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Stock Cam recommendation

PRHeads said:
Fast rate hyd cam........ not really my favorite..........But that’s what sells.

Although that’s not a real big one.
Click to expand...
Does anyone have a link to the Mopar purple Cam idle characteristics? I can’t find where which ones are fair idle, good idle or rough idle.
 
We've used the CompCams XE268H lots, never had a problem..... but again here, we think 280'ish(290 MAXIMUM) Lbs V/Spring pressures at Peak Lift over the nose is LOTS !

Which brings me to my next question because the 911-16 V/Springs don't have an 'inner' spring that can be removed for Cam break in ?
What installed Height ?
What Cylinder Heads ?
and
What Seat Pressure were the 911-16 Springs installed at ?

Just say'in....
in my experience, 300+ Lbs 'over the nose' V/Spring pressures for Cam break in these days is a RED FLAG for us as pretty risky ?
meaning,
if you just installed the 911-16 V/Springs on a set of factory Cast Iron Heads around 1.86-1.87" those lobes may have been seeing 300+ Lbs pressure over the Nose during cam break in ?
 
54BDC843-63F1-47EF-977D-9901F45C61D2.jpeg
View attachment 1250722
Challenger340 said:
We've used the CompCams XE268H lots, never had a problem..... but again here, we think 280'ish(290 MAXIMUM) Lbs V/Spring pressures at Peak Lift over the nose is LOTS !

Which brings me to my next question because the 911-16 V/Springs don't have an 'inner' spring that can be removed for Cam break in ?
What installed Height ?
What Cylinder Heads ?
and
What Seat Pressure were the 911-16 Springs installed at ?

Just say'in....
in my experience, 300+ Lbs 'over the nose' V/Spring pressures for Cam break in these days is a RED FLAG for us as pretty risky ?
meaning,
if you just installed the 911-16 V/Springs on a set of factory Cast Iron Heads around 1.86-1.87" those lobes may have been seeing 300+ Lbs pressure over the Nose during cam break in ?
Click to expand...
. Here is the receipt from Indy. I called them and they assembled a set of 452 heads with springs that supported the cam. Said they supported up to 0.5” lift. Don’t know anything else.

I just ordered a set of 440 source aluminum heads. Will use them with my new stock cam.
 
Last edited:
Sonny said:
View attachment 1250729 View attachment 1250722 . Here is the receipt from Indy. I called them and they assembled a set of 452 heads with springs that supported the cam. Said they supported up to 0.5” lift. Don’t know anything else.

I just ordered a set of 440 source aluminum heads. Will use them with my new stock cam.
Click to expand...

I have Stealth Heads in stock, but I can't remember exact as delivered ? So If I get time tomorrow I will measure Seat Pressure and V/Spring rate and let you know where they are at.
 
In watching many vids on u tube from various engine builders, they all seemed to be saying the same thing on stockish flat tappet cam failures. They said that most/many cam makers use hydraulic lifters ground by one of two main makers. Said one manufacturer has the most cam failures attributed to them and the other , very little . None would name the most failure company by name, but would tell you to use lifters made by this company, and I forget its name. Any body else heard this or is it all hogwash.......
 
The “G911” spring Indy uses has been sourced from a variety of vendors over time, with the seat/open loads varying greatly between the different “versions”.

The ones I’ve had come on their heads for the last several years really wouldn’t be suitable for most HFT cams imo.
Measuring the installed height and checking the closed/open loads might be revealing as to a possible source of the problem.
 
PRHeads said:
The “G911” spring Indy uses has been sourced from a variety of vendors over time, with the seat/open loads varying greatly between the different “versions”.

The ones I’ve had come on their heads for the last several years really wouldn’t be suitable for most HFT cams imo.
Measuring the installed height and checking the closed/open loads might be revealing as to a possible source of the problem.
Click to expand...


I agree
Not trying to throw salt in any wounde, just a good learning curve moving forward in efforts at not repeating.
 
The G911’s I’ve been seeing for the last several years have closed/open loads the same as a Comp 936, at the same heights they are rated at.

[email protected]/[email protected]

Better suited towards a street SFT with EDM lifters imo.

But....... through the years I have seen at least 3 different springs come on Indy heads that were designated as “G911”, which is why they should be checked........ so you know what you really have.
 
Challenger340 said:
I will be Testing the following on the Engine Dyno pretty soon....

I will be using the SUMMIT 6401 Hydraulic Flat Tappet Cam ($92.)
used with
Sealed Power HT976-16 Hydraulic Flat Tappet Lifters ($110.)
installed in....
a pretty basic resto style .030 over 440 targeting 5,000-5,200 rpm

* ICON 9953 Pistons, 5/64" 5/64" 3/16" Rings
* 906 Heads(ours end up around 90+ CC's when finished), and we use 8519PT Head Gaskets.
* HP Exh Manifolds and Factory 1968/69 Cast Iron Intake.

The SUMMIT 6401 Cam is ground on a 115* lsa which should provide a very good Idle/Vacuum characteristic even with the 224* @ .050 Intake Pattern.... and I expect nothing more than a very light 'musclecar' style Exhaust note.

But the real kicker....
I can't see the reason for any more than 290'ish 'over the nose' V/Spring pressures on this Cam for easy break in ?


Any bets how much power/trq we'll see ?
I think we can get close to 420 hp with 510 Ft/lbs with our iron head 2.08" valve prep/angles/bowls
Click to expand...
i used crane 99839-16 springs with the 6401 cam. i had the cam in a stock '69-375hp 440. made good mid-range torque. idle vacuum was 15" at best, but smooth. peak rpm was about 4600-4800 with the engine in the chassis.
 
there's no way i'd go to the expense of a roller for a stock build. not knowing the particulars of the failure, and i know they're messy, i'd just put a stock factory magnum type cam in it with proper springs and good tappets. the summit 6420 duplicates the factory cam and so does the sealed power cs661. the summit 6400 is a near duplicate. rock auto sells duplicate springs but the crane '839 spring will work. use a good break in oil like Driven. the expense and set-up for a roller plus the unreliable fuel pump push rod (which will end up with an electric pump) is just plain unnecessary. just take a breather and then go after this smartly.
 
The Crane 99839 is a good choice for this type of application....... but Crane has been closed since 1/1/21.

The PAC “equivalent” is a 1900.,,,,,,, it has a slightly higher rate.

The as supplied Stealth springs should be suitable.
 
I have been happy with my Hughes cam/lifters, give them a call. The HUG SEH0610BL-13 hydraulic cam shows good idle, high vacuum. The H5001 hydraulic lifters are made by Hy-Lift Johnson. Big thing is to ensure they rotate in the bores and that they have a slight dome to the face.
 
bandit67 said:
In watching many vids on u tube from various engine builders, they all seemed to be saying the same thing on stockish flat tappet cam failures. They said that most/many cam makers use hydraulic lifters ground by one of two main makers. Said one manufacturer has the most cam failures attributed to them and the other , very little . None would name the most failure company by name, but would tell you to use lifters made by this company, and I forget its name. Any body else heard this or is it all hogwash.......
Click to expand...
Only a few experts have the balls to call out bad manufacturers. I suspect that most guys get sweetheart deals on parts and are hesitant to admit that Comp Cams lifters are crap.
 
I would imagine that if you call out a manufacturer, you'd better have material analysis, hardness checks,
and all your i's dotted and t's crossed! They'll come after you like ugly on an ape.
 
Birdsong (junkerup) put a really mild comp cam kit in a Dodge 360 for a pick up and it literally wore a hole through the bottom of the lifter in short order. Don't know spring specs, but really anything 300# or less should be just S.O.P. for break in, no special handling.
 
Disassembled a set of OOTB Eddy 60929's yesterday, just one spring(end of day and tired)
132/133# @ 1.875-1.880" installed
290'ish @ .500"

I'll dis-assemble some new Stealth's later today and measure as I have to Flow both Stealth's and the Eddy's anyway before we start Porting for jobs
 
PRHeads said:
I have a set of very slightly used(100 miles??) Stealths in the shop.
I grabbed 4 springs and tested them.........
[email protected].
[email protected]

Comp 911 advertised specs:
[email protected]
[email protected]
Click to expand...

What it means is with the valve closed the spring will be in the 1.9" range tall and will exert 125-130 lbs holding the valve shut...

Valve open .500 (1.4'") the spring will exert 295-300 lbs trying to close the valve....

300 lbs over the nose is good for keeping the lifter on the cam once the cam/lifters have broken in together but 300 lbs during break-in is hard on the cam & it may not survive....

Some Rollers cams want lots more spring pressure... Actually aggressive flat tappets may want way more pressure as well....

A local SS racer I know use to run over 700 lbs over the nose on a flat tappet cam.... With Schubeck Ceramic faced lifters
 
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