[b-man]

Originally Posted by pmd400

With an iron headed 9.5:1 455, what is the cut off point where roads lifters would be beneficial. With a 068 cam I assume rhoads wouldn't be needed. What about a summit 2802 or crower 60243 cam?

I wouldn't use Rhoads lifters with any of those cams in a 455, and especially not with the 068 in any size engine. Using Rhoades lifters would invite detonation by building cylinder pressure too early. The 455 can easily handle those cams and still have plenty of low-end grunt without using variable-duration lifters.

Once you step up to the RAIV cam or something bigger I'd start thinking about using them in a 455.

[pmd400]

Originally Posted by b-man

I wouldn't use Rhoads lifters with any of those cams in a 455, and especially not with the 068 in any size engine. Using Rhoades lifters would invite detonation by building cylinder pressure too early. The 455 can easily handle those cams and still have plenty of low-end grunt without using variable-duration lifters.

Once you step up to the RAIV cam or something bigger I'd start thinking about using them in a 455.

How would idle, throttle response and cruising change between a 2802 cam with standard lifters and a 041 with rhoads?

[b-man]

Originally Posted by pmd400

How would idle, throttle response and cruising change between a 2802 cam with standard lifters and a 041 with rhoads?

I would expect both to be close to the same. Given the choice I'd opt for the RAIV cam with Rhoads lifters.

[Will]

Originally Posted by glhs#116

OK, so let's just cut to the chase. Let's say a guy had a fairly stock 1971 455 HO engine with the 197 heads and the RAM AIR manifolds and HO intake and 71 455 (though not "HO") carb. Let's assume 3.42 gears and automatic (with future plans to go manual) equipped 1971 Trans Am with no weight reduction. Given all I'm reading here what realistically prevents me going from my 068 to the Old Faithful grind? I'm not seeing much downside and it looks like there should be some good upside!

Also, as a complete non-initiate into the whole Pontiac cam world, what is the Old Faithful grind and where would you get one?

Lastly, I guess my main concern would be that I wouldn't want the car running hotter at idle than it does. I have a big aluminium radiator but I also have to drive half the year in heat and humidity you guys would NOT believe.

Thanks in advance and loving the thread!

Sam

"Old Faithful" is a hydraulic roller cam available from SD Performance. With your setup it should work pretty good but without a good converter in the equation I think I'd stick with SD's "Stump Puller" grind.

Originally Posted by pmd400

How would idle, throttle response and cruising change between a 2802 cam with standard lifters and a 041 with rhoads?

Probably be pretty similar. Rule of thumb is that Rhoads shave off about 8-10 degrees of duration at idle.