Which intake do I use?

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cecil4speed

cecil4speed

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I just got an 850cfm thermoquad from demonsizzler. I have a stock OEM intake and an LD4B. I realize the LD4B is a 318 port size intake, but I'm wondering if I would get more torque on the bottom end with this intake or the OEM. I can always port size the LD4B this winter when I have more time, if you think this one is better. I would have to use a carb adapter with the LD4B. Would this help torque and take away. Is there enough material to grind the carb mounting area out for the thermoquad or would I be better off to use the adapter? It is an open hole 3/4" thick adapter. I'm not sure what is in the eng for a cam, but I'm assuming a Purple shaft. I'm running a fairly stock '69 340 engine, hooker headers with 2 1/2" exhaust, 4-speed with a 3:55 diff. I'm looking for the most bottom and midrange I can get. Thanks in advance guys.
 
On the subject of a cam, you might want to make certain that you have a cam that would maximize power in the RPM range you desire. The proper cam would have alot more impact on low-midrange torque than the difference between those two intakes and whether or not you have a spacer( which in general help higher RPM power). If you have the intake off your halfway to installing a new cam. Purple shafts are fine cams but not exactly cutting edge technology.
 
I ground out the plenum flange on an LD4B no problem - much better idea than using an adapter.

Be aware also - that its only the port openings that restrict the 4B , the runners are the same volume as the LD340.
 
I know I don't have the right cam in the engine now, but I plan on changing it this winter. It's a matter of money right now plus I don't know exactly what to get for a cam. I'm thinking a thumper cam, any other suggestions?
 
Check out the Comp XE High Lift series. ( like the XE275HL) . They have a lobe profile designed for the .904 mopar lifter that is the latest technology. Never hurts to call the cam manufacturer's 800 number tech line and give them all the specs on your car i.e. weight, tranny type, gear ratio, compression, etc., and let the guys who live and breath cams pick the right one for your application.
 
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