Updating a 1967 383

[Guest schlot]

Can anyone give me some insight into the existing cam specs on the 383 2-barrel engine in our 1967 Newport.

I understand it's a 270 hp motor. I'm looking at keeping the look of the car stock. I will be rebuilding the Carter (?) carburetor this winter and would like to update the camshaft a bit. Would anyone suggest a Comp Cam for me. I was looking at low end torque with some possible towing in it's future. Maybe a Comp Cam 260? or 268?

Any help would be appreciated on existing cam, carb or future cams. Thanks!

[keiser31]

A lot of guys with MoPar muscle cars use "The Purple Shaft" camshaft. I used one in my 1968 Dart 383 4-barrel engine. Cannot remember the specs. I have a book with hop-up guides for MoPar engines and if you email me I can scan some pages about camshafts for you. John at "keiser31@charter.net".

[Guest schlot]

Super! I will sendnyou an email...it's a yahoo.com account.

I've had a blast with this car. Hadn't been running for two years and ran rough at best.

Swapped out the fuel pump, added fluids, flushed the tranny and did spark plugs, cap and rotor. Now she starts, shifts and drives great.

Body is super straight and it's all original. We take it out for weekend drives and hope to go to our first car show next month.

[bigaadams]

you may also read and check profiles of cams for this engine at Summit Racing, nice convienent online catalog..do not overlook the summit brand cam as it is an excellent value..just do not make the mistake most builder do and use too stiff of springs that will have too much tensionon the lobes and lifter faces that will cause galling ad breakdown during breakin..if you wish to go with higher rate springs, break in with stock springs first..then change to the higher rate...unless you intend on pulling substained high RPMs there is little advantage for the stiffer springs...if you can get your hands on some molybyendium disulfide power and mix your own break in paste..I would recommend it..

Edited July 25, 2010 by bigaadams (see edit history)

[Rusty_OToole]

With a stock 2 barrel carb engine the stock cam is all you need. Or possibly an RV cam.

Stay away from any purple shaft, or high performance cam. They will give you less power than you have now. Performance cams take power away from the low and midrange to add to the top end. With a 2 barrel carb single exhaust and stock engine you have no top end. So the cam will kill the bottom end and the engine will kill the top end, both kill each other and you have nothing left.

An RV cam made for an otherwise stock engine may give a little more oomph. Other than that the stock cam is best. The engineers who designed your car knew more about picking cams than both of us put together.

[Guest Big_John]

The stock cam is a good recommendation. An alternative is the stock cam for a 68-70 Roadrunner. In this case, less is more.

[Rusty_OToole]

The stock cam for a 68-70 Roadrunner (base 383 4 barrel engine) is actually the cam for a hi perf 440. It was specified for the Roadrunner as much for the lopy idle as for performance.

This is an excellent example of a cam that will give LESS horsepower in a stock 2 barrel 383.

Believe me when I tell you 2 things 1) to get that big whale moving you need high torque NOT developed horsepower 2) compared to today's engines, if you get the 383 running EXACTLY as it did in 1967 with NO changes, it will feel like a Rolls with a jet engine no kidding.

Do not let the "low" 270HP fool you. The large displacement and accompanying high torque will really get the old car moving. Anything you do to increase horsepower will pay off only at speed over 80MPH and most likely kill everyday performance.

The best performance improvement would be from and RV cam, 3 angle valve job, dual exhaust and 4 barrel carb on a stock manifold which was an available option that year. But if it was my car I would rebuild it stock and let it go at that.

Find out how it performs in stock form. I'll bet it has more power than you need. If you are still not satisfied the 4 barrel carb,dual exhausts and RV cam are simple bolt on extras that can be added later.

[keiser31]

I agree with Rusty...I missed the "2 barrel" part of your first post. The camshaft I used was strictly for a 4 barrel. I would go stock. My dad brought home many 383 2 barrel cars when I grew up and they all flew like the wind.

[Guest Big_John]

The stock cam for a 68-70 Roadrunner (base 383 4 barrel engine) is actually the cam for a hi perf 440. It was specified for the Roadrunner as much for the lopy idle as for performance.

This is an excellent example of a cam that will give LESS horsepower in a stock 2 barrel 383.

Believe me when I tell you 2 things 1) to get that big whale moving you need high torque NOT developed horsepower 2) compared to today's engines, if you get the 383 running EXACTLY as it did in 1967 with NO changes, it will feel like a Rolls with a jet engine no kidding.

Do not let the "low" 270HP fool you. The large displacement and accompanying high torque will really get the old car moving. Anything you do to increase horsepower will pay off only at speed over 80MPH and most likely kill everyday performance.

The best performance improvement would be from and RV cam, 3 angle valve job, dual exhaust and 4 barrel carb on a stock manifold which was an available option that year. But if it was my car I would rebuild it stock and let it go at that.

Find out how it performs in stock form. I'll bet it has more power than you need. If you are still not satisfied the 4 barrel carb,dual exhausts and RV cam are simple bolt on extras that can be added later.

I also missed the 2bbl part of the post or I would not have mentioned the Roadrunner cam.

That said, I have used that cam in a number of engines with excellent results, including towing loaded car trailers. While it is not the cam of choice for this vehicle, it is a good all around performance cam that idles well and does everything its supposed to. Depending on the car, installing the cam two or three degrees advanced will give you plenty of low end torque.

[Guest schlot]

Lots of good info. I was thinking the Comp Cam 260 because I threw that in a 351M and kept the two barrel and it really improved torque. Being a Ford man, I wasn't sure how the Comp Cams did with the Mopar.

I determined that the carb is a Stromberg WWC. Doesn't anyone know what kind of CFM that flows?

[Rusty_OToole]

If you just can't live without an aftermarket cam in your otherwise stock 2 barrel motor, phone the cam manufacturer's help line and go by their recommendation.

To me it's like putting a jockey in pink silks on the back of a Budweiser Clydesdale but to each his own.

[Guest schlot]

LOL. Funny. Every car I've had I've modified it. So I'm trying to keep that tendency in reign. I figure if I do the cam, modify the heads and mainfolds (port match) that it will quench that tendency and still keep it stock looking.

[Guest schlot]

Been digging into info about the WWC. Aparently Stromberg never documented CFM - does that sound correct?

[Guest Big_John]

If you do find the CFM for the 2bbl, keep in mind that 2bbl carbs and 4bbl carbs are tested for flow at different test pressure. The 2bbl are tested at 3.0 in/hg (inches of mercury) while 4bbl carbs are tested at 1.5 in/hg pressure drop.

You can do a little math so you are comparing apples to apples. Divide the 2bbl cfm by 1.414 to give you what the rating is compared to a 4bbl.

Edited August 5, 2010 by Big_John
switched the ratings (see edit history)

[Guest schlot]

Ok...have to ask. Why would they tested at a different pressure?

[Guest Big_John]

Ok...have to ask. Why would they tested at a different pressure?

In the fifties, the SAE engineers realized that a engine with a 4bbl carb will not pull 3.0 in/hg at wide open throttle. The 2bbl rating wasn't changed.

[Guest schlot]

Interesting...since we are talking technical numbers...can anyone tell me why with cams, a key number is the duration at 0.050"? I understand the other numbers fairly well, but why is this something that is measured? Why not 0.10" or some other lift?

Thanks....still searching for that CFM rating...beginning to think it's not out there.

[Rusty_OToole]

I guess they had to standardize on some measurement and .050 eliminates any confusion due to clearance ramps. Different cams have different valve clearance, from 0 with hydraulics to as much as .024 in a slant six truck engine, possibly more but that is the widest I recall off hand.

So .050 is wide enough that clearance or valve adjustment specs don't matter. Of course that .050 clearance is strictly for measurement purposes, you would not run the engine like that.