Chrysler Hemi 1/4 scale

[driller1432]

Here we go with hemi build.
Scaling off the real deal, did the crank awhile back did not take any pics of machining.
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Have a good start on heads with combustion chamber cutter made from drill bit
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The scrap head to scale from
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Next will be intake and exhaust ports and spark plug holes.

 

[Cogsy]

That crank is a work of art. This should be another impressive engine.

 

[petertha]

Very nice. What material did you make your model crankshaft from?

Too bad about no pics, hope you document the rest of your journey for us because its a very admirable project.
Can you describe some of the tooling you used - ex parting tool to rough? home cut HSS tools to finish? any lapping?

 

[driller1432]

Thanks Cogsy
And the metal I used for the crank came from a shaft from the draw works on a water well drill rig I once owned. I roughed out the crank on the mill with rotary table and tailstock with a fixture on each end to index rod journals then ground journals to final dimension on the lathe with tool post grinder. As my father owned an automotive machine shop for 52 years I have reground hundreds of crankshafts so it made sense for me to do it this way. I’ll post pics of fixtures next time I go to shop. Thanks for your interest.

 

[Hopper]

Very nice work there. Will be following this one with interest. I worked in a Chrysler factory back when a hemi was the hot money.

 

[driller1432]

Making valve seats on my new to me sherline mini lathe View attachment IMG_1250.jpg
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And spark plug tubes ........next head bolt and pushrod holes and topside of heads for spring seats.

 

[driller1432]

Getting close to finishing head machining .....oil drain back holes, oil feed passage..... water passage and valve cover surface to be perpendicular to spark plug holes then ready for seats guides and valves.

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[driller1432]

Pictures x2 don’t know why? sorry

 

[stevehuckss396]

heads look great. tons of work there.

 

[driller1432]

Yep a little more to do, at least I think I’m past the point where I might screw up and have to start over! [emoji851]

 

[stevehuckss396]

at least I think I’m past the point where I might screw up and have to start over! [emoji851]

Don't think like that or you will be starting over! Hahaha!!

 

[driller1432]

Hi guys got the valve guides and seats installed now will cut down and cut angles in seats with a two step pilot that fits in guide and inner valve seat since the ID of the guide is only .115 also got a start on intake valves tulip style from
.500 drill rod View attachment IMG_1266.jpgView attachment IMG_1267.jpgView attachment IMG_1268.jpgView attachment IMG_1275.jpgView attachment IMG_1277.jpg

 

[driller1432]

Finally back on the Hemi getting the block roughed in, got past the nerve racking part as all the cylinder bores ended up in the proper alignment with crank center line and main bearing webs. Now need to finish hogging out crankcase then the lifter valley will have to be hogged out as well. Then cylinder bores taken to near finish bore for liners then the main bearing caps will be milled away and new ones made. Then align bore the main bearing bores. Now some questions like has anyone used split rod and main bearings? Is so what material was used? Used the washer that is approx same diameter as crank to check for enough clearance for crank the side walls of crank case will also be milled thinner as well.

 

[gbritnell]

I don't think there is any other way to make trapped bearings other than to split them. I turn the bearing inserts to size then part them off and finish the length. From here there's 2 ways to go. First you have to make a fixture to hold them then you can split the with a very thin slitting saw and not worry about the small gap produced or you can split each bearing so that one half is perfectly cut in half and discard the other half. This method requires making twice as many pieces but you get perfectly split bearings. I then drill the cap and one half of the bearing for a brass pin to keep the insert fram spinning.
I have also used a third method which involves taking 2 pieces of rectangular stock and soft soldering them together leaving one piece a little longer so that when set up in a 4 jaw chuck the exact center can be established. First the inside is drilled and bored to size. I don't like reaming because sometimes the pressure of reaming will split the solder joint. Now the O.D. Is turned and the insert parted off. Now it's heated until it separates leaving just a minute space where the solder was.

 

[gbritnell]

Not wanting to hijack your thread I'm going to start another on how I machined the connecting rods and split bearings for them. It will be in Tips and Tricks.
gbritnell

 

[driller1432]

Not wanting to hijack your thread I'm going to start another on how I machined the connecting rods and split bearings for them. It will be in Tips and Tricks.
gbritnell

That would be great can’t wait to see how you machine the rods and bearings I appreciate the help!

 

[CFLBob]

Question if I may.

The only engine that comes to my mind when I read "Chrysler Hemi" is the 426 CI hemi from the late 60s. That would make this a 106.5 CI engine, which is still pretty big for a model.

Is that right?

 

[a41capt]

I read George’s split bearing thread first, and then saw yours. That is a fantastic looking job to this point, and I look forward to seeing the remaining steps in your build.

Beautiful work!
John W

 

[stevehuckss396]

The bore and stroke of the 426 hemi was 4.25 X 3.75 = 425.5877 CID

1/4 scale would be 1.0625 X 0.9375 = 6.6498 CID

 

[CFLBob]

The bore and stroke of the 426 hemi was 4.25 X 3.75 = 425.5877 CID

1/4 scale would be 1.0625 X 0.9375 = 6.6498 CID

Ah! Not dividing the 426 by 4, dividing bore and stroke each by 4. That turns into scaling the displacement by (1/4)^3. That makes sense. Should have thought of that.

Thanks, Steve.