need help w/ my 383

-
9

97051 bigblock

Member
Joined
Jul 18, 2007
Messages
23
Reaction score
0
Location
vancouver,washington
well i have a 69 383 hp in my dart and it just doesn't have the get up and go i think it should have .I has a small comp cam hyd. flat tappet and mopar elect. ingition with the orange box alum. dual plane intake with a 650 holley its been bal. and blueprinted headers and flowmasters trans is a 727 with a 2500 stall and out back dana 60 with 354 gears. any help for me to get more power out of it ( no bottle or turbo or supercharger please) thxs very much....
 
97051 bigblock said:
well i have a 69 383 hp in my dart and it just doesn't have the get up and go i think it should have .I has a small comp cam hyd. flat tappet and mopar elect. ingition with the orange box alum. dual plane intake with a 650 holley its been bal. and blueprinted headers and flowmasters trans is a 727 with a 2500 stall and out back dana 60 with 354 gears. any help for me to get more power out of it ( no bottle or turbo or supercharger please) thxs very much....
Click to expand...

At first glance with what you've got running properly that 383 should be able to boil the tires off her. Since it's not you're going to have to supply some info like what is your timing/ initial, all in RPM and full mechanical set at. Need some numbers on that cam and any idea of your compression, also what dual plane (there's a dozen different makes and models out there) and is it a DP'r holley or vacuum secondary.
 
I agree with Demon.More information is needed, but in the absence of anything seriously MECHANICALLY wrong,(doubtful, sounds like you covered the bases), it is in the tune.
Big motor+light car= scary fast ride.
My .02
 
well the intake is a weiand dual plane and it has a mech. sec. 650 dp I just had it on the dyno and everything is set perfect ,sorry i can not remember the timing or the cam size i know its the one size small than the 480 lift comp cam, it runs good but there seems like i should have alot more asskickin power I was thinking about a 509 purple shaft to put into it,i've also herd that MSD ignition makes a big difference but i'am dont want to waste the money if its not going to help...
 
A small cam and 3.23 and lower numeric gear would be great for a 650 cfm carb. His description is lacking on specifics.
(And that's OK. I can't keep my grocery list in my head for lunch meats)
 
97051 bigblock said:
well the intake is a weiand dual plane and it has a mech. sec. 650 dp I just had it on the dyno and everything is set perfect ,sorry i can not remember the timing or the cam size i know its the one size small than the 480 lift comp cam, it runs good but there seems like i should have alot more asskickin power I was thinking about a 509 purple shaft to put into it,i've also herd that MSD ignition makes a big difference but i'am dont want to waste the money if its not going to help...
Click to expand...

What were the numbers on the dyno? I'd start out first ditching the weiand and go with a Edelbrock RPM Performer (night and day) and a 750dp'r will outperform especially if you later go to a bigger cam. If you're thinking of the MP 509 you've gotto find out what your closest valve head to piston clearance is with the cam you got now. If the engine happens to be a true zero deck block and you're using flat top pistons you could be to close with the .509. As far as the orange box, there's nothing wrong with them I've been using them for years for street strip applications.
 

Attachments

  • P1010023.jpg
    146.8 KB · Views: 646
well as far as compression its 9 to 1 , and horsepower was 250 on the dyno to the rear wheels,so u guys think changing the intake a bigger carb might help and i'am thinking a different cam then, any ideas on the size street and a little strip but it needs to sound good....
 
Google "383 resto to rad". It's a good article on building a 383 from stock to pretty stout, using basic bolt on parts. On a stock 383, a bigger carb was worth 10 HP and 20+ ft. lbs over the stock carb, which is about the same size as your 650. I really like the RPM intake also.
 
97051 bigblock said:
well the intake is a weiand dual plane and it has a mech. sec. 650 dp I just had it on the dyno and everything is set perfect ,sorry i can not remember the timing or the cam size i know its the one size small than the 480 lift comp cam, it runs good but there seems like i should have alot more asskickin power I was thinking about a 509 purple shaft to put into it,i've also herd that MSD ignition makes a big difference but i'am dont want to waste the money if its not going to help...
Click to expand...

If you replace the carb, try a vacuum secondary carb. They are much easier to tune. It's difficult to tune a double pumper for off the line, they usually bog when the throttles are opened too fast and the accelerator pumps and squirters are not perfectly tuned in. Vacuum secondaries are much more forgiving.

The 509 MP cam will be more sluggish at low RPM's than the cam that you currently have in it.

I would verify the ignition timing and distributor curve before trying to replace the parts. Try setting your total timing advance between 34° to 38° and see where it runs best in 2° intervals. Only make one change at a time so you can see what effect the change had on your performance. If it makes it better keep it, if not change back to the "older" setting. What vacuum are you getting at idle and at what rpm does it idle at?

Then try replacing the carb with a vacuum secondary one and get it tuned in. If you go with a Holley, put the lighter yellow spring in the vacuum secondaries to get the secondaries opening up quicker. Make sure that you properly adjust the accelerator pump clearance.

I have run Wiand dual planes on small blocks and they seem to run good. I would change the carb before changing the manifold or cam. If you overcarburate, you hurt the whole rpm band. If you undercarburate, you only hurt the top end rpm. A vacuum secondary carb will be more forgiving to overcarburation by only opening as much as the engine demands.

I would work on the tune up and then the carburetor. I think the cam and manifold are not causing the problem.
 
You must log in or register to reply here.
-

Back
Top