Camshafts and clearance

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1 Bad Duster

Pro Street Duster
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I have looked on this site and I haven't found what I'am looking for. I'am woundering whats the biggest camshaft I can go with.without worrying about valve/piston slap. I would like to go with the biggest camshaft I can without worrying about clearance problems..I would like to go bigger than the 508/509 camshaft..Thanks Jimmy..
 
Can't say without knowing everything about your engine build. Reason is if it has stock low compression pistons and the deck and heads haven't been shaved it'll take a whole bunch of lift (possibly .750 or more) before the valves hit the pistons. If you have dome pistons and the deck has been milled and the heads shaved it may only take .550 lift.

One other thing to keep in mind is how much retainer to valve guide clearance you have. Stock heads don't usually allow for much more than .500 lift (some even less) before the retainer slaps the guide. The guides need to be cut down and PC seals used to allow a lot of valve clearance.
 
Its a 73 340 I believe it has stock crank,rods, and it has flat top pistons.. It has a air gap intake with spacer with 750-850 carb 202/160 915 heads, Next winter I'am getting a 416 stroker kit. I dont want to buy another camshaft. I'am gonna be using 1.5 rollor rockers..
 
I'm sue this is not what you want to hear but it is honest...
You'll have to buy another camshaft for the longer stroke and for what you have for a lower end it's already over cammed and over carbureted.
 
moper said:
I'm sue this is not what you want to hear but it is honest...
You'll have to buy another camshaft for the longer stroke and for what you have for a lower end it's already over cammed and over carbureted.
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The motor is in my shed is a long block,almost ready to be put in the car and I want to put a new camshaft in it for I know what I have instade of thinking whats in the motor. I got the single plane air gap intake for it and 202/160 915 heads. I was thinking about going 750-850 carb. The motor came out a duster that that they said it ran 7.40s but who knows I didn't see it.The motor was in a Ram charger with stock 355 gears and 40 grounds hawks and the motor turned them like it wasn't nothing.

So the motor might be 30 over with aftermarket pistons and rods. I havent had it apart yet. But its coming I'am doing new rod/main bearings..So what cam would you go with. the 508/509 hyd.
 
1 Bad Duster said:
The motor is in my shed is a long block,almost ready to be put in the car and I want to put a new camshaft in it for I know what I have instade of thinking whats in the motor. I got the single plane air gap intake for it and 202/160 915 heads. I was thinking about going 750-850 carb. The motor came out a duster that that they said it ran 7.40s but who knows I didn't see it.The motor was in a Ram charger with stock 355 gears and 40 grounds hawks and the motor turned them like it wasn't nothing.

So the motor might be 30 over with aftermarket pistons and rods. I havent had it apart yet. But its coming I'am doing new rod/main bearings..So what cam would you go with. the 508/509 hyd.
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the air-gap is a dual plane intake.pull the cam out and see whats stamped on it if anything.
 
I think before you get centered on anything you see what you have there. No sense in giving up power if you can run a bigger cam, or losing steam by mismatching. Pull a head and see what's in there. Also, I'd inspect the bearings. If they are bad, turn the crank too. If they aren't leave them alone. Changing just bearings could be asking for headaches.
 
bad440 said:
the air-gap is a dual plane intake.pull the cam out and see whats stamped on it if anything.
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Is the air gap a good intake. Ok I will see whats on the cam.

moper said:
I think before you get centered on anything you see what you have there. No sense in giving up power if you can run a bigger cam, or losing steam by mismatching. Pull a head and see what's in there. Also, I'd inspect the bearings. If they are bad, turn the crank too. If they aren't leave them alone. Changing just bearings could be asking for headaches.
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Ya I will see what I have when I start pulling it apart. Ya I'am gonna look at the bearing, I though new bearing would be good instade of leaving the one on it. I'am gonna find out if its 30 over also.
 
Lift is certainly very important to consider, but the duration is the number you really need to be careful with. It's not necessarily how far you open the valves, but how long they stay open. With factory flat tops with no valve reliefs, you can leave the lift stock and you'll have problems with inerference probably around 240 degrees duration @.050", possibly less. Even though the piston is in the hole at TDC, you're not talking more than .150". The valves open on the order of around .400" on a stock engine. Stretching the duration out even with a mild lift with no valve reliefs and you're asking for trouble. Wanna run a large by huge cam that's horribly mismatched for your application? Go for it. But just know you'll need to have valve reliefs cut into the pistons to make it happen unless you go with a different piston. And if you do that, you may as well make the entire engine package match. It will run much better in the long haul.
 
StrokerScamp said:
Lift is certainly very important to consider, but the duration is the number you really need to be careful with. It's not necessarily how far you open the valves, but how long they stay open. With factory flat tops with no valve reliefs, you can leave the lift stock and you'll have problems with inerference probably around 240 degrees duration @.050", possibly less. Even though the piston is in the hole at TDC, you're not talking more than .150". The valves open on the order of around .400" on a stock engine. Stretching the duration out even with a mild lift with no valve reliefs and you're asking for trouble. Wanna run a large by huge cam that's horribly mismatched for your application? Go for it. But just know you'll need to have valve reliefs cut into the pistons to make it happen unless you go with a different piston. And if you do that, you may as well make the entire engine package match. It will run much better in the long haul.
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Thanks for the info. When I take the heads off to put my 915 heads on. The piston are flat tops with valve reliefs then they are after market pistons right.a 30 over 340 is 4.07 bore right. Iam gonna find that out to if its 30 over. It would be nice if its 30 over and after market pistons already..But it has to have some stuff done to it to run 7s on motor in the 1/8 in a duster street car. I know when I bought the ram charger. I heard it run and it sounded like like it has a healthy cam in it it loped nicely. I bought it just for the motor because it was a 340. I paid 150 for the whole ram charger..
 
Try the new Comp Cams XE series, they work very well.
Here is an XE275XL in my 360.

[ame="http://www.youtube.com/watch?v=DbaR0CuWG4g"]YouTube - Dart Sport 360 XE275XL Comp Cams Idle[/ame]
 
Do you have a valve spring compressor?

You need to get some "checking springs" and install them on a intake and exhaust valves.

We all can guess at how much lift you can use but it's only a GUESS!

and when you guess or ASSuME, The Eng can go BOOOM!

Checking spring and a dial indicator will answer retainer to head and Valve to Piston.

My 340 was a little shy on the valve to piston clearance(.474 lift) do to the valve relief having a ledge. Did a little trimming and i could get .500 lift(where the retainer hit the valve!) With a .474 lift cam, it was good enough.

checking spring are not that much money, well worth the investment!!!!!
 
Sport 360 said:
Try the new Comp Cams XE series, they work very well.
Here is an XE275XL in my 360.

YouTube - Dart Sport 360 XE275XL Comp Cams Idle
Click to expand...

right now I dont have any sound coming from my speakers. the sound from my sound card got deleted some how..Wish I new how to get my sound back..

Cudafever said:
Do you have a valve spring compressor?

You need to get some "checking springs" and install them on a intake and exhaust valves.

We all can guess at how much lift you can use but it's only a GUESS!

and when you guess or ASSuME, The Eng can go BOOOM!

Checking spring and a dial indicator will answer retainer to head and Valve to Piston.

My 340 was a little shy on the valve to piston clearance(.474 lift) do to the valve relief having a ledge. Did a little trimming and i could get .500 lift(where the retainer hit the valve!) With a .474 lift cam, it was good enough.

checking spring are not that much money, well worth the investment!!!!!
Click to expand...

No I don't have one but my buddy has the tool to check the valve springs, What ever cam I get I'am gonna buy the correct valve spring for the cam I get.. I have a parts list wrote down Cam/lifter kit and the correct valve springs/retainers and cam valve locks..
 
1 Bad Duster said:
right now I dont have any sound coming from my speakers. the sound from my sound card got deleted some how..Wish I new how to get my sound back..



No I don't have one but my buddy has the tool to check the valve springs, What ever cam I get I'am gonna buy the correct valve spring for the cam I get.. I have a parts list wrote down Cam/lifter kit and the correct valve springs/retainers and cam valve locks..
Click to expand...

I'm talking about the tool that removes the valve spring(valve spring compressor) so you can install a Light spring.........
these are not for the eng, there for You! A spring that is so light that you can push the valve down with one Finger...........................
 
Cudafever said:
I'm talking about the tool that removes the valve spring(valve spring compressor) so you can install a Light spring.........
these are not for the eng, there for You! A spring that is so light that you can push the valve down with one Finger...........................
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My buddy has the tool to remove valve springs. I don't have a spring to push the valve down with one finger. I looked at the valve springs on the 915s i'am gonna put on the 340 and they have double springs on them already..I don't think mopar put double spring on a head from the factory..
 
Buy the cam next winter when you build your stroker. If you put in a cam for your future stroker, in the engine you have now you will probably be slower and get worse gas milage.

On top of that you run the risk needing a different cam during the stroker build.

I admit it is a bit hard to follow your thread but what i'm getting out of it is a bunch of pointless money spending that will make your car slower for a year.


Can't stress this enough…… When you over carb and over cam you go slower and use more gas. A horrible combination.
 
1 Bad Duster said:
But it has to have some stuff done to it to run 7s on motor in the 1/8 in a duster street car. I know when I bought the ram charger. I heard it run and it sounded like like it has a healthy cam in it it loped nicely. I bought it just for the motor because it was a 340. I paid 150 for the whole ram charger..
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Ok, if it already has a healthy sounding cam in it now and it ran 7's in the Duster what do you think you can accomplish? Sounds like it must be built pretty well now. If you want it to sound like a top fuel dragster go ahead but most likely, like others have already pointed out, you'll just slow it down and waste money doing so. If your plans are to build a stroker why not save the money and use it to make the stroker a killer engine?
 
1968FormulaS340 said:
Buy the cam next winter when you build your stroker. If you put in a cam for your future stroker, in the engine you have now you will probably be slower and get worse gas milage.

On top of that you run the risk needing a different cam during the stroker build.

I admit it is a bit hard to follow your thread but what i'm getting out of it is a bunch of pointless money spending that will make your car slower for a year.


Can't stress this enough…… When you over carb and over cam you go slower and use more gas. A horrible combination.
Click to expand...

I haven't got a carb yet so I thought a 750 would be fine. I haven't bought a cam yet eaither. I want a nice lope and sounding car with the super 44 flow masters..Its gonna be a trailer queen most of the time.But Its gonna be driven on the street.. I have 456 gears and I'am gonna use a 3600-4200 stall..

green1 said:
Is the piston domed? about .017 out of the hole? That is a factory piston.
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I will have to find this out when I take the heads off to put my 915s on..

fishy68 said:
Ok, if it already has a healthy sounding cam in it now and it ran 7's in the Duster what do you think you can accomplish? Sounds like it must be built pretty well now. If you want it to sound like a top fuel dragster go ahead but most likely, like others have already pointed out, you'll just slow it down and waste money doing so. If your plans are to build a stroker why not save the money and use it to make the stroker a killer engine?
Click to expand...

From what I can remember it sounded great with a nice lope. I'am going by hear say about it running 7s in a duster. But I did see it in action in the mud with stock 355 gears and 40s. I want it to have a nice lope to it when I cruise around town..
 
Anything sounds good with flowmasters (to me anyway) and a high stall convertor..lol. See what you have, take and post a pic if you can of the piston at TDC when you have the heads off.
 
moper said:
Anything sounds good with flowmasters (to me anyway) and a high stall convertor..lol. See what you have, take and post a pic if you can of the piston at TDC when you have the heads off.
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Ok sure will with the 456 gear and 3600-4200 stall it should have the low end take off that I'am looking for..
 
My goal is to be in the 7s in the 1/8th.. I'am running a 28x12.50x15 M/T E/T streets on 15x10 weld drag lites. But I have a set of 315x60x15 M/T E/T Drag Radials might be going on it..They are like a 29-29.5x12.4x`15..

I have read from 4/11/72 after 340s are externial balanced I have a 73 so Don't I to find a stall converter with the weight on it like for a 360..
 
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