I am considering ordering a replacement cam from Crower, I like how most of their cams have higher numbers on the exhaust side then the intake side and I like the 112 degree lobe separation. I completed their detailed spec sheet for cam recommendation. They are recommending 50233 0r 50232, both of these cams have a lift that is greater than the cam I currently have. I am right on the limit for lifter preload, actually I have very little or no preload in some cases. However my engine is not rattling at start up, my concern is that if I go to these higher lift cams that I WILL be forced to go to adjustable/custom pushrods. To get = or just under 480 lift I currently have I need to go to their 50231, challenge is that cam has duration at 50 = to 210 intake 218 exh. Worried about pinging etc due to high compression pistons. I am still quite new at this and wondering if someone can confirm that my concerns are valid.
The specs on the current cam are unknown and were not measured. This has been discussed. The 255dur# is what the cam grinder said. Micheal if you used the Poston sb-110 cam in the past with success (260 adv dur./.462 lift on a 110lsa). That cam was small and the description says it idles like a stock cam. There should be no issue using the 50231 cam. Still you may need pushrods as these cams are regrinds. Also just because you have 11.2 pistons does not mean you have 11.2 compression. I've seen stock .020" steel gaskets as well as composte ones .040" and .050" thick. The only way to truely know your static comp. would be to measure the chambers/deck height/piston dish or dome volume and head gasket volume. Ray
Like RG67 said that cam is an unknown and more than likely is 255 advertised which would put it smaller than he's looking at now. If it had 255@.050" in a 300" engine it would be hard pressed to idle below 1200 RPM in neutral which I'm pretty sure it isn't doing now. That much overlap would cause that kind of idle or even worse. The thing that causes the problem with cams is the base circle. You can have different BC even with the same specs if they were ground by a different manufacturer. How do you know you have very little preload. Was it measured? .030" preload is a good high performance preload and you would be hard pressed to tell looking at a lifter as the cup pressed into the lifter that it was that much. If you have the aluminum heads that would knock about a point off of octane requirements. Somehow GM got those alleged 11:1 engines to run on pump gas back in the day. I wouldn't worry. I'd pull the cam in there first and get the official p/n off the back and find out exactly what you have and go from there.
with 255 advertised it sure has a lot of lift 480. the 50231 cam has only 451 lift at 270 degrees advertised. so the 255 is a hell of cam. the 50231 is very very slow ramp at 210 at .050 with a high 270 advertised.
Remember alot of those older cams weren't measured the same way they do it today. I can grind you whatever you need. I'm not sure I'd do it on a 112 though even with the high compression. Let me know if I can help. Thanks Mark
your right cant be 255 at .050 i didnt know if it was a race engine or not. dont forget back then the gas was over a 100 octane.
It idles at 1100 in neutral, it drops 350-400 rpm :error: :error: ..actually 250 - 300 rpm drop when I put it in gear, it runs like a dog for the first 15 minutes, it now gets 11 miles per gallon. A good solid engineer who races and tunes on weekends (people come from far to have look at their cars), laughed when I drove into his drive, "that is a lot of cam my friend". The cam is a cheater cam done by a local guy, no cam card...I was at the counter when my engine builder asked for specs from the grinder. I heard 255 @ 50 for duration...but the minute I complained about drivability and asked why the hell would you put that grind after I gave you guys all the specs on my car....I got the "well I don't think we put that much duration on it..." So really your guess as good as mine as to what this cam REALLY IS. As far as lifter preload, it is currently from 7 to 14 thou..on the ones I checked when I had the intake off. I have iron heads, I polished my combustion chamber enough to not have any high spots or sharp edges, the heads have been decked twice...I do not know how much came off but I was told...next to nothing both times. My gaskets are 40 thou. Mark, I thought a wider lobb separation was better for a heavier car. Thanks to all for showing interest in my little dilemma...After I looked at the lift on the 50232 & 233 I was back to....Maybe I SHOULD just change the TC to higher stall. Decisions, decisions, decisions...
First thing you need to ask yourself........What am I looking to acheive ? The cam you have in there now although a defineate step forward is not that big a grind, And if you go further your driveability is only going to get worse. Sounds to me like your a bit unhappy with the bottom end performane ? There are alot of ways to make the car feel " better " with what you have...more gear, higher stall, carb changes, you could even take those thick head gaskets out for a little help.
Also, not to ask a stupid question but was the cam degreed? Maybe it's retarded from where it should be or wants to be? It's just a guess, but if there are this many questions about what cam it actually is or what the cam specs are; what are the chances that's it's installed on the proper centerline?
It's a dog on the bottom end. I want more torque off the line. Other than cam 1st option is TC. I was open to changing the cam cause I will probably do a front cover swap soon and I would have done it at the same time. Re the 50232, just a bit concerned about valve train geometry with that lift, push rods already a little loose at 480 lift (i know I can correct with custom push rods)...just looking to mitigate cost. I was on the phone with Dave/Bruce?? Crower from Crower cams. He thought that the 50231 should work well with my car, he also mentioned that he could do a custom grind and have LSA at 116. But he kept coming back to the fact that we really do not know what is in my car, he offered to cam doctor existing cam if I wanted to do that and work from there. He was not a big fan of going the TC route (then again he should be a bit biased). Overall to tried to be as helpful as they could given the info that was available. Yes, it was degreed. However done assuming a 110 LSA. Noticed that a lot of experienced builders really like the 50232 for the buick 300 CI, that includes D&D fabrication...
did you change the duration too, a lower LSA makes peak power in the lower rpms. plus theres a lot less over lap with a 116 more pinging. the thumper cams from comp is on a 107 LSA thats there most powerfull cam.
Yes typically a lower lsa will make more power sooner, better for a heavier car and/or smaller motor. The Thump'rs combine a lower lsa but larger exhaust lobe to add some legs and give it that tone. In all honesty a lot of grinders have been doing that for years, they just didn't have the $$$ to market it like Comp does. But interestingly enough, all the tests against their own Xtreme grinds have put the Thump'r ahead of the others in peak power and overall power output. The thumpr's definitely have slower lobes than the Xtreme stuff, so much for their claims on the fast ramp stuff giving you "more area under the curve".
:gp: Found good discussion thread on LSA http://www.ls1.com/forums/f7/how-does-lsa-affect-performance-158701/
it not that i would run a thumpr just making a point about the 107 LSA. i run the fast ramp xfi lope on a 110 LSA. i would never run more than a 112 LSA on the older engines.the newer engine like the ford 4.6 with fuel injet can run more LSA
