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340 intake suggestions

Posted By: 19cuda73

340 intake suggestions - 12/31/10 05:33 PM

I'm rebuilding a 340 and I want it to look stock when complete. It has a mild cam 202 heads and 10 to 1 compression. I have a stock intake but would like any suggestions for another dual plane mopar intake that works with the thermoquad 6318. Or should I just keep the original one on it? Thanks for the help
Posted By: stage3

Re: 340 intake suggestions - 01/01/11 02:23 AM

I always run stock intakes with my T/Q. That said I did buy a very good LD340 that I modified to fit a T/Q ..did not port match or finish. I feel from people that have run them they are one of the best dual plane intakes. Like I said I like stock intakes and if interested it's for sale.
Posted By: ScottSmith_Harms

Re: 340 intake suggestions - 01/01/11 06:14 AM

The stock cast iron intakes flow suprisingly well, the only real drawback is weight, they are heavy suckers weighing as much or more than an iron 440 intake! As mentioned above, the Edelebrock LD340 is a good one but I'd skip right to the modern version, the Edelbrock Air Gap. the carb you have is an EXCELLENT carb, should be no worries there with a proper rebuild,
Posted By: ademon

Re: 340 intake suggestions - 01/01/11 06:53 AM

You may have to run a spacer with the air gap, i modified a 71 340 intake haven't run it yet, but i did mill the divider and slightly enlarge the plenum area, Hit all the turns trying to radius them to a nice rounded turn, then gasket matched the ports as far in as i could get with a 6" bit, also got rid of some of the lumps on the roof of the ports. Then made a larger oil splash shield for the bottom of the intake. Have about 20 hours in it and you would be surprised how much metal was removed.

Attached picture 6389602-71Demon340(92).jpg
Posted By: ademon

Re: 340 intake suggestions - 01/01/11 06:54 AM

2nd

Attached picture 6389606-71Demon340(90).jpg
Posted By: ademon

Re: 340 intake suggestions - 01/01/11 06:55 AM

3rd

Attached picture 6389609-71Demon340(94).jpg
Posted By: ademon

Re: 340 intake suggestions - 01/01/11 06:56 AM

4th, i would at least mill the divider if its going onto a hotter mill

Attached picture 6389615-71Demon340(96).jpg
Posted By: JonC

Re: 340 intake suggestions - 01/01/11 06:27 PM

Quote:

You may have to run a spacer with the air gap, i modified a 71 340 intake haven't run it yet, but i did mill the divider and slightly enlarge the plenum area, Hit all the turns trying to radius them to a nice rounded turn, then gasket matched the ports as far in as i could get with a 6" bit, also got rid of some of the lumps on the roof of the ports. Then made a larger oil splash shield for the bottom of the intake. Have about 20 hours in it and you would be surprised how much metal was removed.



What advantage to milling the divider???
Posted By: GO_Fish

Re: 340 intake suggestions - 01/02/11 12:09 AM

removing most of the divider was a common modification on LD340's and advised by Direct Connection back in the day. I think later LD340's came from the factory with the divider removed.

It helps performance by making the intake a little more hybrid, that is giving the dual plane manifold some single plane characteristics.

Nice modification work done on the iron intake pictured!

I've read you don't want to polish the intake ports, you want them a bit rough to help keep the fuel vapor in suspension/ atomized. Smoothing them out is fine.
Posted By: 19cuda73

Re: 340 intake suggestions - 01/03/11 06:19 AM

Thanks for the info Will the thermoquad fit on the Air Gap?
Posted By: 70AARcuda

Re: 340 intake suggestions - 01/03/11 06:45 AM

Quote:

Thanks for the info Will the thermoquad fit on the Air Gap?



only with an adapter..the air gap has a square bore carb flange.
Posted By: Paul_Fancsali

Re: 340 intake suggestions - 01/03/11 09:53 PM

Unless your going over 7000 don't waste your time on milled divider. I have both a milled and stock and I ended up going back to divider as it will slighltly affect the low end performance. I know it will give bump less then .05 over 6000 but frankly won't run my engines over 6000 if not needed. But then agin thats my experiance and it was running with Holley Dbl pumpers not a TQ I ran a TQ for 5 years and never once got performance that a DBL pump will give but I also lost gas mileage using the dbl pumper. But frankly .4 or more in a qtr is worth it with a dbl pumper
Posted By: thedriver

Re: 340 intake suggestions - 01/03/11 11:24 PM

Quote:

Unless your going over 7000 don't waste your time on milled divider. I have both a milled and stock and I ended up going back to divider as it will slighltly affect the low end performance. I know it will give bump less then .05 over 6000 but frankly won't run my engines over 6000 if not needed. But then agin thats my experiance and it was running with Holley Dbl pumpers not a TQ I ran a TQ for 5 years and never once got performance that a DBL pump will give but I also lost gas mileage using the dbl pumper. But frankly .4 or more in a qtr is worth it with a dbl pumper




i always read that my air gap intake would benefit from an open 1" spacer, so i ran it that way. then one day a fellow advised me to try a 4 hole.
the tourque i picked up downlow was way more beneficial than the 6000rpm+ gain the open spacer gave me....
i guess thats why we dont race dynos tho.
Posted By: GO_Fish

Re: 340 intake suggestions - 01/04/11 01:03 AM

The carb spacer is another issue. Generally a 1" will help performance, but from what I read, a 4 hole spacer is usually better unless the engine is full race.
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