Picking a cam for iron 528

[TetanusShot]

It won't be long until I have to make a final decision on my cam. I've got it narrowed down to a few, but it's always good to hear outside opinions. Here's the combo:

528 hemi, factory iron heads, compression target was 10:1, worst case scenario could be 10:25:1 (will probably be right at 10)... 2 1/8" headers on the exhaust side, factory intake and carbs up top.

Those details are pretty much set in stone, what I don't have yet are: cam, lifters, pushrods, valvesprings, locks, or retainers.

Goals: first and foremost, I want it to live on 91 pump octane. Second I would like to keep the power band as low as possible, redline at or below 6500rpm.

Durability is way more important to me at this point than Hp. Its primarily going to be a street engine. The brakes on the car are manual discs so vacuum isn't a big deal. The cooling system is capable as well.

lastly i prefer a solid flat tappet cam.

-Thanks FBBO members for the help, and merry christmas folks!

 

[Cranky]

Do a custom grind whatever you do.

 

[lewtot184]

a lot of stuff out there, but i like engles for reliability. i run a k65 profile in my 65 coronet and it's pretty darn reliable and low maintenance. i'd look at a k7 profile with those cubes.

 

[cryplydog]

I really like my tool steel f/t lifters with the oil hole in the lifter face. And they are less than 80 grams. Good luck

 

[TetanusShot]

Thanks for the responses guys

a lot of stuff out there, but i like engles for reliability. i run a k65 profile in my 65 coronet and it's pretty darn reliable and low maintenance. i'd look at a k7 profile with those cubes.

for whatever reason, my computer doesn't like engle's website and I can't find a phone number for them. after some searching I found the k65 spec's but not the k7.

I was thinking Crane's 660941 cam might work well. It's .565/.568 lift, 294/304 adv and 248/[email protected] on a 112 lsa. I like the wide lsa and lift numbers but not too crazy about the split profile since the exhaust side isn't as limited on hemi heads.

Like I said, I'm most concerned with it pinging on 91. To tell the truth, the only other motor I've built carb to oil pan, was a low compression 440 that probably wouldn't have pinged on diesel fuel.

Cryplydog, are those lifters like amc lifters?

 

[IQ52]

Just hoping this information may help you choosing a cam.

We just finished a 572 hemi with aluminum heads. It is to be fuel injected and we had to have 8" minimum vacuum at idle for the fuel injection. The motor is 11:1, has 165 PSI cranking compression @ 4,900" elevation, runs on 91 octane, makes 733 lb-ft @ 5,000 rpm and 784 hp @ 6,200 rpm. The dyno won't pull this engine down below 3,100 rpm where it makes 658 lb-ft and at 6,300 rpm the torque is still 650 lb-ft. Idles at 800 rpm w/ 10" vacuum. The cam is a solid roller, 258/260 @ .050 w/ 114 LSA installed at 107 ICL. 2-1/8" TTI headers.

 

[TetanusShot]

Thanks for the comparison IQ52. So, with a point less of compression but 10deg earlier intake closing on the crane cam, the effective cranking pressure could be near to or higher than that 165 in your example.

I can find quite few builds on the net using aluminum heads, but its tough to find examples using iron.

May just have to commit to a cam and measure since every build is different.

 

[IQ52]

Thanks for the comparison IQ52. So, with a point less of compression but 10deg earlier intake closing on the crane cam, the effective cranking pressure could be near to or higher than that 165 in your example.

I can find quite few builds on the net using aluminum heads, but its tough to find examples using iron.

May just have to commit to a cam and measure since every build is different.

Well, 10 degrees longer duration would roughly be 5 degrees on the opening side and 5 degrees on the closing side.

 

[TetanusShot]

Well, 10 degrees longer duration would roughly be 5 degrees on the opening side and 5 degrees on the closing side.

Ya got me, i goofed.

 

[lewtot184]

the k7 grind is [email protected]"/.533 lift. advertised is [email protected]" lobe lift; real seat timing will be close to 300. these have fairly gentle lobes, longer closing ramps that you may be able to use to control cylinder pressure. should be easy on parts, maintenance, and break-in. there's a k8 thats [email protected]"/.573 lift. you may also want to call isky. right now crane is too difficult and expensive to deal with, but i do like some of their stuff. there may be something to look at in the comp cams xs lobes, but in my opinion dealing with comp cams is like dealing with a diseased prostitute.

 

[IQ52]

the k7 grind is [email protected]"/.533 lift. advertised is [email protected]" lobe lift; real seat timing will be close to 300. these have fairly gentle lobes, longer closing ramps that you may be able to use to control cylinder pressure. should be easy on parts, maintenance, and break-in. there's a k8 thats [email protected]"/.573 lift. you may also want to call isky. right now crane is too difficult and expensive to deal with, but i do like some of their stuff. there may be something to look at in the comp cams xs lobes, but in my opinion dealing with comp cams is like dealing with a diseased prostitute.

Wow, I have an outstanding relationship with Comp. However, I don't talk to the people on the tech help line.

I entered a dyno contest being run on Comp Cams dyno. We kinda blew the competition out of the water in hp/ci.

A Comp engineer came up and said, "What kind of cam are you running?" When I told him it was an Erson solid roller he got a strange look on his face.

The engineer called a mutual friend of ours and asked him, "What do we have to do to get LaRoy to run Comp Cams?"

Eventually I tried Comp for a coupla' grinds, had good success and no parts failures of any kind. So I stick with them. Any 'custom grind' I always get from Comp. Occasionally I get a shelf grind from somebody else, mostly Lunati.

 

[lewtot184]

i've never had any parts vendor cost me more money and been more failure prone than comp cams. i detest them and their clearasil junky phone creeps. next is crummy machine work.

 

[Burns69RT]

I have always had luck with lunati's shelf grinds, as for custom grinds I always call George (Mr Horsepower) at clay smith engineering.

 

[TetanusShot]

Just found an old moparts thread from 5 years ago. There was a combo posted incredibly similar to what I'll have:

"My Street Hemi is 438" (+.060), ported iron heads, old Crower 260 @ .050, .565/.547 lift mech tappet, Hooker Comp+, tweaked stock AFBs on stock intake, 10.8:1 measured CR, in a '68 4-speed RR, 4.10s. Never a detonation problem even with 91 octane, probably aided by overlap. Power band 3500-7500+. 540HP. It's a bit like a locomotive at low RPM but once all that mass spools up, it gains RPM QUICKLY. Built & dynoed by Bob Lambeck back around '87 or '88. Carbs took some work by my "guru" Eric Johnson, and if anything it makes more power and runs much better now.
The Hemi chamber is less prone to detonation, one of the reasons Chrysler developed the 1st generation motors.
If I had it to do over, I'd reduce the reciprocating weight, maybe use a more modern cam, and I'd be tempted to stroke it, but as it is now, traction is severely limited."

I should have at least .6 less compression and about 90 more cubes than this guy. Looks like I can get away with 91 pump gas after all.

 

[IQ52]

I realize you are quoting someone else, just remember........."Never a detonation problem even with 91 octane, probably aided by overlap." is bologna.

Overlap is during the intake opening event. It is the intake closing event that helps control detonation. Sometimes with more overlap the intake valve closes even sooner and contributes to detonation.

You gotta be smarter than your camshaft.

 

[lewtot184]

I realize you are quoting someone else, just remember........."Never a detonation problem even with 91 octane, probably aided by overlap." is bologna.

Overlap is during the intake opening event. It is the intake closing event that helps control detonation. Sometimes with more overlap the intake valve closes even sooner and contributes to detonation.

You gotta be smarter than your camshaft.

i agree with this. this is one reason i like an asymmetrical solid lobe. it lets you tinker with the intake valve closing event.

 

[383man]

Do a custom grind whatever you do.

I agree with this. I have been a tech all my life and built alot of engines and know cams pretty good. But I dont do cams everyday like a Pro does and thats why I had Dwayne Porter spec my cam for my eng. I can spec a cam and do a pretty good job but a Pro that works with cams every day for years is going to better them most of your average eng bulders. Good luck what ever you decide. Ron