Alright...I've got a HughesEngines HE3844AL hydraulic flat tappet cam in my 360 motor right now. This is in my M-body coupe, about 3600 lbs. w/ driver (175 lbs).

This is a weekend driver, not a daily driver. Something to have fun with basically.

Engine is a 0.020" over 360, hyperutectic pistons (Sterling H116CP), 9.8:1 static CR, 170 psi cranking pressure. The cam specs are: .535/.540 lift, 237/243 dur. @ .050", 286/290 adv. dur., 108 LSA. This combination with 9.5" Dynamic 4K stall converter, 727 trans and 3.91 rear end makes for a fun ride.

OK...but that's never enough right? LOL

So the other day I was looking at eBay...all of a sudden I come across a speed-shop listing for a custom CompCams Hydraulic Roller cam, Grind # CRS 13084B/3039B HR 112+4. Specs are: .547/.544, 240/248 dur. @ 0.050", 290/300 adv. dur., 112 LSA with 4 deg advance ground in (see attachement for full details). OK, price was good, I ended up picking the cam for $155...mostly b/c I thought this would be an ideal cam to try in my current 360 setup. Nearly a match to my HE3844AL, a tad bigger I suppose, but a roller version, so I'm curious.

I called the CompCams tech-line today just to see what they thought about using this roller in my setup. The guy I spoke with thought the roller will be better mid-top range, but was worried it will be soft at the bottom end due to the 112 vs 108 LSA. As he put it, "..it won't have the hit, the pick up and go your 108 LSA cam has...". There is no denying the Hughes cam packs a good punch!

So...what do you guys think? I have the retro-fit roller lifters already, so this is really time & effort, maybe new set of pushrods, doesn't seem like a huge mountain to climb to try the roller stuff. But...is it worth it in the first place?

Give me some ideas...I'd hate to pull things apart only to get a combination that is worse as compared to what I have right now.

BTW: My current combo ran a best et of 13.10 @ 104mph...this was a first and one-time only track outting though...

Being a street car and low compression.. I would leave the
cam in it... you need the torque to move the car

I am running a set of ported iron head castings...I could always shave them a tad to raise the CR, if I was to do this, what would you recommend to aim for? 10.5:1???

Yeah, I'm sort of trying to find an "excuse" to try the hydraulic roller...... my next build is going to be a 408" W2 headed stroker so I'd rather expriment on my current setup and learn a thing or two before I get to the stroker build.

Try what ever you want then... 10.5 is what I'm running with
my 416 W-2.. my cam is a solid roller 260/270 with .560/.560
on a 105 lsa installed at 105... so far I've been running 87
octane with no knock issues and the cranking pressure is 180
if I remember right
EDIT
this is in my street/strip rod

Try it, but I'd install it at 105 or 106 to help the bottom end.

That's a lot of work for 3 degrees@.050" and 012" lift.

Your combo probably won't like the 112lsa either.

Don't use the wrong cam just because you got a steal of a deal on it.

OK, I'm all ears, this is why I posted in the forum.

Please explain your reasoning behind the "...combo won't like the 112LSA..." comment in particular. I actually thought that the wider LSA would give me a more docile idle/low RPM motor, and maybe a better throttle response for the city-traffic given the better vacum@idle it should pull, which would be a good thing given that it really is a street/weekend driver kind of a car.

My level of camshaft technology understanding indicates that the wider LSA, while improving idle/vacum and broadening the power band, will however lower the max torque potential and move it to a higher RPM. If that is correct then I suppose I understand the comment a little better...am I on the right path here?

What I'm struggling with is this: the 4K stall converter allows the motor to get up into the power-band pretty quick, this is great for when it's a real WOT run. But otherwise, especially for lower RPM usage (like street traffic) we are always told by countless magazine articles, on-line stories, etc, etc, that a roller cam has so many advantages over the old flat tappet designs. So where are the benefits if I'm hearing you guys tell me this hydraulic roller is not worth pursuing?

Remember, I'm not going for an all-out effort here. Just aiming to pretty much stay at the same power level with better lower end behaviour.

Because of the roller wheel geometry compared to the flat tappet geometry, small cams like this can’t take advantage of what the roller can offer in ramp rates on bigger cams. This is why the .050” and overall lift numbers are so similar on these two cams.

If you were talking about a 260@.050” flat tappet vs. roller, you would really see a difference in lift/intensity that just doesn’t show up on these little cams. Hydraulic rollers are certainly more durable, but for most of us weekend warriors that’s of little concern.

With a heavy car/no compression, you need to error on the side of caution with the intake valve closing point because it is what will determine your dynamic compression/cranking compression/cylinder pressure.

Look at the cam events… I have both your current cam and new cam in 4 degree’s advanced for an apples to apples comparison.

Current Cam-
IVO is 14.5 ° BTDC ( - indicates ATDC)
IVC is 42.5 ° ABDC
EVO is 53.5 ° BBDC
EVC is 9.5 ° ATDC ( - indicates BTDC)
Overlap is 24 °

New Cam-
IVO is 12.0 ° BTDC ( - indicates ATDC)
IVC is 48.0 ° ABDC
EVO is 60.0 ° BBDC
EVC is 8.0 ° ATDC ( - indicates BTDC)
Overlap is 20°

Couple things to note here… First there are two things that make low/mid range torque. Earlier intake valve closing, or later Exhaust valve opening.

Earlier intake valve closing makes more torque because as the engine runs at low/mid range RPM, the airspeed in the intake port is slow. As the piston starts to come up from BDC, it is trying to push the air backwards through the intake port (emptying the cylinder). The speed of the air coming through the port is fighting the piston from pushing the air backwards. If you keep the valve open too long, at some point the piston will overcome the air speed in the port (inertia), and will cause reversion into the intake. The only way to combat this is to increase the air speed (more rpm), or close the intake valve earlier. This is where the correlation between RPM and Intake Valve closing point comes in.

Later exhaust valve opening also increases torque at low/mid RPM. This is because if you open the exhaust valve too early, the pressure is released that could be used to continue pushing the piston down on the power stroke. If you wait too long to open the exhaust valve, at high RPM the exhaust doesn’t have enough overall time to evacuate the cylinder.

So looking at the events of these cams, the hydraulic roller closes the intake valve 5.5 degree’s later AND opens the exhaust valve 6.5 degree’s earlier. These are both bad things when it comes to low/mid range torque. Since your car is heavy, not much gear, and has low (pump gas) friendly compression, you can use all the low end torque that you can get. More cam will probably make the car MPH better, but probably make the ET slower. My buddy had a low compression 318, tight converter,4.10 gear and 236@.050” cam in a dart. Used to run 14 flat at 101mph. An extream example but shows how important low RPM torque is vs. HP. The big high RPM cam gave us good HP, but the lack of torque killed the ET.

For your idle comment… Because the new cam is bigger than the old, it partially negates the overlap/idle improvement you would normally get by just changing overlap. If you look, the overlap numbers are only 4 degree’s different between these two cams which is not significant.

You are right that the vacuum might get better, but it will be coupled of lost torque at low speed driving because of the later IVC and EVO events. So overall drivability might be worse.

Make sense?

Those comp lift #'s are for a 1.5 rocker. Not sure what you are running,

The HR will also have more lift under the curve than the hughes is my guess.

A true 4K converter wipes out a lot of the low end issues.

Alright...awesome explanation...appreciate the details...great stuff, thank you! For those interested in further details check out the following HotRod mag article.

I pulled up my HE3844AL cam card, the specs @ 0.050" are a bit different from what you show, but at the end of the day what you walked through still holds true.

So, here is what I have:
IVO is 13 ° BTDC ( - indicates ATDC)
IVC is 44 ° ABDC
EVO is 53 ° BBDC
EVC is 11 ° ATDC ( - indicates BTDC)
Overlap is 24

I'm curious, where did you pull/obtain the CompCams roller cam duration number from? They only show the adv duration numbers on their specs page...LOL...go figure, by now I think everyone looks at the 0.050" numbers to compare cams, or am I wrong?

OK, so the plan at this point in time is for me to do a season's worth of test&tune on my current cam. I am moving back to my Performer RPM intake (from Strip Dominator) to get back some of that low-end grunt I lost. I hope that will get me into the 12s...beyond that, I will most likely try the roller cam and do a 'side by side' comparison so to speak.

I am running CompCams 1.5 rocker right now...but I have a set of Crane iron 1.6 ratio rockers...was thinking of trying these out actually...that would already get my current cam into the .571/.576 range...which is proably as big as I'd dare to go.


You know, this was my thinking behind the 'hydraulic roller test'...LOL...yeah, I wish we could get a graph of the actual cam lobe profile that shows the lift vs degree rotation. Maybe there is a poor-man's setup that could be used somehow? The lift would be easy to track, just not sure how to track the crank rotation...can't think of an easy way without having to pull the timing cover off and tossing a degree wheel on...

You can find the .200 duration numbers for the comp in their master lobe catalog. IIRC, that intake lobe is in excess of 160*, that would be crazy long duration at .200 for a lobe you have in a hydraulic.

You might ask hughes the .200 duration numbers on your current stick. Bullet cams may be cutting cams for hughes, maybe check their .904 master lobe index. Most of those 904 cams are in the low 150 range for duration at .200.

I'd stuff the roller in as someone else suggest in the 106 ICL range. That will get some cylinder pressure back. According to the sticker, the recommended ICL is 108 based on the 112+4. Bump it two more if you have room.