Kevin Mason

I know, folks, this topic has been beaten to death, but my '69 350/300 (3.36 rear, M20) is in need of a cam change. Right now she has a 2 1/2" exhaust and block-hugger headers, and I will add heads, manifold, carb, and possibly gears at some point in the future. Car currently has a Crane Powermax cam, 270/276 duration, 210/216 @.050", .440/.454" lift, 114 LSA, and generally lacks low-end. Reading the cam description, it is designed for a car with at least 3.73 rear end.

Ordinarily, I'd just install a CompCams XE268H and be done with it, but here and elsewhere I've heard that CC quality control is not the best. I know a lot of Forum members seem happy with the 268, although it may be a bit much for my car right now?

Some other possible candidates include a stock L-82 cam,

or the Crower Torquebeast (288/288 duration. 214/224 @.050", .450/.470" lift, 112 LSA),

Crower 0223 (262/270, 214/222, .450/.470, LSA 110)

or a Lunati 01002 (287/287, 214/214, .444/.444, LSA 112),

Lunati 1003 (288/298, 214/224, .444/.467, LSA 112),

or Lunati 0016 (284/294, 218/218, .458/.458, LSA 110), ferinstance.

Any other suggestions? Maybe the CC DEH 265H? I need a cam that will be reliable on long distance trips, and since my heads probably still have press-in studs, I want to keep total lift down (I'm out of the coutnry, so cannot verify). I know that the engine has high-rev lifters and heads have performance springs.

Thanks in advance.

Matt Gruber

since you want a reliable long distance cam, you can forget about most aftermarket cams. they make more power but don't last 100000 miles.
maybe others wll chime in 'cause i don't drive much and don't mind the "short" life.

Vetterodder

Most of the cams that you listed would have less low end torque than what you already have. Typically (but not always), the greater the duration the less low rpm power but more high rpm power. I'd expect that the cam you're running would have excellent low end power. If more bottom end is your goal, make sure that you've optimized your advance curve. If you haven't already done so, the improvement can be dramatic and will take much less money and work than a cam swap.

The vast majority of cam failures are the result of improper break-in, improper related components, or some other condition that would have ruined any brand of cam and not because the cam was faulty. Considering the popularity of Comp cams, it should be no surprise that their share of failures is greater than that of mfg's that sell fewer cams.

vettfixr

Kevin
I don't understand why your cam is giving up all that bottom end. I have a Crane Max Velocity 272 with 216/228 @ .050 (The equivalent of the Powermax 272) and I have plenty of bottom end. Before changing cams I would give a thorough check into your distributor timing curve. I found that the original curve really sucked and getting that in order felt like another 100 horspower. I can lug my car down to 1000 rpm in fourth and pull smoothly from there to redline. Might be worth a check before you start tearing into the engine. If you want more torque than the cam you have you're going to have to go with a Comp Cams 268 or possibly 260.

Kevin Mason

Thanks for all the help. What do you suggest I do with the timing/advance curve to get the low-end torque in line? (Stupit question, I know...)

Vetterodder

Get a recurve kit. A lot of guys are very happy with Lar's kit and they are also available at many auto parts stores. They usually come with several different weight springs to adjust how quickly the mechanical advance comes in. The goal is to get as much advance in as early as possible but too early can cause problems. Car weight and gearing are the major factors that determine how soon you can bring it in.

Start with 36º total and go from there. If you have a dial back timing light set it at 36º and rev the engine until the timing mark stops moving and then adjust the distributor until the marks line up. If you don't have a dial back light, measure the circumference of the balancer, and divide that figure by 10. Put a mark on the balancer that distance from the 0º mark. That will be 36º. Rev the engine until the marks stop moving and adjust the distributor until the new 36º mark lines up with the 0º mark. If you're doing this with a stock distributor, be sure to rev it high enough for all the timing to be in. With most stock distributors, total timing may not be all in until well past 4,000 rpm and setting total timing at a lower rpm is a waste of time.

Kevin Mason

Assuming my ignition timing is on, I also was wondering whether the cam timing might be off. Is this a possibility, and if so, should I advance or retard cam timing?

The only car I really know how to work on is the VW Beetle. Unfortunately, I learned this skill after I got sick of paying people to do incompetent work.

Ganey

If you want more low end advance cam 4 degrees. You probably want to do this & report back w/ your comments before a cam change.

When a cam fails shortly after install, you can expect that the problem is the installer.
You probably do not want more than 268H or XE-262.

Except for you wanting more low end, would rec. more cam than any of the other possible candidates listed.

:cool:

Vetterodder

"Assuming"?? If you don't now what your timing is there isn't much point in going any further until you do know. Don't be so eager to spend a few hundred $$ on a cam swap when your source of dissatisfaction may just fixed be a timing adjustment that can be done for no $$. If your ignition timing is off, a different cam won't help.

Cam timing can be off a little from chain stretch and not have a drastic effect on performance. If it's off big time from the timing chain slipping, the engine would probably run so bad that you'd know it. Ignition timing may not be your problem but it's much more likely than cam timing and it would make a lot more sense to spend a few minutes checking it than to spend several hours checking your cam timing.

zwede

The cam you have now should be a torque monster. something is amiss. Many moons ago (1990) I installed a similar cam in a 75 Camaro. With a TH350 w/ 2000 stall & 3.23 rear gears that thing would roast the tires.

As far as longevity, that cam is still in the car today (dad bought the car from me) after 13 years of which many were daily driver years and the cam is still fine. I bought it from summit for under $100 including lifters. Sometimes the cheap stuff is actually good. :lol:

Kevin Mason

No, no, no. Don't be too quick in assuming that I want to swap cams. The cam my Vette has now is probably not ideal, but I'd rather build up the engine to where I want it, including cam, all at once, than find a cam that will work decently both with my engine as it is now and the way I want it to be.

I asked about cam timing, as another alternative to a cam swap. Am I correct in assuming, then, that playing with cam timing will not likely do any good?

Once more, VetteRdder, VetteFixer, Ganey, Zwede, anyone else I forgot, thanks for the advice.


[Modified by Kevin Mason, 8:58 AM 5/6/2003]

KJL

I have a CC XE256 w/1.6 rockers and a Turbo 400 with a 3.08 rear. I have wheel spinning torque and good top end. To re-curve your dist. take the springs off and disconnect the vacuum advance. Rev the engine enough to make sure the mech advance is fully employed. Whether you use the tape method or an adjustable lite, turn your distributor until you are at 36 degrees. Now, using your spring selection, find the combo that brings in the full 36 at about 25-2800 RPM. You need to have a vacuum advance unit matched to your system. You can buy adjustable units. The key is to have 52 degrees of total advance at 25-2800 rpm. Lars has an excellent paper written on this topic.


[Modified by KJL, 11:17 AM 5/6/2003]


[Modified by KJL, 11:19 AM 5/6/2003]