Cam question

[G8One2]

Originally Posted by acammer

I agree - a well spec'd "big cam" with proper tuning will drive just fine. I'm interested in what your overlap @.050" is - that usually has a very large influence on driveability.



If we're calling anything over 228@.050 on the intake side a "big" cam then the GPI SS3 in my car (at a 233/253) is "big cam" I don't have any significant driveability issue, and I have plenty of bottom end torque - I've yet to meet I hill I can't cruise up in 6th gear at 1500rpm. It's true, I don't make peak torque until about 5350rpm (stock cam peaked at 4500), but I'm ahead on torque vs. stock cam from 3250rpm on up, and was still making over 300ft/lbs at 2750rpm where the pull started. So, I definitely disagree that a "big" cam can't make reasonable, driveable, bottom end.



I agree - that you need to know what you want to do with the car before you choose a camshaft. Gear, converter for auto guys, compression, intake manifold, heads, and most importantly what you want from the car, all influences your choice. I struggle with your 520/430 vs. 470/450 example - horsepower is a measure of how much work can be accomplished, and 10% more work being accomplished is going to get it done faster. You gave the modifier "all else being equal", there are a lot of ways to interpret that. I'm guessing you meant same car, same weight, same tire, same gearing - and I think that without the right setup the big rpm car is not going to show it's full potential, but it's still gonna be quicker down a quarter mile.

I'd interpret that different though - with all else being equal meaning each car is the same power, weight, traction, and the driveline (converter, gear) is optimized for the combo. In that case, the 520hp car is really gonna stomp on the 470hp car.

Overall, I get your point. I see plenty of guys putting donkey dick cams in cars that aren't otherwise really optimized for them, and they'd likely be better off with a more appropriately sized stick. Heck, I bet half the cammed cars out there rarely if ever truly get revved through their full powerband to the very top where they really should be shifted. Don't get me started on the "shift at peak torque" crowd!

But, the big cams have a place for guys that are willing to build the car to suit that choice, and use them as intended. They certainly don't have to drive like crap and be dead on the bottom end. Just food for thought - I enjoy a good conversation like this.

Well said! That really was my point in that people put donkey dick cams in their cars that are not optimized for them. It can be hard to explain to those who don't understand how it all works. A lot of it, is also all opinion, making it even harder to help people understand their cam choices.

[CFD]

Originally Posted by acammer

I agree - a well spec'd "big cam" with proper tuning will drive just fine. I'm interested in what your overlap @.050" is - that usually has a very large influence on driveability.



If we're calling anything over 228@.050 on the intake side a "big" cam then the GPI SS3 in my car (at a 233/253) is "big cam" I don't have any significant driveability issue, and I have plenty of bottom end torque - I've yet to meet I hill I can't cruise up in 6th gear at 1500rpm. It's true, I don't make peak torque until about 5350rpm (stock cam peaked at 4500), but I'm ahead on torque vs. stock cam from 3250rpm on up, and was still making over 300ft/lbs at 2750rpm where the pull started. So, I definitely disagree that a "big" cam can't make reasonable, driveable, bottom end.



I agree - that you need to know what you want to do with the car before you choose a camshaft. Gear, converter for auto guys, compression, intake manifold, heads, and most importantly what you want from the car, all influences your choice. I struggle with your 520/430 vs. 470/450 example - horsepower is a measure of how much work can be accomplished, and 10% more work being accomplished is going to get it done faster. You gave the modifier "all else being equal", there are a lot of ways to interpret that. I'm guessing you meant same car, same weight, same tire, same gearing - and I think that without the right setup the big rpm car is not going to show it's full potential, but it's still gonna be quicker down a quarter mile.

I'd interpret that different though - with all else being equal meaning each car is the same power, weight, traction, and the driveline (converter, gear) is optimized for the combo. In that case, the 520hp car is really gonna stomp on the 470hp car.

Overall, I get your point. I see plenty of guys putting donkey dick cams in cars that aren't otherwise really optimized for them, and they'd likely be better off with a more appropriately sized stick. Heck, I bet half the cammed cars out there rarely if ever truly get revved through their full powerband to the very top where they really should be shifted. Don't get me started on the "shift at peak torque" crowd!

But, the big cams have a place for guys that are willing to build the car to suit that choice, and use them as intended. They certainly don't have to drive like crap and be dead on the bottom end. Just food for thought - I enjoy a good conversation like this.

I completely agree and there are trade offs with big cams, mostly maintenance. After straightening out my issues with a block replacement my weak link where the aluminum rockers, fatigued way to early for a daily driver, went with steel rockers and had no issues. I normally, being old school, wouldn't share specs on what I would consider a winning combo but seeing that I'm not in competition here are my cam sheets. The first one would be as you described a "donkey dick cam" lol. the second my current set up, very well mannered on the street, regardless of cruising, getting on it ,heavy traffic, ran great all across the board. Also consider I am a 418 stroker, 11.8 compression and at that time a holley mid rise sheet metal intake.

[G8One2]

See the problem is though, you yourself and I'm sure some other on the board KNOW what your doing, and how your component choices affect other parts in your build, and how the car will behave. Many other people though, do not necessarily know what they are doing, come to the board for recommendations and don't plan on doing any of the maintenance to their cars in that way. They just want to slap parts on it and drive it, not knowing how it will effect drivability, or how certain parts, like valve springs, need checked periodically. So when I see someone ask about a cam, and it's their daily driver, I automatically assume it someone who doesn't really know what they want, because if they did, they wouldn't be asking for cam suggestions on a forum.

[CFD]

Originally Posted by G8One2

See the problem is though, you yourself and I'm sure some other on the board KNOW what your doing, and how your component choices affect other parts in your build, and how the car will behave. Many other people though, do not necessarily know what they are doing, come to the board for recommendations and don't plan on doing any of the maintenance to their cars in that way. They just want to slap parts on it and drive it, not knowing how it will effect drivability, or how certain parts, like valve springs, need checked periodically. So when I see someone ask about a cam, and it's their daily driver, I automatically assume it someone who doesn't really know what they want, because if they did, they wouldn't be asking for cam suggestions on a forum.

It's the same thing with gears, people ask what gear ratios are best, it all depends. Some say 410's break to easy, I say improper set up breaks gears more than the ratio. There are thousands and thousands running 4:10's, 4:56's and so on without breakage, why because they're set up right, sometimes it can even be something simple like tire pressure, how do you know, you break things and try again. lol. It depends how much you're willing to spend and how much effort you're willing to put in. If you're just looking for a little more and dependability do what others who have had good luck do but then you will be the same, if you want more, bite the bullet and spend the time and dollars!!!!

[G8One2]

Originally Posted by CFD

It's the same thing with gears, people ask what gear ratios are best, it all depends. Some say 410's break to easy, I say improper set up breaks gears more than the ratio. There are thousands and thousands running 4:10's, 4:56's and so on without breakage, why because they're set up right, sometimes it can even be something simple like tire pressure, how do you know, you break things and try again. lol. It depends how much you're willing to spend and how much effort you're willing to put in. If you're just looking for a little more and dependability do what others who have had good luck do but then you will be the same, if you want more, bite the bullet and spend the time and dollars!!!!

Aint that the truth! Gotta pay to play for sure lol.

[G8One2]

I'm just in the "keep it conservative" camp because I too, daily drive my vehicle. I really hate a car that has no power down low, but again, its all opinion. I'm in my 40s now and feel differently about driveability, than I did when I was in my 20's. When I was younger, I was much more tolerant to driveability and vehicle behavior on the street than I am now. I like a nice chop or cam lope, don't get the wrong. Just been there done that, over it lol. I don't need a 10 second Street car. A low 12s car is pretty darn quick for a street car. Hell 11s street car is hauling azz on the street. That's plenty fast enough for me, and is pretty easily attainable with milder mods.

[acammer]

Originally Posted by CFD

It's the same thing with gears, people ask what gear ratios are best, it all depends. Some say 410's break to easy, I say improper set up breaks gears more than the ratio. There are thousands and thousands running 4:10's, 4:56's and so on without breakage, why because they're set up right, sometimes it can even be something simple like tire pressure, how do you know, you break things and try again. lol. It depends how much you're willing to spend and how much effort you're willing to put in. If you're just looking for a little more and dependability do what others who have had good luck do but then you will be the same, if you want more, bite the bullet and spend the time and dollars!!!!

CFD - first - that's a pretty dramatic difference between those two camshafts. Your first one was extremely rowdy - 37* overlap at .050! No wonder it drove awful. I bet it was asleep big time on the bottom, and then wanted to be pulled out past 8000rpm on the top. Would need a short runner intake manifold to even begin to tap into it's full potential. The second cam looks far more reasonable - I'm sure it drives a whole bunch nicer, and still pulls real hard upstairs. Still would love short runners, but would place a little nicer with a stock manifold.

I agree with you on the gears too - setup is super critical on a rear end, and getting it just a little wrong will wear out a set of a gears and lead to breakage 10 out of 10 times. With these cars I think a good launch technique is also crucial to keeping the rear end alive. These cars won't tolerate a clutch dump, and they won't tolerate wheel hop - they just aren't that strong. I'm a firm believing in a little preload on the hit, takes out all the slack dropping the "snap" of the initial hit, and helping with wheelhop by reducing the "wind up" in every bushing in the rear.

I wish we had a 4.56 option for the stock carrier! I have 26" tires on my for the track now - needs all the RPM I can give it!

[G8One2]

Who did you guys, have your rear ends setup by?

[Chris49066SS]

GPI did my gears, 3.91

[acammer]

Originally Posted by G8One2

Who did you guys, have your rear ends setup by?

The first, second, third, or fourth time? Seriously, it's been a bad go for me. The first 4.10 I put in the car was a complete rear end taken out of another car, with something like 40k miles on the gears, some of that while the car was twin turbo. They were Richmond's, which don't have a stellar reputation, and it was an unknown installer. I got a good deal, and it was a great way for me to see what I thought of 4.10s without a big invest. I learned that I loved 4.10s, and they made it about a year, whining pretty good most of the time.

After I broke the first set, I bought a set of Motive 4.10s with the install kit, and found that not a lot of local installers wanted to touch it. I ended up going with a recommendation from a buddy, towing it about 150 miles to a shop, and getting a deal on install for $500. I followed break in carefully, and didn't make a single hit on the until they were well broken in. I added the LPW cover at this point for additional strength. I had about 3,000 miles on it when I lost all pinion preload at a airport drag event. I drove it home like that, about 200 miles. I took it to a local shop I had overlooked, the found a failed crush collar, and resultant dusted pinion bearings. We did new pinion bearings, new crush collar, and sent it back down the road - but the whine was insane. The car has solid aluminum cradle bushings and solid poly BMR diff bushings, and the gears had taken too much abuse when run with no preload and were just awful noisy.

So, this spring, I had the rear rebuilt again. I went ahead with all new top end Timken bearings, a trutrac, and gave Yukon gears a shot this time - they have a pretty good warranty. The local shop that diagnosed the failed crush collar on the previous set credited me all their labor trying to make the previous set right towards this job - talk about customer service! They did a great job with the install, showed me the pattern and the lash which were beautiful.

I'm about 6k miles into that set of gears and they are doing well. They are still noisier than I would prefer, but I think the LPW cover (with the load bolts right onto the ring gear caps) coupled to the car with all solid bushings just creates a very direct path and transfers any noise. They have around 20 drag strip passes with stick tire 5000+rpm launches on them and seem to take it just fine. I'd love to go a full year without touching the rear end, other than maybe for a fluid change.

[CFD]

acammer, it is a huge difference and it showed in driveability. That cam was ground before the Holley manifold, when I was running the stock one but still had bad habits, I wanted top end power but it was too much of a tradeoff for a street car. That's why there's so much debate on "large cams". It depends on what you call large.

I

[Camaro2ss2010]

Thanks for the info. I already had an idea what I wanted to install along with the supporting mods. I have built multiple motors and went to the drag strip most of my life. I have spent my life around cars but the were built specifically for 1/8 or 1/4 mile. I do not DD my car but I do want that to be an option incase I want to hit the road and drive for thousands of miles on a trip. Thanks for the info.

[CFD]

Originally Posted by acammer

The first, second, third, or fourth time? Seriously, it's been a bad go for me. The first 4.10 I put in the car was a complete rear end taken out of another car, with something like 40k miles on the gears, some of that while the car was twin turbo. They were Richmond's, which don't have a stellar reputation, and it was an unknown installer. I got a good deal, and it was a great way for me to see what I thought of 4.10s without a big invest. I learned that I loved 4.10s, and they made it about a year, whining pretty good most of the time.

After I broke the first set, I bought a set of Motive 4.10s with the install kit, and found that not a lot of local installers wanted to touch it. I ended up going with a recommendation from a buddy, towing it about 150 miles to a shop, and getting a deal on install for $500. I followed break in carefully, and didn't make a single hit on the until they were well broken in. I added the LPW cover at this point for additional strength. I had about 3,000 miles on it when I lost all pinion preload at a airport drag event. I drove it home like that, about 200 miles. I took it to a local shop I had overlooked, the found a failed crush collar, and resultant dusted pinion bearings. We did new pinion bearings, new crush collar, and sent it back down the road - but the whine was insane. The car has solid aluminum cradle bushings and solid poly BMR diff bushings, and the gears had taken too much abuse when run with no preload and were just awful noisy.

So, this spring, I had the rear rebuilt again. I went ahead with all new top end Timken bearings, a trutrac, and gave Yukon gears a shot this time - they have a pretty good warranty. The local shop that diagnosed the failed crush collar on the previous set credited me all their labor trying to make the previous set right towards this job - talk about customer service! They did a great job with the install, showed me the pattern and the lash which were beautiful.

I'm about 6k miles into that set of gears and they are doing well. They are still noisier than I would prefer, but I think the LPW cover (with the load bolts right onto the ring gear caps) coupled to the car with all solid bushings just creates a very direct path and transfers any noise. They have around 20 drag strip passes with stick tire 5000+rpm launches on them and seem to take it just fine. I'd love to go a full year without touching the rear end, other than maybe for a fluid change.

Failed crush collars are not common, it's possible who ever set it up may have torqued it, checked clearances, made adjustments and re-used it. I've seen it before. It's hard to say even after inspection.

I've always lived by the rule, make as much power as possible, if everything is working right all will come down to tires and throttle control. Never shoot for a dead hook if you're making real power, something WILL BREAK. controlled tire spin is your friend.

[havelegs]

How bad is my cam? This is for an auto with a 3200 TC.