Testors 1/4 scale Dodge Hemi

I like it, looks sharp.

I hate to ask this stupid question, but I know nothing of this model........"Is it operational?"

 

Nice work!

Sweet!  Really captures the look of the beast.  And it beats the hell out of the old "Visible V8" that didn't represent anything and had no detail.

You did a very nice build that would looks right at home on the kit box top.  They oughta hire you.

wolfpac wrote:

I like it, looks sharp. I hate to ask this stupid question, but I know nothing of this model........"Is it operational?"   Nice work!

Thanks!

It has a electric motor in the base that turns a rubber o-ring that turns the flywheel. You can see it in the "Right front" picture. The crank turns, the pistons go up and down, the cam moves the pushrods which move the rockers that push in the valves. It turns at about 15 rpm. There are two more o-rings that act as the fan belts and turn the fan, alternator and power steering pump.

I didn't follow the instructions on which belt to use where as this was discussed on Scale Auto last year and it looks as though the kit instructions have it wrong. It says to use the medium belt on the flywheel drive and the large belt around the crank pully, the alternator and the power steering pump and the small pully around crankshaft pully and the fan. That makes the drive pully and the alt. pully too tight and tends to rip it or the power steering pump off the cylinder heads. What was suggested was to swap the large belt to the flywheel drive and the medium pully to the crankshaft pully, fan and alternator and use the small belt between the cranshaft pully and the power steering pump. It leaves one groove on the alt. pully empty but that isn't unusual in a real engine.

There was some discussion about it turning backwards. I'm not sure what the deal is but the fan turns clockwises from the "driver's" point of view and is pitched so that it would suck the air forward from the engine instead of backwards through where the radiator would be, but... I looked at a picture of a real Hemi and the fan is pitched the same as the kit's and if you look at the valves in the model they appear to be opening and closing at the correct points in the piston's movement, the intake opens as the piston moves down, they are both closed when the piston goes back up, and back down, the exhaust opens as the piston comes up the second time and then the intake opens up again as the exaust closes as the piston reaches the top.

I don't know which direction the real engine spins, if it spins the other way and the model turns backwards, the fan is right and the cam shaft is timed backwards. Otherwise the model is correct. I don't know and it doesn't bother me if the cam is backwards.

There was a sound chip that supposedly played a digital sample of a real Hemi but it sounded like static and didn't relate at all to the rate at which the model turns so I disconnected it.

I just noticed I had the "Right front" picture under both "Right front" and "Left front". It's fixed now.

There was some discussion about it turning backwards. I'm not sure what the deal is but the fan turns clockwises from the "driver's" point of view

Dave,

If from the drivers point of view if the fan spins clockwise, looking at your photo and my model as well, wouldn't this be pushing air forward out of the radiator? Seems to me that either the fans are angled wrong or the motor spins backwards.

BigJim wrote:

There was some discussion about it turning backwards. I'm not sure what the deal is but the fan turns clockwises from the "driver's" point of view Dave, If from the drivers point of view if the fan spins clockwise, looking at your photo and my model as well, wouldn't this be pushing air forward out of the radiator? Seems to me that either the fans are angled wrong or the motor spins backwards.

The fan on the model is pitched the same way as that shown on the photo of a real Hemi that I have. The motor was from a '69 Super Bee but at the time I took it, it was residing in a '67 'Cuda. Tight fit...

The valves seem to open and close at the appropriate part of their piston's cycle so I think the cam is designed to turn the way the model turns.

So, if the motor turns the wrong direction it looks like the cam is timed backwards. I doubt Testors is going to fix that. I'm not going to worry about it.

 

So, if the motor turns the wrong direction it looks like the cam is timed backwards. I doubt Testors is going to fix that. I'm not going to worry about it.

Obviously Testors isn't either. They have sent me three replacement bases that all turned the wrong way.

As for me, the fan turning backwards is infinitly more visable (and disconcerting) than the cam timed backwards. I haven't actually checked the valves to see if they open in the correct order. Have you? I still think it is a cool model to watch operate.

Did you have any problem with the air cleaner base fitting on the carbs? Mine didn't fit right after the carbs were installed on the intake manifold.

I would like to see them do a Visable Ford 427 SOHC and a Cosworth DFV.

That looks pretty good! I built one of these when I was a kid... it turned out like crap! Yours looks good though, I am tempted to buy another one just because its a neat conversation piece. They do have a rotary and a couple other kits like this, but they aren't from Testors? I have seen them at Hobby Lobby.

Big block Chevy ... 427 Tri-power would do nicely.

BigJim wrote:

Did you have any problem with the air cleaner base fitting on the carbs? Mine didn't fit right after the carbs were installed on the intake manifold. I would like to see them do a Visable Ford 427 SOHC and a Cosworth DFV.

Yes, the air cleaner doesn't fit firmly on the carbs. It fits well enough that it doesn't fall off but it isn't a positive fit. I don't want to glue it on because it would hide the detail around the carbs.

I'm glad glued the valve covers on with white glue in case I had a problem with the valve train. I see that was a good idea as one of the push rods is out from under its rocker. I think I'll leave it be for now but I should be able to pop the valve cover off to fix it pretty easily.

One other little thing I did was wire in another button that runs the motor only as long as you press it. It by-passes the 60 second timer circuit. I'll disable the timed button when I bring it to shows so it doesn't get run too much but people may still see it work by pressing the momentary button. That's another reason I left the speaker out, it would get pretty anoying to listen to that all day.

I could see having a couple of different motors as a display. They are kind of big though. Maybe I'll look for the old Entex Wankel rotary kit. I had one as a kid but never finished it. I'll have to check and see if I can find the Harley V-Twin visible kit on sale some time, I won't pay 80 bucks for it. Must be licensing fees jack the price, it's got to be about a quarter or less of the parts of the Hemi.

Dave DeLang wrote:

There was some discussion about it turning backwards. I'm not sure what the deal is but the fan turns clockwises from the "driver's" point of view and is pitched so that it would suck the air forward from the engine instead of backwards through where the radiator would be, but... I looked at a picture of a real Hemi and the fan is pitched the same as the kit's and if you look at the valves in the model they appear to be opening and closing at the correct points in the piston's movement, the intake opens as the piston moves down, they are both closed when the piston goes back up, and back down, the exhaust opens as the piston comes up the second time and then the intake opens up again as the exaust closes as the piston reaches the top. I don't know which direction the real engine spins, if it spins the other way and the model turns backwards, the fan is right and the cam shaft is timed backwards. Otherwise the model is correct. I don't know and it doesn't bother me if the cam is backwards.

Nice job on the kit Dave.

Here's a little help in engine rotation and operations, simplified LOL.

Humm... It's been a long time since I thought about this, but I believe American engines usually always rotate clockwise when looking from the front (counter clockwise from the drivers seat). So your fan is pitched correctly but the engine is rotating backwards. Possibly changing the polarity on the electric motor that spins the O-ring would solve the problem (swap the batteries negative and positive wires).

A camshaft can not spin backwards from a crankshaft unless someone configured some weird gearing to cause that to happen. If the engine has the usual crank gear, cam gear and chain, (or even a timing gear set, 4 gears no chain) then all is fine. The timing (valve opening) will be the same (very close) no matter which direction you turn the crankshaft. For every two rotations of the crankshaft, the camshaft rotates once (cam gear twice as big as the crank gear). Everything is based upon a certain degree from TDC (Top Dead Center).

When a camshaft is said to be out of timing, that's because the opening and closing points are not as they should be. It can be caused by the chain and gears being installed without lining them up properly (timing marks on the gears). A worn chain and gears that have jumped a tooth or more. For racing or serious high performance applications setting the proper cam timing is more involved. You'll need a cam degree wheel, dial indicator, special cam gear, etc...

Hope my simiple explaination helps you understand the basic workings of your nice looking Hemi model.

jhande wrote:

Humm... It's been a long time since I thought about this, but I believe American engines usually always rotate clockwise when looking from the front (counter clockwise from the drivers seat). So your fan is pitched correctly but the engine is rotating backwards. Possibly changing the polarity on the electric motor that spins the O-ring would solve the problem (swap the batteries negative and positive wires). A camshaft can not spin backwards from a crankshaft unless someone configured some weird gearing to cause that to happen. If the engine has the usual crank gear, cam gear and chain, (or even a timing gear set, 4 gears no chain) then all is fine. The timing (valve opening) will be the same (very close) no matter which direction you turn the crankshaft. For every two rotations of the crankshaft, the camshaft rotates once (cam gear twice as big as the crank gear). Everything is based upon a certain degree from TDC (Top Dead Center).

Hey Jim, thanks for the info.

I tried reversing the polarity of the voltage to the motor when I was adding the momentary on button I mentioned in a previous post. It didn't like running backwards. I don't know if it was the reduction gearing or the circuit board, but when I ran it backwards it ran very slow and lurchy.

The way the cam is driven is one big gear on the end of the crank directly turns the small gear on the end of the cam. The cam turns the opposite direction from the crank at, like you said, half the rate because of the gearing.

Where abouts in Cow Hampster do you live? (I'm in Vermont) If you go to any of the shows I bring it to you'll have to grab me so I can show you what I mean about the valves looking like they're opening when they should be in relation to the piston's position while the engine is turning backwards. That's what I meant about the cam being "timed" backwards, it looks like the engineer who drew it up intended it to work backwards, it might be kind of a "mirror image" of how the lobes of the cam are arranged. There are timing marks on the crank gear and the cam gear so you get it aligned right during assembly.

Humm... just two gears and no chain, that's a new one on me. 
I've been out of the wrenching circuit a few years now, since my accident, so I'll have to check into that. Sounds strange to me that it would be that way in real life.

Think of the valve timing (cam) with the crank like the hands on a clock.
Turn the minute hand (crank) clockwise two hours, the hour hand moves the two hours.
Turn the minute hand counter clockwise two hours, the hour hand moves two hours and lines up as it should. Kind of the same principal LOL.

I live on a mountain (beginning of the White Mountains) in Orford, it's across the CT river from Fairlee, VT. I'd like to find out about any modeling shows in the area. My 10 year old son loves going to the races with me and he's the one that got me started again in modeling after 30+ years.

jhande wrote:

I live on a mountain (beginning of the White Mountains) in Orford, it's across the CT river from Fairlee, VT. I'd like to find out about any modeling shows in the area. My 10 year old son loves going to the races with me and he's the one that got me started again in modeling after 30+ years.

I live in Cambridge, VT. About a hundred miles northwest of you in the northern part of the Green Mountains.

Here's a list of shows this spring:

2 April 2006 Valleycon, Chicopee, MA
IPMS Wings and Wheels

2 April 2006 MASSCAR, Taunton, MA
IPMS MASSCAR

9 April 2006 Buffcon, Buffalo NY 
IPMS Niagara Frontier

22 April 2006 Can-Amcon, Plattsburgh, NY
IPMS Champlain Valley

29 April 2006 Downeastcon,  Biddeford ME
IPMS Maine

19/20 May 2006 Noreastcon , Marlboro MA
IPMS Wings and Wheels, Patriot, Bay Colony and Granite State

I'll probably go to Buffcon, CanAmCon and Downeastcon and maybe Noreastcon.

Thanks Dave, I'll mark them down and see what I can do. 

"I'm glad glued the valve covers on with white glue in case I had a problem with the valve train."

What did you use to glue the rest of the engine? I used Testors glue for clear plastic on anything clear and regular glue where crazing wouldn't be a problem. 

I'm glad that I didn't glue the valve covers so that I can easily correct problem push rods when they sneak out from under the rocker arm. The cover stays on very well without the glue.

BigJim wrote:

"I'm glad glued the valve covers on with white glue in case I had a problem with the valve train." What did you use to glue the rest of the engine? I used Testors glue for clear plastic on anything clear and regular glue where crazing wouldn't be a problem.  I'm glad that I didn't glue the valve covers so that I can easily correct problem push rods when they sneak out from under the rocker arm. The cover stays on very well without the glue.

Mostly Tamiya thin cement. There are some areas where a white crazing shows at the joint of clear parts. Most of it is hidden by being behind several layers of clear plastic or under where something colored is glued. The worst is where the piece that traps the lifter ends of the pushrods to the valley piece, but, like I said, it's way under the intake manifold and you can't see it. I wanted a strong bond so everything would stay in alignment so the moving parts wouldn't bind. I figured any crazing was just the way it had to be to get a strong assembly.

Is the Testors glue for clear parts a solvent cement or more like white glue? I've never tried it.

Maybe when I take the valve cover off to fix the one pushrod that's out of position nw I won't glue it back on and see how it goes. I didn't want it falling off and pulling all the plug wires loose so I glued it with the Elmer's.

Is the Testors glue for clear parts a solvent cement or more like white glue?

It is more like a white glue, but not as sticky at first. I had my doubts going in as I had never used it before either. I found that using this glue you need to be prepared that this thing isn't going together in one night or even one week. It takes some time for the glue to cure. I used a lot of rubberbands to hold parts together and let sub-assemblies dry for a day or more. Some parts like the exhaust manifolds, after a day, I went back and filled in around the joints between the head and manifold runners to get a better bond. I have had no problems and I would recommend this glue for use on any clear part where crazing would detract from the final appearence.

I did use Testors regular liquid cement on the colored parts where crazing would not have been a problem.

Now, to tear the base apart and swap wires on the motor to get this thing running in the right direction.