You will need an adapter to go from the spread bore manifold to the square bore carburetor or find an early 340 intake. The intake you have has larger ports than your 318 heads. It will work, but won't be ideal. If you are going to stick with the 318, at the very least you should add 360 heads when you rebuild it to match the ports. I do have a '69 340 intake that I am selling, but shipping from California would be about the same as what I want for the manifold...
The Carter AFB 9511 that I have may be a square bore, but the front primaries are smaller & not as far apart as the openings on the 340 manifold. The ideal adapter would be a wide to narrow spread bore if such a thing exists. The fear with adding an adapter is linkage issues & hood clearance because the 340 manifold is already substantially taller than the 318-2V manifold on there now.
I did see your ad & agree that the shipping would be crazy. I was hoping to score something local or even meet someone at Carlisle to pick it up.
The 340 and 360 intake ports on the heads and intake manifold are larger than the 318 heads and intake ports which will cause reversion
Sell the Thermoquad intake and buy a AFB style 318 intake so the motor will like your changes
Been looking for a different intake that's reasonable but no luck yet.
The 340 and 360 intake ports on the heads and intake manifold are larger than the 318 heads and intake ports which will cause reversion
That is really a non-issue except in a max effort engine build and you wouldn't being doing that to a 318 anyway. I don't know why people keep bringing that old chestnut up, got any dyno pulls to prove it is an issue?
All that said, I ran the factory spreadbore intake on my otherwise stock 87 2bbl 318, yes the small port heads with zero reversion issues. Ran an Edelbrock 1406 carb on it without an adapter. What I did was run a thick (~3/8") carb base gasket. Don't have a PN though, I just picked it off the shelf back when there were speed shops and carb mounting gaskets to look at. Might look at Edelbrock Carburetor Adapters 2732, it's about as thin an adapter as you will see, probably thinner than my thick gasket trick.
You will also need the kickdown linkage addressed as the 2bbl stuff doesn't play so well with a 4bbl, did you get the adapter for the throttle and kickdown linkage as well?
Years ago I did the same swap on my 318 Scamp for almost the exact same reason, to not spend money on a beat 2V knowing I was going to switch to a 4V anyway. It ran fine with the stock 318 with an Edelbrock Performer & a Holley 600. When I had the motor rebuilt a year later with a bigger cam & some other mods I reused the same intake & carb & it ran a 15 second quarter with the 7-1/4" rear & 2.76 gears.
I do have that same 2732 adapter but it's not going to fix my issue. I need more even height to clear the cast iron between the two openings. That's why I was mainly asking if anyone knows whether the carb will fit on an older 340 manifold. Of all the things I've been reading the carb I have is for the 273 Commando.
I am aware of the linkage differences & had found what I needed in a junkyard back then. This time the parts were available new & I bought them from Mancini.
Thanks guys.
