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I ran the edlebrock and hated it. It is super easy to tune, but does not make a lot of power. I have went with fcr 39 mm but have not got to try them out yet. Stay with stock. If you just have to go with edlebrock , I got one I'll sell you. Good luck
 

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Yhe stock Carbs are dual 32mm Constant Velocity carbs
 

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as arough guide you can probably replicate stock performance (34 - 38hp) with an edlebrock carb setup, but not much more. The 1 advantage is the ease of tuning.

With good mods & jetting you will be able to get into the 50 hp range with the stock carbs, but yes getting the jetting right can be time consuming, however once sorted they work pretty well.

With 35mm FCR's you will be able to get into the 60-70hp range (depending on build) The 35's tend to give very good bottom end to mid range responce, but you (apparently) lose out at top end.

With 39mm FCR's you will be able to get into the 80hp range (anything over 75hp is a VERY serious engine build)
The 29's will give better top end than the 35's but at some possible expense to the bottom end responce.

When I finally finish my 719/14:1/X-4/39mm FCR build it will be very interesting to see what numbers I get.
Next step after that will be 3 plugs................
 

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as arough guide you can probably replicate stock performance (34 - 38hp) with an edlebrock carb setup, but not much more. The 1 advantage is the ease of tuning.

With good mods & jetting you will be able to get into the 50 hp range with the stock carbs, but yes getting the jetting right can be time consuming, however once sorted they work pretty well.

With 35mm FCR's you will be able to get into the 60-70hp range (depending on build) The 35's tend to give very good bottom end to mid range responce, but you (apparently) lose out at top end.

With 39mm FCR's you will be able to get into the 80hp range (anything over 75hp is a VERY serious engine build)
The 29's will give better top end than the 35's but at some possible expense to the bottom end responce.

When I finally finish my 719/14:1/X-4/39mm FCR build it will be very interesting to see what numbers I get.
Next step after that will be 3 plugs................
Good right up, i did squeze 55 hp out of edlebrock, but that was with a 719 and many mods. Hp should have been more. Have recieved my new ( used ) fcr 39mm in the other day. When i get head back and all installed i will update.
 

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I can tell you that we worked with Edelbrock when that carb was first designed. After hours and hours of dyno testing and tuning we concluded that we would not be selling Edelbrock carbs. When it comes to FCR's on a 660 We have tried many different combinatioins over the years. On a well built 727 we saw about a 1.5 RWHP gain with 39mm FCR's. At the time they were quite spendy and for the $1200 I don't think most recreational riders can justify the cost per HP. Just my 0.2.

Nate
Alba Racing
 
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