If you decide to do the thermoquad swap,make sure you get a spread bore intake or the tq won`t fit. the bolt pattern is different and the back butterflies on the tq are much bigger than the regular manifold.Up until 1970 the 340 came with a carter avs carburetor but in 71 they came with a thermoquad.Back in the day I replaced an eldebrock ld 340 intake and a 750 cfm holley with a stock dual plane 71 intake and a 850? cfm thermoquad off a dodge motorhome and was amazed at the difference it made.I always thought the tq was great for the street because the primarys are small and dont waste fuel when you`re just cruising but when you step into the secondarys---hello! Carter used to make what they called a strip kit for the tq which was different metering rods but I dont know if you can still get them.Those magnum heads breathe ALOT better than your old stock heads.You need more fuel to feel the gains you`ve made.I think you will be surprised when you feed that thing some fuel.Please keep us informed

 

Well have you been up the road and back in it yet?

 

Thanks for the heads up. Another reason to get a Q-jet I guess

I've only babied it around town a bit but it sounds like everything is working like it should. No valvetrain noise. I'm trying to get ahold of those 4bbl parts now and get them installed before I swap out the break-in oil and really get on it. It's just not fair to judge yet with that 2bbl strangling the power. I've got some calls to make next week but it's looking like I'll be getting an '86 4bbl intake and Q-jet needing a rebuild. Another week or 2 and this rig should be on the highway towing my boat to the Lake. Hopefully it does better than it did last time. That pic I'm using as an avatar... that's me broken down on the side of the interstate towing my boat last summer. I had to have the truck and boat towed back home in shame. Needless to say, this truck has a lot to prove.

 

One thing on the Q-jet rebuild. If you've never done one,be sure to JB Weld the plugs in the bottom of the main body directly under the jets. These are about5/16-3/8' in diameter. They are prone to leaking,and willcause hard starting and oil dilutionafter the truck sets a while because itdrains the bowl. You gotta cuss and crank till it gets fuel again. Have ever adjusted the secondary air doors on a Q-jet?
If your luck's like mine,the boat'll quit next.[:@]

 

PLEASE OH PLEASE don`t put a qjet on a Mopar.They don`t belong there and it`s like a crime against nature.I know it`s your truck I just thought maybe you needed my unsolicited opinion.By the way qjets are spread bore carbs too.

 

And I blame the boat for the truck breaking down.bad boat

 

Too late! I've got an '86 intake and carb en route. If it's junk you can say 'I told you so'

Will do.