[dmac]

Good cam for 400, 8.75 cr, headers, ported, daily driver/highway, maybe with Rhoads lifters- are the 067, 068, 744 cams suited to this use, or is there something modern that will perform better?

[PAUL K]

I would go with an aftermarket cam. The factory grinds work good especially with 1.65 rockers. But looking at your combination, I think you could do a lot better with a modern designed camshaft and probably find something that wouldn't require the Rhoades lifters.

[dmac]

Thank you Paul. I appreciate the info. I might have the wrong idea on using Rhoads lifters. And I would like to use the full roller 1.6 ratio rockers that I already have also. I'm trying to use parts on hand to save my son as much as possible. I know the 041 cam in the block now probably won't work.

I already have a set of Rhoads and have always thought that using them allowed for use of a bigger cam while preserving low end, so my thinking is that I can go with a cam one step up from what may be better without the Rhoads.

I don't think of it as requiring Rhoads, but as using them to add another tool to add a little lift and duration as the rpms increase. The normal usage of the vehicle would be in the 1200-3500 rpm range, so if I use a cam made for say 2000-5000 range, the Rhoads would take it down to where most use would occur. But I know it will not just be driven like a little old lady's car when the kids aren't in the car.

I think of it like having two different cams in one motor- one for low rpm and one for high rpms. If I have this all wrong, please, let me have it and tell me why it is not a good idea.

If I don't use Rhoads, or even if I do, what modern cam would be a better choice?

[ponyakr]

With reg lifters and 1.5 rockers I'd go with a Voodoo 256, for the 1200-3500 range you mentioned. But, 1.6 rockers will give you more lift than you really need.

http://www.lunatipower.com/Product.aspx?id=1774

With the 1.6 rockers and Rhoads lifters you have, I'd go with an 068 clone, such as a Melling SPC-7. For the 1200-3500 range there is no reason to go any bigger. IMO

http://www.ebay.com/itm/Engine-Camsh...25.m3641.l6368

This one has a damaged box. It's $110 shipped.

http://www.ebay.com/itm/Engine-Camsh...BXj9VQ&vxp=mtr

But, if you want more, the 744 clone will work. They were used mostly in high compression 400's. But, the same grind was used in the lower compression SD455. So, with the Rhoads lifters, it will probably work with your CR.

http://www.ebay.com/itm/Engine-Camsh...9XgN6D&vxp=mtr

I love Rhoads lifters, and have used 'em for a long time. But, I assume you already know that they produce a "ticking" sound at idle and very low rpm.

[dmac]

I like that voodoo cam. Thinking that between the 1.6 rockers giving me more lift, and the rhoads reducing lift at the lower RPMs, it would be a wash at lower RPMs. I had a lunati cam years ago and was very happy.

[PAUL K]

You have a grasp on how Rhoades lifters function and they do work. They are an excellent product. Sometimes people are annoyed by the ticking and when you mentioned "daily driver" I thought you might be happier without them. I don't know enough about your combination to recommend a specific cam. But I can tell you, if you want to use the Rhoades lifters I would look at a camshaft with a somewhat lazy profile and probably lean towards a dual pattern cam over a single pattern. I also agree that the 041 cam you have now, would be a poor choice for this engine.

[dmac]

The ticking doesn't bother me at all while driving, just when I am under the hood and think it might be an exhaust leak. Maybe something like the voodoo cam mentioned above, but with a tiny bit more duration and a tiny bit less lift would be what I'm looking for.

Thinking something like 225*/230* at .050, with 270/280 total duration, and around .420 lift. With Rhoads and 1.6 ratio, That would end up very much like the voodoo cam at low rpms.

I think I need a comprehensive list of cams available for pontiacs other than just what Summit or Jegs have.

[ponyakr]

Originally Posted by dmac

I like that voodoo cam. Thinking that between the 1.6 rockers giving me more lift, and the rhoads reducing lift at the lower RPMs, it would be a wash at lower RPMs. I had a lunati cam years ago and was very happy.

Yeah, you don't need the Rhoads lifters on the Voodoo cam. It only has 256 degrees of adv intake duration, with reg lifters. Don't need any less.

And, you can do the math for the 1.6 rockers. They will put the exhaust up in the .500 lift range. Don't need that much for the rpm range you say you will be running.

Just curious, are the rockers really 1.6, or 1.65 ?

[ponyakr]

Originally Posted by dmac

The ticking doesn't bother me at all while driving, just when I am under the hood and think it might be an exhaust leak. Maybe something like the voodoo cam mentioned above, but with a tiny bit more duration and a tiny bit less lift would be what I'm looking for.

Thinking something like 225*/230* at .050, with 270/280 total duration, and around .420 lift. With Rhoads and 1.6 ratio, That would end up very much like the voodoo cam at low rpms.

I think I need a comprehensive list of cams available for pontiacs other than just what Summit or Jegs have.

You can have a cam custom ground to just about any specs you want. Here is a list of master lobes Bullet can grind. They show several lobes that will fit your specs. And you can have it ground with 112-114 LSA and have good idle and vac.

http://www.bulletcams.com/Masters/Hlobes.htm

There are plenty of shelf cams with 220-225 intake dur. But all of 'em I can think of have more than .420 lift, with 1.5 rockers. Bullet grinds NHRA Stocker cams, some of which have a max lift of .425 and less. But they can grind 'em with just about any duration you want.

I'll look up some shelf grinds, and see if anything looks close to what you have described.

So far, the closest thing I see is the Lunati version of the 744.

http://www.lunatipower.com/Product.aspx?id=1756

This one has less adv dur, but has .454 lift, which is .500 with 1.65 rockers.

http://www.lunatipower.com/Product.aspx?id=1759&gid=278

This Summit description says Olds. But it's the correct Pontiac number.

https://www.summitracing.com/parts/lun-10510312

[Will]

You mentioned "ported" in your original post. You mean the heads have been ported?

I'm a firm believer in running as much lift as you can for a given duration. That's the whole reason roller cams work so well - they get the valve open faster and hold it open longer for a given seat-to-seat duration.

I think you'd be pretty happy with a Crower 60916 with your rockers and Rhoads lifters. I'm having a total brain-fart and can't remember the part number but Crower makes a spring that installs real close to stock height that would support the lift that combo would provide.

[Squidward]

I'm running the Voodoo 702 cam (219/227) and standard HFT lifters in my 350. It is totally streetable. I get 15" vacuum, and I'm not a super tuning expert. I imagine it would have even slightly better manners in a 400. My 400 build for my Lemans has the next step up Voodoo cam (703). I have no operational data on that one yet, but I expect good things.

The 702 cam got a little bit squishy off idle in the 350 with 3.23 gears, but a tiny touch more converter and steeper gears made that a non-issue. I can't remember what your gears are.

If your heads are OK to support the lift of around .480-.500 (screw in studs, retainer-seal clearance, valve spring coil bind), then I'd go with one of those. If you are stuck on stock lift #'s, then it would be a different story. I could regurgitate a suggestion based on reading about others' experience, but I will pass on that for now.

[HoneyHush]

I have the lunati ra lll in my current 400.. I've used it in the past as well. It has plenty of power everywhere and isn't hard on the valve train at all, and with 420 lift you could use the 1.6 rockers without too much worry. I usually build more race type engines with bigger cams but this 400 was meant to just drive around good and have decent power and it does.

[dmac]

Heads have been mildly ported and gasket matched- I would call it a cleanup. Big valves, already notched for the 1.6(not 1.65) rockers.

One of my concerns is the lower compression, and how some of the factory performance cams will run when they were designed largely when CRs were higher from the factory.

Would a single pattern cam work better or maybe a smaller LSA with the lower compression?

[Bruce Meyer]

Originally Posted by dmac

Heads have been mildly ported and gasket matched- I would call it a cleanup. Big valves, already notched for the 1.6(not 1.65) rockers.

One of my concerns is the lower compression, and how some of the factory performance cams will run when they were designed largely when CRs were higher from the factory.

Would a single pattern cam work better or maybe a smaller LSA with the lower compression?

I don't think a single pattern cam would be the best idea. Low compression needs more exhaust duration. A summit 2801 would be my choice. Cheap too.

[ponyakr]

Originally Posted by Bruce Meyer

...A summit 2801 would be my choice. Cheap too.

By my calculations, the 2801 exhaust lobe will have .497 lift with 1.6 rockers.

Intake dur @ .050 lift is only 214 degrees. You mentioned that you'd like about 225 min.

Again, the only way I have found to get exactly the specs you have mentioned is with a custom cam, such as those sold buy Bullet. Did you go down the list of master lobes to see how close you can get ? I count 7 lobes with 225 dur @ .050 lift. Adv dur ranges from 269 to 280 degrees. Lobe lifts range from .2720 to .3220. With 1.6 rockers that would be from .435 to .515 lift.

How about 277 adv, 225 @ .050, .464 lift with 1.6 rockers. It's the # H277/290 lobe. That looks pretty close to what you posted, for the intake lobe.

OR, the H280/300B lobe has 280 adv, 225 @ .050, .480 lift with 1.6 rockers.

http://www.bulletcams.com/Masters/Hlobes.htm

Then you can go down the list and choose an exhaust lobe with about 8 to 10 degrees more duration.

How about the H282/298 lobe. 282 adv, 234 @ .050, .477 lift with 1.6 rockers

Or, the H285/300C. 285 adv, 235 @ .050, .480 lift with 1.6 rockers.

And you can get these ground with about 112 LSA--not over 114, so you'll have plenty of low end torque, vac, and a good idle.

A cam with these bigger lobes would look like this: 280/285 adv, 225/235 @ .050, .480/.480 lift, 112 LSA

Hey, my math may be a little off. But you get the picture. You can zero in on exactly what you want.

[dmac]

Originally Posted by ponyakr

By my calculations, the 2801 exhaust lobe will have .497 lift with 1.6 rockers.

Intake dur @ .050 lift is only 214 degrees. You mentioned that you'd like about 225 min.

Yes- duration at .050 around 225 minimum because the rhoads lifters will cut that down some at low rpms so even at 220 I shouldn't lose low end torque. Looking at the Lunati version of the 744 as about the closest I can find on Summit to what I can use without getting into springs. Springs/valves are already set up for max of about .520 lift.

I'm not sure what the higher duration of that Lunati will do once the Rhoads lifters are fully pumped. With duration over 300* starting around 3500 rpm, what can I expect with the low compression?

The low lift and long duration seems like it must be a slow ramp on the cam, and easier on the cam.

[Johnny406]

If you're insisting on using the Rhoads lifters (I use and love them), then look at the Summit 2802. That is also a good cam, I've gone low 13's at altitude with that cam on a iron headed 400. Like others said, the 2801 and a good regular lifter will work very well for your combo.

[rexs73gto]

I use to run the 041 cam, well the Crane Blue Print RA IV cam from them in my stock bore 400 with Jahns free floaters & # 48 heads . The pistons were blower pistons & gave me a CR of 8.7 to 1 & in my 73 GTO with headers & a 4 bbl Q-jet & at that time running a 3:08 rear gears. The can ran & idled good & got 17 mpg's & went 13.02 in the 1/4 mile with street tires. I use the RA IV cam from Crane in my engine right now but it's .60 over & I have E-heads round port & love the way it runs. I now have 9.9 to 1 CR with the E-heads & the last time I went to the track it went 12.87 1/4 mile at 106 mph. I will be using the RA IV cam in my new build to which will be a 455 .60 over with a bunch of good stuff in it but with the RA IV cam again. The 041 cam is a good cam & makes good power. I also HATE Rhodes lifter as I can't stand the engine making that mush noise , the ticking drove me crazy for the few days I had them in. I can't say they did anything special for me because I took them out very soon because of the ticking noise. Sounded like the top[ end was always coming apart. I know some like them , but not me.

[dmac]

Originally Posted by ponyakr

Again, the only way I have found to get exactly the specs you have mentioned is with a custom cam, such as those sold buy Bullet. Did you go down the list of master lobes to see how close you can get ? I count 7 lobes with 225 dur @ .050 lift. Adv dur ranges from 269 to 280 degrees. Lobe lifts range from .2720 to .3220. With 1.6 rockers that would be from .435 to .515 lift.



Hey, my math may be a little off. But you get the picture. You can zero in on exactly what you want.

I did check out the list and actually looked at the lobes you mentioned. The Lunati cam I saw had a lot of total duration and I don't know what that actually would mean as far as performance in a lower compression motor.

OKAY- edit- I see that a longer duration moves up where peak power is produced. I want peak power at maybe 3000-4000 rpm, not 5500-6500. So maybe the Lunati isn't my best choice. The 2802 has too much lift, the 2801 may be the best choice at $73. With this being a low budget build, I think a custom cam isn't going to be in the picture, even though they look very reasonable priced. Maybe when I redo the 455 in my Grandville vert.

[pastry_chef]

Lunati Voodoo 10510702

----------------------------
Hydraulic Flat Tappet Cam. Great torque monster for 400-455 c.i. daily driven street performance vehicle. Excellent torque and HP production with heavier emphasis on the low to mid range.

Advertised Duration (Int/Exh): 262/268
Duration @ .050 (Int/Exh): 219/227
Gross Valve Lift (Int/Exh): .468/.489
LSA/ICL: 112/108
Valve Lash (Int/Exh): Hyd/Hyd
RPM Range: 1300-5500