Induction/exhaust systems

464Saloon

OK time to get the hot rodders going here. I have pretty much lined up everything to do a Twin H on my Hornet. I seem to get about a 50/50 mix on if it will make more power or not than my current 2bbl. Appears to me that most seem to run pretty small on the induction on the Hornet. Most of my experience up till now has been with flathead Fords. I've seen as much as 4 2 bbls on a Ford and fully bored they are only about the same size as the Hornet engine. So why don't more people run multi carbs or 4bbls on the big Hornet engine. Does anyone know the CFM difference between the Twin H and the 2bbl? Actually I was thinking down the road that 2 2bbls on a Twin H manifold flowing around 400 CFM would be perfect, but I had a Hudson expert out here in CA tell me I was crazy and it is a waste of time to spin the 6 more than 3000 rpm. I thought with a good intake and exhaust the 308 would spin 4500-5000 and make power. Speaking of the exhaust, how much difference can headers make? My 2.5 exhaust and Dynomax muffler seemed to help, but it wasn't a breathtaking difference.

[Deleted User]

The engine will not make more power at 4500-5000 and if you stay in that rpm range you will be picking your main bearings out of your pan. Your Hudson expert is right the 308 will peak its torque(ie power) at around 3200 rpm after that you are not getting anything.



Remember this a long stroke engine and its not made to rev its designed to give you torque and below 4000 rpm. When you keep a Hudson flat six at over 4000 rpm for any length of time the usual thing to fail is the number one main bearing.

464Saloon

The Ford is a long stroke too. 3.75 for the 239 and 4.00 for the 255 (Mercury). Actually I think most flatheads are long strokers, just want to know why more carburation works on the Ford but not many do it on the Hudson. They must have spun them pretty good in the Nascar days???? Especially if they were manual trans cars which came with the 4.59 rear end like mine has. Now thats another perplexing thing about Hudson to me. With such a big slow turning inline motor, why such low rear end ratio's? My 51 Ford PU and 55 Ford PU have 3.92's and we all know PU's were not freeway flyers in those days.

[Deleted User]

Marshall Teague said he could wind his Hornets up to 7000 rpm and he came to the factory and did just that the engineering staff were standing around waiting for the crank to blow. Didn't happen. The only difference is Teague took his engines down and did a lot of machine work to get the engine to run the way he wanted. Only caveat to that is he was replacing engines every few races because he drove the piss out of them.

Which is the real difference here. He was racing in Nascar. He wanted to win and thats what you did. Most of us want a nice car to drive. What you get is a car with a lot of torque so reving it high doesn't really get you anything.

The gear ratio issue is something I wonder about most of the old timers I talked to say it was the roads at the time. They geared them for the type of traffic they normally saw. Guess thats why overdrives were popular.

I would hazard a guess that most don't carburate anymore than Twin H because with that you get really good performance and how much do you need. I know a lot of the Hudson race guys have experimented with more carburation. Clifford had a triple carb setup and I have seen four barrels, twin two barrels and the like. Guess if your racing its good but who needs it for the type of driving we do. I just do the cruising myself. (except for the back roads where I drive a little faster)

464Saloon

I really don't know how much better Twin H is. I originally thought it was 2 2bbl's and when I found out it was 2 1bbls, frankly I was disappointed. I wouldn't think if the 2 bbl was better which many old timers have told me then all the race cars, and Jack Cliffords car wouldn't have Twin H. I don't think Clifford would have come out with a 4bbl manifold if it didn't help. I know a few of the guys have made these changes here so it will be interesting to see what they said made a difference and what didn't. So far I have been told my car runs strong, but I am hardly impressed. I think something is holding it up and when I find out I am going to unleash it.

50C8DAN

I would talk to Randy Maas who still races Hudsons to get his input. Edmunds made 2x1 and 2x2 manifolds, Clifford still makes the single 4bbl manifold and also still has the 3x2 Weber manifold. You can run the 3x2 with Weber FI since they can use the DCOE throttle bodies for the FI units. I am not sure many are all that concerned anymore about max output of their Hornets and that may be part of the reason for not having a big interest in this area.

464Saloon

Oh I am not looking for max output, that would be unreliable and unstreetable, just wake it up and catch some unsuspecting people off guard.

[Deleted User]

I know a guy up here who has a Hornet with a Clifford four barrel intake running I think a Holley carb and a Clifford header. It got these parts from Clifford in the early 60's. I thought it was cool to see older hot rod parts. He is still driving it like this today.

J Spencer

I am running Clifford headers, Four barrel, and '56' cam in my 51 Pacemaker coupe with 232 motor. Not as effective as on a 308 i'm sure, but still run OK. I have a 1979 Chevy Quadra-jet on mine. It's a bit much for it tho. Origanally I had a 400 cfm Carter AFB on it and that is probably a better sized carb for it..



This was origanally done in 1986 before I owned the car. I helped insatall these parts though. I still have the Carter Carb and have considered going back to it.



J Spencer

Unknown

I have run the Clifford 4bbl manifold and headers. They work well together. I wouldn't recommend over 500cfm on the carb though. Currently I have Twin H and headers on my '54 and it will probably stay that way for a while. Either works well, the 4bbl is a bit more responsive if set up right.



The Twin H is effective not because of the cfm but the distribution of the two carbs. Each cylinder gets a more effective fuel mix than the 2bbl which can starve #1 and #6 just a little bit. Just my experience...

464Saloon

Interesting. Well I think I am going to see what the Twin H does, then maybe headers. Haven't really heard anyone say if the headers are really worth it or not. Some cars they make a big difference and some they don't. Looking at how they had to neck my 2.5 headpipe down to fit the manifold, tells me the headers probably make a noticeable difference on an engine this big. I am really thinking two holley Weber two bbls on a Twin H manifold might be the best of all worlds. Have to try one part at a time to really see. The 4bbl would certainly be the easiest, but I would think the fuel distribution would be the same problem as the single two.

bob ward

Headers are definitely worthwhile.



I've done before and after dyno tests on a 308 when swapping to headers and there was an extra 7 to 8 HP at the back wheels. Nothing else on the engine was changed or tweaked, just the header swap.

[Deleted User]

don whitekcer used to bore the 308s 7x blocks 125k put in 4 in. caddy pistons and it ended up with 300 hp.with twin h. an artical in a hot rod book said some one in so cal. kocked a 308 out 165k with a 4 1/4 piston and a 6 1/2 in. strock this little hummer runs out at 500 hp. just a thought if you want go fast. Hudson Dave

Unknown

Talk to Randy Maas and he will tell you, torque in an engine is what makes it perform. 308 CID inline Hudson six produces just that and you don't need high RPM. Make it work between 3200 and 3500 and it will remain happy. The twin-H induction may not flow much more CFM then the 2bbl, but it's been said, better fuel distribution to the intake ports is the key. Adding more fuel to a streetable Hudson engine will not make it perform better. With un-modified block, cam and valves the flat head engine does not breath well enough to see any gains from more fuel than a correctly operating twin-H can give.

464Saloon

Well being a 54 it supposedly has a little more cam and some relieving to the block. As I understand the reason the 54's were bumped up to 160 hp. It already had a 262 head on it when I got it so I have no idea what real difference that makes. Anyone have an ideas what cfm the 2 bbl is and what the Twin H is? I might be able to do some measurements and see if one of my blueprinting books has a formula tofigure it out.

7XPacemaker

My 7X is out to 4" with Jahn's pistons. I am running an Isky track cam with a stock twin H and the factory exhaust manifold with 4:11 gears. The car has enough torque to break driveline parts. I would have to see someone bore a 7X larger than 4" to believe it. My cylinder walls are very thin at 4". Not to mention, it is awfully hard to keep this engine cool in traffic. I had a radiator redone for this car, and it now holds almost five gallons of anti freeze! I can at least sit in traffic a little bit without the worry of overheating!

Unknown

I just took off the tunnel ram and two Rochester 2G carbs off my race engine, and installed an old "Edmunds Custom" intake that has been modified to accept two Holley 2300 series two bbls. (500 cfm ea.). Two barrels are not rated the same as 4bbls are. These two carbs actually make the equivalent of a 750 cfm 4bbl. I will be racing it next weekend, and will let you all know how it works out.

[Deleted User]

springspeeddemon wrote:

I just took off the tunnel ram and two Rochester 2G carbs off my race engine, and installed an old "Edmunds Custom" intake that has been modified to accept two Holley 2300 series two bbls. (500 cfm ea.). Two barrels are not rated the same as 4bbls are. These two carbs actually make the equivalent of a 750 cfm 4bbl. I will be racing it next weekend, and will let you all know how it works out.

Which Edmunds manifold variation did you try Dany? I'm interested to know the result.



Don't think I'm not keeping up with this thread, I am with alot of interest. I haven't contributed much because I'm asking myself alot of these questions and getting more and more serious about the answers.



Headers? Definately an improvement. Clifford Headers will not fit with the Twin-H, at present the only manifolds they will fit is thier 4-barrel manifold and the close carb spaced Edmunds variant. They won't fit with the triple weber manifold either. I spoke with Clifford about this and they are supposedly redesigning the headers to work, the two center tubes will need to be repositioned. I knew up front they wouldn't fit the Weber manifold, as Larry told me, so the 3&4 tube modifications are up to me to do. Exhaust restriction is a major power robber with all the stepdown engines, wide or narrow block. The other option is the 7x adapter for the exhaust manifold, which will probably net you about 1/2 the hp gain of headers. At the very least the adapter would help rid you of some heat due to the restriction of the stock outlet.



You can get the Twin-H to work with the headers if you grind off the exhaust manifold flange on the header side. That is the only thing that keeps it from fitting; however, that kinda makes it look bad and I'd much rather use the exhaust porting inside the Twin-H manifold to route water from the heater core tube to convert it to a water heated manifold rather than exhaust. A block off plate on the bottom, water in atop the block side flange, water out the fenderwell flange. The partition inside the Twin-H would force the water to flow around the plenums just as the exhaust gases once did.



The original exhaust manifold leaves alot to be desired in the 3&4 exhaust port. The only snafu Hudson made was the restriction in these ports to accomodate the heater box interface with the intake. Take a good hard look at an original exhaust manifold and you'll see what I'm referring to. The evidence to support this is the cracking of the exhaust seats/blocks - its almost always in #3 or #4 - or BOTH. Most all the exhaust manifolds I have are cracked in the same location - around #3 and #4. Too much heat, too little breathing. The rest of the exhaust ports are on the verge of overheating as evidenced by the valve guides being in such poor shape usually, but the restriction is entirely too much at #3 and #4, just enough too much to chalk up your seats/block if you run it really hard.



Intakes? The jury is still out on that one. This much I have seen in dealing with other inline engines - distribution is very important. Multiple carburetors that even out the fuel/air distribution make a difference in performance. Two carbs are better than one, three is better than two. The same applies to throttle body electronic fuel injection units. If a person were to use direct port electronic fuel injection, the multiple carb advantage is negated due to the fuel being delivered at the same point for each intake port and the air/fuel mixture is the same for each cylinder.



I have a suspicion that the best dual carb manifold is the Twin-H. The intake runner design of that manifold accomplishes the "even" distribution of air/fuel to the ports better than any aftermarket example I've seen, much better than the "narrow" Edmunds. I've not had a "wide" Edmunds to examine. I'm going to venture to guess that Clifford produced the single 4 barrel due to demand, didn't make a dual because the Twin-H was more than adequate, and for the ultimate in performance - the triple Weber. Of all the Hudson pieces reproduced, I'd really love to have a modified Twin-H manifold that would accept the Weber DGV derivatives and/or the Holley 2 barrels and be rid of the exhaust interface in lieu of a water heated path similiar to what the Twin-H already has.



Mark Hudson

EssexAdv

Here is a neat old story. It goes something like.... Teague had a new hornet with twin H and he qualified with the car. The inspectors checked over the car and said the twin H was not approved. Teaque got ticked, pulled the 2bbl of his street car and put it on the racer. He then proceeded to set a new track record with the car. I don't know if the car ran any better but I'm sure his anger helped a lot!!!



Anyway, fro my money the 2bbl car is a lot better car on the road. It starts better, idles better and stays in tune for ever.

464Saloon

Well I just got my Twin H manifold carbs and air cleaners. The air cleaners don't match but I will deal with that later along with getting a linkage. Upon initial inspection, I was quite surprised at the size of the portsand how smooth and even they are. I was expecting to do some porting and polishing, but there really doesn't seem to be much to do. The two center ports have what look to be tubes I assume for the carb heating. I am not crazy about the placement of those, they have to disrupt the flow. I may just pull them since I really don't need a choke here in So Cal. Looks to me to be a pretty good exhaust manifold other than the collector is small. If I can do something with that, I really don't think the cost and hassle of the headers would make much difference except for a race car where every tenth counts.There is a tube on the outside of the manifold that is rotted through. Not sure what it's purpose is other than to supply vacuum to the wipers. Unless it serves another person, I may just block that off.

dwardo99

That's a balance tube. It would be best to leave it on.

[Deleted User]

I just took the modified twin-H manifold that I made into a 2x4bbl intake off my 50

Pacamaker. It had a bad flat spot around 1500 and up to about 2000 rpm.

It ran great up to 1500 but the accelerator pump shot felt dead above this until

2000 rpm. You would have to pump it three or four times to keep it from killing

the engine. Once above 2000 rpm it would rocket to red line at 4800 rpm like

nobodies business.

I was using twin AFB Carters off of early 60's Caddy 390 cubic inch engines. Nothing

I did would correct this problem. These carbs were in real nasty shape when I got

them for free and I think that the rear one has something plugged up causing the

problem.

So off it came and I installed the Clifford 4bbl intake with a new Edelbrock 650

thunder AVS. I pulled it out of the box and didn't have to change anything at all.

I still havn't adjusted the idle mixture screws or the idle speed screw at all!

The difference was night and day. Exellent power from idle all the way to 4800

rpm. No hesitation, no bog, no flat spots- just tire smoking power everyware.

Much easier to drive in traffic without that big dead spot.

My guess is that since it drives so much better that it will be quicker in the

quarter mile with this set up. The low end response is that much better. One

thing fore sure it will be much easier to keep in tune and not eat quite as much

fuel.

Race track here I come...

PaceRacer50

Unknown

The Edmunds Custom intake I just put on my race car is the wide one with the carbs spaced farther apart.

[Deleted User]

I'm also watching this thread with great interest but I'm now wondering if it's worth all this effort. For 300+ HP why not swap to a big block GM/Ford/Mopar and be done with all this inline engineering that may be to outdated for most exceept those that have an inline power axe to grind or true Hudson power enthusiasts?



Am I missing some secret Hudson power point? I don't mean to offend but I'm thinking my original plan of big block power/trans/rear transplants might be easier for more power.

[Deleted User]

ndustrl wrote:

I'm also watching this thread with great interest but I'm now wondering if it's worth all this effort. For 300+ HP why not swap to a big block GM/Ford/Mopar and be done with all this inline engineering that may be to outdated for most exceept those that have an inline power axe to grind or true Hudson power enthusiasts?



Am I missing some secret Hudson power point? I don't mean to offend but I'm thinking my original plan of big block power/trans/rear transplants might be easier for more power.

Yeah, its easier - its also common as cornbread. Its something I'm sick of seeing and the main reason I work with flathead inlines. There is plenty of power in the Hudson to do some serious street storming. The deal is, you won't get it by buying Edelbrock packages from JEGS, which is the attraction to die hard gearheads like myself.



I used to collect $20 bills all night long from guys with big blocks in dainty little camaros - took them away with a really plain looking Impala with a innocent sounding 350. Just having a big block isn't enough, its what you do with it that counts.



To some of us, we live for the guy who strolls up beside us with a transplanted engine, put off our flatheads as archaic garbage - then leave his posterior in a swirl of tire smoke and confusion. Some on here can read that and remember the times they did it - I'm still looking forward to it. I've done that on the antique pulling circuit with a 230 mopar, and looking forward to what happens at a "Rod" function with a Hudson.



Hope that answers your question.



Hud

464Saloon

Well said Hud, the reason for having these cars is for what they are. There are plenty of fast cars with every convenience in the world on them. If that is what you want then go get one, just doesn't make sense to me to take an old car and start changing suspension, drivelines interiors, etc etc, might as well just go buy a new car and be done with it. I wanted a Hornet because it had the special 308 Hornet only engine, other that that it is just like the other stepdowns, which I also think are cool, but the Hornet has the big motor and that is what mine is going to keep.
Now back to inductions. Got my Twin apart and notice that the carbs are pretty darn big. Certainly bigger than the two bbl venturis. My manual says they are 1 3/8 though they measure at 1 3/4 so ?????. Anyway the manifolds are in in pretty rough shape, full of mud and weeds. Almost every bolt broke off taking it apart. It is at the machine shop now for hot tanking and bolt repair. The collector on the exhaust looks to be the big restriction. I am thinking of removing the butterfly and closing off the heat riser to keep the intake cool when I reassemble. Really doesn't get cold enough here to worry about it. What is the story on the tube on the outside? Do you have to have it? My ends are good but the tube in between is rotted out.

`Hudsonator wrote:

Yeah, its easier - its also common as cornbread. Its something I'm sick of seeing and the main reason I work with flathead inlines. There is plenty of power in the Hudson to do some serious street storming. The deal is, you won't get it by buying Edelbrock packages from JEGS, which is the attraction to die hard gearheads like myself.

I used to collect $20 bills all night long from guys with big blocks in dainty little camaros - took them away with a really plain looking Impala with a innocent sounding 350. Just having a big block isn't enough, its what you do with it that counts.

To some of us, we live for the guy who strolls up beside us with a transplanted engine, put off our flatheads as archaic garbage - then leave his posterior in a swirl of tire smoke and confusion. Some on here can read that and remember the times they did it - I'm still looking forward to it. I've done that on the antique pulling circuit with a 230 mopar, and looking forward to what happens at a "Rod" function with a Hudson.

Hope that answers your question.

Hud

hudsonguy

464Saloon,



For what it's worth, when I recently rebuilt my engine, I also cut out the heat riser completely. I used a hacksaw blade by itself, and cut the heat riser cross shaft right at the inside surface of the manifold. Then I tack welded these cut shaft ends to the manifold, just to hold in place. From the outside, it looks no different, and inside is as smooth and clean as can be. You'd never know unless you try to move the counterweight!



Even 'up north' here in Wisconsin, a heat riser is only really needed in the winter, so it's never an issue on a summer car. The car warms up within a few minutes, anyway.

464Saloon

Don't you have to put a plate between the two manifolds also. Looks like the heat feeds up through the center of the Twin H and keeps the manifold hot. I figure if I can block that off and make some type of plenum that feed air from the scoop to the Twin air cleaners, I should have a pretty nice cool charge all the way through. All easier said than done though.

[Deleted User]

ndustrl wrote:

I'm also watching this thread with great interest but I'm now wondering if it's worth all this effort. For 300+ HP why not swap to a big block GM/Ford/Mopar and be done with all this inline engineering that may be to outdated for most exceept those that have an inline power axe to grind or true Hudson power enthusiasts?



Am I missing some secret Hudson power point? I don't mean to offend but I'm thinking my original plan of big block power/trans/rear transplants might be easier for more power.

Here is the answer to the "Hudson secret". It's all in the reaction. Take any Hudson with a Twin-H set up to any car show and open the hood. Now watch everyone stare in amazement. It is self-explanatory!

[Deleted User]

ndustrl wrote:

I'm also watching this thread with great interest but I'm now wondering if it's worth all this effort. For 300+ HP why not swap to a big block GM/Ford/Mopar and be done with all this inline engineering that may be to outdated for most exceept those that have an inline power axe to grind or true Hudson power enthusiasts?

Am I missing some secret Hudson power point? I don't mean to offend but I'm thinking my original plan of big block power/trans/rear transplants might be easier for more power.

ndustrl:

Beauty is always in the eye of the beholder! I have noticed at the car meets around here that the Hudson mystique seems to be age related (no offense guys). I have seen a couple of Hudson originals show up around here and mostly the only people hanging around them are people who probably owned one new (or wanted to and couldn't afford them-as one guy told me). Rarely do you see the "hot rod" crowd googling over them. At a recent event, I saw many more people looking at the SBC powered T-Buckets (which I think tend to all look the same) and the custom chopped 49 Merc, than the original Hornet sedan parked 3 cars down. I have seen this at every car show I've been to around here. Not many folks hanging around the Hudsons, but plenty around the hot rods (though once I saw large amounts of folks checking out a Blown BBC powered Nash Metro!- close relative?). It is probably much different at mostly Hudson meets. I'm not saying thats bad, just different strokes for different folks. Most hot rod guys I talk with think thats okay for purists to drive around with flatheads, but not many give them a second look. I think its the main difference between "hot rodders" and purists.....purists want to maintain the original integrity of their autos, and hot rodders want to update their cars with more modern drivetrains, suspensions, etc. That has been the root of hot rodding since it began. Each side will have their own arguments and neither side will ever convince the other to change. I think thats probably a good thing. Leaves some variety in the auto world.

But (ha ha) having said that, I can see no reason for keeping a flathead if you want modern performance. If flatheads were such the rage, they would still be making them and you'd see them in most of the new cars and trucks. In fact you don't. The main idea in hot rodding is that you can take any old car with great body styles (of course you can also do this with newer cars), update the drivetrain and suspension, make some cool body changes if you like, and drive the heck out of them. If this wasn't the case, why do we have such a large aftermarket industry? If everyone believed you have to have a new car to enjoy newer drivetrain features (and thus never modify an old car), there would be no hot rod industry, just a bunch of people driving Miss Daisy! Sorry, but personally for me (and this is just me), I wouldn't own an original....way too boring for me. Some even will hot rod a flathead. And thats fine for those who wish to, I don't take that away from them. At least the originals and the hot rod cars aren't being crushed!

So the decision is yours! :-)

Jay
...another darn scorpian in my yard today!.......

[Deleted User]

Back to induction and the venerable Hornet Twin-H



I also have one of those less than perfect Twin-H intakes with the rusted out heat chamber. Not only that, but the freeze plugs were rusted out. The intake side is good, the heat side - BAD.



What I had intended to do was cut out the interior partition and plumb the heater tube through the manifold via the freeze plug holes. Also, use a plate to block off the exhaust manifold from its original circulation through the intake. A water heated intake and no more exhaust gas circulating.



I may still do that and modify that particular manifold to work with headers, someday - LOL.



Mark Hudson