motor cut-out install ??

[Hydrive53]

Thanks for all the input, I just wanted to put one of these thing on my X-brand car for the fun of it. Sounds that there is not to much to wory about in the way of motor damage. So I think that I my put one on the car when it comes time to do the tail pipe work. ;)

[David Pollock]

I do not believe a cut out is worth the trouble to install but I do confess to having one at one time.  Carla mentioned the traditional split manifold and I agree with him, not so much for the performance but for the pleasing sound that a Chrysler product six with a split manifold makes.   Music ! Sounds just like an Austin Healy 6 or a Corvair with duals.   If I wound  my 52 Plymouth coupe with the Canadian engine ( 4 1/16 stroke) absolutely tight, it would make 5000 rpm in low gear according to the tachometer I had. ( OK fellas maybe it was a cheap tach, and the older I get the faster I went) but at 40 mph in low, the intake valve on #6 would float and hammer the spark plug gap shut. Find a side street and do a quick regap and get on out there again. I remember one time pulling out onto a major thoroughfare and putting the pedal down hard only to have the engine crap out due to fuel starvation at the 30 mph mark.  Good thing too because the cops had a radar trap right in front of me.  This car had the dual intake dual exhaust used on some 3 ton Dodge trucks.  We still have the manifolds but they are now on a 47 Dodge panel.  If only I could hang out the back doors while driving, so I could enjoy that stereo exhaust....

[12905]

There are pros and cons to installing exhaust cut outs. A well-designed, freely flowing exhaust system actually helps to scavenge the cylinder of exhaust gas. If back pressure is minimal, and the exhaust pipe immediately aft of the manifold outlet is able to dissipate heat quickly the resultant drop in pressure in the pipe and manifold helps to clear the cylinder during the final moments of the exhaust stroke. If there is no pipe at all aft of the manifold, the gas faces no back pressure, but also loses the ability to work as a scavenger.

This is one reason why 'splitting' a manifold works well - two pipes to cool outgoing gases and reduced back pressure.

At one time I was pretty sceptical as to whether or not having a well-designed exhaust system, especially ahead of the muffler, helped to improve cylinder scavenging, but after witnessing many dyno 'before and afters' I became a convert. I guess what I'm really trying to say is that a cut out properly sited will help, but one too close to the manifold most likely will not.

[Carla]

Years and years ago, some number of car owners would have a cut-out fitted, usually a lever or cable-controlled one which could be operated from the normal driving position whilst on the road.

The idea, or so it would appear, was that they would have a really quiet muffler fitted for city driving, and the option of opening the cut-out for whatever hp gain the nil back-pressure in the exhaust system would provide, once on the open road.....also, in the days of manual spark advance and manual main jet adjustment, it was easier to 'feel' or 'sense' the optimum spark and fuel settings by listening to the exhaust bark when the engine was under load.

Back in those days, the common type of 'quiet muffler' was most likely to be a really restrictive one. Today, relatively quiet free-flow mufflers are an 'off the shelf' item at any good exhaust supply firm, so the most practical arrangement, in my opinion, would be to simply fit a new best quality straight-through, or free-flow muffler.

For many of the older engines, a very worth-while modification is to 'split' the exhaust manifold, and fit dual exhaust pipe/muffler assemblies. The 'splitting' work, which is simply welding an additional outlet to the original manifold, can be done by any good welder who specialises in cast iron repair welding, but probably really should be sent to one of the specialist welders who advertise exhaust manifold modification. A look at the 'Inliners' web-site would find a few of those. After the manifold is done, any good specialist exhaust system shop can bend the pipes to suit.......a little detail to remember is that the earlier versions of this work.....unlike the '50's hot-rodders' style.......usually had both pipes coming out at the same side, at the back of the car.

I've done this manifold work myself, a number of times, and recommend it for any older car which is regularly driven. The gain in performance over an original exhaust system isn't 'spectacular', but is certainly worth-while, particularly if you run roads with moderately steep hills.

There are, of course, some people who might object to this mod, on grounds of 'originality'......personally, I take the position that, if one uses early pattern free-flow mufflers, and does the work as it would have been done when the car was new, or nearly new, it is about the same as fitting a 'period accessory', in terms of 'maintaining originality'.......after all, this mod was written up in some of the automotive magazines back in the '20's, maybe earlier. I'd be curious to hear how others here might feel about this, tho......

cheers

Carla

[57plymouth]

Are you referring to exhaust cut-out's?  If so, I just put a set on a buddy's 454 El Camino SS.  There is no adverse effects, and they helped his 1/4 mile times.  They will attract law enforcement attention when they are open.

[Hydrive53]

I am thinking of putting a motor cut-out on one of my cars (1930) X-brand. It has a in-line eight motor. I have never seen one of these things on a car, or seen them work for that matter. I would like to know the best way to install this thing, and make it work. Also is there any BAD side affects of putting one on the car ?? thanks for any help.