. One needs to realize here that both of those moves INCREASE cylinder pressure, narrow up power, and spike dynamic compression higher (and earlier) as the engine revs thru the power range. At the same time this INCREASES octane requirements. So one can very quickly get into trouble trying to manage pump gas with a 455 build even if you have lowered the static compression ratio.

Below is a CLASSIC example of how this works. I've put it up here many times but it is a great example and we can learn from it. Here is the entire story.

Customer calls me up, he owns a speed shop, builds engines, ports heads/uses a flow bench for a living and owns a dyno. He is doing his first Pontiac build, but has vast experience with 460 Fords (and stroker variants) and Big Block Chevy engines. He is stroking a 400 and has custom ported a set of #96 heads for it to 250cfm. He is going to use a later model Q-jet on an RPM intake. He asks me to spec out a custom rebuild kit with tuning parts for the Q-jet he is going to use on this engine. At that time he hasn't nailed down a cam selection but tells me it will me a moderate size hydraulic roller cam.

The next phone call I get is dyno day for the engine and he tells me the engine is on the dyno, ran-in, and they were trying to make pulls but ran into detonation issues and power production is WAY less than expected. The static compression is only 9.3 to 1 so he isn't understanding it. Of course everyone right down to the guy taking out the trash is blaming the Q-jet. So I dodged all the questions about the carb being too small, fuel bowl too small, etc, etc. Instead I asked about the cam choice and he tells me he ended up with a Comp XR-276HR cam, recommended by the tech at Comp Cams. I told him that he should remove the cam and install a larger cam on a wider LSA. Instead he removes the Q-jet, installs his "dyno mule" Holley 850DP carb and commences to add timing to make better numbers and immediately blows up the engine. He ended up pinging it so hard that it spun most of the rod bearings!

So I get another call and he asks me for a cam recommendation. I spec out an Old Faithful clone with the older Magnum lobes on a 114LSA and tell him to put the ICL at 110. A little bit of silence then he says OK.

Couple of weeks later I get another phone call. He also sends me a dyno sheet from both cams. They are shown below. During the conversation he also mentioned that he put the Q-jet back on the engine (he had sent it here for me to check out and "tweak" if/as needed) and it was flawless. He also mentioned that the engine idled smoother with the larger cam in it and the "quirky" shake at idle was gone. He also noticed that it was more responsive to quick throttle movements and that he was able to throw more timing at it without any detonation.

That is the short version of the long story with more details than I've put up here before and below are the overlaid dyno charts from the XR276HR cam and the Old Faithful clone out on a 114LSA.

Morel of the story here is to realize a couple of things. A 455 engine is a HUGE engine. They have a long stroke and cylinder heads with no more cross section than an average Small Block Chevy performance head. They need a LOT of cam to make great power. With it's great piston speed they are sensitive to the intake closing point plus exhaust scavenging. For all the naysayers on here who continue to promote tight LSA none of this means you can't go that direction. I've ran into this same scenario before tuning troubled 455 Pontiac engine builds. Small cams on tight LSA's are the WORST possible direction you can go with them. When you start using larger cams you can get them to work just fine, and about all tight LSA does is give them more "attitude" at idle and stinky exhaust. The best thing about the story above is that it was a rare occasion where only ONE change was made and I had nothing to do with any of it besides supplying carburetor parts and checking the customers work........Cliff