Looking for any info on where to get or what they used on the Twin engine dragsters like the FREIGHT TRAIN. I am getting ready to start on a Twin Inline SBC set-up in a '32 pontiac as soon as I finish Mammas Henry J. How the hell do I couple the dam things together. What are the common problems I am going to run into. Any info would be greatly app.
You could have a flange made that bolts to the flywheel of 1 and the crank snout of 2. Or, if 1 won't have a flywheel, a crank flange to crank snout coupler could be machined up. I'm not sure what your plan is, but if I were building an inline setup like yours, I'd put starters on both motors. That way a single starter dowsn't have to spin 16 high compression cylinders. It would also be easiest if the engines were both internally balanced so you don't have to worry about balanced dampers/flywheels.
Didja' do a search? Someone posted a pic of such an item here that mod bog pull guys use to couple engines. BTTT for ya... -bill
scs out of belleview ohio is makes what a lot of pulling tractor guys use....i have a portion of a coupler that was in a late 60's fed with 2 427's......its basically 2 sprockets ****ed together and a chain to hold them together......just not sure how they attached to the motors.....brandon
I have no experience in this particular area but it would seem that if a guy were to couple the front motor to the back motor with a bellhousing and clutch in between, the clutch could be disengaged to the front motor, start the rear motor and then engage the front clutch to start the front motor. There are probably better ideas out there from people much smarter than me.
Good idea. Being able to run the motors seperatly would also probably aid in tuning. However, them you run teh risk of the motors being "out of phase" with eachother. instead of the cylinder pulses being timed like a V16, teh phasing would be random which could lead to wierd harmonics and bad vibrations.
Brandon hit the nail on the head, I got to do a walk around on a twin inliner a bit ago, they used a sproket on the front pully of the rear motor, a sproket on the crank and a industrial lookin chain wrapped around the two (***emble the clinch pin whilst installed) unfortunatly I didnt look at the starter though I believe he was only using one....
I believe it's a good idea to machine a second keyway (180 degrees opposite) in the snout of the rear engine. A single key won't handle it.
Lot of good ideas. I'd planed on double or tripple key waying the crank. i know that 8th Grade Genius spun a brand new balancer with just the blower, let alone a whole other motor. Just wasn't sure if there was a placeto buy a coupler pre-machined. The clutch idea is a killer one, but I would also worry about the harmonic of the two engins. Twin starters I think will diffenetly be the way to go. Thanks for the help and keep it ***ming if anyone comes up with a name or in idea.
[quote=pontiacguy]Lot of good ideas. I'd planed on double or tripple key waying the crank. i know that 8th Grade Genius spun a brand new balancer with just the blower, let alone a whole other motor. Just wasn't sure if there was a placeto buy a coupler pre-machined. The clutch idea is a killer one, but I would also worry about the harmonic of the two engins. Twin starters I think will diffenetly be the way to go. Thanks for the help and keep it ***ming if anyone comes up with a name or in idea.[/quote] If one Hi-Perf starter would do the job, I would install it on the forward block using a ring gear plate? At least the two cranks would be equally loaded when starting. Seems that you'd want the engines phased, so your firing order would be 1-1-2-2-3-3-4-4- etc. This would mean using sprockets with multiples of (16) teeth, to set them 22.5 degrees apart. I believe the SBC offered a forged crank on the small journal motor 327 tho I'm not up to date on this as things have evolved quite bit in 25 years.
Let me know when you figure it out 'cause I'm gonna build one after the Merc. I'll bring it to the drags and whup your ***. (as usual) Glad to see you hanging around a bit. See you in a year, -Abone.
Many years ago I was on the show car circuit and Jay Ohrburg (Mr. Roadster) had that red '32 Hi-boy on display that had two BB Chevy powerplants under the hood. (It even won the A.M.B.R. trophy) He only used a single starter on the rear engine and while it didn't spin it fast, it spun it fast enough to fire the engines with two Vertex mags. This was before gear reduction starters were prevelent on anything besides a Mopar. Makes you wonder... While the phasing may be an issue, if you watch the multi-engine tractor pullers, many of them fire off one engine with a blower starter, and then use a large break-over bar to engage the clutches on each of the different engines. It is fun to listen to the first engine "pull down" as the clutch is engaged on the 2nd engine as it begins to spin. Then the 3rd, 4th (and 5th) engines all follow suit as each one is fired. I kinda feel certain that these guys are not too concerned about "phasing". Lord knows they have the Rev's Up and the Throttle Buried when they make a pull, and they definitely run high-dollar engine combinations so you would think they would be concerned about harmonics, huh.
We run a twin engine dragster with two 500 Cadillacs. We first used the double chain set up and it worked great and was simple to work on. Unforunatley and flex between the motors was transmitted to the front of the crank on the back motor and we were always breakin cranks. Since then we moved the front engine ahead 4 inches and use a shor PTO drive shaft off a dump truck. Thats been trouble free for about 6 years now. You definatley want a starter on each motor. Takes a lot of beans to turn them both enough to start good. Once in a while ours will sneeze when it starts and almost always takes the snout off one of the starters. Makes a big difference. As far as motors being in phase, neve been a problem. One motor just helps out the other. They don't care whether they're balanced or not. Hell they don't ever care if they are the same kinda motor! Your just makin a bigger air pump and if they all fire it just makes more energy. Have fun, two motors don't go any faster but they are sure an ego trip when they light up
My pal, Van, has two 1951 Prefects. The white one is all original right down to the 10 hp 4-banger. The primered one, on the other hand, has two 350 inch Chevys inline on a tubular subframe. He sits in the back seat to drive the thing....and he says it "pulls real hard" !! One thing I found interesting is how they're timed. He tried several combinations and the smoothest was when he spaced the firing between the two at 45 degree intervals. The number one on the forward engine fires 45 degrees ahead of number 6 on the rear engine. In other words, number one on the rear engine is 225 crankshaft degrees behind number one on the front engine. His coupler consists of a plate with a double-keyed crank snout hub attached to it and the plate attaches to the forward engine's flex plate using the same holes the torque converter would use. Oh, yeah.....it's street-legal. He's driven it in parades.
Chet Herbert (Herbert Racing Cams) used to sell the chain coupler - - probably still has them(g) time it like a V-16... Fred
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