Max Lobe Ramp For Solid Flat

-
Man....
as the ramp speed goes up the valve closes harder,you better have a very good
valve train..
Flat tappet cams with 165 to 170 @200 should keep your hands full and wallet empty for a while...no need for a 1" lifter you can get yourself in more than enough trouble with the stock diam lifter. just my two cents..I've been there done that.
 
"as the ramp speed goes up the valve closes harder,you better have a very good
valve train"

Yup. I know Jesel or T&D made a setup for the Jeep 4.0L. It might end up being a $4K long block with a $1800 set of rockers...lol.
 
moper said:
The problem I see is the spring pressures with the factory rockers... I haven't really thought that part through yet but I would not go with any higher ratio than 1.5 for that reason. I may just end up reinforcing them and having them cryo treated. It's too early at this point to worry about it.
Click to expand...

stock rockers have been run with over 700 lift cams, they are really strong so thats not a concern
 
Rob R said:
:shock:..

I think you might be a little mistaken on that point.. ;)
Click to expand...

stock slant rockers have...

.675 lift with just clearancing...

second page, second paragraph on the "Deep Six" article about the cricket... i cant get the page to load as its to big so i'll try to cut it down to make it work.
 
I would just order a full race cam and call it good. Hehe
 
Damn I wish I could get some lift but I'm just old. lol

How's your ride been running?
 
skypower said:
Damn I wish I could get some lift but I'm just old. lol

How's your ride been running?
Click to expand...

finally pick it up again! most of the interior has been redone and will probably be pulling the motor for rod bolts and main studs, and probably alot more compression... thinking 11:1 or more to get my cranking pressure up around 180 and dynamic up :glasses7::glasses7:
 
From the original question I think you'd be better thinking of more important things if your not building a heads up class car. Maxing the area is not likely to be your best approach and yes, If you got the $$$ to have custom lobes ground for the lifter go for it,then you will spend more on spintron work and don't forget the rest of the valve train to work with these parts. what I'm getting at is that even with a good .904 lobe design the other components are the weak link. Without a bunch of $$$$ it's not going to be the out come you are looking for. The entire Valvetrain must work as a unit or you'll be wasting time worrying about those cam lobes. 20 yrs ago a very good lobe designer told me that without being able to sell a customer EVERY component in their valvetrain how could he possibly know if it would work as intended? With EVERY detail of your build call Tim @ Bullet cams and I'm sure you'll be in good hands.
 
805moparkid said:
finally pick it up again! most of the interior has been redone and will probably be pulling the motor for rod bolts and main studs, and probably alot more compression... thinking 11:1 or more to get my cranking pressure up around 180 and dynamic up :glasses7::glasses7:
Click to expand...
Dynamic comp has no bearing on power output.
 
goldmember said:
Dynamic comp has no bearing on power output.
Click to expand...

sorry i call bs on this and so will everyone else... you can run 10:1 but with a ton of duration (lots of overlap) you dynamic will be low meaning its making less power unless you spin the cam to its operating rpm. the inverse is true as well if you have 10:1 and a very high dynamic (low overlap) it will make more power lower because you getting less bleed off and More effective firing.

but yes i understand on the previous post that its a system, everything has to be matched. our slants are very limited in performance stuff, but i plan on 7mm stems and bigger valves, correct springs etc...

worst thing that happens is i break something trying to push the envelope.
 
LOL cool story. I do however agree that you can kill a combo if you really screw up. Dynamic comp has nothing to do with power output or ET's at the track,it's been proven many times,no you may not get it and I'm sure others will come to your rescue(LOL),but that doesn't make it true.If you want to keep wasting time on this silly myth let me know.If you want a street car with longevity you shouldn't be worried about your original question as your wasting time. Class racing you may want to waste the time but I don't get the feeling from your post that you got that in mind.
 
here is a close cam with a chevy lobe and small lifter. im getting a .385 lobe lift on 242 @ .050 which is getting close. i wonder how much of a increase ther is available from the chevy lifter to mopar 904, then to 1", even just .020 lobe would put me where i need to be.

http://www.summitracing.com/parts/cca-11-653-47/overview/

EDIT: chevy lifter looks to be .842
 
I'd guess you'd need pushrods about 3/4" diameter and ceramic lifters along with 550lbs open if you want to spin that over 5500rpm. Your questions should be to someone with experience with this combo as someone dealing with typical stuff and giving lobe recommendations based off other engine combos will be of no use. Have the heads been on a bench? Post up those details,might help with the other side of this puzzle.
 
goldmember said:
I'd guess you'd need pushrods about 3/4" diameter and ceramic lifters along with 550lbs open if you want to spin that over 5500rpm. Your questions should be to someone with experience with this combo as someone dealing with typical stuff and giving lobe recommendations based off other engine combos will be of no use. Have the heads been on a bench? Post up those details,might help with the other side of this puzzle.
Click to expand...

lol they are shorter than hemi rods and with better angles so i dont see your concern. and 550lbs on a solid flat LOL... come on dude One one head and its been worked really well, but still probably gonna go 7mm stems and a 1.75/1.44 sizes. you must have missed this is for a slant

As for the puzzle there is non. all i want to know is that the max lift vs a given duration is, and yes i know there is alot of variables to make it live but im just on lobes right now.
 
I spoke to Crower, at the PRI show a couple of years ago, about a mushroom lifter grind for a slant. They could and would do a cam, BUT: They want all the other info on the engine "INCLUDING HEAD FLOW NUMBERS". I sould not even bother calling them, without all this info. If you are serious about this, send me a PM. I should have the business card with the proper direct phone number in my file.
 
HOTMOPR said:
ok heres some technical stuff for ya.. I'll give ya the specs on this whole cam. I love it and will use it again..

Its a Crower specd with 1.5 rockers
Adv duration 346* .633 lift
lobe seperation 105*
Duration @ .050 298*
Lobe lift .422
Install at 101*

Not sure if this helps you or not but its about as nasty of a solid lifter cam as I have seen. Idles like no others I have heard before. kinda has a growl growl growl instead of the lumpity lumpity lumpity. HAHA
Click to expand...
thats a nasty sumofabiotch
 
Charrlie_S said:
I spoke to Crower, at the PRI show a couple of years ago, about a mushroom lifter grind for a slant. They could and would do a cam, BUT: They want all the other info on the engine "INCLUDING HEAD FLOW NUMBERS". I sould not even bother calling them, without all this info. If you are serious about this, send me a PM. I should have the business card with the proper direct phone number in my file.
Click to expand...

Hey thanks for the note Charrlie, yes i do have all the head specs and such but those will be changing here shortly as im working on some thin stem valves and more port work.

And PM sent :glasses7:

jimjimjimmy said:
thats a nasty sumofabiotch
Click to expand...

yes that cam is scary lol...
 
its actually fairly drivable with the auto and 4000 stall converter.. Does sound scary though! lol
 
goldmember said:
I'd guess you'd need pushrods about 3/4" diameter and ceramic lifters along with 550lbs open if you want to spin that over 5500rpm. Your questions should be to someone with experience with this combo as someone dealing with typical stuff and giving lobe recommendations based off other engine combos will be of no use. Have the heads been on a bench? Post up those details,might help with the other side of this puzzle.
Click to expand...


I don't often agree with goldmember - but I do in what he's posted thus-far with the exception of pushrods and ceramic lifters. Dynamic compression is a result - a variable. You can try to predict it and that can be used as an aid to parts choice but when push comes to shove it's not an absolute that indicates power in and of itself. I am a big proponent of using it but it's no more valid than a head flow number as far as power production.
I don't think pushrods will be quite the problem - the inherent harmonics in the straight six will negatively affect things way more than flexing pushrods once we get into any rpm where it will make power - and that's assuming the head can be worked enough to feed the cylinders. I think under 5500rpm the worst issues will be head flow and rocker setup. There's no way I'd consider the stock, shaft mounted, stamped & welded steel rockers as a performance part. They might have survived some racing, but they are not a race peice. So it's there where I think the money will need to be spent.
 
I'm no expert on all this by any means, however, if DCR has zero effect on power output, then consider and explain this. DCR certainly has an effect on detonation. So, if we have an engine whose DCR is so high that it detonates on pump gas, that engine would not make the power on pump gas that it would on race gas. DCR has a direct effect on cylinder pressure. More DCR equals more cylinder pressure. More cylinder pressure equates to more power. I am all ears as to details on how DCR does not effect power output. If that's the case, then why even worry about it? In general, the limit for pump gas is 8.5:1 DCR. Above that threshold will require race gas, or at least a mix. Are you trying to say an engine with 9.5:1 DCR will not make more power than an engine with 8.1:1 DCR? I am sorry. I don't buy that. I think the assertion is incorrect.
 
On the money ,Rob. D.C.R = cyl psi. If cyl psi goes up,so does the chances of detonation. A lot probably counts on the lobe centers,intake valve closing point and actual mechanical compression.
 
You must log in or register to reply here.
-

Back
Top