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1805 -6s carbs on a hemi ?

Posted By: calrobb2000

1805 -6s carbs on a hemi ? - 12/26/21 06:19 AM


hi
anyone using edelbrock 1805s and 1806s thunder carbs on their hemi inline ?

would like to get a jetting baseline as l these carbs and i am sure jetting is too rich with the original rods and jets .

pump gas 10-1 34deg 511


thank you !
Posted By: dragon slayer

Re: 1805 -6s carbs on a hemi ? - 12/26/21 03:42 PM

I have seen these put on as is on inline motors about your spec except 426 or so cubes. The instruction show the values, only thing I saw missing was idle jet size. The power step on the rods are richer along with the primary and secondary jets, but you would need to see the air bleed size to correlate to any stock hemi specs in the service manual. The bigger issue in my mind is the fuel distribution. Hemi carb had some stagger jetting even rod stagger, and distribution tabs. I would love to hear or see someone that put the combo on a dyno and measure all 8 cylinders for mixture.
Posted By: second 70

Re: 1805 -6s carbs on a hemi ? - 12/26/21 03:47 PM

What manifold ( single or dual plane) and are you using carbs 1 to 1 or progressive?
Posted By: Uncle Barry

Re: 1805 -6s carbs on a hemi ? - 12/26/21 06:26 PM

I just put a pair of 1912s on mine. Haven't messed with them yet other than put light springs in them and they seem pretty good. I have to wait for better weather to dial them in. I had 1407s on it and they worked but it took alot of tinkering to get them right. 10.5:1 pump gas 528 hemi. Eddy heads and intake.

Posted By: Cab_Burge

Re: 1805 -6s carbs on a hemi ? - 12/26/21 07:43 PM

Are those smog carbs or performance carbs.?
I won't use any smog carbs now on any muscle cars or street and strip motors twocents
IHTHS up
Posted By: Uncle Barry

Re: 1805 -6s carbs on a hemi ? - 12/26/21 08:03 PM

Originally Posted by Cab_Burge
Are those smog carbs or performance carbs.?
I won't use any smog carbs now on any muscle cars or street and strip motors twocents
IHTHS up

I believe those he posted are just regular 650 avs carbs, Cab.
Posted By: calrobb2000

Re: 1805 -6s carbs on a hemi ? - 12/27/21 04:54 AM


stock intake street hemi, progressive linkage, 6903 fuel pump .
Posted By: lewtot184

Re: 1805 -6s carbs on a hemi ? - 12/27/21 01:45 PM

the carbs will be small for 511" but would work well with a stock dual plane. the edelbrocks have a 1 3/4" secondary throttle bore vs 1 11/16" for stock carbs so there may be some blending on the intake needed. i think the calibration will work as they come out of the box. i've tried using factory jetting specs with the edelbrocks in different applications and it just didn't work for me. those old factory sand cast carbs have different clusters/emulsion tubes/fuel passage size. in the end i always had to revert back to edelbrock's calibration and go from there.

i do believe the 1407's would be a better carb for that engine and intake. the '67 hemi s/s cheater carbs are the same throttle bore/venturi as a 1407. many years ago i put some big carters on my brothers stock street hemi just to see what it would do. back then we had no test and tunes, dynos, 60fts; we just street raced. we used to get together after work during the summer of 1970, tune a little, and head to some vacant interstate. the difference between stock carbs and big carbs was car lengths. seemed like you couldn't over carb that hemi; it just wanted air and a lot of it.

i think the 6903 pump will be marginal without mods. i use a 6903 pump with some mods on a 440 with an edelbrock ch28 and 600's (i'd put 1407's on this if i had a matched pair) and think it might be getting close to the end of it's rope in my application. your hemi should make at least 100+hp more than my 440. the bench testing i've done with OOTB 6903's was about 3/4 of gallon in 60 seconds.
Posted By: second 70

Re: 1805 -6s carbs on a hemi ? - 12/30/21 05:17 PM

Originally Posted by calrobb2000

stock intake street hemi, progressive linkage, 6903 fuel pump .


Thanks for the info but my settings won't help since I run a Stage V open and 1 - 1 linkage. I can tell you even thou mine is only a 426 it did like the 1407's better at WOT. But again this was on an open plenum manifold.
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