A camshaft essay.

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Rat Patrol

Rat Patrol

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OK...I got peeved because I was sick of reading people canning the idea of carb induction ...so this is my little "eye opener" for all those EFI guys running aftermarket cams...


When I installed my Inertia SRT Max Plus cam...I was surprised to see it installed on a 114 ICL...when the Crower cam card supplied with the cam stated it should go in at 106!

A couple of international calls to Stu and it soon became apparent that Piston to Valve is a real issue with factory slugs in the G3...and the only way to get around it is for the cam suppliers to get these cams ground on a RETARDED ICL......by 6-8 degrees .......to get reasonable P-V clearance.

Trouble is...a retarded grind has the following effects....

- Reduces cylinder pressure
- Moves the torque band higher
- Reduces the scavenging effect at low rpm
- Kills low end torque


Of course...........these are things anyone running a carb inducted motor definitely DOES NOT WANT..

But hey...I'm 800lbs lighter than a LX car, I run qtr mile gears and a 3800 stall.


but what about you EFI guys running aftermarket sticks and factory slugs?

so,...this post is a bit of a crack at those that are assuming all our issues are "intake related" ..............put simply...they're not.

If you're running an aftermarket stick with factory slugs....you're still leaving plenty on the table...EFI or Carb! ......even in an A Body :p

But don't get too down.....makes you wonder how these guys with EFI 4300lb cars and 3.00 gear sets are feeling don't it? ;)
 
so I have to retard the cam in my stock 6.1? Do I need a new gear set for that?

Did you dyno your engine to say the torque band went higher?
 
That 6 to 8 degrees was pointed out before. If my memory serves it was stated that every stock cam grind had the same slight retard incorporated. There was a mechanical principle involved but I can't recall what/where. Timing chain stretch, crank twist, rod length growth, something.
Anyway... It was concluded that aftermarket cam spec states what the difference is from stock instead of actual.
 
My first cam (that fits in stock piston motors) was 218/223 113+3 (advanced).

The key in stock piston motors is to keep the duration down.
 
The cams install retarded because they are ground on a retarded ICL...This is how they are ordered by Inertia, PWR and Mod Muscle etc...

The cam blanks are actually designed to go in a on an earlier ICL..(eg 106- 108 etc)....but the re-sellers know this will cause P-V clash.

It has nothing to do with the factory timing set or how you degree it - they are simply ground retarded.

Redfish - As stated - this is the ONLY way they can supply a cam with more duration and not cause piston to valve clash with stock pistons.

Like I say..no one is criticising them..they are working between a rock and a hard place...but don't kid yourselves these sticks are generating optimum output....they are not.
 
Uhcoog1 said:
My first cam (that fits in stock piston motors) was 218/223 113+3 (advanced).

The key in stock piston motors is to keep the duration down.
Click to expand...

The card would have said that - I bet if you degreed it..it would have gone in at 113...just like mine ;)
 
So my reason for posting was simly to point out that -

- Unless you run aftermarket slugs with valve reliefs, and
- buy a multi key way timng chain so thst you can degree the camshaft correctly

...the commercial grinds are a compromise so that we can run more duration without valve clash.


I'll admit to being a ***** about it...but I get little tired of being told running carbs is a mistake.....when half the issue is about retarded ICL installation creating **** cylinder pressure.

Just thought people should know the reasons are not all intake related. Chris from Modern Muscle has already confirmed there's no way around this without changing slugs on this forum....I guess people missed it.......

Maybe Chris will step up and confirm it again-


Please understand that with factory slugs...there's no other option option for these guys but to supply a a grind on a retarded ICL.
 
Buschi340 said:
so I have to retard the cam in my stock 6.1? Do I need a new gear set for that?

Did you dyno your engine to say the torque band went higher?
Click to expand...

Buschi - not being rude but you need to read up on the effects of cam timing and ICL.

NO..YOU INSTALL AS IT GOES IN...the point is.....the grind is not as " perfect" as Crower or Comp or Crane or Lunati intended ......because of the changed ICL.
 
You can still advance it no matter what it goes in straight up as. I wont give you ANY grief about running a carburetor, its just the stubby runner Modman that I have yet to see anything impressive out of that is all. A shelf cam is a handicap but the real handicap is the lack of valve reliefs in a stock 6.1. Mine has a 114 intake centerline, so I will be handicap too.
 
We had .068th piston to valve on the intake side when we installed it straight up at 114

You're welcome to try it advancing it from there with factory slugs if you like......BUT NOT ON MY DIME! Lol!

Re the carb stuff - I have never disagreed the !odman is less than ideal - but when I discussed my cuurent cam specs with a local grinder - it soon became apparent that Im fighting a war on two fronts - the 114 ICL is doing me NO favours as far as low range torque.......and that was really my point.

I just dont think many people realise these off the shelf cams are a compromise unless you use relieved slugs and a multi key way chain
 
Rat Patrol said:
The card would have said that - I bet if you degreed it..it would have gone in at 113...just like mine ;)
Click to expand...

Not like yours.

I degree all my cams. This one was degreed. 113.5 LSA in at 110.5 ICL. Factory timing set.
 
Uhcoog1 said:
Not like yours.

I degree all my cams. This one was degreed. 113.5 LSA in at 110.5 ICL. Factory timing set.
Click to expand...

Wade did you find an offset dowel or crank key? Im not there yet but will be tomorrow :burnout:
 
I stayed factory. Not adjustable.

The Manley double roller is supposedly good. Stu also sells a crower piece.
 
So you got lucky. Andy said reatedly to just install mine "straight up" lol. Well if it aint 114 it wont be "straight up". I'll be using 6.1 timing set too.
 
Uhcoog1 said:
Not like yours.

I degree all my cams. This one was degreed. 113.5 LSA in at 110.5 ICL. Factory timing set.
Click to expand...

Who supplied your stick Wade?

Did you get a cam card? Who did the grind?

From what Ive seen...the PWR, Inertias amd Modern Myscle sticks all go in btwn 112 and 114.,,,,which is retarded to the optimum ICL
 
72BBSwinger said:
So you got lucky. Andy said reatedly to just install mine "straight up" lol. Well if it aint 114 it wont be "straight up". I'll be using 6.1 timing set too.
Click to expand...


FWIW...mine is also on a 110 LSA.....If yours is on a 114lsa, it will seriously help your p-v and you may be able to advance it a couple of degrees.
 
Mine has 114HR stamped on it. My pistons have .100 deep valve notches. I will probably check p-v for good measure. This cam is an older grind that he basically tested to see if it could be tuned. His new "Stage 4" stroker cams say 117LSA and 114ICL in their specs. Im tempted to put an offset crank key in it and put it at 110 but he says "DONT".
 
114 ICL wont be quote so bad with a stroker as well....faster piston approach speed will mean qucker cylinder filling...and of course yours is injected which helps also.

Which make s yours?
 
Its a custom Comp Cam grind from Andy at PWR. He has switched to Lunati for all his cams now. This cam has been a consistent 530-580 whp cam depending on heads. And those number are all from LX cars. Here is an idle video with slightly less duration @.050
[ame="http://www.youtube.com/watch?v=ojnNWlEgJfM"]420 Hemi Stroker - 800 rpm idle - YouTube[/ame]
 
Frankly, I still don't see what your rather rambling, obtuse rant has to do with carb vs EFI?

And..............seems to me a degree wheel and proper engine setup will tell the story of "valve clash"..............
 
67Dart273 said:
Frankly, I still don't see what your rather rambling, obtuse rant has to do with carb vs EFI?

And..............seems to me a degree wheel and proper engine setup will tell the story of "valve clash"..............
Click to expand...

Really?

So when I said that the Inertia cams install at 114 which is where they said they would,

BUT , the Crower card said they should install at 106 for OPTIMUM performance,

AND ...even 114! left us with .068th p-v on the intake side,

AND .., because these cams CANNOT be advanced with factory slugs,

THAT - this effects low end tq, especially with carb inducted motors


BUT ...that cars running EFI are not getting the most out of these cams either....

AND.....this proves the under performance of carb inducted G3 motors is not all about the carberation....

....THAT ....this means nothing to you?

OK...whatever....but Id have to suggest that you are the subject matter expert on OBTUSE.
 
72BBSwinger said:
Its a custom Comp Cam grind from Andy at PWR. He has switched to Lunati for all his cams now. This cam has been a consistent 530-580 whp cam depending on heads. And those number are all from LX cars. Here is an idle video with slightly less duration @.050
420 Hemi Stroker - 800 rpm idle - YouTube
Click to expand...

Like I said 72BB....the EFI covers a bunch of " sins".... But a 114 ICL cannot be ideal if Crower recommends 106!
 
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