Max RPM with stock cam 383?

[SomeCarGuy]

After the carb swap, I now feel like I can really rev the 383. I remember from years ago the MP books saying the bottom end would do 6200. I don't think the stock HP cam will get anywhere near that.

I let it go to only 5K on the test runs, but I'm already day dreaming about the spring and really letting it go. The AVS just didn't like to pull over 5200, but of course it was much smaller, 650 or less compared to a 750 now.

5200 may be all it has in it since the valvetrain is 40 years old. New chain.

 

[mcmopar]

Your valve springs will be the limiting factor at this point. A new set of Hemi springs would probalby get you 5500-5700 on a factory cam, maybe.

 

[SomeCarGuy]

The Mark 8 in the back ground turns 6K with ease, has 4 valves that open up after 3500 RPM!

 

[SomeCarGuy]

I do have a set of the springs that come on Eddie RPM heads, were taken off and boxed when brand new.

Maybe I will look at that.

If I do a spring swap, I might as well change cams. Hmm

Maybe should just drop in the 440 if that is the route. I have a decent 71 model with a new Com Stick. Not a XE, but close to HP grind, new chain. Could do a spring swap on it and then swap it out.

But that would take some effort, driving what I have is as easy as turning the key.

 

[mcmopar]

Yeah - I hear ya. I hate it when I start planning something because it always leads to something else - which in turn leads to something else, etc., etc. It's called the "Snowball Effect." I'm planning on a cam swap sometime in the spring. The question is: do I want to just remove the timing cover and mess up the gasket at the bottom of the cover (I have the windage tray with gaskets above and below) and then repair it with Ultra Blue RTV silicon gasket material?
-or-
Do I want to remove the oil pan at the same time I do the cam swap so I can replace the oil pan gaskets and inspect/clean out the oil pan if necessary? In that case can I come up with enough cash to splurge for a 7 quart pan and 3/8" pickup?

The questions hurt my head! I'll probably only have the means to just swap the cam and lifters, water pump housing gasket and timing cover gasket and then fix the gasket on the oil pan with Ultra RTV Blue. I just don't want an oil leak under the timing cover. I HATE oil leaks... :brickwall: :brickwall: :brickwall:

 

[droptop]

I agree, your valve train will be your rev limiter.

 

[SomeCarGuy]

I guess the follow up is what RPM did they turn new?

If it was 5500, I would think that 5200 from tired springs is about right. If it was more like 5800+, then things must be really bad and I had better plan on diving in before I munch the engine playing around.

 

[moparchris]

Rev it till it quits making power, usually around 5500. My rustyrunner would wind that all day with 117K on it.

 

[sixgunrunner68]

Rev it till it quits making power.
x2 :yesnod:

 

[generaljmwlee]

Rev it till it quits making power.
x2 :yesnod:

and hope it dosent quit making power by going BOOM!! LOL :drive:

 

[zupanj]

I just checked the dyno sheet when I had a 383 in my RR. It maxed out at about 5000-5200 with a "509" cam, a 750 cfm carb and electronic ignition. I was not happy with this engine mainly due to low compression and a long duration cam. That's a bad combination.
I don't think carbs buy you much except at the top of the power band. I had a 351 ci Cobra that had a 750 Holley that ran good when the rpms were up but was a little soggy under normal driving. I put a 650 Holley on the car and it was much nicer to drive on the street. I never dynoed that car but I don't think that change cost much on the top end.

 

[Basketcase]

I just don't want an oil leak under the timing cover. I HATE oil leaks... :brickwall: :brickwall: :brickwall:

that reminds me........ :huh:

 

[mcmopar]

I just checked the dyno sheet when I had a 383 in my RR. It maxed out at about 5000-5200 with a "509" cam, a 750 cfm carb and electronic ignition. I was not happy with this engine mainly due to low compression and a long duration cam. That's a bad combination.
I don't think carbs buy you much except at the top of the power band. I had a 351 ci Cobra that had a 750 Holley that ran good when the rpms were up but was a little soggy under normal driving. I put a 650 Holley on the car and it was much nicer to drive on the street. I never dynoed that car but I don't think that change cost much on the top end.

The reason the 650 worked better than the 750 was probably due to air flow velocity. The 750, being too large for the engine, caused a drop in velocity while the 650 actually had a higher velocity due to the restriction in size. Depending on the carb used you can pick up some usable horsepower. The stock 383 Carter AVS was notorious for being on the small size. I once read that actual flow through that carb was somewhere in the range of only about 450 cfm even though it was rated at 600 cfm. A Holley 600-650 will wake up a stock 383 and a 750 is good for the 440. The 750 can be used on a 383 but some mods are recommended (cam, intake, compression, headers & stall converter if automatic). I once used a 600 Holley single feed carb on my mild 440 I put in my 1st road runner. It had a TRW "non-high performance" cam in it (350hp rating) and an Edelbrock Torker intake with stock exhaust manifolds and 2-1/4" piping. The Holley/Torker combo picked up .6 et in the 1/8 mile over my tired old 383 (with over 100,000 miles on it) which it replaced and also picked up 2-3 mpg in town over the 440 cast iron intake/383 AVS carb combo.

 

[moparchris]

Even my stock 7 to 1 small block 360 picked up 25hp and 20 ft lbs torque when I went from a 650 to a 750 dp holley. I think that horse has been beat to death in all the dyno work you see in the magazines. Basic rule of thumb is if it makes more than 300hp it will make more power with a 750. Another thing to remember is that Holley rates cfm differently than Carter/Weber/Edelbrock (@5 inches). Holley also rates its 2 barrels (@ 5 inches) different than the four barrels (@ 3.5 inches). This is why some say a six pack is really only worth 950cfm in holley four barrel terms. A 750 Edelbrock is really more comparable to a 650 Holley.

 

[SomeCarGuy]

The 3310 has part throttle power like the 750 Eddy that came with the had when I first got the 383 going. Had a 440 before.

750 just really suck though and I was better off with the small 440 AVS that I had to replace it. The small 440 AVS is the same as the 383 HP AVS. A 440 HP AVS would have been much better than a nonHP 440 AVS. So the 3310 is the best deal going.

These carbs generally rock, but I will be eager to see if I still get 15-16 MPG.