vegascarnut

Hi everyone,

Don't shoot, I'm a Ford guy...ouch! That hurt. I've been a long time member of the Vintage Mustang Forums, and don't know what I'd do without it! We're making progress tuning this car, but since I'm more of a 302/351 guy than a 383 guy, I feel it's time to get some informed opinions.

Ok, so my friend has a '67 Charger with a 8,000 mile 383 rebuild, running a "mystery" purple cam. It has never liked to idle in gear, but runs like a raped ape otherwise.

Car Specs
383 big block
Mopar Purple Cam of unknown spec
Carter AFB Performance 650, also rebuilt
Stock Intake Manifold
Stock Heads
Stock Exhaust Manifolds
Stock distributor with the electronic pickup
Power Brakes
727 Torqueflight, rebuilt with stock converter
Appx 3.90 rear gears by my calculations of RPM/Tire Size/Speed

Where we are with tuning:

No Vacuum Leaks

Initial Timing
We have tried it all over, but it prefers about 35 initial. That puts us way over on total right now, because of the mechanical advance. Seems that a lot of people running various purple cams lock out their timing, and that is probably going to be my next step unless we have a revelation here.

Tuned Carb with all vac lines plugged, and tuned with a vac gauge to get max vac in idle.

Vacuum
Vac 10 at 1250 in park, but it dies when we put it in gear
Vac 13 at 1700 in park
Vac 6 at 1000 in gear (700 rpm drop seems huge to me)

It runs now, idles, but what bothers me is the RPM drop from Park to Drive. 700 just seems enormous to me. If that is normal, I'm just going to lock out the distributor between 34 and 38 and be done.

Here's a link to some photos so you can see what he's got, and we will sure appreciate ANY advice we can get.

https://www.dropbox.com/sh/x1p5kiveb...PM_Gwc5da?dl=0

Thanks so much Mopar fans!

Coronet 500

Hot rod guys working on V8's together is great regardless of brand.

Any Purple Saft cam was it in it's day (40 yrs ago) the one to have and every member here has probably run one and would probably agree with me when I say, compared to today's modern cam technology they are JUNK.

The issue along with poor cam design below 3500rpm is based on timing, vacuum and rpm drop I'll bet the cam was not degreed in and is probably WAY off.

Taking the time to diagnose cam timing is a waste. That engine has the compression, heads, manifold, carb and ignition so that with a say 440hp cam or proper modern cam it should have high vacuum, purr like a kitten and ROAST the tires with a touch of the gas pedal.

That engine is being wasted and possibly harmed with cylinder wash by that cam.

Oh, I back halved and added a 351w to my son's '88 Mustang sitting in my garage right now.

RacerHog

Hello Sean,

My 2 cents is this...... I agree with Coronet 500 mostly..

Use the carb for a wheel calk and replace it with a holley 750 vac with electric choke.....
Install a VooDoo Cam & Springs... Hyd is ok..... But use something closer to the converter he is using... If your not looking at changing it....

Bottom line.... Not enough compression.... Not enough converter.... Not enough carb... and that cam is probably for like a 4 speed car or high stall converter....

Too Of my Ford Buddys....
"It's not over till the fat lady's sing"

Keep us posted...

Rooty

You really need to get away from the stock stuff if you want to light up that 383. It needs to breath and do it in a modern way. Running a VooDoo valve trane mated to Edlebrock aluminum heads and intake with TTI exhaust and FireCore distributor I'm making about 430 HP at 3200 rpm. The EFI throttle body guarantees no wash in the cylinders ( it would run way rich with carbs) and I run an advance of 16 static, 31 all in. Yes it was an expensive journey but the results were worth every penny.

vegascarnut

Well, I know he's using oldschool parts, and he could take the route I did with my Mustang and throw a lot of money at it, but I think we will be going oldschool with our solution. I feel he has parts that will run, but it will take tweaking.

I do believe that even after we get it all tuned, it's going to need a different converter, probably more like 2,500 or so. I will probably start by locking out timing, and working on a good idle situation.

May have to degree the cam.

Like I said, it really runs great off idle, and if this was a 4 spd we would be fine.

Any suggestions that are along the lines of keeping the parts we have would be much appreciated.

Thanks again!

Iowan

Stock heads, manifolds and converter, get a cam with 220 degrees duration @ .050 and possibly a timing set.

vegascarnut

I've had really good luck with my Edelbrock carbs actually. Not ready to give up on the Carter yet!

You are right--if this was a 4 speed car we would not even be having this discussion! I wish!

That's a great video bye the way, thanks!

Coronet 500

I really like that carb, have one that we have put on everything. If your good with Ed's you'll be good with the Carter.

If you look up Purple Shaft hydraulic cams you'll find the lift will tell you which one you have.

You can do a simple degree without taking the front off if nothing more than to get centerline and that will decide how much further to go.

If you search Big Block cam timing you'll probably find some who have had problems with some sprockets dot to dot that have been way off. Manufacturers defect or dots not marked correctly for easy install.

I would definitely find where cam is before wasting time or money.

Rooty

Perhaps it's as simple as choosing a different cam that matches the rest of the original hardware.

Iowan

That's what I'm saying.

RacerHog

Check the plugs..... If its lean.... Fatten it up...
Sounds like it runs good up about 2600 rpm?
Makes me think it might be around the old D.C. 292/509

vegascarnut

Yeah, that's about right. We are going to work out the best possible timing curve, probably somewhere around 20 initial, 34 total, all in by 2,300. Then vacuum advance (Manifold not ported) will be connected to add some for idle and cruise. If we can tune the carb and get it happy there, I'm going to take a hard look at the converter to be sure stall is in the right range for the combo. If we strike out on timing and tuning the carb, I won't even look at the converter--I'll pull the cam.