[Half-Inch Stud]

In the pursuit of a 70 MPH Highway application, 455 Pontiac getting good MPG in Overdrive, and may be towing. Is there a Pontiac Roller Cam with;

low lobe lift and long lobe ramps for sustained highway use,
no lifter brace needed and Valve springs typical to a High-lift Flat HYD cam (110 Lb closed, 2xx open)?

I have a darn-good Roller cam core with 0.442" lobes; would be ashamed to get it reground to meet the above goal, if the small roller is off-the-shelf.

[77 TRASHCAN]

Originally Posted by Half-Inch Stud

In the pursuit of a 70 MPH Highway application, 455 Pontiac getting good MPG in Overdrive, and may be towing. Is there a Pontiac Roller Cam with;

low lobe lift and long lobe ramps for sustained highway use,
no lifter brace needed and Valve springs typical to a High-lift Flat HYD cam (110 Lb closed, 2xx open)?

I have a darn-good Roller cam core with 0.442" lobes; would be ashamed to get it reground to meet the above goal, if the small roller is off-the-shelf.

Well.....
Butler now sells Hyd roller versions of the popular Pontiac HFT cams, 067, 067, 744, and 041.
Might check their website. Made by comp...

[i82much]

I think the old comp lobe families like high energy and magnum might be close to what you are looking for.

[steve25]

Why don’t you first try to sell your .440” lobe lift roller to partialy fund a custom ground solid roller.

[Steve C.]

A fwiw, About a year ago I had a solid roller cam reground at Bullet Racing Cams with less lobe lift it was $157.50 + freight.

Obvious the lobe separation cannot be changed but instead of solid roller lobes it could of been reground using profiles for a hyd roller.


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[Steve C.]

Also you might find a cam can only be ground so far based on potential surface hardness issues.

Related article:

Camshaft Heat Treatment Explained

https://www.cpgnation.com/camshaft-h...ent-explained/
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[GTOLou]

3162/3163 - 230/240 @ 110 .428/.428 HR - ???

[Steve C.]

Those lobes in conjunction with 110 LSA would have 77 degrees overlap based on the advertised duration.
Not a good fit if one were to adhere to this....

These are the valve timing overlap ranges that are most likely to work correctly (thanks to David Vizard for providing this):

trucks/good mileage towing 10-35 degs overlap
daily driven low rpm performance 30-55degs overlap
hot street performance 50-75 degs overlap
bracket/oval track racing 70-95degs overlap
dragster/comp eliminator engines 90-115 degs overlap

( Information provided in this post does not represent any endorsement of those overlap numbers and is offered for general interest only. I might suggest David Vizard had a small block chevy in mind )


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[70GS455]

Clay Smith has gentle, non aggressive roller profiles with lots of seat duration

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[Steve C.]

Again, not as any sort of recommendation but only to serve as an example of a cam with the specific description as follows:

"Smooth idle, good mileage for 455, strong towing cam".

That is for the Comp High Energy 260H cam. It's a hyd flat tappet cam but note it only has 212 duration at .050" ! The lift is .440".

And for interest that single-pattern cam has 40 degrees overlap. If you had it ground with 6 degrees additional exhaust duration and with 114 LSA it would have 35 degrees overlap.

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[GTOLou]

Originally Posted by Steve C.

Those lobes in conjunction with 110 LSA would have 77 degrees overlap based on the advertised duration.
Not a good fit if one were to adhere to this....

These are the valve timing overlap ranges that are most likely to work correctly (thanks to David Vizard for providing this):

trucks/good mileage towing 10-35 degs overlap
daily driven low rpm performance 30-55degs overlap
hot street performance 50-75 degs overlap
bracket/oval track racing 70-95degs overlap
dragster/comp eliminator engines 90-115 degs overlap

( Information provided in this post does not represent any endorsement of those overlap numbers and is offered for general interest only. I might suggest David Vizard had a small block chevy in mind )


.

Good stuff Steve - that HR is the only thing I've got on the shelf w/ super low lift!

[tom s]

I have been REALLY happy with the Stump Puller!Have it in my 434 RA V.70 MPH at 1900.Tom

[Steve C.]

Bottom line Half-Inch Stud needs to come back with a bit more specifics. At least some thoughts on his idea of "low lobe lift and long lobe ramps". And at least a general idea of the .050" duration.

And the 110 lbs seat pressure for a roller cam might be a somewhat of a controversial topic

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[tom s]

FYI,George at Clay Smith runs 150 seat on his hyd roller street cams.Tom

[Half-Inch Stud]

Originally Posted by Steve C.

Bottom line Half-Inch Stud needs to come back with a bit more specifics. At least some thoughts on his idea of "low lobe lift and long lobe ramps". And at least a general idea of the .050" duration.....And the 110 lbs seat pressure for a roller cam might be a somewhat of a controversial topic
.

Good to expand on. Assume 1.5:1 rockers. I will be willing to keep exhaust lift real low. Lets say 0.40" Valve lift, since EXH lift really doesn't make HP on the street.. The Lever force to crack open the EXH valve is more important to me. 110 Lb EXH Seat pressure ought to play.

As for Intake, the lift ought be 0.5" for traditional inhale need for HP. I just don't see the need for high seat pressures for rpms kept below 5000 rpm, for a long ramp profile. 230* duration at .050" should be capable with slow ramps. Asymetric ramp? i dunno.

im definitely not looking for fast ramps; Seems stoopid for street, high mileage goals. No lifter brace in this deal.

Sealed power ht-2148 lifters seem similar in weight to the Flat HYD lifter. So the spring pressures i've been using appear viable.

[Jay S]

With Bullet cams you can at least ask them what the specs are on the opening and closing rates. It will give you and idea what the true seat timing are. At least I do. I call up, ask the specs for the cam at the tappet lifts I am interest in and they tell me.

From compcams one of the marine HR lobes would likely be one of the their gentler profiles with more seat timing and easier on components. I think Bullet can easily beat that though.

FWIW...I have been surprised how much overlap can run and not effect economy. I think early EVO cam events seems like they can kill economy as bad as anything. Seems like it has adversely effected economy on most the engines I have done. I would look at single pattern cams for economy. IMO, Best economy will have lazier ramps, good compression, and be a single pattern or reverse split installed strait up.

It takes a little more seat pressure to hold the roller to the profile versus a flat tappet. Force vectors for the roller go from the the roller contact through the axle. Flat tappet vector is at the edge and more straight up. Gentle roller profile you can run less spring rate though.

[Steve C.]

Again offered for general interest only and to serve as an example to something close to the ideas in post 15........

Intake:
Lobe number HR296/345
.006"- 296
.050"- 230
.517" lift

Exhaust:
Lobe number HR291/300
.006" - 291
.050" -236
.450" lift

I used 6 additional degrees exhaust duration only because it's common. However that could be adjusted to suit the exhaust-to-intake flow ratio of the cylinder heads in use, that and the exhaust system in use.
The cam could be ground with what ever lobe separation desired.

https://www.bulletcams.com/Masters/HRlobes.htm


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[70GS455]

Originally Posted by Jay S

With Bullet cams you can at least ask them what the specs are on the opening and closing rates. It will give you and idea what the true seat timing are. At least I do. I call up, ask the specs for the cam at the tappet lifts I am interest in and they tell me. No corporate BS. On solids I do the same thing but add the lash in.

From compcams one of the marine HR lobes would likely be one of the gentler profiles with more seat timing and easier on components.

Isky has very gentle profiles for street solid rollers. No idea what they have for HR though. At least the isky SR’s I have had seemed to have less acceleration on the lash ramp, and easy on the valve terrain. Comps seem like that have been the harshest, but the engine I used compcams in cam and valve terrain life was not one of the areas we were concerned about. Probably not relevant is this thread is just referring to HRs. But again, Bullet has that cover also.

FWIW...I have always been surprised you much overlap you can run and not effect economy. I think early EVO cam events seems like they can kill economy as bad as anything. Seems like it has adversely effected economy on most the engines I have done. I would look at single pattern cams for economy. IMO, Best economy will have lazier ramps, good compression, and be a single pattern or reverse split installed strait up.

It takes a little more seat pressure to hold the roller to the profile versus a flat tappet. Force vectors for the roller go from the the roller contact through the axle. Flat tappet vector is at the edge and more straight up. Gentle roller profile you can run less spring rate though.

EVC instead of EVO?

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[Steve C.]

Here is an example of what Jay mentions regarding calling Bullet and asking what the specs are on the opening and closing side of the cam.

UltraDyne lobe number R10
Rated with 288 degrees at .020" tappet lift and 255 degrees at .050" tappet lift. The lobe is asymmetrical with opening and closing rates that are different.
As it opens it has 282 degrees at .020" and 252 at .050" lift. When closing it has 258 at .050" and 294 at .020".

The lobe is listed here:
https://www.bulletcams.com/Masters/u...nemasters.html

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[Jay S]

Originally Posted by 70GS455

EVC instead of EVO?

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EVO. A near as we can figure the power stroke mainly is pushing longer on the piston before the valve is opened. Like it has a smaller cam, and the pressure differential are high enough on the exhaust the engine can get by ok with less cam on the exhaust. It lets the exhaust pollute the intake charge sooner up top. But for street duty, as long as the cam is big enough you don’t miss it.

Best results seem to be an asymmetrical intake profile with more seat timing, and the exhaust can be a symmetrical profile that is more aggressive and less seat timing. Usually see a drop in exhaust temps for heavy towing. It helps the exhaust valve spend extra time on the seat to transfer heat. That is why they shorten the seat timing on the exhaust. Both Bullet and Jones cams seem to go that direction for towing. For both power and economy we have ran asymmetrical single or nearly single patterns. Ussually 2 or 4 larger on the exhuast. But I am not sure they are better than the Asy/Sym combo.