4 barrel 318

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The Topless Fish is a 68 convertible. Bone stock 318 With 90000 miles, automatic transmission. The car is a Saturday Night Drive-in vehicle, slowly being restored and driven about 500 miles per year.

I'm looking, in a few years, to do a Coast-to-Coast drive on US-6 and before then would like to install a 4 barrel carb for better fuel mileage (and slightly better performance, of course). The engine compression checks all cylinders at 115-125 PSI. I had not planned on changing anything other than the intake and carburetor. I have been vacillating between installing a 340 intake (which I have) and 318 4 barrel intake (which seem hard to find).

I have been a offered a new Edelbrock Performer intake PN 2176 with a cam and lifter set PN 2177 to match for less that $200.00. Since I like Edelbrock Carbs, anyway this seems like possibly a more sensible way to go. Edelbrock calls this a Street Performance combo, and does recommend it for the 318/340/360. But here's the question.

If I install the cam and intake without head work will I ever get it running right? Will it do any good to install the intake without the cam? The transmission will get overhauled eventually, should I change the torque converter from stock if I do change the intake and cam?

The easiest thing for me to do is install the stock 340 intake and a 4 barrel Edelbrock, will I be be happy with the way that combo runs?

Thanks for the help!
 
There is no such thing as a "318 4 barrel intake". The factory never made one with the smaller ports for the 318. They all used the 360 intake manifold and mismatched the ports right from the factory. The only exceptions to this were the 273 4 barrel intakes, which did have the smaller intake ports. I would use the 340 intake. That's a fine piece and will run well.
 
If you think you will get better mileage...........you won't.................

If you want a bit more performance, you could install dual exhaust, if you do not, Ed Performer, or stock 340 / 360 intake, and a small 4 bbl and do well on a performance boost, but you will NOT do better than the stock factory 2 bbl for mileage
 
Welcome to FABO Top Down. :thumleft:

What seems like a very simple question, is actually more involved then at first glance. At 90k, if it runs well and is well sealed, I'd be hesitant to touch it at all. With that said, the timing chain would be my first concern at some point.

If you do decide to go into it, i'd go ahead and do the Performer cam/lifters.....with a new chain set. As far as the intake/carb, the Performer with a Thermoquad would give you the best mileage along with a good performance increase. A 600 Eddy would be my next choice as far as the carb goes. Linkage compatibility plays a roll also, depending on whether you want stock parts, or are willing to do a little fab work?

And a dual exhaust would be a must in my opinion if you decide to go into the mods. A nice 2 1/4" system would be a great addition regardless of which way you choose to go.
 
Thanks, guys

It sounds like I will be sticking with the 340 intake, and a small Edelbrock 4 barrel.

I'm surprised to hear that Chrysler Mismatched the ports at the factory, but it sure explains why the Part Numbers don't pan out for the "318 Four Barrels" on E-Bay and such!

The old boy runs so well that I want to do the least invasive stuff possible, I'm glad you all agree on what that entails
 
At the very least I would put a new timing chain in the motor and a good set of duel exhausts, then compare it to your baseline milage figures.
Life expentancy of a stock small block chain is iffy after about 80K miles.
 
I bet summit has a small port offenhauser dual port. Old tech, but great mpg vs power. Put a 500 edelbrock on it, a new chain, and enjoy.
 
They may show one, but I bet they ain't got it in stock. Offenhauser ain't cast anything new in a WHILE.
 
I got two a year ago. Nobody buys them anymore.. Because old tech must be bad tech, even tho i'll put my money on a small port offey vs any dual plane EB, weiand DP manifold. Doesn't hurt to call.
 
I may be wrong, but I thought the Edelbrock Performer had small ports like a 318, and the RPM has the larger for 340/360.
 
The PO had already installed a dual 2 1/4" exhaust, so that part is covered. Since I will have the engine out of the car to repaint the engine compartment sometime soon I think the timing chain would be a better use of my money than the Offenheiser intake. I have no objection to "Old Tech" (at my age, I am Old Tech), but I already have the 340 intake, and you can't beat free!
 
dodgetkboy78 said:
I got two a year ago. Nobody buys them anymore.. Because old tech must be bad tech, even tho i'll put my money on a small port offey vs any dual plane EB, weiand DP manifold. Doesn't hurt to call.
Click to expand...

The weiand actually has a good port match to the 318 heads.
The eddy performer is in between 318 and 360 port size.
The stock 340 you have will also work.
They still make the weiand.
 
dodgetkboy78 said:
I got two a year ago. Nobody buys them anymore.. Because old tech must be bad tech, even tho i'll put my money on a small port offey vs any dual plane EB, weiand DP manifold. Doesn't hurt to call.
Click to expand...

Oh I am sure there are some still on shelves somewhere.
 
If I wanted to bang one around town until I tore it up I would throw a bunch of aftermarket performance goodies on it and do that.
If I wanted to drive one trouble free across the country I would do nothing more that the maintenance services on the original. Timing set ( may as well replace water pump too ), tune up, belts, hoses, trans service, brake inspect/service, and hit the road.
Honestly, after having been there and done that, I would rent a car for the road trip.
Cruise control alone is worth the cost.
 
I have.2 offenhauser dual port intakes the ones with the divided runners.I beleive they would be perfect for a 4 barrel 318 conversion
 
RedFish said:
If I wanted to bang one around town until I tore it up.
Click to expand...

Fiddle faddle

I put over 80K on the low miles 340 I put in the old 70, pulled it out, re-ringed it and put a mechanical cam in it and beat it some more in the landcruiser. You are not gonna hurt a mild 318 with a 4 bbl and small cam, with less power and lower compression
 
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