biggest cam?!

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dartkid68

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whats the biggest cam you can run on a low comp small block 340? with x 202 heads?
 
Are you planning on a spring change or just a slide in replacement?
 
i was looking into the mopar purple cams so i guess if springs are needed i would install them, looking for the most lope with best drivabilty its also a 4 speed
 
Lope comes from duration and overlap. Lift is limited by stock springs and the valve guide height. Most heads can handle the .509 lift without mods but you always need to check. There are several cams designed for that sound you are looking for without sacrificing power. The Thumper series comes to mind. I hope some of the guys that are using them will chime in or post a vid link.
 
This is my 75 Dart 4 speed car with a 292 / 465 hydraulic that was "on sale" from PAW I think a few years ago. I bought it just for the sound but runs pretty decent in a 325 CID with about 9:1 compression. Sorry about the wind noise....

[ame="https://www.youtube.com/watch?v=9MbTXrOsvps"]75 Dodge Dart start up & idle - YouTube[/ame]
 
Whiplash camshafts from hughes. They are designed to run in low compression street engines and dont require valve guide cutting.
 
Springs will "be needed" with any camshaft you choose.
 
RustyRatRod said:
Springs will "be needed" with any camshaft you choose.
Click to expand...

Although always a good idea, the key word here is "ANY". Cheater cams for claimer engines, special regrinds to measure as "stock" and other cams with little tweaks to either move the power band or get the sound you are looking for may not exceed the limits of the factory 340 springs. I'm not sure of the lift limit on yours but probably not much over 0.450... If you plan on winding it up get the springs.
 
stock mopar heads flow stall around .485 lift
gear and converter have an effect as well as duration
lo compression...i would keep the duration low
 
You can easily put a purple performance 462 lift 284 duration. it would be a total waste of time and money to put new Springs in though. The 4 speed will let you use a longer duration with no problems and it will have a great sound.
 
dartkid68 said:
i was looking into the mopar purple cams so i guess if springs are needed i would install them, looking for the most lope with best drivabilty its also a 4 speed
Click to expand...

Personally, I wouldn't risk throwing a new stick in without matching the springs to the cam, but that's me.

Piston to valve contact ain't pretty. If you plan on some higher RPM romps, change them.
 
mguner said:
Although always a good idea, the key word here is "ANY". Cheater cams for claimer engines, special regrinds to measure as "stock" and other cams with little tweaks to either move the power band or get the sound you are looking for may not exceed the limits of the factory 340 springs. I'm not sure of the lift limit on yours but probably not much over 0.450... If you plan on winding it up get the springs.
Click to expand...

Ok.
 
Springs lose pressure after a lot of miles. I would definitely get the recommended springs. Checked some 440 hp springs with high miles seat pressure was down to 50 lbs
 
For a low compression engine, I would go with less overlap (more lobe centerline) to keep cylinder pressures up.
 
All 4 of the stock 340s I've had, including the nearly new 70 Swinger 340, I bought in the fall of 1970, suffered from premature valve float with oem springs.One went flat as early as 5500.

I'd leave the stock cam in there, and put springs on instead. And headers if you dont already have them. Then wind it up til she blows. Then, finally, you wil have a have a good excuse for a stroker kit.
 
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