426 dual carb questions

[INTMD8]

Very nice! Sounds like it has great throttle response!

It does! Thumbs up on the recommendation

 

[black64]

I used two 1406 carbs on my 392 hemi and am pleased with all around performance. Of course cam, compression and rear axle ratio's have a lot to do with performance of carbs but the 1406's worked fine in mine.

 

[lewtot184]

I haven't messed with street hemi carbs in decades, but I do know that an eddy 600 has the same throttle bore and venturii as the stock carbs. I also know the eddy 750 has the same throttle bore and venturii as the '67 cheater carb. I do remember putting big carbs on my brother's hemi road runner, way back in the day, and it made a noticeable performance increase with a stock intake.

fast forward some decades and about 4 years ago I switched to an edelbrock ch28. at the time I bought a 1406 for a primary carb and a 1405 for a secondary. thinking all they needed was jet changes (1406 being lean from the factory) and i'd be good to go. WRONG! the 1406 and 1405 don't have the same clusters! my recommendation is no matter what you buy just make sure both carbs are the same and I've noticed clusters may change thru the years. I tried about every kind of change to these carbs as is possible. there wasn't anything I didn't monkey with. in the the end I found that the 1405 OOTB jetting was about as good as it got and both carbs are set up the same. I also found that a .033" idle jet is about ideal (1406 had .033", 1405 had .028") for these carbs. I use the 750's accelerator pumps with .028" squirters. I played with needle and seats. I started out removing the .093" and replacing with .110". this didn't work well. the edelbrock small float doesn't control fuel well so I went back to the .093" and everybody is happier. carter made a .101" at one time but I don't know of any being reproduced. I did the math on seat area and the four .093" is more favorable than a pair of holley .120" which handle about anything.

I haven't worked with the 650's but do think they'd be good, just buy a matched pair. I also think a pair of 750's will work fine, preferably 1407's. I use the edelbrock linkage which should work with that intake/carb spacing. I know this for a fact . that ch28 and 600's is absolutely the best most trouble free intake/carb combo I've ever run. I consider the 500's worthless. I was a die hard 6pak guy for decades but there is no 6pak or single carb i'd trade for those quads. they burn clean, drive good, make gobs of torque, with very smooth power.

 

[Justin Smith]

Runs pretty good so far, just changed to lighter metering rod springs, set idle speed and adjusted idle mixture. Will dial it in on the dyno in the spring.

The AVS2 steps up a bit at the air cleaner stud so I'll need to either raise or remove the bridges on the air cleaner base.

Also, the ports on this intake are raised a bit in comparison to the stock hemi heads. I used Cometic C5598-047 (.047 thick) gaskets instead of the stock thickness .060 which dropped it down a bit. Port floors then lined up perfect. Top of intake port was about .025 above the port on the head which I thought was OK for now.

I plan to pull it apart at some point to do a roller cam and head porting and I'll match it then.

Which Throttle Linkage set are you using on your set up?

 

[INTMD8]

https://www.manciniracing.com/maheinlisetw1.html