250 w/ offy & 4bbl

[DWright]

I'm sure this question has come up a million times but i just cant find a direct answer using the search option on this site. i'm waiting on my new offy 4bbl intake and holley 390cfm carb to come via ups and was wondering, how much of a difference am i gonna feel over the stock 1bbl intacke and carb? the only other mods i've done to it so far are a mallory unilite distributor, 8.5mm wires and an electric fuel pump by holley.

[ol Curt]

My experience was that you will get a great feeling when you step on it, but without a little cam(like an RV cam), you can float the valves real easy. The important thing to remember with the 250 is in order to hot rod it you have to make it breathe better. The best money spent is on the head....porting/polishing and possibly putting lump port heads on it. Headers helped a little.

[MacAttack]

About 5 miles per gallon less?

But yeah, a cam and maybe a hot ignition set-up may really help.

[DWright]

thanks for the replies. will that little bit of off-idle hesitation go away with this combo?

[MXmaniac]

Originally Posted by MacAttack

About 5 miles per gallon less?

Actually, I usually hear that people get better mileage with the more efficient 4 barrel as opposed to the stock single barrel. With the smaller venturies and the secondaries. Someone correct me if I'm wrong.

Originally Posted by DWright

thanks for the replies. will that little bit of off-idle hesitation go away with this combo?

I'm sure it will if its tuned up well. I've heard great things about this set-up, and once my truck is on the road and I can spend money on the "fun" stuff I'll be running this set-up.I'm curious, did you get a water-heated intake?

[DWright]

its very well tuned up. i just replaced the old points dizzy with a new mallory unilite unit. new msd 8.5mm wires, new plugs, coil. i even rebuilt the rochester 1bbl carb and advanced the timing 5 degrees. no matter what i do i cant get rid of that hesitation. and as far as the intake goes, I'm not sure if its water heated or not; maybe someone can tell me by looking at the pic. i havent received the intake yet. it just shipped friday.

[ol Curt]

The water heated part has to be plumbed. I think the offy intake is set up for that...if not it would involve having a port drilled and tapped so you could put a fitting in there for your water hose.

The better mileage might result if the particular four barrel is progressive where the back two only open when you get on it. I used a progressive Holley/Weber two barrel on mine and it helped with mileage, although I am having an electric choke 1bbl Rochester built so I can be as original as possible.