354 carb...

[mrossbach]

Morning, new member here...
I rebuilt a 354...went .030 over, stock valves, ross pistons, hotheads intake, cam= dur..050, adv dur= 300-300, lift=480-480, deg lobe=108...
Mallory dist...
vacum at idle is 11...what is the correct carb to go with?. I currently have a demon 750. mech secds.
Its from a friend , used...
engine starts hard...wont idle untill warm.....
vacum secds. ok to use?....
Thanks mike r.

[392heminut]

Some might say a 750 is too big for a 354, but I would go with a Holley 750 vacuum secondary carb. It can be tuned to the engine and will run great on it.

[polyspheric]

Before you do anything else:
1. where is your initial advance set?
2. what power valve?

[mart]

Morning, new member here...
I rebuilt a 354...went .030 over, stock valves, ross pistons, hotheads intake, cam= dur..050, adv dur= 300-300, lift=480-480, deg lobe=108...
Mallory dist...
vacum at idle is 11...what is the correct carb to go with?. I currently have a demon 750. mech secds.
Its from a friend , used...
engine starts hard...wont idle untill warm.....
vacum secds. ok to use?....
Thanks mike r.

-----------------------------------------
'Back in the day', circa 1972-73, I built a 354 with very similar specs to yours. The intake was different - there were no nice Hotheads aluminum intakes available back then! Instead I used a stock 392 dual plane intake off of a '58 Imperial and played with a bunch of different carbs. The two carbs that worked best were 1) - out of the box - a Holley list number 3310-1, 780 cfm vacuum secondary 4-bbl., on a 1-inch high, 4-hole spacer - and 2) - with a bunch of tuning, jetting and and playing with different vacuum secondary diaphragm springs - a Holley list number 3916-15AAS 950 cfm vacuum secondary 3-bbl. For the 3-bbl, I used the same 1-inch high, 4-hole spacer that I used with the 780, except that I ground out the center between the two holes on the secondary side of the spacer to create a single 'oval shaped' opening that matched the carb's single oval secondary throttle plate. On the primary side of the spacer, I left
the two separate holes intact. A 950 3-bbl would definitely be cool,
would work killer (after setting it up it to get it to work properly) and I'm sure, have some real "wow" factor, but decent ones nowadays are pretty scarce and probably expensive. Newer, "universal" versions of the 780 cfm 3310 4-bbl though is still in production and should work nicely with minimal mods.

mart
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[oldngood]

Morning, new member here...
I rebuilt a 354...went .030 over, stock valves, ross pistons, hotheads intake, cam= dur..050, adv dur= 300-300, lift=480-480, deg lobe=108...
Mallory dist...
vacum at idle is 11...what is the correct carb to go with?. I currently have a demon 750. mech secds.
Its from a friend , used...
engine starts hard...wont idle untill warm.....
vacum secds. ok to use?....
Thanks mike r.

Demon 750 is fine, as long as it takes the 4 bbl opening without bogging. I prefer a vacuum secondary 3310 myself.

that sounds like a pretty big cam. I've had to drill idle feed restrictions open 2-3 thousandths to get big cams to start/idle for street use. They need more fuel at idle

Run a direct vacuum advance to intake, it will pick up the idle- also run as much initial timing as you can, without pinging at WOT, do road tests to find the knock point- timing helps tame a big cam.