Staight 8 overhaul

[Fossil]

Just out of curiosity and to help plan ahead just in case, would any of you have a ballpark figure on what it would cost to overhaul one of these early DeSoto 8 cylinder engines? Are pistons still available.  

I would also like to thank any and all of you that have been kind enough to help me get through this project. You folks have been great!!!!!!!!

Hopefully someday I can help someone in some way. 

Chris

[mobileparts]

That is unfortunately way too open ended a question -- depending on what it needs.... Does it need bottom end, with crank, rods, and mains??? If no,

$ 0, if yes, $ 500.   Was it a frozen motor, whereas now it probably needs to be bored ???? If no, $ 0, if yes, $ 800. What is needed on the heads ???? Do you need accessories, like Valve Lifters, rocker arms, push rods, valves, valve keepers, etc., etc.????

 

What you need to do is assess what is needed, bring it (hopefully you have one in driving range) to a QUALITY shop .... And find out whether you are going to be able to supply parts, or are they going to be the sole supplier.

 

 If you need parts, I will be able to supply you with ++ N.O.S. ++ U.S.A. ++ made parts.....

 

Always best to simply call me --- Craig --- 516 - 485 - 1935....  New York....

To answer your piston question, for example, availability starts with the question: Standard, .030 oversize, .040 oversize...???? Answer: To be determined......

Edited May 8, 2020 by mobileparts
Add on (see edit history)

[Fossil]

Yes the block is cracked. One in the lower crankcase near the oil pump and one freeze crack. These would be corrected at the time of overhaul. Fortunately neither is causing problems. I'm guessing the engine would require a re-bore and pistons, cam bearings, soft plugs, and connecting rods as they do not use inserts. The crankshaft does. Would also be a good time to replace the timing chain and all gaskets and seals. 

Just trying to get my ducks in a row for a next winter project as the car will be setting idle then.  The engine starts and runs well but is starting to smoke when warm and isn't as quiet as I think it could be. 

Thanks for offering your input and we will probably be visiting in the future. 

[stakeside]

Be careful here. If it has a known crack there may be some deep cracks or damage. I had my second 29 DB 6 engine both tanked and cracked for cracks. Then I had it sonic tested. 

My first engine had damage inside the water jacket and was in an area that could be repaired. 

Since all my bearings are babbit type, seven mains and six rod bearing, my rebuild will be $6000 ++. This include all hard parts such as pistons, valves and etc.

Now I know why these early six cylinder engine were replaced with later engines. 

[Fossil]

Thanks for the information. This is one of the reasons I'm seeking a replacement. The crack near the oil pump was welded years ago but still weeps a little. The frost crack only seems to be to the outside as there is no sign of moister in the oil. It's my understanding that the block castings on the early 8's is not real thick. 

It would be nice if a later straight 8 was available to swap. How about a slant six? 

[stooy]

Hi Chris, 

 

A full rebuild on our CF8 Engine cost us $8k Australian.  We got our pistons made locally, they cost about $700US to have made in AUS. 

 

With some looking I think you will find a block. I saw one for sale for $500 the other day on facebook but I can't find the link right now. 

 

If you were going to swap to another engine a later model Chrysler Straight 8 299/323ci would be best.  It will bolt up to your engine mounts and existing transmission. They also have slipper shell bearings in the bottom end which will make a rebuild cheaper. 

 

I will see if I can find that link for you. 

 

Cheers 

Stewart  

[Fossil]

Stewart that is great information. I'll do some research into that engine. Thanks for taking the time to post. The hunt is as much fun as the buy.  😉

Chris

[stooy]

Hi Chris, 

 

I have been doing a bit more thinking, I think Dodge Vintage City - https://www.dodgecityvintage.com/  Had a 1930 Dodge DC8 sedan in their wrecking yard with an engine in it. 

 

As you may know the Dodge DC8 shares the same engine block as the DeSoto CF8.  The share the same casting number, but the DeSoto engines are stamped CF and the Dodge ones DC. 

 

The Dodge gets its extra capacity 220ci vs DeSoto at 207ci by having another 1/4 inch of stroke. 

 

Cheers 

Stewart 

[Fossil]

You've got a good memory and must be somewhat younger than me. 😀

I'm thinking your suggestion of the later Chrysler 8's is a good as they have the bearing inserts and hopefully a better block casting. My block appears to be cracked next to the center main bearing.  Would imagine it was thin there or a bad casting or maybe the crankshaft broke and cracked it? 

[stooy]

Haha I am only in my mid 30s, so I presume so. 

 

I will be surprised to hear you have a broken crankshaft or block (other than from frost damage),  I am of course not saying it is impossible, but over the last 25 years one way an another I have met probably 30 or 40 CF/DC owners and never seen another one. 

 

The later block has a larger cooling capacity and more reinforcement around the oil pan, so it is probably stronger.  You can see in these photos on ebay the extra reinforcing and also note 4 freeze plugs. https://www.ebay.com/itm/OEM-1935-Chrysler-Air-Flow-Straight-8-Engine-Block-Core-SR-Ask-about-shipping/254354012990?hash=item3b38ae3b3e%3Ag%3ALioAAOSwz3ZddWSQ&LH_ItemCondition=4

 

I would suggest buying whole engine, as they are around and the crank and rods etc are different. 

 

I am not sure if the later Spitfire engines fit, but they look quite different. Note here - https://www.ebay.com/itm/Chrysler-Straight-8-Spitfire-Engine/114219152197?hash=item1a97fdf345%3Ag%3AJvwAAOSwOWdepRFd&LH_ItemCondition=4

 

Cheers 

Stewart 

Edited May 10, 2020 by stooy (see edit history)

[Fossil]

On 5/8/2020 at 6:22 PM, stooy said:

If you were going to swap to another engine a later model Chrysler Straight 8 299/323ci would be best.  It will bolt up to your engine mounts and existing transmission. They also have slipper shell bearings in the bottom end which will make a rebuild cheaper. 

Whats the difference between one of the above engines and the Spitfire engine?

I'm a little confused as to where the cut off date for bolt in interchangeability is. 

I'm just about 70 years old.  

Edited May 10, 2020 by Fossil (see edit history)

[stooy]

I am not 100% sure as I haven't seen the spitfire engine in person, it may fit, but I am just not sure. 

 

I am confident that all the Airflow/Airstrem engines up to 1937 fit. As best as I know all the 299ci and 323ci engines with the physical appearance of the bare block I linked you to fit. I would be fairly sure all of them up to WW2 will fit. 

[Fossil]

Thank you, that narrows it down. I appreciate your input. Put 8 miles on it today and it runs good. Pulls like a mule. 

 

[Narve N]

I have managed to hook up a '47 323 cui with a '38 transmission (to be put in a '29, but that is another story). Flywheels have different bolt patterns, but will physically fit. Several others have done similar swaps, eg a well known '31 CD racing Roadster had 323 engine/trans combo straight out of a '38 Imperial.

[Fossil]

Thank you Narve. I'm really grateful you folks are coming forward with your experiences. The biggest issue is finding a combination that will bolt together without a lot of modifications. Like you said the flywheel issue can be done.