Id like to place an Aussie Hurricane manifold (2 barrel) but I have some doubts:

–Could I use it with positive results keeping my original camshaft?

–Do I have to increase the compression ratio?

And finally:

–Will I get more torque in case of placing this manifold without any other change in my Slant? I mean, will I increase acceleration power in green light or in final speed?

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Mopar or no Car!

You can accomplish quite a lot keeping the original cam. I knocked 2 seconds off my 1/4 mile ET and retained the stock 1967 mechanical cam. With good good intake and exhaust systems the head will be the next choke point. My personal opinion is first use a free flowing exhaust system, then the carburetor and intake. If you can afford to do head work a more comprehensive upgrade is larger valves, some mild port work, cut the head for increased compression, carb/intake and exhaust system. This is what I did for my Valiant to go from 19.2 ETs to 17.0.

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Joshua

My head is already lower (0.5 mm), I have competition metal gaskets (0.7 mm) and flat head pistons, so the compression is already higher than the original.

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Mopar or no Car!

I forgot... My Slant came originaly with a compression of 7:3, I guess now (with those changes) it must be 8:2 or may be more...

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Mopar or no Car!

I had to cut my head .080" to get a true 8.5:1 compression ratio. Have you measure the deck height of the pistons and the volume of the combustion chambers?

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Joshua

No, I just changed the pistons (they were low compression), gasket and cut the head 0.5.
Our Valiants III (Dodge Dart, 137 HP) came with low compression pistons, two years later came the Valiant IV (Slant RG, 145 HP) with high compression pistons, and the compression ratio was now 8:2. I think that was the main difference, cause heads are the same.

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Mopar or no Car!

Without measuring your deck height and combustion chamber volume we can't calculate the compression ratio. What was supposed to be an 8.4:1 engine here measured only 7.7:1. That was an early '70s 225. My '67 225 was 8.0:1 before installing the milled head.

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Joshua

That is true, Is hard to say without measuring... sometimes a simple thing like a gasket changes the numbers.

But, according to your experience, I wouldnt have any problems installing the manifold.
Will I loose some torque or power in low range of RPMs?

What will I win?

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Mopar or no Car!

To make the best use out of a long ram manifold the efficiency of the engine needs to be increased...

Bolting one onto a 8:1 is just not going to do it (you'd get less headaches bolting a short ram 4 barrel on the stocker engine). The manifold is usually selected to provide ram tuning at a specific rpm range...typically you also would select the cam and compression to support this, also thinking about a cam in mind with a shorter overlap event to keep the pressure wave from reverting back up the runner and spoiling some or most of your fuel/air being ram delivered.

To get the manifold to deliver at street/highway rpm...It's best to build with someing in the mid-9:1 range...a short overlap cam similar to the RV15 cam would be plenty and a little more lift than stock (but not a huge amount as that can cause things to get 'lazy' in the runners). For more low and midrange torque get the manifold plenum separated so each end of the engine sees 1/2 of the carburator (i.e cylinders 1-3 sees a primary and secondary side of the carb, and cylinders 4-6 sees the other primary and secondary on the carb).


-D.Idiot

Good info! Thank you. Ive been looking for a special cam, but I cant decide which is better. Ive always defended the idea that the secret for a good performance is in the ignition and in the correct tune up of carb and distribution.
But the hyper pack has always been my dream! Id like to get a cam shaft that came in ours Valiants GT, its a 276 dur. cam.
The more powerfull cam that COMP CAM offers is a 264 or so... Someone offered me a 280 Mopar cam, but only the cam, no springs and valves. I think 280 is too much. May be a 275 or less would fit my requeriments.
My actual carb is a 500 cfm 2 barrel Holley.

I want more torque, not a RPMs cam.

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Mopar or no Car!

No that's about right...

I ran a 10:1 SCR motor with 1.70/1.44 OS valves, clifford Hyperpak, Dutra Dual setup and the Erson 280/270 and a Holley 390cfm Vacc secondary...Pushing a 3200-3300 lb Duster with 3.55's and the A-833OD...regularly got 21 mpg on the highway (24 mpg all highway to and from the Medford Race that year ran in the 16's).

-D.Idiot

I will go a bit against the grain here and propose that the Hurricane long runner 2 bbl intake would work pretty well on a stock cam engine, OR a big cam, high comp engine. The long runners will suit the low torque/HP range of the stock cam engine, That intake has fantastic low end throttle reponse on my bigger cam engine. It is probably the most responsive intake (low end) I have used. I have just replaced mine (w/Holley 500 2bb) on my race motor since I think it is holding the engine back above 5500 RPM. We will see what the Clifford 4bbl and 650 4bbl does for it on the dragstrip and road course.

Headwork is the best way to get big gains, as Josh said. You can do a lot without even having high compression or a big cam, although those will also help you once you have improved the head. Even a true 8.0:1 comp is better than stock and can let you make some power.

Again, I can't say for sure if that intake will work well on your engine, but my guess is it would work better (power-wise) than a stock 2bbl or 1bbl intake/carb and would probably have similar response.

Just a few ideas...

Lou

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