Intake recommendations for my 73 Road Runner 340

[Rangepony]

Use what you have, unless you're racing for world record. Does the extra weight really matter? HELL NO! When you use the factory stuff everything fits. Spend your money elsewhere. For a street driven car, it's hard to beat the factory Thermoquad setup. I've been using them for 45 years, I won't use anything else!

The Thermoguad was in a box when I got the car....I haven't really checked it out but I would assume it needs a rebuild. It has a Edelbrock 1406 on it now with a spacer/adapter under it. The car runs well but not a head snapper. During the breakdown I discovered some questionable vacuum lines so I'm hoping when back together we'll be a little better

 

[Photon440]

So I pulled the heads on my 74 Road Runner 340 to do some valve work and drill out some broken off bolts. I think the original intake weighs around 10,000 pounds.....I'm thinking an aluminum upgrade...any recommendations?

View attachment 1778689

Is that original? I thought the 340 was replaced with a 360 for 1974.

 

[HawkRod]

Is that original? I thought the 340 was replaced with a 360 for 1974.

The thread title says 73, but (perhaps a typo) said "...my 74 Road Runner 340...".

I agree with you - I think 73 was 340 and 74 was 360.

 

[496 polara]

By all means run the stock one if you want to.It is free,paint it and go. If you ran across a performer or ld340 for a deal then pick one up.It can be painted to look stock.

A good performance valve job and some new valve springs if they are old doesn't cost much more than a stock valve job.Mill them a touch for a little compression increase.

Your money and car so have fun no matter which way you go.

 

[dvw]

The stock intake is pretty decent with a properly functioning TQ. The compression ratio and cam are lame. If it doesn't have headers? I'd start there first. If the heads are apart? Read up on how touch up the valve bowls a bit. Steel shim head gaskets will be as good as it gets without milling. 3.55 or more gear will help as well.
Doug

 

[WileE]

Is that original? I thought the 340 was replaced with a 360 for 1974.

The thread title says 73, but (perhaps a typo) said "...my 74 Road Runner 340...".

I agree with you - I think 73 was 340 and 24 was 360.

Yes. 1973 was the last year for the 340. In 1974, the 360 replaced it.

 

[GTX JOHN]

On a Stock style engine is a street application you will
not notice any improvement seat of pants over a stock
340 Intake. Especially a 025 or a 318AL last 3 digits intake.
I have raced this combo over 50 years and that is my opinion!

 

[HawkRod]

...A good performance valve job and some new valve springs if they are old doesn't cost much more than a stock valve job.Mill them a touch for a little compression increase.

@Rangepony

The reply above is a great idea. I saw, but didn't think about, that you are having head work done. In 73, the stock heads have smaller valves than the earlier performance 340s. I had my valves enlarged from the stock 73 1.78" (?) to the 2.02" intakes, and similar for the exhausts.
If you are having head work done already, springing for head upgrades are probably the best way to increase a bit of performance. I've said this many times before: an engine is, at it's core, an air pump. The easier to get air in, and air out, the better it will run. The 73 heads can absolutely use some improvement, so for my money (if I had it), I'd rather spend it on the heads than an intake - I believe it is more bang for the buck in your case. The heads are off the car, so now is a good time to do that.

Regardless, make sure you check the straightness of the heads. They may have worked fine, but heads often warp. They will often warp in the center. If you lay a straightedge across the head (in an X pattern, plus straight), the max you want to see is about .002" warpage. Any more than that and you should definitely mill them.

Good luck!

 

[GTX JOHN]

73 340 were 1.88 Intake.
73 318 were 1.78 Intake.

On a relative stock 340 head, I could not
find any difference on a flow bench or at the
track between the 1.88 and 2.02. On a modified
head properly ported = yes there was a difference but
not really as much as I would have expected.

We race a 73 Roadrunner with a 340 in Stock Eliminator so
we have so experience in this combo.

 

[kiwigtx]

I think the original intake weighs around 10,000 pounds.......any recommendations?

Use it as a boat anchor.

 

[496 polara]

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