I'm thinking of going hydraulic cam for my 273/302 build the reason is I'm trying to preserve as much bottom end as possible so after reading about Rhoads lifters they might be worth switching to hydraulic since I'm gonna run a 280ish with .525ish lift with 1.6 rockers. The question will a hydraulic cam work up to 7000-7300 (is where i want my valve spring to work too) with light enough valvetrain? I'm gonna run under cut hollow ford stem valves 1.85-1.55 with beehive springs and titanium retainers.
Going Hydraulic
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moper
Well-Known Member
"1" vote for solid flat tappet 
I'm trying to put valve float at 7000-7300 Peak power is gonna be around 6600 so along the hydraulic doesn't give up before 7000 everything should be fine.
You are headed,in an expensive direction. If you are needing mid range torque through turns,stay with the solid.The guy I worked for,did a mid 60's Stingray,set up for autocross.406 Chevy,Eddy heads.went with a off the shelf solid.For your gig,stay solid.
OldmanRick
Well-Known Member
I vote solid on this one also. Can a hyd go to 7000+, yes on occasion, but why flirt with the need to have the r's available on a consistant basis. I can't tell you the perfect grind, but it's out there and can give you the streetability you need with no worries when track day comes.
Solid or solid roller been the plan all along, I guess I'm just trying have my cake and eat it too, with the Rhoads lifters. In this design I've been trying to protect what little bottem end my 273 can make while extending the powerband far as possible.
OldmanRick
Well-Known Member
goldmember
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There are hyd lobes that work well at 7000 rpm,but you'd be better off sticking with a flat tappet if you want reliability at that RPM. Tim @ Bullet cams has what you need. The H10 hyd lobe would be a good choice if you must stay hyd and I've used them in several 360 builds for customers. They pull well to 7000 rpm with 3/8" valves and other garbage so I'd think you'd be safe with better components.
Thanks Rick it must the most over thought 400hp sb build, it's gonna be my 1st full build and I want it just right. As for the cam I think I'm gonna stick with solid for now I figure I might have to try a couple of different cams anyway to get it dialed just right won't know what I really need until I get it on the track, the car is gonna be my daily driver locally in the summer and trailered to 5 events with race setup (front end alignment, slicks, etc..) so I'd say the cars gonna be 80% street 20% track I don't mind if the car is on the edge of street ability as long it isn't a dog around town.
pishta
I know I'm right....
X2 or whatever the counter is now on solids. Youll have a larger power window with solids too.
Stinktooth
Active Member
I converted my solid to hydraulic in my 273 and I'm going back to solid! My engine is a 64 and I start getting float over 3 grand thats with a .425 lift cam and stock springs. So I am thinking of trying the schneider solid unit.
Stay solid
Stay solid
Check out Seebees 273 thread. Real sweet small Engle solid Wild n Crazy chose,to match mild ported heads.Check it out.
Babyblue66
Cool dude
Solid. No doubt.
Gator
Mopar or No Car
509 purple cam with Hyd flat tappets and I have had no problems at 7000 which I have been there only a handful of times, didnt want to push it. Have my tac set at 6500 and runs really strong.... So I guess everyone has their preference but for me solids are to damn noisey....
K.O. SWINGER
Meeting in the alley since 1976
I agree with Gator 100% The main advantage of the solid lifter platform is lifter weight allowing for a more aggressive cam design for a given spring pressure. There are some very hot cam grinds for hyd. cams that will easily exceed 6500 with the right parts. I run a M1 single plain and shift at 6700. I have never floated a valve. Its a hot set up for the street and a 400 hp 345 ..I may go to a solid someday if I set my car for the track but I love a hot hyd. for the street theirs good reasons the factory stopped using solids.
moper
Well-Known Member
I believe you're incorrect. The advantage of the solid is the lack of the hydraulic "shock absorber" affect. That inherant "squish" means spring rates have to be lighter and opening ramps have to be slower on hydraulics. Which is what usually leads to loss of valve control and "float".
A solid flat tappet ramp can be much faster and much more stable as a result. They have the capability to come close to rivaling roller cam profiles.
K.O. SWINGER
Meeting in the alley since 1976
perhaps with a crap lifter or at the extreme end of the operating range but its not a issue when proper parts are used in a normal operating range. you lose more lift in solids need for lash , but the advantage of solids is "weight"
moper
Well-Known Member
No, any hydraulic lash adjuster - not just the stock replacement type - will compress before it moves the valve. Lash is not lost lift. You calculate it, and account for it. but there is a certain amount of lift you cannot account for that the hydraulic lifter uses up to do it's job.
I'm not debating that hydraulics can't be made that are stable - A friend set records in Stock Eliminator trapping at 7800 with one in a Ford and there has been a ton of spintron work to figure things out. But he had to use some tricks to make the valve train stable regardless. Valvetrain component weight has very litle to do with the reasons a solid is better.
Do you also believe a roller lifter is better because there's a weight advantage?
K.O. SWINGER
Meeting in the alley since 1976
The main question I was asking can a hydraulic cam can stable to 7200rpm with a relatively light valvetrain I know solid cam a better performer but it tempting to go hydraulic to use Rhoads lifters since my engine will spend a lot of time under 3500rpm since its 80% street car.
K.O. SWINGER
Meeting in the alley since 1976
sorry 273 in my opinion based off running what I consider hot hyd cams on the street for 20 year or so you are asking a lot from a hyd set up, but yes its totally doable, but the cam specs needed to have that rpm capability and gears needed to match 456 or so well not much fun to me on the street I ran 430s at one time it was a great match for my cam but i don't like my car winding like that on the freeway!
moper
Well-Known Member
I believe is valve train component weight is one of the most determining factors in valve train stability...do you think roller cams use such high spring pressures for no other reason than profile
Gotcha. I don't agree with you there. I feel component weight has an amount of bearing on stability, but no way is it on of the "most important". Not even close. IMO the most important factors in terms of stability (on a mopar) are the valve job - (setting the rocker geometry) and the pushrod. Not because of weight, but because of deflection.
My understanding is rollers use high spring pressures for several reasons: They are a little heavier individually; they have the added friction of the linkage; they have to follow a much more aggressive ramp on opening and closing; they have to maintain control of the spring harmonics over a much wider rpm range due to the expected higher rpm usage. I don't feel weight is a major concern given the last two.
Gotcha. I don't agree with you there. I feel component weight has an amount of bearing on stability, but no way is it on of the "most important". Not even close. IMO the most important factors in terms of stability (on a mopar) are the valve job - (setting the rocker geometry) and the pushrod. Not because of weight, but because of deflection.
My understanding is rollers use high spring pressures for several reasons: They are a little heavier individually; they have the added friction of the linkage; they have to follow a much more aggressive ramp on opening and closing; they have to maintain control of the spring harmonics over a much wider rpm range due to the expected higher rpm usage. I don't feel weight is a major concern given the last two.
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