D25 Engine Rebuild thread

[greg g]

I woud be concerned if you had a short block I might be more concerened with the OS, but I believe there is more meat between the cylinders on the long blocks. What diameter were the pistons on the Chrysler 251 and how much could they be overbored?

I remeber 3 7/16 I think so those should be sized to take a 251 or 265 +.030. If the blocks are the same through the line at 25 inch you should be OK. Interesting way to get 230 cu in.

[Billy Austin]

Chris, This is a photograph of a 25 inch block cut away. As you can see the casting wall is a nominal thickness and has no extra metal due to bore spacing or lenth of block. The cross section thickness of a 251 block or a 218 block are probably about the same. I think your biggest problem boring that much would be finding a casting defect. Note the core shift in photo.

I would play it safe and bore casting to a minimun clean up dimension, and swap pistons with VPW.

[PatS....]

It's my understanding that the Canadian long blocks can be safely bored to 251 cid plus 30 thou. The rebuilt industrial I had and sold had this done in '56 according to the rebuild tag.

I have a 251 block and crank from the 49 and my nephew has 3 long blocks of unknown heritage in good condition if you run into a defect.

Edited January 18, 2012 by PatS....

[bamfordsgarage]

To clean the Cosmoline(?) off the pistons I used a coffee can of Varsol (mineral spirits) sitting on my workshop space heater. The workshop door open provided decent ventilation and also caused the heater to work overtime, bringing the Varsol can up to a cozy temperature. Five minutes soaking and a bit of sloshing worked like a charm.

Billy that is a very interesting picture of the cut-away block, and It helped me make the decision about boring out for 0.092" oversize pistons. I'm going to do it. To my inexperienced eye it sure looks like there is ample room on each wall for a 0.045" cut without getting seriously thin.

It stands to reason that the Canadian block raw castings were the same for all displacements — I'm putting in Canadian pistons, all should be good. If worst comes to worst, my fallback will be sleeving, my spare block, PatS' spare engine, his nephew's blocks...

So its off to the machine shop today. My big concern there is not the quality of the work, which I know to be good, but that some worker will inadvertently hot tank my parts as part of their standard procedure. And who could blame him — what customer would not want their parts machined, clean and pristine? While I'll stress to the manager I am fanatical about my patina, it seemed prudent to also attach these brass instruction tags to the block and head as a backup. I understand hot-tanking will ruin brass so these tags will surely be noticed before the parts go into the soup.

[RobertKB]

Chris, looks like you are making good progress. Pistons cleaned up nicely. Pat S has graciously donated the other pistons my way as I will eventually rebuild the engine in my '48 D25 which is a truck 251 CID and will already have the 3 7/16" bore. My '38 Chrysler also has a truck 251 CID and when it was rebuilt by a reputable shop, it was bored .040 as the tag attests. I have never had an issue with overheating or anything else with this engine. It is a very strong runner. Good luck with the rest of the project!

[bamfordsgarage]

Things have been a little quiet on the rebuild lately while my parts have been out at the machine and radiator shops. However, today I got the rad back and visited the machine shop as they were doing some of the work on my engine...

My brief to the rad shop was to flush, test, and repair as necessary — but no tanking or paint so as to preserve my "precious patina" (a running joke between friend Jerry and me). I know this may mean a little less cooling capacity but hope it will still be OK considering all the rubbish I got out of the block passages. The rad was tested to 7 psi and showed a bit of seepage around the upper hose connection which was then resoldered.

Our visit to the machine shop was most interesting. All along I have assumed that my engine had never been out of the car nor overhauled in its 90K mile life— not so! Turns out the bores were already 0.020 oversize from stock, so in order to fit my new 0.090 oversize pistons only about 0.070 bore and hone was required. (Granted, several posts up I reported relatively little wear in the bore, so either I or the machine shop made some kind of error. I vote for me.) The factory repair manual calls for piston skirt clearance of "4-6 lb pull on a 0.002 x 1/2" feeler at 70°F" which is exactly how they did it, resulting in about 0.003 clearance on the diameter. That's about 0.002" less clearance than a similarly sized aluminum Model T piston so I hope it's not too tight.

There must also have been valve work done not many miles before I got the car, as the stems and guides showed barely 0.001 wear each with next to no wiggle of stems in guides. The shop is proposing to knurl the guides slightly and ream to fit. Tim Adams speaks upthread against this practice — I've since done some online reading about this and it appears that knurling will only suit guides where the wear is less than 0.006-7 and even then it is not as long-lasting a repair as new guides. My thinking is that with only 0.002 wear to correct, perhaps knurling would be reasonable for my engine — and is certainly a period-appropriate approach. Comments?

The cam shows next to no wear and will only be polished and Parkerized, and installed into new bearings.

The crank cleans up nicely with a 0.010 grind on rods and mains. Now that I have this information, I can place my engine parts order. However, I am a little confused about the correct inserts: My 1940-47 parts book shows the same part numbers for 0.010 crank (1056025) and 0.010 rod (1150970) bearing sets for all DPCD models. Fair enough. On the other hand, Bernbaum's catalog lists different numbers for Plymouth, Dodge, and Chrysler/DeSoto at this page: http://www.oldmoparts.com/l.htm. My feeling is that the same inserts should fit short or long block P15/D24/D25 etc. and that the Bernbaum catalog is misleading. Comments?

Edited January 18, 2012 by bamfordsgarage
Speling misteaks

[T120]

Hi Chris, Those numbers as you mentioned 1056025,1150970 apply to all Canadian long block engines...In the US, it appears there is a difference in the bearings as outlined in these pages...Don't know if this is the information you are looking for,perhaps someone else can add some further information

[T120]

Here's some more info - journal diameters.I don't know if this will be of any use to you.Copied out of Hollander Interchange.Shows the difference as well between Dodge/Plymouth and Chrysler/Desoto - US

Edited January 18, 2012 by Ralph D25cpe

[bamfordsgarage]

Thanks Ralph for your two posts. I'm more confused now — your second post of journal diameters definitely shows larger rod journals in the Chrysler & DeSoto engines. At the same time, my factory parts book shows the same part number for replacement rod bearing shells for all of 1947 Dodge, Plymouth, Chrysler & DeSoto. And this includes, for example P15 and D24 (and of course D25). Unfortunately, I'm out of town for a couple days and my parts book is at home so I will not be able to explore further until Saturday.

[T120]

Hi Chris,

You had mentioned Andy Berbaum's part numbers were different for the Dodge,Plymouth

Chrysler and Desoto 6 cylinder engines and that's why I posted those pages to show the

difference in the US engines...It gets confusing.I'm not sure what correlation there may be

(if any) between US and Canadian engines for the .010 bearing packages you require.

As you pointed out in the Canadian parts manual the bearing packages have the same part no.

for all Dodge,Plymouth, Chrysler and Desoto 6 cyl engines manufactured in Canada 1940-1948

The following part numbers are taken from the 1940-1948 Canadian Chryco Parts List

- probably the same one you have

The crankshaft bearing package for .010 is part # 1056025 and consists of -

6 ea. #957647 (bearing 1,2,3)

2 ea. #957652 (bearing 4)

The connecting rod bearing package for .010 is part # 1150970 and consists of-

12 ea. #956287

Ralph

[bamfordsgarage]

...As you pointed out in the Canadian parts manual the bearing packages have the same part no. for all Dodge,Plymouth, Chrysler and Desoto 6 cyl engines manufactured in Canada 1940-1948...

Thanks Ralph — and what I tried to also say was that American cars, such as P15 and D24, were also listed in my parts book as taking this same bearing package part#. Peculiar. Anyway, my book is in Edmonton but I'm not so will look again and post that page when I get back.

In the meantime can members suggest a good source for bearing inserts for these Canadian engines? Collectors Auto Supply in Kelowna has been slow to respond and the fellow in Winnipeg that Rockwell suggested is closed 'till March.

[Guest P15-D24]

I will check Hollanders to confirm the type.

[T120]

Well I found the corresponding part numbers that agree with the MoPar Streamliner in this Canadian parts book and it covers all Canadian Chrysler (DPCD) engines from 1939-54.The .010 bearings you require are basically the same as some years of Chrysler/Desoto engines in the US...

Don Coatney has rebuilt a Desoto engine and can maybe put you on to a parts supplier..

part # 1238561 is Con Rod Brg pair pkg.

part # 1238455 is CS Brg # 4 Upper and Lower pkg.

part # 1238454 is CS Brg # 1,2 or 3 Upper and Lower pkg.

Edited January 19, 2012 by Ralph D25cpe

[greg g]

Give Terrel Machine in Texas a call. Number is in the links section. Reasonable price and quick shipping, at least so when I dealt with them. Fellow knows his early engines also. Might be a bit hard to undestand as he does have the Texas drawl.

[bamfordsgarage]

Well I'm back in town, unfortunately too late to be calling Terrill in Texas or going to the machine shop to measure my crank. Monday AM for both.

I've attached the two pages from my Canadian Parts Book which show only one part number for all connecting rod bearings for DPCD '40-'47 (including D4 and D25 which we understand to have different rod diameters), and one number for all crank bearing packages for DPCD '40-'47. Also attached, from that same book, is the General Information and Specifications for all DPCD models '40-'47.

Ralph kindly copied me the Specification pages from his Canadian D25 manual last week — the bearing sizes page is my last attachment.

So in that last attachment it is clearly stated that the D22, D23, D24, D25 engines all have 2-1/8" rod journals. Yet in the Hollander info Ralph posted earlier, the American Dodge (presumably D24) is listed as having 2-1/16" rod bearings. Sheesh.

Anyway I've decided I am making this too complicated and wasting too much time... I've got a Canadian engine, I've got Canadian part #s, and Monday I'll have the actual measurements from my crank. So I'll just order to the part #s and ask the vendor to physically confirm the sizes. Done. Thanks Greg and especially Ralph for all your assistance — much appreciated.

[Frank Elder]

Here Chris...

[bamfordsgarage]

I.. uh..well.. hmm...

Hey now I remember — that was so Andydodge could read it easier!

[T120]

..."Only in Canada,you say" same for Chrysler and Desoto six (bearings)

Edited January 21, 2012 by Ralph D25cpe

[bamfordsgarage]

Greg, your referral to Terrill Machine in Texas was excellent — I was most impressed with Feltz Terrill's knowledge and pleasant manner. The fact he had nearly everything I needed in stock at a comparable or lower than the other suppliers didn't hurt either. Cam, rod and main bearings, timing gears and chain, and front and rear seals are all winging their way north.

I received my complementary new front and rear motor mounts from PatS last Friday, thank you very much. The new rear rubbers are 0.100 thicker than the originals, the new front mount is 0.900 thicker. Not that the new ones are incorrect, I attribute this difference to deterioration of the old parts. Everyone who encouraged me not to reuse the old ones were correct.

I thought it wise to replace all the head bolts since I had already broken one last spring when I had the head off to investigate a banging noise. Terrill couldn't help with head bolts and I had no luck sourcing them locally. Bernbaum was $63 for the set and VPW was a rather astonishing $126 per set. Terrill mentioned that small-block Chev head bolts were similar but I could only find them here in sets that included 10 head bolts (I need 21) packaged with others I don't need. At $53 per set, that option had little appeal and besides, the bolt-head style looked all wrong for this car.

Instead I bought 21 Grade 8 7/16-NC 3" bolts for 80¢ each and made my own. Considering the five operations per bolt there was precious little saved if my time had any monetary value but it was a pleasant way to spend a couple hours in the workshop. Photo 2, Left to right: Store-bought bolt; head markings ground off and pilot hole in thread end; Lower shank turned down to 0.390 per original; thread end cut to length; head sandblasted; head chemically gun-blued; original Mopar bolt. Only noticeable difference is the 1/16" small head size.

Picked up my flywheel, pressure plate and relined clutch disc today from the local rebuilder and they look excellent — a fair bit of grinding was needed to eliminate the heat-checking and hard spots. I get the engine parts back tomorrow AM and can start some reassembly this weekend.

[Don Coatney]

Good job on undercutting the new head bolt shank. Due to this undercutting the bolts should work well.

[bamfordsgarage]

...Due to this undercutting the bolts should work well.

Thanks Don. I figured this undercut was important, but don't know why. Can you elaborate?

[Don Coatney]

Thanks Don. I figured this undercut was important, but don't know why. Can you elaborate?

With no undercut the shank can and will rust fast to the head making removal almost inpossible.

[Alshere59]

I have always thought it was for stretch and torque. Never heard of it helping with rust.

[Don Coatney]

I have always thought it was for stretch and torque. Never heard of it helping with rust.

How could the undercut help with stretch and torque?

[Alshere59]

How could the undercut help with stretch and torque?

I am not the expert but I did find this.

Gives the proper amount of stretch to get the proper amount of torque.

Page 37 in the 5th paragraph

http://video.arp-bolts.com/catalog/ARPCatalog.pdf

So how does it help with rusting solid?