# Challenger V8



## Dan11 (Jan 18, 2012)

I'm looking for advice on machining a crankshaft for a Challenger V8. Specifically, can this be done without a tool post grinder? If I machine it down to finish tolerances and then heat treat it will it bend? If I heat treat first will I be able to turn it in a lathe? It calls for 1018 hardened to Rc 62. I welcome any and all advice. Is there anyone out there who has already done this?


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## b.lindsey (Jan 18, 2012)

Dan, just doing some quick checking on material properties I think you may have to use O1 or A2 tool steel (drill rod) to achieve a hardness of Rc62. I haven't found a reference yet that shows 1018 capable of that hardness. Hardening and then finish grinding would be IMO the best though not easiest route to go. 

Bill


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## doc1955 (Jan 18, 2012)

1018 can not be hardened to that extent it can be case hardened 1018 isn't a tool steel. And are you sure it is calling for 62Rc that is pretty brittle at that hardness and will not except much shock without breaking. I would think a crank would be more like 42 to 45Rc just guess.


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## Dave G (Jan 18, 2012)

Hi Dan, For crankshafts I use 1144 stressproof. It comes preheat treated to around 22-24 rockwell C scale and the lack of stress in the raw material is perfect for making crankshafts. A-2 and 0-1 steels are through heat treated which means the core is as hard as the outside surface. I know of people who have made cranks from these steels but I wouldn't. I have made parts from 0-1 steel and had them hardened to 60-62 RC then ground the sufaces to size and a week later the part has warped beyond repair. A-2 is very stable but also very brittle at 62 RC. Alot of gun parts are made from A-2 steel such as sears and triggers, but the hardness is kept to around 54-56 RC to keep breakage down. If you want a strong crank I would use 4140 or 4340 steel as in full size practice. Whenever I use 4140 I make sure it is of the preheat treated variety. You can buy this already at 28-32 RC and it is very strong. 
 When the automakers were still making forged cranks in their high performance applications they were made from 1050 steel. 1050 steel is used in alot of shafting applications where stength is needed. Billet cranks that the full size manufacturers make are made from 4140 or 4340 steel. 
 As for machinability you can't beat 1144 stressproof. Don't be afraid to machine preheat treated 4140, I much prefer to machine it at this hardness than dead soft. Carbide tools and rigidity are the secret to machining it. 
 We used alot of 8620 steel if the part was to carburized and hardened, it machines better than CRS and after heat treating it has a higher core hardness than CRS. Automotive ring and pinions are made from 8620 steel. Low carbon steel such as CRS and 8620 need to be carburized before hardening. They don't have enough carbon in them to allow proper hardening. To get a hardened surface they are put into furnace that has a carbon enriched atmoshere for a predetermined amount of time. The longer in the atmosphere the deeper the case. After enriching the surface with carbon the part is then heat treated as other steels. One good feature of case hardening is that you can have some surfaces hard and others not. The way to do this is to leave additional stock on the surfaces you want to remain soft when the carburization proccess is done. Before heat treating you just machine away the extra material where you want to remain soft. This removes the enriched carbon surface. We used to insert setscrews into tapped holes before carburization to leave the threads soft also. 
 I started to make the Challenger a while back and I made the crank from 1144 SP. I also made my crank with 90 degrees between rod journals instead of the 180 degrees described in the drawings. I made my crank entirely on the mill using a rotary table with a tail stock. After all the machining was finished the crank was placed in my OD grinder for finishing. An indicator was used to check runout at the center of the crank and I was quite pleased to find I only had .0015" runout before grinding. 1144 stress proof is good stuff. When I first got into model engine building I used CRS for my cranks and found that it doesn't hold up well when soft. 1144 SP has given me no wear issues after many hours of running. Our engines don't see much load on them so I don't think going to a bearing journal hardness of 62 RC is neccessary. I hope this helps and good luck with your Challenger. Dave


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## Dan11 (Jan 19, 2012)

Thanks for the replies guys. Dave, I'm curious, did you ever complete your challenger project? I'm especially wondering if you have notes on new firing order and cam arrangement.


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## Dave G (Jan 20, 2012)

Hi Dan, I started the Challenger when I was fairly new to the hobby. I thought it would be a good project and made the block from billet and also the crank. I have since lost interest in it and will probably never finish it. Since overcoming the usual difficulties of model engine building such as piston rings and good valves I have found that I much prefer to build engines of my own design. I like to have something a little different to display. 
 I fool around with old Mopars and drag race in the summer time. I was going to use the firing order and cam layout from a Chrysler V-8 engine as I have a few laying about to copy from. The cam arrangement has to mirror the valve placement. Most Chrsler engines used a valve layout of E I I E E I I E with E being exhaust and I being intake. Small block ford engines use a layout of I E I E I E I E. Small block Chevys use the same layout as the Chryslers. If you decide to change the design of the Challenger as I was planning I would pick out an existing full size engine with the same valve arrangement as the Challenger and study the layout carefully. A local engine builder would probably give you a used camshaft for free if you tell them your plans. I copied a 318 V-8 engine crankshaft layout for my crank as I had one laying on the floor of my shop. I haven't ruled out building a V-8 and I will probably use my crank in another engine and the block will become a paper weight.
I hope this helps and if you have any other questions there is a wealth of knowledge here at HMEM so don't be afraid to ask. 
 If you would like, I can take a few pics of my crank and block and post them here. Let me know and good luck with your project, Dave


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## Dan11 (Jan 21, 2012)

Thanks Dave. I think I'm going to stick to the original design. This being my first attempt I don't need to throw myself any curves.I was wondering if you could do me a huge favor and give me a count of how many drawings came in your set. I am having problems with Coles Power. They sent me the first set with duplicates of some and others missing. They sent me more but now I've discovered more missing. They can't even tell what a full set consists of.


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## Dave G (Jan 23, 2012)

Hi Dan, I just thought to dig out my Challenger drawings. Here is a list of the drwgs, I didn't put them in numerical order for you but this is what I received about 10 yrs ago from the original Coles in Ca. 
I will give you the number of the drwg, description, and size of drwg. 

L-300 block  D
L-600 assembly  D
L-311 left exhaust  C
L-301 crankcase  C
L-332 camshaft  C
L-305 right exhaust  C
L-310 crankshaft   C
L-353 water pump housing  B
L-304 intake manifold   B
L-302 oil pan  B
L-337 cylinder liner  B
L-336 piston   B
L-309 connecting rod  B
L-382 oil pump block  B
L-329 dist base   B
L-330 dist cap   B
L-338 flywheel   B
L-354 waterpump cover  B
L-358 valve train cover  B
L-359 stand   B
L-303 head   B
L-355 waterpump shaft  A
L-483 access cover  A
L-316 oil pump cam  A
L-328 dist cam  A
L-360 pipe flange  A
L-317 cam follower  A
L-315 front cam bushing  A
L-314 rear cam bushing  A
L-351 valve spring keeper  A
L-350 wrist pin plug   A
L-349 wrist pin  A
L-327 dist shaft bushing top  A
L-333 dist shaft spacer   A
L-323 dist shaft  A
L-321 valve guide  A
L-320 valves  A
L-319 push rod guide  A
L-308 rear main bearing housing  A
L-367 carb base   A
L-368 waterpump impellor   A
L-369 oil pump lever   A
L-334 fan support shaft   A
L-339 fan blade   A
L-340 fan spider   A
L-341 fan adapter  A
L-331 dist rotor   A
L-352 water pump impellor  A
L-346 water pump pulley   A
L-345 fan pulley  A
L-344 crank pulley  A
L-343 dist contact   A


I wrote down the info as I went through my pile of drwgs and I figured if I tried to put them in numerical order for you I would probably screw up and leave something out. I hope this helps and good luck. If I can be of any further assistance don't be afraid to ask, Dave


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## dsquire (Jan 24, 2012)

Here is a sorted list for you

L-300 block  D
L-301 crankcase  C
L-302 oil pan  B
L-303 head  B
L-304 intake manifold   B
L-305 right exhaust  C
L-308 rear main bearing housing  A
L-309 connecting rod  B
L-310 crankshaft  C
L-311 left exhaust  C
L-314 rear cam bushing  A
L-315 front cam bushing  A
L-316 oil pump cam  A
L-317 cam follower  A
L-319 push rod guide  A
L-320 valves  A
L-321 valve guide  A
L-323 dist shaft  A
L-327 dist shaft bushing top A
L-328 dist cam  A
L-329 dist base   B
L-330 dist cap  B
L-331 dist rotor  A
L-332 camshaft  C
L-333 dist shaft spacer  A
L-334 fan support shaft  A
L-336 piston  B
L-337 cylinder liner B
L-338 flywheel  B
L-339 fan blade   A
L-340 fan spider  A
L-341 fan adapter  A
L-343 dist contact  A
L-344 crank pulley  A
L-345 fan pulley  A
L-346 water pump pulley  A
L-349 wrist pin  A
L-350 wrist pin plug   A
L-351 valve spring keeper  A
L-352 water pump impellor  A
L-353 water pump housing B
L-354 waterpump cover B
L-355 waterpump shaft A
L-358 valve train cover  B
L-359 stand  B
L-360 pipe flange  A
L-367 carb base  A
L-368 waterpump impellor  A
L-369 oil pump lever  A
L-382 oil pump block  B
L-483 access cover  A
L-600 assembly  D


Cheers 

Don


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## Dan11 (Jan 24, 2012)

Thanks Dave & dsquire, After comparing your list to mine I find I am missing L352. I don't know if this matters because L368 is also listed as a water pump impeller. Maybe L368 is a newer revision. What neither of us have is 3 drawings referred to in L332 (camshaft assembly). Those are L313(shaft)-L322(intake lobe)-L739(exhaust lobe). I need those to get the lobe profiles.
  Also, what I find lacking is any drawings referring to distributor drive gears and camshaft drive gears. And, any specs on camshaft timing vs. piston TDC.
  Anyway, my quest will continue. Thank you again for all you've done.
                                 Dan


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## johnhank (May 31, 2013)

Hello Dan,
Was there any further progress on your quest for the camshaft drawings and the drive gears?


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