| Author |
Message |
    
Denny
| | Posted on Sunday, June 9, 2002 - 11:46 pm: |       |
Scott do you think the 650 speed demon carb would be good on my 383 Vortex stroker? Have you tested any with the 650 speed demon?
thanks |
Scott
| | Posted on Monday, June 10, 2002 - 1:44 am: | |
I think that with the larger displacement of the 383 that a 750 would be a better choice. I would run a vacuum secondary model for mostly street use, and if you see a lot of track use, then a mechanical secondary carb. The Demon carbs typically make slightly more horsepower than the competition. They are good carburetors, the only drawback being that if you have one with an electric choke, it's hard to get an air cleaner to clear the choke shaft. |
Denny
| | Posted on Monday, June 10, 2002 - 9:25 am: | |
Thanks for the info Scott. I really like your forum area. One thing I noticed about the 383 Vortex is that the manifold has very poor fuel distribution. I have a 600 cfm holley vacuum secondary on here now. Demon carb company recommends the 650 for my application. My engine does not perform very well in overdrive with the 700r tranny. What scares me about a 650, 750 Holley or Demon would be the larger 1 11/16 throttle plates. The 600cfm Holley I am using now has 1 9/16 plates and engine performs poorly in overdrive. My truck never gets raced and I use it mainly for highway cruising. What jet sizes have you found to work best with motor on the dyno? I am starting to think that the only carb that might run good on this engine with the overdrive is the spreadbore carb. I have a feeling in overdrive I am running on the idle transfer slots and now the main system. |
Scott
| | Posted on Monday, June 10, 2002 - 9:26 pm: | |
I'm assuming that by Vortex you are referring to the Vortec heads? Is the engine the HT383 GM crate engine? If it is, you are probably correct on the carburetor situtation. With the combination in this engine, the Q-jet is hard to beat. As far as dyno results, we haven't done a lot of dyno testing on this engine with different carburetors. We may have some in the past, but I don't recall, and I am at my house. I will look tomorrow and see what we have done. I would use the Q-jet carburetor if it was mine, and I wanted to use it for the intended purpose of the HT383. |
Denny
| | Posted on Monday, June 10, 2002 - 11:27 pm: | |
Hi Scott, My 383 is the HT383 GM crate engine. I am still wanting a demon carb real bad. I talked to them today and they can't believe the cam specs on the the HT383 roller cam. It sounds like they can possibly set up a carb for me. What Demon company is having a hard time with is the duration a .050 lift. Their 650 speed Demon is set up for cams with alot more intake duration, 220 and up.I called Crane cam company and they verified the specs on the cam. One thing real funny though is that when I talked to the tech department they insist that cam number is for for marine applications. Thanks for checking on the dyno tests for me, I appreciate it. |
Scott
| | Posted on Tuesday, June 11, 2002 - 2:26 am: | |
That camshaft did indeed start it's life as a marine camshaft. It is a very mild camshaft that makes excellent torque. Depending upon what type of vehicle you have this in, the Q-jet is still probably the best choice. There are some changes that you could do to your engine to improve it's performance, depending on vehicle, intended usage, and budget. |
Denny
| | Posted on Saturday, June 15, 2002 - 9:44 pm: | |
I got a Road Demon at the recommendation of Demon Co. I am still working out the bugs. I have to get idle restrictors from them because the idle system is too rich for for the engine. |
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