[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/
.

[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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[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!

[70GS455]

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

Sent from my SM-G991U using Tapatalk

[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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[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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[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.

[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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[GTOLou]

Originally Posted by tom s

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

Would guess the stump puller lift is too high (can't remember it offhand) for HIS wants/needs. BTW - what lift are we talking about?? And..why the want for low seat pressure on a HR?? Heads already set up for that???

I also run a Stump puller in a low compression 455+ w/ low enough compression to run 87octane - and yes. A great cam. Aluminum heads, etc.

[ta man]

Originally Posted by GTOLou

Would guess the stump puller lift is too high (can't remember it offhand) for HIS wants/needs. BTW - what lift are we talking about?? And..why the want for low seat pressure on a HR?? Heads already set up for that???

I also run a Stump puller in a low compression 455+ w/ low enough compression to run 87octane - and yes. A great cam. Aluminum heads, etc.

This would be my choice something similiar..what I would want is to make the engine efficient at cruise and the higher lift will not hurt.
I'm not why the OP is afraid of lift..this isn't the old days..modern engines have lift.
If aluminum heads were in the budget..combined with a cam similiar to the stump puller with an overdrive it would be 20mpg plus at 70mph.

[Stan Weiss]

Originally Posted by ta man

This would be my choice something similiar..what I would want is to make the engine efficient at cruise and the higher lift will not hurt.
I'm not why the OP is afraid of lift..this isn't the old days..modern engines have lift.
If aluminum heads were in the budget..combined with a cam similiar to the stump puller with an overdrive it would be 20mpg plus at 70mph.

While it does come down to lobe design. But in must cases the more lift for a given duration the more velocity and acelleration the valve will see. Mark put some limits on what he wanted for valve spring pressures.

Stan

[tom s]

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

[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.