Unknown Cam

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808 DUSTER

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I picked up a 72 duster that has a 1968 383. the guy i bought it from told me it has a "mild" purple cam but does not know the grind.(it was installed as a gift). I am looking at options for upgrading the heads but dont know how this unkown cam will affect my options.
First question is how can i check the cam specs? will i have to completely remove it?
As for the heads i am looking at the Edelbrock performer with 84cc chamber. Should i just plan on getting a new cam setup?
 
I myself would put base a new cam that suited my plans.

Put your thinking cap on! Here we go, basic instructions.

To check the cam specs in engine you'll need a degree wheel and at least one each of the following parts. Solid tappet, an adjustable rocker arm of known good quality and ratio of 1.5 and a pushrod sized to work with the previously mentioned parts. A dial indicator with a way to mount it to the engine so it can read the lift ethier at the cam lobe or on the valve retainer to measure the lift.
A top dead center tool. Even a simple screw driver cam help you find this.
A buddy for extra hands is also a useful thing.

Once you find the intake lobes base circle, zero out the dial indicator and start rotating.
Mark down the numbers of the cams lift and when the cam opens and closes the valves.
 
Oh. If you have the MoPar engines book, now would be a god time to read the camshaft section. Also, a visit to various cam we. Sites for there take on cams should be helpful. Crane, Comp Cams have some good reading (paper catologs at least) on there cams. A lot of I do is contained in there pages covering many subjects a out there material
 
Dial indicator off the top of the valve will give you lift at the valve. X 1.5 will give you the cams advertised lift.
 
for what a new cam/lifters cost, I would just install a new one that fits your build. There are much better cam grinds available today than in the past.
 
Adam, you're right on the money. A dial indicator on the valve retainer will give you a good idea of which cam it is. If you want to post the results, we should be able to make a really good guess.
 
well since im feeling lazy and still really just looking at options let me ask you guys this. If i keep the bottom as is..stock, what cam/head combo will give me some good street punch? I do not plan on any strip use...for now. just want to wipe the smiles of these damn rice rockets running around base! i have a dual plane performer intake and will be changing my 600cfm double pump to match the cam/heads. I would like to keep my budget around $2500-$3000 tops.
As mentioned i am also looking to change the torque converter to one best suited to the final engine build. Currently running 3.55 sure grip, dont want to change that if i can help it.
 
Yes, but how many older camshafts give lift at the lobe?
 
808 DUSTER said:
well since im feeling lazy and still really just looking at options let me ask you guys this. If i keep the bottom as is..stock, what cam/head combo will give me some good street punch? I do not plan on any strip use...for now. just want to wipe the smiles of these damn rice rockets running around base! i have a dual plane performer intake and will be changing my 600cfm double pump to match the cam/heads. I would like to keep my budget around $2500-$3000 tops.
As mentioned i am also looking to change the torque converter to one best suited to the final engine build. Currently running 3.55 sure grip, dont want to change that if i can help it.
Click to expand...

How do you know the cam in it isn't a good one?
 
Only info I have is that its a "mild purple cam" according to previous owner. I will dig into it this weekend, just curious about types of build ups I could go with.
 
Well if you measured it, you'd have more info.
 
Find out some more about the cam before you start to determine what kind of converter you want to buy...but buy a good one the first time suited to your needs. Off the cuff, I'd venture a mild purple cam in a 383 should benefit from about 2500 worth of stall, but keep in mind, the engine's powerband (torque) will play a role in where the converter actually stalls, and how high it will flash.

All that being said, if you're planning on tossing on a set of aluminum heads, I'd recommend you let one of the gurus on here go through them before just bolting them on...several folks on here have had issues out of the box with guides too tight, inconsistent spring installed heights, leaky seats, etc.

Also consider some chassis/suspension mods...having power is nearly worthless (except for demonstration) without being able to put it to the pavement.
 
abdywgn said:
if you measure at the valve, hasn't the rocker arm already multiplied the lift by 1.5?
Click to expand...

Yes, I was thinking pull the rockers off but then the valve doesnt open. This is why I dont build motors LOL
 
It's usually easier for the DIYer to measure with a dial indicator at the retainer. In order to get an accurate reading at the lobe, you need an adapter that fits into the lifter bore and holds the dial indicator directly on the lobe. Not everyone has one. Hell, I don't even have one. Once you get the lift at the retainer, you can divide by whatever the rocker ratio is to get the approximate lobe lift. So if you come up with a lobe lift of say, .495 and your rocker ratio is 1.5 then .495 divided by 1.5 is .330 lobe lift.
 
...not to muddy the waters here, but aren't we taking a pretty big leap assuming the rocker ratio to be accurate 1.5?
 
txstang84 said:
...not to muddy the waters here, but aren't we taking a pretty big leap assuming the rocker ratio to be accurate 1.5?
Click to expand...

I didn't assume anything. I was giving an example.
 
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