I have never tried one but I have read that a roller cam will allow you to use a larger cam without sacrificing some drivability. I am building a street 340 to 1970 specs. It is 0.30" over and balanced but otherwise stock. I am running in a Demon with a 4 speed and a 3:55 gear. I know I also need to run a bronze drive gear. Two cams I have been looking @ are the Lunati Voodoo 20200712LK and the comp Thumper CL20-600-9. Can I get some feedback on this?

Since you are looking at a 70 340 block, I thought that I would ask this question.
I found on the Hughes websight that a LA block could come from the factory with three different types of chamfers on the lifter bores. None, small, and a large chamfer. They say that before cosidering a Roller cam, the size of the chamfer should be looked at.
I would like to upgrade to a roller sometime next year but after finding this info, I am not sure how big of a chamfer is too big. I have attached a picture of my 70 340 block for reference.
How big of a chamfer is too large?
Sorry for jumping in, but this might affect your situation too. It appears that Hughes has a lifter that may fix this issue.

Note: I am also curious about the size of roller cam for your 340 rebuild.

This is the picture off of the Hughes web sight for reference.

""For use in LA blocks with hydraulic roller camshafts. Sets include link bars.
Before purchasing the HUG5008A retro-fit lifters, be sure to check the lifter bores in your block.
The photo below shows an unmolested 360 small block. As pointed out by the arrows, some of the lifter bores are chamfered, or counter-bored. We do not know why Mother Mopar chose to do this. As you can see they are randomly bored to differing depths. The problem with this is that when you want to retrofit your block to a hydraulic roller cam the lifters that you need to use may come up high enough that the oil groove around the outer perimeter of lifter becomes exposed into this chamfer. This is not acceptable. If your block has these chamfers, you can usually use our HUG5321 lifters with the lowered oil band that will work on these blocks.""

Interesting. I have not heard that one before. I wonder why they are so random? I have 3 blocks. One is done and ready to build and the other two are at the machine shop right now. I will have to look @ this. It may not be an issue with other manufacturers if their lifter oil hole is lower.

I thought Crane Cams designed a roller lifter that doesn't need extra clearance??

It is a counterbore, not really a chamfer, either way it COULD be cured by sleeving the lifter bores, which would also put them in the right location three-dimensionally, though it's costly to do so.

Remember that these were passenger car blocks, and the way Chrysler operated, anything that wouldn't get a new car back to the dealership for warranty work was pretty much OK. That's why their balancing was the worst of the Big Three, and they were the only car builder to use oversize lifters, undersize crank journals, and a few other things in order to get fewer pieces going into the reject bin.

R.

""Two cams I have been looking @ are the Lunati Voodoo 20200712LK and the comp Thumper CL20-600-9. Can I get some feedback on this?


bump

Here are the specs of the two cams:

COMP Cams CL20-600-9 - Comp Cams Thumpr Hydraulic Roller Cams Details
Valve Setting: Intake - Hyd, Exhaust - Hyd
RPM Operating Range: 1900 to 5600
Cam Grind Number: 283THR7
Duration Advertised: Intake - 283, Exhaust - 303
Duration @ .050'': Intake - 227, Exhaust - 241
Valve Lift: Intake - .511, Exhaust - .497
Lobe Sep. Angle: 107°
-----------------------------------------------------------------
Lunati VooDoo
RPM Range: 2200 - 6200
Lift with 1.6 Rocker: .535"/.550"
Duration @ .050": 231/239
Advertised Duration: 282/290
112/106: 110/106
Valve Lash: Hyd/Hyd
Camshaft: 20200712
Complete Kit: 20200712K

Looks like Hughes has some comperable specs in their hydraulic roller selections. I see the writeup on the lifter bores. They recomment the HUG 5321 roller lifter with low oil hole.

HUG HER1828ALN-10
HYD ROLLER CAMSHAFT 110º LSA +3
HYDRAULIC ROLLER; NEW CORE 110º LSA
Camshaft Technical Details
Intake Valve Lift 1.5 .510"
Exhaust Valve Lift 1.5 .510"
Intake Valve Lift 1.6 .544"
Exhaust Valve Lift 1.6 .544"
Intake Duration at .050" 218°
Exhaust Duration at .050" 228°
Lobe Separation Angle 110º
Intake Centerline 107º
Intake Opening at .050" 2° BTC
Exhaust Opening at .050" 47° BBC
Intake Closing at .050" 36° ABC
Exhaust Closing at .050" 1° ATC
Min. Suggested Cylinder PSI 165
Sweet Spot RPM 1800 - 6100

The three cams you listed will have very different characteristics. Are you looking for the choppy idle ,or just a nice smooth street cam??
Keith

Being a street car I would like a little lope @ idle but want something drivable that will pull good from about 1500-5500.Was trying to decide if a roller is worth the extra $ and if it would be worth it for my combo. Again just heard you can get more power with good drivability with a hydraulic roller on the street.

I don't agree with the roller theory Until you get aggressive with ported heads and high lifts. The advantage of a roller is pretty limited on a low lift short duration cam.
Looking at a flat lobe versus a roller lobe,the flat tappet has more low lift velocity. The roller doesn't lift the valve as much as fast down low. The only advantage in a mild application comes if your worried about flat tappet but a good oil prevents that You can buy a lot of food oil for the cost of going to a roller.
Keith

Call Mike Liston @ MRL Performance. I have a custom roller cam that he spec'd for me which is 227/231 .530"/.530" lift that idles cream smooth at 900 rpm and runs like stink...the engine made 470hp and 455 lb-ft with basically stock edelbrock heads, and 9.7:1 CR. He also has the right lifters at a reasonable price.

I used the Comp Cams beehive springs with the edelbrock heads since the edelbrock heads take chevy springs.

Do you mind telling me what your vacuum reading is at idle and what the LSA is on that cam?

Thanks

its 110 LSA and the idle vacuum is 13-14 at 900 rpm with the clutch out (I have a 4-speed)

Here it is running before I had the initial timing where it liked to be. It sounds LESS mean at idle now actually.
https://www.youtube.com/watch?v=iXKZO7J8Qaw

I don't know anything else about the cam specs. Like I said, Call Mike. It doesn't need a bronze gear either. We were both blown away at how good the engine turned out. Its not a super torque monster down low, but my car has 3.23's and its not like it has issues moving. When you get above 2500, this thing is a total monster. It makes 400 lb-ft or more from 2900-6000. I can leave 10-15' of rubber on the 1-2 shift at 52 mph.

We used a lot of good parts in here. Nothing super exotic either.

It's all about area under the lift-vs-degrees of rotation curve.

In theory, a short roller cam can get as much lift under the curve as a flat tappet cam of longer duration. You can see this with modern engine hydraulic roller cams that make 1 hp/cubic inch with 210 degrees @ 50 lift cams.

The issue is that roller cams have normally been aimed at the maximum performance crowd, so most roller lobes are pretty long duration for all-out effort. With the advent of hdraulic roller cams, new families of higher lift shorter duration roller lobes have been developed.

Bullet Cams, for example, has quite a few hydraulic roller lobes with short duration. I'm sure the other guys have them, too.

R.