1970 300 Hurst motor.

Mopar001

Mopar001

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Getting ready to get the 440 rebuilt. (35-85lbs of compression) Thinking about a mild cam, just enough that you can hear it. Here is my question, what size should I go back with? Which is the best brand to go with? So many out there to choose from. Everything else will be stock. Might, MIGHT go back with headers...
 
I find that the stock 440 TNT specs work best on these big cars. Headers would be a mistake (traps the starter, don't seal, burns wires, rust out etc.)
 
I would have to agree with Mr C on this one for sure but its your car so do what you want with it. The stock size cam in these 440s works very nicely with the stock valves and exhaust manifolds, they sound like no other big block and they provide good vacuum to stop these heavy cars. Chrysler engineers knew just what they were doing.
And gas ain't 25 cents a gallon anymore.
 
Mopar001 said:
how about one step up from stock cam? you know, just to let it breath a little more...
Click to expand...
Assuming you have the non-TNT 350hp motor, I would say too the next step up would be the TNT cam/profile....yea you will find headers to be a bad thing when it comes to the starter motor....unless you dump the stock starter for a mini. Still headers can be a PITA insofar as leak issues are concerned (never fit exactly right). Score a set of the factory HI-Po logs.....worth their weight in gold.
 
I did upgrade the cam in my Imp from the stock 350 horse to something more resembling the HP version of the year as well as putting bigger exhaust valves in. Since he's talking about the 440 from the 300 Hurst I am assuming its already an HP unit.
 
Yea, forgot the "HURST" name. That's a 375 hp motor right of the back. Maybe it might be easier if you decide how much HP you want to make above the 375 your current engine makes in stock form. That should make it easier to pick a cam. Cam vendors?....dozens to choose from. It's my understanding however there are only a few who grind cams that are uniquely designed for Chrysler engines.
 
I have to agree with the above, you could go up to the mopar performance P4452993 which is basically a "hemi" grind with a wedge pattern, will have a bigger lope at idle. stay with hp exhaust manifolds unless you are going really big on cam no real gain. the exhaust system and carburetor are you best gains. I think you car would have had afb or avs stock both are only 625 cfm I would put a 750 performer or thunder, I would use the thunder series easier to set up secondary, you can use a holley but not as mpg friendly out of box. BTW if it did have holley stock it is also small the smaller carbs are fine I'm just giving options. the exhaust is a big improvement since it has probably been changed already and usually not done right. needs to be 2 1/4 minimum 2 1/2 better also add a x after trans crossmember this will help breathing and mpg. DO NOT FALL FOR the statement that a small diameter exhaust will give you more torque this is a muffler shops lazy cop out to use smaller pipes and make their life easier, leave that shop immediately and tell your friends not to go there either. I think TTI has some pipes for your car a little pricey but high quality stuff.
 
I did both Holley and Carter on a 440. Both had distinct characteristics. The Holley was an animal, made the motor run like a raped ape, (I think it had mechanical secondaries, can't remember). BUT for some reason it was very temperamental on warm humid and/or rainy days. Just didn't seem to run right to me...finally it started leaked. It was old so I chucked it, was not interested in rebuilding the damn thing. Got an E-brock AFB carb. I think it was about the same CFM. Ran nicely, but not like the Holley...however, it wasn't finicky like the Holley either. I dunno some people have had better luck with Holleys, some swear by the E-brocks. Its a toss up.
 
If it iz a Hurst it came with an AVS Carter carborater. AVS4147S to be specific. It also came with hi-rise cast iron exhaust that is hard to improve on with any headerz as all ready stated and dual exhaust came without any cross over. All 485 of 'um produced were spected with 323 gear and on the Proving Groundz Oval in the summer of '85 Five of 'um topped out at 138 MPH. How fast you wanna go, or do yeah have ah fondness for small roomz with no view and heavy finez?
 
I think your right Jer most states 30+ will reserve your room at the graybar. Still one of my fondest memories was watching my buddies needle disappear UP into the dash in a fusey 300
 
Building a 440 to 1969 375 hp specs is the best, most reliable, and cost efficient way to build one of these.
The pieces practically fall into place, cost chump change, and will give you another 100,000 miles without breaking a sweat.
Other than spark plugs, you will never touch another thing again.
 
Yah I wish I would have put the 383/440 hp cam in my challenger would have saved a lot of extra tuning time for about the same results.
 
Good advise here. Stick with the 69 375 HP grind cam from Mopar performance, (beware of aftermarket cams), Your torque convertor may not agree with a more agressive grind.

A three angle valve grind and hemi springs are a nice upgrade also.
I installed an Edlebrock 1407 carb and it really woke the engine up, reliable and economical, (as economical as a 440 can be anyways),

Hp manifolds, an "H" pipe and a pair of stainless Borla's ...... you'll have a well balanced package.
 
bluefury361 said:
Good advise here. Stick with the 69 375 HP grind cam from Mopar performance, (beware of aftermarket cams), Your torque convertor may not agree with a more agressive grind.

A three angle valve grind and hemi springs are a nice upgrade also.
I installed an Edlebrock 1407 carb and it really woke the engine up, reliable and economical, (as economical as a 440 can be anyways),

Hp manifolds, an "H" pipe and a pair of stainless Borla's ...... you'll have a well balanced package.
Click to expand...

Just curious, what does the "H" pipe actually do for performance over straight dual exhaust?
 
Also when having heads done I would upgrade to a set of one piece stainless steel valves cheap insurance and the backside already has the lip machined away to improve flow, win, win after all the originals are 40+ years old
 
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