I've got a 65 Valiant 4-door with the 170 Slant Six that runs decent with the Holley 1920 1bbl. But I want a little more kick if possible plus I may want to add an underdash A/C. I know this a 1966 170 block and rebuilt before with not many miles on it but milegae unknown. I see the Offenhauser 4bbl intake is just like a stock setup. I know there are issues converting to a 4bbl because mine uses the rod type throttle. I see that Offenhauser sells a 4bbl cable conversion kit. Is that all I'm going to need to install this? Or will it be more trouble? This one also has an automatic with the cable operated transmission. Is it worth the trouble? What's a good carb, not knowing what cam is in this engine? Probably just a stock cam. It was just a driver. I know the 170 was rated way lower in power compared to the 225. My 65 actually came with a 225, but for some reason someone put in a 170, probably couldn't tell the difference. I bet they did after they drove it though.
How easy is the Offy Slant Six manifold 4bbl setup?
- Thread starter wh23g3g
- Start date
-
C130 Chief
Mechanical Genius
The V-8 cars used a cable throttle. If you get the pedal linkage off a 64-66 V-8 car you should be able to fairly easily adapt a new cable of appropriate length. I would think the little 390 CFM Holley should be about right for a 170.
805moparkid
Slant and AFX Guy
you'll not see much even with headers... you need to yank that head and have some work done and a good shave approx .090. then the 4 barrel will really work for you
You need to measure combustion chamber dimensions, employ a compression calculator to design your performance up grade. As stated above; “Have some work done”, includes gasket matching, mild porting, oversized valves, larger diameter exhaust, and most likely a camshaft up grade. A stock /6 head and cam just won’t flow enough to take advantage of the smallest 4V carb.
Then there is the drive train side of a performance up grade. One has to be careful to resist “mission creep” on these projects. Best bang for the buck up grade would be to install a factory Super Six set-up with larger exhaust system.
There are members here and at slantsix.org that have successfully retained their throttle rod linkage system with swapped carbs. You have to mount the carb sideways (rotate it 90 degrees) and then make an adaptor to attach it to the carb, but it allows you to retain your factory kickdown linkage and accel pedal.
roadrunnerh
Well-Known Member
Not to stir the pot too much, but......
Why is this 4bbl swap on a Slant 6 so polarizing?
Ther ARE people who have completed this swap on a stock 225 and reported a noticeable gain in pick-up. Then you have a lot of guys (especially on /6 .org) that insist you need to make 5 other mods to even notice an increase in performance.
So you guys are saying "there will be no performance gain swapping a 390 4bbl on a stock motor"?
Why is this 4bbl swap on a Slant 6 so polarizing?
Ther ARE people who have completed this swap on a stock 225 and reported a noticeable gain in pick-up. Then you have a lot of guys (especially on /6 .org) that insist you need to make 5 other mods to even notice an increase in performance.
So you guys are saying "there will be no performance gain swapping a 390 4bbl on a stock motor"?
6pakattack
Well-Known Member
Well I for 1 will say that when I milled the head.090,hooker headers,and a 390 carb, I was totally satisfied with the seat of the pants feel as well as having a kool sounding / that still got 15mpg's !!
805moparkid
Slant and AFX Guy
well look at it this way... go onto the killer bees racing site and look at the times and mods. alot of people are running 18's with intake and headers, maybe even a cam. i did that on a STOCK engine, no compression increase, no oil pressure, and 300K miles. my point being that the stock slant head isn't big enough for a STOCK engine, why why would making the hole on either end make it better?
it not like popping the head off while you have the manifolds off and have it cleaned up is hard or expensive, especially with a pre 73 soft seat head.
I had a stock set up on my 66 Valiant when I got it and it took (seems like) for ever to get up to 4.500 rpm's , getting about 17 mpg..
I removed every bit of the small exhaust system... manifolds was split with 305 flanges put on each exhaust manifold... an Offenhauser 4bbl intake with a newly rebuild on my 390 Holley... Pulled the old spark plugs out and installed a set of NJK plugs..changed to mopars electronic ignition. Did I feel the difference... Yes I did and got better mpg, getting 21 to 22 mpg..
I agree that doing a supper six 2 barrel intake and removing the small pipe/exhaust system and go 2 1/2'' pipe to a new muffler then do a 2'' tail pipe..... These little slant six engines in stock form needs a little back pressure and this could be a problem some /6 builds are missing by going big pipe
I added a recurved distributor and that alone did help to keep the nose up all the way threw the gears ..
I have had this system on the road for 3 years now all stock /6 running a cool 11.27 1/8 mile
I had some folks say why did I run 2 into one exhaust, because I listen to good advise and it was the smart move for my stock 68.000 mile /6.
Nothing pretty to look at but this system works, it may have had allot to do with the carb getting cool fresh air but I did all these upgrades at one time after doing all the bearings front and rear, not that they needed it everywhere bit I believe if they role easy it will take less hp to move them
sorry so long winded but I just had to put my experiences I have learned in here .
I removed every bit of the small exhaust system... manifolds was split with 305 flanges put on each exhaust manifold... an Offenhauser 4bbl intake with a newly rebuild on my 390 Holley... Pulled the old spark plugs out and installed a set of NJK plugs..changed to mopars electronic ignition. Did I feel the difference... Yes I did and got better mpg, getting 21 to 22 mpg..
I agree that doing a supper six 2 barrel intake and removing the small pipe/exhaust system and go 2 1/2'' pipe to a new muffler then do a 2'' tail pipe..... These little slant six engines in stock form needs a little back pressure and this could be a problem some /6 builds are missing by going big pipe
I added a recurved distributor and that alone did help to keep the nose up all the way threw the gears ..
I have had this system on the road for 3 years now all stock /6 running a cool 11.27 1/8 mile
I had some folks say why did I run 2 into one exhaust, because I listen to good advise and it was the smart move for my stock 68.000 mile /6.
Nothing pretty to look at but this system works, it may have had allot to do with the carb getting cool fresh air but I did all these upgrades at one time after doing all the bearings front and rear, not that they needed it everywhere bit I believe if they role easy it will take less hp to move them
sorry so long winded but I just had to put my experiences I have learned in here .
-
