StrayDog

My 780 Holley has been rebuilt many times & is worn out, a 750 Demon is listed in Summit for $399, part # GPT - 140201VE, recall several months ago a forum member did this swap, :confused: any comments & suggestions appreciated , my 66 is a 427, street driver , looking for good throttle response & a timed vacum port all of which the Demon has.....

Milehigh66

I put on a demon carb on my 427/390. One of the best decisions I have made regarding my car. The performance over the Holly is fantastic!!!! I had to rejet it down because of the altitude in colorado, but since you are at sea level it should run straight out of the box. I put on the speed demon 750 with vacuum secondaries and electric choke. not to kicked on the electric choke, but probably operater failure and not carb related. blkblt also has the same carb on his BB and has had the same results, the best part about the demon is that it is so easy to tune, rejetting is a piece of cake and the glass sights for the float bowls are great. You will probably want to get the fuel line setup for it at the same time it makes installation alot easier. the only problem with the demon fuel line is that it doesn't look stock at all, got that dang blue and red anodized aluminum all over it.
You can't go wrong with the demon, enjoy.

Kurt :cheers: :seeya

Blkblt

As Kurt (Milehigh66) stated, I replaced the Holley on my '66 streetable 427 L72 a while back, and it is likely that the Holley will be staring at the inside of the box for years to come. Lars and I baselined it with an onboard, plug-in computer and it showed an additional 28 ponies and about a second off the 0-60 mph time out of the box with rejetting for altitude (about 6000'). :D

Throttle response is much improved with mid-range acceleration and deceleration something akin to FI. I have the same BG you listed. My electric choke works just fine...tap the throttle and turn the key once and she boils to life every time.

Also as Kurt mentioned, you will need a fuel line setup, and it won't look stock (see my pic) if you are doing the NCRS judging route. If you wish, I can send you the tech paper Lars and I (I just took pics; Lars is the brains) put together on the fuel line construction and set. Just e-mail me at: blkbelt5@attbi.com .

:cheers: :cheers: :seeya

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Jeff
Ô66. Modified L72
ÒThe Silver BeastÓ
Keep on :lol: :seeya :flag

oger

A 780 is a 780 if it meters right there should be the same max HP. I have played with every carb made and have not found a better carb than the fac 780 with the mixture distribution tabs when used on the stock L72 manifold. That is what the carb was designed for not to be a generic fit anything.

kahuner

StrayDog;

Awhile back I had switched over to a Speed Demon 750 w/ Vacuum secondaries which at the time I was running a stock 427 L72.

The Demon is a superior carb when compared to a Holley and you'll feel the improvement off idle and mid-range.

Last weekend I bought a book titled "How to Tune and Win with Demon Carburetion" by Ray T. Bohacz. The book covers all of the tuning circuits for all models of Demon carbs. And after reading the book I can understand why a Demon worked better than the old Holley.

Just last weekend I finished installing my new engine which is a 509 ci :cool: and I now have the Demon carb on the new engine. Right out of the box it's working fairly well. There are some adjustments that I'm going to have to make but it's a very tuneable design.

If you make the switch, I think you'll be very happy.:seeya

Good luck.

Colevette

You will not be sorry moving away from a Holley and into a Demon we put one on a 502, check the forum with a search you find some good threads :cool:
Cole

64BB

WILL THE TYPE OF CAM USED IN THYE BB MAKE A DIFFERENCE HERE?? I AM RUNNING A CRANE CAM [SUPPOSED TO BE EQUIVALENT TO THE ORIGINAL GM 425 CAM-IF THAT MAKES ANY SENSE]. I HAVE A WORN HOLLY 4160 [3310], BUT AM NOT SATISIFIED WITH LOW AND MIDRANGE RESPONSE. ANY THOUGHTS??

oger

Did you try to figure out what was wrong with your Holley? Did you have the OEM one or a generic replacement? If you want to buy a new carb instead of fixing the old one fine but don't say that a Demon is a better carb it isn't. I have seen some real problems with them on the dyno and their workmanship is a little shakey to say the least.

StrayDog

OGER........the 780 holley was on my 66 when I bought her approx 7 years ago...not the original carb but a 1970 replacenment of the same type.....I have rebuilt the carb 2 times...the throttle shafts are worn & the carb is " TIRED" so to speek....the other problem is the vacume port on the holley is live all the time & the advance has been modified for 14 at the crank & 36 total ...the vacme advance is always on even at idle & when i back off the throttle on the highway i get backfireing due to to much advance...need vac advance for good part throttle response...the demon has a timed vac port & 750 with vac secondarys is perfect for my street driver...i am not :mad dissatsfied with the Holley, merly time for a new carb & others have good words for the demon...... :seeya

StrayDog

Just Ordered 750 Demon from Summit, awaiting delivery , full report in a week or so..................... :yesnod:

StrayDog

Demon just deliverd today...what a beauty ...interesting that all Denom carbs come with a video tape .....full report in a few days....... :yesnod: :)