Smallie cam question

-
Captainkirk

Captainkirk

Old School Mopar Warrior
Joined
Apr 24, 2006
Messages
3,371
Reaction score
1,510
Location
Northern IL
I'll be getting to my engine build some time next year. My machine shop guy tells me that I should not reuse my cam because the lifters have rust on them. He claims that most of the cams he's seen reused with new lifters fail due to the changes in engineering and metallurgy over the years (this cam was made in the late '70's) OK; this much makes sense, a new cam and lifters can be had for around 2 bills.
I loved the way that cam ran and sounded. It was a split-lift, which apparently they don't make any more. I would like to duplicate as closely as possible without breaking the bank.
Here are the numbers off the box:

Lift (net) .450(I) .475(E)
Duration 298 308
Opens 37 86
Closes 81 42
Overlap ------79 degrees-------

@.050 lift
Intake Exh.
Lift -------- ---------
Duration 232 242

Engine/chassis specs (proposed):
340, 11.5:1 TRW pistons (originally 13:1 but heads cc'd to lower compression)
Forged crank
J-heads w/1.88s and mild porting
Holley 650 DP w/Eddy Torker or TQ and dual plane (probably Weiand or Eddy)
Headers
Chrysler electronic dizzy
A-833 four speed
3.55 or 3.91 Sure Grip

This engine guy says this cam profile is obsolete as was the engine build, however the car ran 12's and wound like a raped ape. (What's not to like about that?):burnout:

Anyway, looking for a build with similar specs and a cam to match...unless you guys think my engine guy is right and I should be starting from scratch? I loved the sound of that cam and the way the little 340 ran in the old configuration. What do you experienced engine guys think? Me, I think I'd like to duplicate the old motor as close as possible, but I'm open to suggestions.
 
Kirk, I could care less what the lifters looked like.....how's the cam look? And could it be "polished" out :D.

I'll look into a similar grind, if one is available off the shelf. I'm sure the modern grinds have advantage's over it, but it's still cool to use a old school cam.

P.S. Your compression ratio may come into play here? Seem's a little high for a pump gas engine with a fairly mild cam.
 
Found 1 close,Crower 31919. 112 lobe centers.232/[email protected],.450/.476 lift. Advertised duration318/328 (ouch). That sounds like a older Mellings/Trw grind.
 
rumblefish360 said:
I've told him that .......
Click to expand...

Yes, you have. And I'm listening.
I'm considering having the domes milled to drop it down to a more 'streetable' 10-10.5 to 1 CR. I will say it ran well with leaded premium pump gas back in the day. I think the octane then was around 97, if I'm not mistaken? But there was lead then, and no ethanol. So it might present a problem this time around. Forgot to mention that spark advance was set at 32 degrees full advance with a quick-advance kit and no vacuum advance; might have played a factor.
I'm trying to keep the build as close as possible as previous at the lowest cost I can. Play Money is at a premium these days.
But man, that thing was a lightning rod!
 
OldmanRick said:
Kirk, I could care less what the lifters looked like.....how's the cam look? And could it be "polished" out :D.
Click to expand...

I'll drag it out and look.

OldmanRick said:
I'll look into a similar grind, if one is available off the shelf. I'm sure the modern grinds have advantage's over it, but it's still cool to use a old school cam.
Click to expand...

I see Comp Cams has their "Thumpr" series which is supposed to mimic the Old School sound......

OldmanRick said:
P.S. Your compression ratio may come into play here? Seem's a little high for a pump gas engine with a fairly mild cam.
Click to expand...

Yeah, I've been warned that might come around and bite me. Problem is if I change over to say, KB pistons, the heads have been cc'd to 67 cc's and stock 10:1s will drop down to...what? That would probably require me to go with my X heads and all the machining that goes with it. Pistons, heads...$$$
 
I see Comp Cams has their "Thumpr" series which is supposed to mimic the Old School sound......
They BUILD cylinder pressure,the last thing you need(lol). The older ,slower cam ramps,are needed to keep it alive.
 
Call Oregon cams, they resurface and recondition old lifters for pretty cheap. I'm unsure if they can grind a split-pattern cam like that though.
 
Sometimes the way to solve a problem,look at a broad horizon. If that makes sense....
 
IMO, your going to want a C-ratio of not more than 9.5-1 with the iron heads. Today's octane limits are the issue. The cam is small which is also a problem with the high ratio. IMO, new slugs are in order.
 
Captainkirk said:
Anyway, looking for a build with similar specs and a cam to match...unless you guys think my engine guy is right and I should be starting from scratch? I loved the sound of that cam and the way the little 340 ran in the old configuration. What do you experienced engine guys think? Me, I think I'd like to duplicate the old motor as close as possible, but I'm open to suggestions.
Click to expand...

The thing that no one has stated is. It will not be the the same, with 2 points dropped off the compression ratio (13:1 to 11:1). If that cam ran good at 13:1, it will not be the same at 11:1. Acually the cam seems very mild for 13:1. You really need to pick a cam for the CR, of the engine, and the use of the car.
 
No one argues that point I'm sure but the comp ratio is out of control at 13-1 and still very high for pump gas @ 10-1 with the small cam. This has been brought up before but he still wants to do things his way.

Let him build it the way he wants and when he comes back with problems galore , just say "I told you so!" Until then, let him waste his money.
 
rumblefish360 said:
No one argues that point I'm sure but the comp ratio is out of control at 13-1 and still very high for pump gas @ 10-1 with the small cam. This has been brought up before but he still wants to do things his way.
Click to expand...
Actually, with the cc'd heads, CR is in the 11:1 range at present


rumblefish360 said:
Let him build it the way he wants and when he comes back with problems galore , just say "I told you so!" Until then, let him waste his money.
Click to expand...
I haven't decided on a course yet, Rob. That's why I'm asking questions instead of simply forging ahead. Wasting money is what I'm trying NOT to do. A set of KB forged pistons will set me back at least another 3-4 bills; if I can re-use the TRW's I'll be way ahead of the game!
 
PanGasket said:
Call Oregon cams, they resurface and recondition old lifters for pretty cheap. I'm unsure if they can grind a split-pattern cam like that though.
Click to expand...


You can also call Dave Crower directly from the number on his website and he can custom grind any cam you like. He did a custom grind cam for my ex's slant 6 when we built it and it ran great. Tell him what you want and what you got and he will design a grind for you or even touch up your old cam profile.
 
rumblefish360 said:
IMO, your going to want a C-ratio of not more than 9.5-1 with the iron heads. Today's octane limits are the issue. The cam is small which is also a problem with the high ratio. IMO, new slugs are in order.
Click to expand...


Not sure Rob, but I think the cam might be a small lift/long duration due to the piston domes. That's just a guess, however.
 
Abodybomber said:
Found 1 close,Crower 31919. 112 lobe centers.232/[email protected],.450/.476 lift. Advertised duration318/328 (ouch). That sounds like a older Mellings/Trw grind.
Click to expand...

I'm looking on Crower's website. Nice stuff and very economically priced. Thanks for the heads-up! I will probably give them a call tomorrow with my needs and see what they recommend. Both the 31919 and 31916 look like pretty good cams close to what I was running. Thanks coming your way.
 
Charrlie_S said:
The thing that no one has stated is. It will not be the the same, with 2 points dropped off the compression ratio (13:1 to 11:1). If that cam ran good at 13:1, it will not be the same at 11:1. Acually the cam seems very mild for 13:1. You really need to pick a cam for the CR, of the engine, and the use of the car.
Click to expand...

Never ran this cam at 13:1. The heads were cc'd and ported when I built the engine 1st time around so all I ever ran was 11-11.5 CR
 
Captainkirk said:
Not sure Rob, but I think the cam might be a small lift/long duration due to the piston domes. That's just a guess, however.
Click to expand...

Lift is not the consideration when thinking about piston to valve contact, duration is. It's not how much the valve is open, but when.
 
That looks like a good cam to me... Similar to the Crane H-302-2. I'd put a set of new lifters on it and run it. I've run that Crane cam with static from 8.7:1 to 10.5:1. Most modern street type cams are split pattern. Between the reasons for not running it and the "nobody runs split pattern cams nowadays" remarks I'd be worried...lol
 
Just got off the phone with Jerry at Crower Cams. He says the grind I had previously was (surprise!) about as good as it gets for that motor/application and recommended his 31919 grind Beast cam. The specs are almost identical.

http://www.crower.com/index.php/cam...60-67-up-318-la-v8-hot-street-beast-318h.html

FYI-here is the tag off the box of the original cam (yes, I still have the original box...I'm anal like that!)

10595228446_39df37fd60.jpg


His remarks were that the shorter overlap/duration than some of the lumpier cams would ease cranking pressure and detonation and that it should work fine with pump gas premium and 11.5:1 compression....

Now to see if the original cam might be re-useable?
 
moper said:
That looks like a good cam to me... Similar to the Crane H-302-2. I'd put a set of new lifters on it and run it. I've run that Crane cam with static from 8.7:1 to 10.5:1. Most modern street type cams are split pattern. Between the reasons for not running it and the "nobody runs split pattern cams nowadays" remarks I'd be worried...lol
Click to expand...


I do worry. Jerry at Crower Cams remarked that the HP engines and components built back in the '60's and '70's are still difficult to improve upon today for all-out performance. In the back of my mind I sorta knew that anyway. A twelve-second street machine is a twelve-second street machine, whether built today or 40 years ago.
When your 'engine guy' is younger than some of your kids, you gotta wonder.....
 
You must log in or register to reply here.
-

Back
Top