340 intake on a 318?

[RustyRatRod]

I have seen only 2. Came factory on a 78/79 1/2 ton. I did measure the ports which were the small ports. That was in the late 80s or early 90s. Haven’t seen any since. Kim

Thanks. I've always read they made them but to date, I've never seen one.

 

[kork340]

According to an old Chrysler guide for A engine modification printed in Hot Rod back in the 70's :
Step 1- Add headers and good low restriction dual exhaust.
Step 2- If working with a 318, install the 4-barrel induction system from a 340/360
Step 3- Lighten the car
Step 4- Add MoPar D.C. electronic ignition kit (part No. P3690426). If car already has electronic ignition recurve distributor and use D.C. control box.
Step 5- Upgrade fuel delivery system. Install Carter No. 4594 electric pump (P4007038) at rear of vehicle. The high-output mechanical pump(P4007040) may also be desirable.
Step 6- Install 4.10 or 4.30 ring and pinion. Adding 9" slicks mounted on 7" or 8" wheels for strip use only is also recommended.
Step 7- 318 engines should be fitted with the 340-type hydraulic cam and valve springs (part Nos. 2899206 and P4120249 respectively)
Step 8-318 engine should be fitted with 340/360 cylinder heads.

I believe this was all in the Direct Connection book as well.

 

[Dartswinger70]

You all must be driving in your sleep! To put a set of 360 340 heads on a 318 without matching the ports is a waste of a lot of time and performance. To start with the ports are large enough the 318 is going to suffer in response and power. If you match the ports in the heads than it would work acceptable but not optimal. I tried it and wound up installing a 273 single plane and the engine came to life. The engine had ported heads with headers and early 340 cam. It ran fair with the 340 intake but I had already done a match up of the ports. Now if you use the 360 heads with the 1.88 intakes and the manifold stuff lines up a lot better and upper rpm perf is a lot better but the low end suffers some. It's the same with any engine accept a BBC which is always under valved no matter what combination is being used until you get up around 2.030. READ up on cylinder heads and port design. Some here are saying just run it but if it's worth doing, do it right and match the heads up to it. You will be glad you did. I ran mine with a TQ at first also and it worked ok but it worked be with the AVS and the small port 273 intake, it was way better off the bottom and the top didn't seem to suffer much, it was noticeable but I dealt with it because I like anyone else isn't in the throttle to the floor all the time, just part of the time and an engine that stumbles off the line is nothing to brag about no matter how hard it runs above 3k, you've already lost the race and playing catch up isn't a winners game.

Yeah but who runs a 318...? thats the thing 318 guys go to all lengths to work them when they should just get the 360 and call it done. the 5.9 magnum has to be in abundance in scrapyards. Now you want to him and haw about port matching when ya should just have the bogger bore and bigger flowing heads to begin with ...

 

[TF360]

And I would just run the right size intake. There's nothing like making it right..