67 special engine awap

[robs67gsspecial]

hello team buick just bought 67 gs special original 340 enigne .would ilke to increase hp.is there any aftermarket intakes out there. if not does a350 swap right in

[Dr. Frankenbuick]

Rob,

There are no aftermarket manifolds for the 340. It might respond to a good tune up as the 340 can definitely get out of it's own way when tuned-in. There are cam and carburetor improvements that are available. There had been headers available, but no longer. The engine responds well to rear gear changes (3.08 and numerically higher) and a three speed trans (TH 400, TH 350 or an over drive 200-4R). The TH 350 and 200-4R will use the same driveshaft with minimal changes. A good dual exhaust system would also help.

We have the 67 Chassis Service Manual in the reference section here. It would go a long way in aiding you with a tune up, and it also lists the various engine, trans rear end combinations that were available then if you want some ideas.

[65specialconvert]

Sanderson does still make the headers for the 340.
https://www.premierstreetrod.com/det...0_Headers.html
But for the money,I don't think you'll see much improvement over the factory manifolds.I had mine port matched & honed

[bob k. mando]

There had been headers available, but no longer.


the Buick 340 has the same exhaust layout as the Rover 4.6L, so that's where i'd go looking for a premade set nowadays. be careful that the ID for the Rover headers is larger than the 340 exhaust ports, that would be an ugly reversion step if it was too small.



is there any aftermarket intakes out there.


no, any custom intakes would be from the Rover engine ( 3.5L, 4.0L, 4.6L ) and would all require spacer plates to even fit your engine due to it's taller deck height.

the bad thing about the 340 is that it was only a two year production ( 1966 and 67 ) engine, with a different deck height than all of the other 'Rover style' ( 215, 300 and Rover ) engines in the family.

this means if you want an aftermarket intake you'll probably need to learn to TIG weld.


if not does a350 swap right in


there are a couple of minor changes from the 340 to 350 ( bore size, valve layout, cam order change because valves are in the 'wrong' place ) but externally it should be almost exactly the same size.

you can grab an HEI distributor off of a late 70s Buick 350ci and it will drop right in.

[65specialconvert]

Your calling this a 67 GS Special....all 67 GS 340 cars are Specials & kinda hard to find.Is it infact one of these cars? If so,you might consider keeping the 340 instead of doing a 350 swap.Post a picture of your car.

[robs67gsspecial]

thanks for the info I believe car was assembled and mfg. in California will try to upload a picture of body tag if I am right the 340 special cam as a coupe with bench seats which this has it is originally artic white as well