From a solid roller to hydraulic roller

[Bishop540]

I have finally had enough with my 10:1 compression 540 solid roller on the street. Runs very good at WOT but not very streetable in the cruising rpm's, especially with the A/C on and cruising the freeway with my OD trans (at those low rpm's there just isn't any torque). My current SR is 286/296 - .255/.263 -.685/.680 - 107/101 .030 lash - 1.7/1.7. For a Hydraulic Roller, Comp has recommended 299/303 - 245/249 - .654/.659 107/103. - 1.7/1.7 (the 107 LSA is at my request) and beehive springs. The Lobes are the QXX which I hear are not real aggressive.

I only want to spin my engine to 6500 redline (Scat 9000 crank). I realize that I currently have too much exhaust duration for my AFR 325cc heads (2101-1) with my current SR. Over the years I now realize my heads don't need extra EX duration, but only about 4 degrees.

The Comp lobes give me about the same lift as I have now, minus lash, but the duration @ .050 is 10 and 14 degrees smaller. The overlap, however, is 87 compared to my 77 I have now. Seems like this new cam will be tamer than my SR but with the extra overlap I'm not sure I am going in the right direction. I am not gonna spread the LSA wider. If anything I would use less duration or a Single Pattern cam.

Of course I don't want to loose any power (730hp@6100 /692tq@4500) but would like to gain more low end torque for better street cruising. My question is: Will this new HR cam, and the extra overlap, give me more low end torque without the expense of giving up too much HP? Thanks!

(and I am not here to debate the LSA. For street performance I have always been happy with the narrow torque-y powerband it offers. I'm not spinning it to 7000+)

[1980RS]

Me I would put the LCA on a 114° you would never notice the loss of low end tq. and the 540 would have great street manners with a lot of vacuum. I know you said you don't want to debate LCA's but the reality is that a narrow LCA does ruin street manners somewhat and it's not like you would need to spin the engine that tight anyway to make great power with a 540. The old saying still rings true to this day, "where do you want your power band".

[Stan Weiss]

I have finally had enough with my 10:1 compression 540 solid roller on the street. Runs very good at WOT but not very streetable in the cruising rpm's, especially with the A/C on and cruising the freeway with my OD trans (at those low rpm's there just isn't any torque). My current SR is 286/296 - .255/.263 -.685/.680 - 107/101 .030 lash - 1.7/1.7. For a Hydraulic Roller, Comp has recommended 299/303 - 245/249 - .654/.659 107/103. - 1.7/1.7 (the 107 LSA is at my request) and beehive springs. The Lobes are the QXX which I hear are not real aggressive.

I only want to spin my engine to 6500 redline (Scat 9000 crank). I realize that I currently have too much exhaust duration for my AFR 325cc heads (2101-1) with my current SR. Over the years I now realize my heads don't need extra EX duration, but only about 4 degrees.

The Comp lobes give me about the same lift as I have now, minus lash, but the duration @ .050 is 10 and 14 degrees smaller. The overlap, however, is 87 compared to my 77 I have now. Seems like this new cam will be tamer than my SR but with the extra overlap I'm not sure I am going in the right direction. I am not gonna spread the LSA wider. If anything I would use less duration or a Single Pattern cam.

Of course I don't want to loose any power (730hp@6100 /692tq@4500) but would like to gain more low end torque for better street cruising. My question is: Will this new HR cam, and the extra overlap, give me more low end torque without the expense of giving up too much HP? Thanks!

(and I am not here to debate the LSA. For street performance I have always been happy with the narrow torque-y powerband it offers. I'm not spinning it to 7000+)

The Comp lobes give me about the same lift as I have now, minus lash, but the duration @ .050 is 10 and 14 degrees smaller.

Without Cam Dr files for both cams it is just a guess on my part. But I would guess that the effect 0.050" Intake Duartion is almost the same for both cams.

Stan

[mt-engines]

I'd fix your carb..

[mt-engines]

Me I would put the LCA on a 114° you would never notice the loss of low end tq. and the 540 would have great street manners with a lot of vacuum. I know you said you don't want to debate LCA's but the reality is that a narrow LCA does ruin street manners somewhat and it's not like you would need to spin the engine that tight anyway to make great power with a 540. The old saying still rings true to this day, "where do you want your power band".

Its a 540.

His tune and or timing must be out in left field.

[Bishop540]

I'd fix your carb..

Explain please

[Bishop540]

His tune and or timing must be out in left field.

Explain please

[Tom68]

Extra overlap shouldn't kill torque, just idle and the revs you need to be at for drivability. Intake closing will move your curve peaks.

[Geoff2]

Taking into account the lash for the solid cam, there isn't much difference in the effective duration of both cams.

Spending a lot of money to make the switch....for not much difference. Plus, have you read the horror stories about hyd roller lifters???

In a 540 engine, the current cam should be quite torquey, so maybe something else is wrong.

If you do go to a smaller cam, do not widen the LSA. Reduce the duration...

[RevTheory]

Can you find out the overlap triangle between the two cams? There may be a lot more area change than just looking at .050 duration and total lift would suggest. And there may not, lol. But I suspect a milder hyd/roller isn't coming off the seat near like an aggressive solid/roller so the overlap triangle could be reduced by quite a bit.

[F-BIRD'88]

I want a 7000 rpm race cam so I can drive around at 1500 rpm in overdrive with the A/C on. An a set of curb feelers...

[Bishop540]

Taking into account the lash for the solid cam, there isn't much difference in the effective duration of both cams.

Spending a lot of money to make the switch....for not much difference. Plus, have you read the horror stories about hyd roller lifters???

In a 540 engine, the current cam should be quite torquey, so maybe something else is wrong.

If you do go to a smaller cam, do not widen the LSA. Reduce the duration...

My current cam is VERY torquey, just in the wrong RPM range. It wants to spin to 7000+, even in a 540. It didn't "eat up" the cam as I thought. It just moved peak power to a lower rpm in a bigger engine. That's why I want to learn if it's just a matter of wrong duration on the wrong side of the lobes and not necessarily too much overlap.

I'm guessing that's why Comp steered me away from the more aggressive Lobes and lighter Beehive springs/ keepers, to not destroy the HR lifters.

[Bishop540]

Can you find out the overlap triangle between the two cams? There may be a lot more area change than just looking at .050 duration and total lift would suggest. And there may not, lol. But I suspect a milder hyd/roller isn't coming off the seat near like an aggressive solid/roller so the overlap triangle could be reduced by quite a bit.

Now this is the kind of info I am looking for. Something that makes me dive in deeper. The slower open ramp on the intake side, and slower closing ramp on the EX side. Is there an online Program or software that can show how balanced they are? And should they be perfectly balanced? Originally I had a 1.8 rocker on the intake but never retarded my cam on the Dyno to "make up" for the quicker opening rate. I bet there was some power to be found, if it was at the correct IN centerline to begin with.

[Bishop540]

I want a 7000 rpm race cam so I can drive around at 1500 rpm in overdrive with the A/C on. An a set of curb feelers...

Oh, you again. The hotrod Troll. And thanks for asking. It will cruise at 45mph in OD very nice, or 70mph. It just rolls over a bit at the slightest throttle when accelerating. But that got better the other day when I replaced my spark plug wires. Now, its just a slight "roll over". Maybe a slight lean issue. Gonna go back to opening the rear blades on the Dominator slightly, and closing the fronts a bit. Didn't work in the past because dumbass me had a set of 15yr old (yes, he said 15) plug wires. Amazing -the difference in tune- when you have good wires, cap, rotor and plugs. Who knew....

[Bigchief632]

I want a 7000 rpm race cam so I can drive around at 1500 rpm in overdrive with the A/C on. An a set of curb feelers...

Oh, you again. The hotrod Troll. And thanks for asking. It will cruise at 45mph in OD very nice, or 70mph. It just rolls over a bit at the slightest throttle when accelerating. But that got better the other day when I replaced my spark plug wires. Now, its just a slight "roll over". Maybe a slight lean issue. Gonna go back to opening the rear blades on the Dominator slightly, and closing the fronts a bit. Didn't work in the past because dumbass me had a set of 15yr old (yes, he said 15) plug wires. Amazing -the difference in tune- when you have good wires, cap, rotor and plugs. Who knew....

One of my customers did exactly what you want to do this spring on a 533, 4.470 bore 502 block, 4.25 stroke. It had a fair bit more cam than your solid roller, in the 272-280 at .050, but no overdrive or ac, but he cruised it A LOT. Engine made just shy of 800 on pump gas. He bought a twin turbo chevy 2, and his wife took over the Chevelle. She didn't like the lumpy cam, so he put a Jones hydraulic roller in it. 241-248 .640 or so lift, on a wide 114 lobe sep. It idles and drives like a kitten, drives really well, and still made 730hp, tq is still a non issue, or I should say it's still an issue, because it makes a lot more at lower rpm, and it had traction problems before too. It's down 68hp from the solid roller, but it's 30+ less at .050 with a a lot less lift. It also now gets 13+ mpg now. Your engine may not lose as much power, because the difference in cams isn't as big as it was on his.

Like said above, the 107 lobe sep on a street 540 is wrong in my opinion.