what carb are you guys running on 390?
 

I ended up with a 390 a couple weeks ago. I replaced the turd badger pistons with flat top silvolites. Now there riiiiight near 0 deck. Heads are d2 with stock valves. New valves and springs etc etc. No port matching. Flowtech headers. 1961 ford aluminum 4 barrel. Elgin 966 cam. Heads have been surfaced. Compression is 9.something. But with flat tops, d2 heads, and right at 0 deck I'd say 9.4-9.5 should be a safe assumption. Anyway. I have two carbs. 1406 and a 1407. Engine is going in a 73 f250. 4 speed trans. 3.73 rear. Never really driven hard. Will pull a small boat and haul firewood and whatever else needs to be done. Which carb would be better suited for this truck? I'm seeing opinions for both. I could try both and see which works best, and eventually I'm sure I will, but my biggest concern for now is which carb will work best during break in period. Might not even really be that big of a deal but I just thought I'd ask.

Between the 1406 and the 1406 I guess I would go with the 1406.

You may want to correct your post as I think you made a mistake.

About 500 cfm should run the truck just fine, no more than 600.



John :-X06

Haha thanks raptor.

Ditto. His comp ratio is in the low tens. My choice for it ? Holley 3310 750

For future clarification I have a 1406 and a 1407. I'd run a qjet if I could but I don't like adapter plates.
On another note...reallt think my cr will be in the low 10s?

Definitely. You've built what amounts to a GT390 with those pistons and heads, along with the hotter cam. I upgraded the high compression 390 2V in the 68 Merc I had a few years back with a Crane 272* Energizer, keeping the factory flat tops and C8AE-H heads (same heads as your D2's) topped with a 428PI intake and a 750 Holley. It wouldn't digest 87 octane fuel but was fine with 89. Also ran a 67 GT390 in a 70 F100 with a similar cam, it too was fine on 89.

my truck likes the 3310 750 , just need to change the primary jets down a size .
I had a 600,650dp on there for a little runs much better with the 750.
oh I did put an adjustable vacuum secondary diaphragm on

I run an old Autolite 4100 on my 416, easy to rebuild, tune, might not be the newest technology but it get's my 75 F100 down the road.

Thanks for the info guys. I'm gonna try the 1405 I ended up with. It was in a 1406 box. The guy let me have a jet kit since I didn't argue with his price so I should be able to get it where it runs right. Hopefully the engine swap will happen this weekend

Big port manifold to small port head... You might get better throttle response from a later intake and 600 cfm carb.

Something like that. I'll run this intake for the time being. I was curious to see how it runs with the mismatched ports myself. Since I'm not building an engine for all out performance I probably won't be too upset. If it were something I'd race and spend time at high rpms I'd not even consider the intake/head combo. But we'll see.

Stock Autolite 2V 2100 with retrofit manual choke.

Large port manifold to small port head might cause gas to drop out of the mixture as it hits the "wall" surrounding the small port. Causing all sorts of weird issues that'll have you thinking the carb needs more tuning.

I could be wrong of course }>

"Loading up" at idle or low revs could be one result. Followed by a bog and a cloud of black smoke when you step into it a bit more.

ymmv, doesn't cost much to try it.

I've got a 410 and I'm running a EB 1825 on it, I think its a 650cfm. runs good but very hard to start cold.

It wasn't as bad a deal as some make it out to be, Ford did this on a couple of factory combos, on the 429's Seen this on a factory jet boat engine too with an SCJ intake on an otherwise stock 460.

So far the intake/head combo is running like a champ. Pulls hard through all gears at the revs I've been running so far. Idle is smooth. Vacuum is steady.
When I put it together I reminded myself my aim was a low rpm engine to run in a truck that weighs 4900lbs. I figured the port mismatch would likely cause problems at higher rpms, if any problems were to arise. And I doubt I'll spin this thing 5 grand.
If it ever becomes and issue I'll sell that intake, cause I guess it could be kind of rare, and buy a performer rpm or similar.