Dual carb 305

[C0dy]

Whose running duals on a mild sbc 305? What's your setup

 

[Blue Eyed Devil]

Better question is why? WAY too much carburetion for that engine.

 

[C0dy]

I agree it's unneeded. Why?? Looks mostly I would say...reason I ask is I'm building a rat rod and I've acquired a rebuilt 305 with a edlebrock tunnel ram intake manifold but no carbs..

 

[Willowbilly3]

About the smallest 4 barrel carbs are 390 cfm, making 2 of them around 780. If you have some really big heads, 12:1 compression and plan to spin it to 10 grand, then that would be about right. For the street 500 cfm on a 350 would be happy. Can you change the top to a single?
I have worked on a T bucket with a stock 350 and tunnel ram 2x4. The original builders disabled the secondarys and the accelerator pumps so it would be drivable. I told the lezzy who owns it that was a crappy setup and now I don't work on it any more.

 

[Flipper_1938]

I would think you would need to adapt two progressive two barrels. Kinda hard to find old carbs in junkyards these days. It would need to be old enough to not have all of the electric solenoids built in like they did in the early 80's. A while back I found a 1965 mercedes in pull a part that had dual carbs on an inline six. Something like that ought to do OK on a street motor.

 

[C0dy]

The tunnel ram is actually 2 pieces and they do make a single carb top half I was considering finding one of those and getting a 500cfm..390s are a little pricey and I think would still be too much for the 305 (my motor is mostly stock besides a mild cam also has 416 chevy heads)..someone had reccommended to me getting a couple ford auto lite 2 bbl carbs. My other option was, if I'm going to start dumping money into this maybe pick up a 350 my understanding is if it's from the same era as the 305 the intake mani will fit (along with the headers that came with it) and then I'll have little more nut, but I could always do that later on down the line

 

[Flipper_1938]

Tunnel rams are for high rpm, max horse power. Any motor will need good heads and a big cam.

Undersized carbs are a bandaid to try to make it work at lower rpms. A single 4 on a dual plane intake will run A WHOLE LOT BETTER!!!!

 

[Bamamav]

Tunnel rams are for high rpm, max horse power. Any motor will need good heads and a big cam.

Undersized carbs are a bandaid to try to make it work at lower rpms. A single 4 on a dual plane intake will run A WHOLE LOT BETTER!!!!

I agree. My neighbor had a built 383 in a 69 Camaro. It had a huge cam and head work and headers and a 2.75 exhaust. He put a tunnel ram on it with two 550 Holley's, it was a dog on the street and the drag strip. Over 4500 RPM, it ran like a scalded dog, under 4500 RPM, it would barely run. Taking off from a dead stop, it spit and sputtered like crazy. I changed the pump cams to the largest that Holley made, still not enough. After a few weeks of this, he put on a Edelbrock Air Gap with a 650 Holley. It had great street manners from then on, idled great, and ran some good numbers at the track.

 

[bob w]

I built this car with a 305 in it. Sold it to a RRR member from Alabama. He put a two 4bbl tunnel ram on it. I received some videos of it going down the highway and it ran fine. I'm not disagreeing with the guys saying it is over carbing a 305 but it looks cool and with a little tuning can be made to run well.

 

[soltz]

Here's My 2Cents

I put this on a stock 302 Ford just because it looked cool and ran great. All I did was put a block-off plate under the front carb, ran fine on just the rear. All linkage and fuel lines are dumbies[S

 

[21willys]

My brother in law had a 307 Chevy with dual fours and a stupid big intake in a shoebox ford. Somehow it actually ran good with mostly stock internals and stick heads. It had two Holley four barrels of some sort.

I never did understand how it ran as good as it did. Maybe he was just lucky.

 

[C0dy]

Haha I like the idea of a dummy carb but with this manifold it seems like if I did that only the back (or front) cylinders would get fuel.

Bob w any chance you know what size carbs they put on?

Great info guys!

 

[donsrods]

Every car we own is over carbed, I have two 600's on my 331 Ford, my one Son has two 600's on his 302, and my other Son has two 600's on his 455 Olds. Is that way too much? Sure, but they are hot rods and need to look the part. Ours run right down the road and the plugs burn pretty clean, considering.

You can rejet your carbs really easily, costs about $20 per carb and takes about 15 minutes. Edelbrock stock primary jets are 98's and if you go to 95's and put in 73-47 metering rods you will lean it out by about 6%.

Don

 

[soltz]

Haha I like the idea of a dummy carb but with this manifold it seems like if I did that only the back (or front) cylinders would get fuel.

I'll let you know, i'm putting the same manifold on a 350, the top section is an open plenum so i'm thinking it might work[S

 

[C0dy]

Yes it is open but the fuel from each carb has a pretty direct route down to just half the cylinders..maybe I'm just being pessimistic definetly keep me posted if it works ..if not I was considering fabing up my own top section of the manifold out of some .125 alum. to hold a centered single 4bbl carb. Would be a whole lot cheaper than the edlebrock single and a fun little bench project

 

[rex1927]

Had a tunnel ram on a 305 in a gasser about 15 years back.It was just for looks and run sort of ok with Holleys after some jets,pumps,etc.
Never drove it much before selling it.
Got a 350 for my next project.
Looking for 2X4 intake for it.They just look cool.
I am hoping to go with dual plane 2X4 intake this time,but will probably get tunnel ram if it is what I find first.
If performance was my goal I would use single carb dual plane intake,but I just want 350 to look cool and the more carbs the cooler it looks.
Good luck with your tunnel ram.

 

[Undercover Customs]

I ran the same dual quad set up on two different engines. I used two 625 AFB's and had them set up progressive. The back carb is what it ran on most of the time then it kind of acted like a it had three sets of secondaries.

The first engine was a stock 307 with a comp cams 268 cam and headers. The set up ran best in with this motor. Once I had it jetted properly I really had no issues with it. It was more for looks than performance but it did perform well. Everyone I told that I was doing it said it wouldn't work and I'd have all kind of issues with it. I ran that setup for 6 years.

The second engine was a fairly built 283. It has the comp cams 292 cam, more compression etc. It wasn't as crisp on the low end but it really cam alive above 4k rpm. Everyone told me that the dual quad set would run better on this setup. Could never get quite dialed in as good as on the 307. Ran it on this one for 5 years and a whole lot more miles.