73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Performance => Topic started by: CruzByU on September 28, 2010, 09:36:19 pm
-
I just started taking the truck to the track last week. It's momentarily falling on it's face out of the hole, or anytime I hit WOT. It has a 383 Stroker, Full roller motor, Edelbrock intake, Edelbrock 650 carb, and Hooker Headers. I bought the truck just like it is, so not sure on all the internal goodies, I'm not and engine guy, suspension, paint & body is more of my thing. Can someone give me some ideas on things to try?
-
Are you sure it's a 650? What's the part#? Have you adjusted your timing and fuel metering yet? Do you have the accelerator pump set on long or short stroke?
-
Vile,
I somewhat fixed the problem today, I found two different vacuum leaks on the carb. And I have no idea about any of the questions you asked. I'm not too engine savvy.
-
X2 on what Vile said about the accelerator pump setting. I also have an Edelbrock 650cfm 1406 and had a lean spot that caused it to bog at part/WO throttle and set my pump rod to the lowest notch of the 3 in the pump arm, which makes the pump stroke longer and gives you more fuel at throttle. You'll find the pump arm and rod on the front driver's side of the carb...it's right above your throttle return spring. It helped, however, in addition to this, I had to buy some of the step-up springs and change them out until it eliminated it altogether. The part number for the step-up springs is #1464 and changing them out is very simple and can be done without removing the carb. The springs are only around $5 and some auto parts stores have them on hand. Your carb owner's manual will explain how to do this, and if you don't have it, it can be downloaded from Edelbrock's website. So if eliminating the vacuum leaks doesn't work, try this and it should solve it.
Come to think of it, I think these carbs are only 600 cfm.
-
This might help you a little more...
(http://i203.photobucket.com/albums/aa84/jlane1820/EdelbrockCarbPump.jpg)
-
I might have to try that step-up spring trick on my 1406. What I found really helped was changing out the nozzle head on my accelerator pump. I had the factory one in there and found that one side was plugged. I bought the upgrade kit that includes 3 new nozzle heads before I discovered the plug though. I put in the largest one, and put the rod on the biggest stroke hole. That did help out a log. I still have a tip-in slight bog though at moderate to heavy throttle. Not near as bad as it used to be though. The nozzle on that picture is right at the bottom of the carb throat 'circle' that the air cleaner mounts on top of. It has two little nozzle jets that squirt fuel into the secondaries. You can see it if you take the air cleaner off but you have to take the top of the carb apart from the bottom to change it out unfortunately.
-
Guys,
Thanks for the info. The vacuum leak fix did the trick, I took it back to the dragstrip last Thursday night and improved my time from a dismall 10.29 to a 9.70 in the 8th mile. Now all I need to work on is traction(open diff) and reaction time. Thanks again.