You've heard it before ?

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Matt Gentile

Active Member
Joined
Jun 2, 2018
Messages
36
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25
Location
MA
First slant six in my Mopar career...always 440's...now I want the challenge of the six that's in my newly acquired 68 Valiant . I have headers ( 2-3's ) , a Clifford intake ( with a single , dual and four barrel adaptors ) , will be doing an electronic distributor and full dual 2 1/4 exhaust...to start . So to start off , what carb ? Looking at a 390 cfm Holley 4 bbl or a 350ish cfm 2 barrel Holley ? Prefer not to dig into the engine , looking for reliability first , but if something looks do-able well....

So anyways , I'm open to most anything as this route is all new , so what do you'ze guys think ?

Thanks .
 
I think you should post this in the /6 section.

What are your goals for this engine and car?
 
First slant six in my Mopar career...always 440's...now I want the challenge of the six that's in my newly acquired 68 Valiant . I have headers ( 2-3's ) , a Clifford intake ( with a single , dual and four barrel adaptors ) , will be doing an electronic distributor and full dual 2 1/4 exhaust...to start . So to start off , what carb ? Looking at a 390 cfm Holley 4 bbl or a 350ish cfm 2 barrel Holley ? Prefer not to dig into the engine , looking for reliability first , but if something looks do-able well....

So anyways , I'm open to most anything as this route is all new , so what do you'ze guys think ?

Thanks .
A few years back I built a /6 in a little rat rod , Put an Offy 4 barrel intake ,390 holley and performance cam in and it ran great.
 
You really need to up the compression to take advantage of any external mods. I decked my block 90 thou and cut the head 10. Should up the CR to around 9.5 to 1. I haven’t decided whether to go 4 barrel or triple Weber’s
 
A few years back I built a /6 in a little rat rod , Put an Offy 4 barrel intake ,390 holley and performance cam in and it ran great.
I use a 350 holley with pertronix and dual exhaust with Dutra manifolds, 833od. Lots of fun and i can cruz at 65, 75 very easily!!! Lots and lots of fun!!!
 
First off, nice score on the 68 Valiant. I'm jealous, while keeping an eye out for the same car. I agree with all the above advice. Making a master plan is important, what are your goals for the car? With a slant, balancing complementary parts is a huge part of improving performance as opposed to throwing parts at the project. Doing the HEI ignition and recurving your distributor are a good start. Living in MA, unless you only drive this on only your hot summer days you will regret not having any intake manifold heat. Does your Clifford manifold have the water jacket? A far better route for a street driven car than headers are Dutra Duals. Yes, they are now more expensive since they were bought out by Aussie Speed, but they really work and are worth the coin. If you don't want to get into the internals, you are wasting your time and money with any 4-barrel carb. You need a bigger cam, more compression, and head work to get any benefit from a 4-barrel. The 2-barrel Holley is a better way to go (or a Carter BBD, or a Ford 2100). For exhaust, on any slant full duals are not necessary. If you want them because you like them, then fine. But it's extra weight that won't improve your performance a bit. A single exhaust properly set up will be better and cheaper.
 
For a little kick and efficiency I addressed my Six with (and this is a ‘77 model engine) a Mopar elect. Ign. With orange box and HO Accel coil. Then moved to an open element 14x3 K&N air filter, a Super Six intake and 2bbl Carter BBD, Hooker headers 3into1, real 2 1/4 aluminized dual exhaust w/ H pipe. 2 Glas Pak mufflers out to the back. A Nippondenso HO alum. starter for giggles. An 8 3/4 out back with a 3.23 gear set doesn’t hurt either, Auto. 904 all packaged up in a ‘70 Challenger. I think it sounds and runs great, nothing really over the top. Just damned efficient with 87 at the pump.
 
Mill the head, and choose a camshaft based on your rear ratio and compression ratio. Adding more gas and air to a stock slant camshaft is death.
 
3.40 x 4.125, makes a swept of 613.72;That's
~9% more than a 273(562.2), and
~94% as much as a 318(652.27).
that's a lot, eh?
Huyp, that will make, making cylinder pressure, a little easier. And you only have to cut ONE head, and it doesn't mess up the valley seal,lol.
 
6 cyl. w/ glass packs ? -----------------
not as bad as it sounds Bob! 2, 26” on each pipe with the H pipe connecting the two separate pipes together, at idle at the back it has a nice almost small block rumble.when I take off then you get the 6 cyl. sound. Thanks, Al
 
not as bad as it sounds Bob! 2, 26” on each pipe with the H pipe connecting the two separate pipes together, at idle at the back it has a nice almost small block rumble.when I take off then you get the 6 cyl. sound. Thanks, Al

I just changed solid roller cams, mine makes more noise underneath now than it did w/ a hair bigger cam ???
 
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