1937 Special - 248 General Engine Rebuild Help Tips

[70sWagoneers]

Im gearing up for my first engine rebuild on my first vintage car! It is a 1937 Buick Special Trunkback Sedan with the 248ci engine. The previous owner ran it out of oil and it sounds like a connecting rod bearing is gone. So Ive cleared some garage space, got a heavy duty engine lift and stand, and even sourced some later connecting rods with insert style bearings. But at this point Ive got a few questions I'd like to hear peoples' opinions on....

 

First of all, what is the best way to remove the front doghouse? Do you recommend to take off each part individually or could one seperate and lift the fenders and grill pieces as one unit?

 

I would like to know what a good compression ratio to shoot for is. Is 9:1 to 10:1 range too high and why? What are the weakest mechanical links in the engine?

 

I would like to add a oil filter to the engine, but keep a factory look. Has anyone converted a later Buick model canister for modern filter elements? Perhaps I just need some pictures of later 1938+ oil filter setups to get some ideas.

 

Otherwise, Id like to know any problems, issues, or wisdoms people have ran into while building their engines. Any parts that were unobtainable or bad quality, or little tricks for oiling issues, whatever.

 

Thanks,

James C.

 

[MCHinson]

Welcome to the AACA Discussion Forum. In addition to the help that you find here, there are several other sites that you should visit. If you are not a member, you may also want to join the Buick Club of America. You should visit the website of the 36-38 Buick Club, a Division of the Buick Club of America, at this link: http://www.3638buickclub.org/Home_Page.php 

 

I realize the 36-38 Buick Club website is a bit out of date but a new webmaster will be updating it in the near future. You should consider joining that club too. You will find a membership form on the site's membership page. 

[Dwight Romberger]

Welcome James and congrats on the new trunkback.

 

It looks like a very solid car.

 

I can't help with the technical stuff, but I admire you courage to do the rebuild.

 

I do know that there are a lot more engine parts available to rebuild your straight eight than there were for my '30 straight six. There are even performance parts and restomod upgrades (not that anyone one would ever consider doing any of those)

.

Good luck with the rebuild and keep us armchair quarterbacks informed.

 

No guts. No glory!

 

Dwight

[LAS VEGAS DAVE]

Welcome James, I will be following this thread with great interest as I have a 38 Special that I drive every day. I have a question, why do you want 9 or 10 to one compression in one of these engines? They only have about 6 to 1 stock. I think that the higher compression would be hard on everything plus develop more heat which I doubt the cooling systems if left stock could handle. The only advantage to higher compression is more power but the rest of the engine needs to be modified also if that is the goal. I dont think you could mill the head enough to get 9 or 10 to one compression so it would have to be in conjunction with different pistons and the cylinder head combustion chamber shape along with the valve angle would probably not be ideal for high compression pistons. I find that the biggest problem with these Specials is the gearing if you want to drive it at hiway speeds. Even if the motor made twice the power the gearing would still be to low to use it. I think the insert rod bearing modification is a great upgrade since the engine will be apart anyway. I'm looking forward to seeing what you end up doing and how you go about it.

[Ben Bruce aka First Born]

  Welcome, James,

     I believe the front clip can be removed as a unit. I KNOW it can on a '39, and they are similar.  Just check closely for any wiring that is attached to both the inner fender and the body. You might want to confirm the engine is, in fact, a '37. The engine serial number is stamped on a machined pad just in front of the distributor. Post that number, and I will bet Sean, or some one, will confirm the engine year.

 

  Ben

[Dwight Romberger]

Ben is correct. Check the engine number. It is good to find out now that you have a '39 engine rather than half way through the rebuild. Good advice.

 

Plus, if it not the correct engine you have some additional options.

Edited November 1, 2015 by Dwight Romberger (see edit history)

[C Carl]

Hi , James , raising compression a bit is a very good idea. Your present compression was compatible with the octane of gasoline in the mid/late '30s. Bringing it up to 8:1 would match modern 87 octane very graciously. You would not be loading anything beyond what your engine was designed for. Going for 9:1 or even 10:1 would necessitate other changes , carburation and cam profile among them. You would then have to use high octane gasoline , and the engine would indeed be working harder. If you have the money , know how , and time , you could consider something like that , but I think you would be wise to contact old time Buick hotrodders who have played around with such mods. Hopefully someone who has done so will join in. One of the joys of old cars is in using them just as they would have been driven back in their time. 8:1 will give very similar performance to original. Bearing loads are at max on power stroke , not compression stroke. The slower flamefront propagation rate of 87 octane has to be compared with the faster burning old gasoline. Power stroke bearing loads on an 8:1 engine on 87 , would be similar to a 6:1 on , say , 70 octane. Your exhaust valves may thank you , too. Raising compression on overheads should generally be done with pistons , not milling the head.

I expect you have read what Las Vegas Dave has been doing with his low-mileage , original '38. If you are looking to get the most joy from your bucks , go O.D. And in closing , a public safety suggestion : Any juice brake car returning to the road should should have the brakes checked and serviced to make sure they are in PERFECT condition. Maybe also a dual master cylinder . All the best to you , James. You will have a very sweet running old car ! - Carl

[pont35cpe]

James, the front-end assembly should come off as one piece with radiator. Disconnect rods from firewall to top of rad. support, remove bolts where fenders attach to body, and where rad. support attaches to frame. Disconnect wiring for headlights/park lights at terminal blocks, disconnect rad. hoses. Probably have to remove front bumper and supports, then should lift off.  I have a `41 248 super engine that I rebuilt here on my shop floor, it is originally equipped with an oil filter, and the strange thing is, the filtered oil does not feed any bearings or the top end, the filtered oil drains back into the side of the block back to the sump. I also up dated to insert type rods. Some other things... there is a little screen in the head where the oil feed hooks up, this screen could be stopped up, don`t forget to check it. When you take the brass fittings loose that are screwed into the block and head, take note so they go back in the same place, they may have different size holes, mine did. The mains on the crankshaft are all different diameters, so don`t mix the bearings up, the mains will also have to be shimmed for correct clearance. Then there`s the timing chain/gears, gear timing marks are clocked at 3 o`clock with 11 links (pins) between them, an original chain will have two copper colored washers for the timing marks, after market chains don`t.  Also mark your pressure plate to flywheel and flywheel to crankshaft before you take them off so they go back in the same place..  Good Luck  Tom

[Chrysler300XMan]

My 80 year father is currently rebuilding the engine for our 1937 46C. The 248 came out of a parts car that was built about a week after our car, which had a later (around 1949) engine in it. I had to remove the front end in stages as my dad was not up to muscling an entire front clip off the car as one unit. We had the 248 bored .030 over and it is receiving a new set of 1938 style pistons from Egge. The cam was reground and the crank journals polished. Both my father and the machinist agreed that the original babbitt bearings from the parts car engine were in excellent condition and are being reused. We changed the timing chain case cover to the newer style in oder to use the modern seal. The rear main seal is also of the modern style. The oil pump has been cleaned and will be rebuilt, but will have the spacer plate between the drive gear and rear cover as found in later years. When I carefully sanded the mating surface of the rear cover, I found clear evidence of a gap developing from the oil pressure bulging out the cover. Not bad enough to cause a significant drop in oil pressure, but there was a gap. The cylinder head will receive a valve job.

We found a way to evenly heat the starter ring gear for installation onto the flywheel during the summer. We placed the ring gear in the outdoor grille and heated it for a half hour at over 550 degrees. It dropped right onto the flywheel without any problems. 

[Dwight Romberger]

I like the outdoor grill idea.

I am going to remember that one!

Dwight

[DonMicheletti]

The old Torque Tube Magazine had lots of information on rebuilding these engines. Look around here.

 

http://www.1937and1938buicks.com/The-Torque-Tube/Torque%20Tube%20Technical%20Index%20By%20Frank%20Freda.pdf

And here

http://www.1937and1938buicks.com/The-Torque-Tube/The-Torque-Tube.htm

 

It is possible to adapt a modern full flow oil filtration system without making it to obvious, but it is a major job. A partial flow oil filter is simple.

 

With the stock restrictive manifolding, both intake and exhaust, I'd think twice about raising the CR ratio to much.

[70sWagoneers]

Yes; I have no goals of pushing the compression thru the roof. I should have just asked what CR people ended up with. The original CR is 5.7:1 so 7:1 or 8:1 sounds awesome. Seems like Ill probably need new pistons....

 

Cylinder - Compression :   rear engine  8-95psi; 7-87; 6-82; 5-85; 4-85; 3-85; 2-80; 1-80 front engine

                   with oil:                            8-105psi; 7-97; 6-85; 5-107; 4-90; 3-90; 2-85; 1-102

 

The more I think about it; the more I think my goal is a stock-ish rebuild (the car is all original). Nothing exotic.

 

I'm definitely set on adding an oil filter and would like to know more about ideas on where to plumb the oil in and out of the motor.

 

Anybody have any opinions on NOS bearings? Or can I find everything new (mains, connecting rods, and cam bearings)?

 

And Im also very interested in the rear main seal not leaking! Can I retrofit to some sort of rubber seal or should I stick with the rope seal?

 

Oh yes, Im working thru the Torque Tube; it's a lot to digest

 

Thanks 

James C.

[Chrysler300XMan]

I should correct and expand on my remark about the rear main seal. My father and I replaced the rear main bearing seals, but not the rear main seal because the engine did not have one originally. We confirmed this with Egge. The 1937 crankshaft has a machined flange that sits in grooves cut into the top and bottom main bearing pocket. The flange acts as an oil slinger. Any forum members know when Buick started installing the rear main rope seal? The parts book does not provide a definitive answer. 

[DonMicheletti]

I have had '38 Buicks for over 30 years. They do not have a rear main seal and oil leakage has not been a problem.

However if an engine is really shot ant there is a lot of blowby, then there may be a problem of oil leakage.

 

It worked before, it will work again.

[jenz38]

They start with a seal in '39 , i had the same problem with my oem '38 engine, leaking and a oily clutch. I use the two piece rubber seal from best gasket, now in my newer engines,a 248 from '48 (for spare) and a 263 now in the car, ..it works perfect.

[pont35cpe]

James, I bought most of my parts for my `41 248 at Terrill Machine, DeLeon Tx., Feltz Terrill 254 893 2610. He took my Babbitt rods in exchange for up-dated insert type rods, he also had main bearings, rod bearings, and rebuilt my water pump, he should have cam bearings also... He`s been listed in Hemmings for 30+yrs.  Tom

[Buicknutty]

 I had the rods for my '41 Roadmaster by Terrill Machine, good, quick service, and all was fine. What he said about old babbet, is that it can fatigue over time even when the tolerances are still good, and after a certain point, it will give out quickly. I have no idea if this happens often, or is common at all, but that's what they told me.

 I also raised my compression a point or so by milling the head. It has been running great now with about 5,000 or so on it.

 Keith

[critterpainter]

The rear main bearings are wider on the pre 39 engines and that rear main bearing is hard to find.  The rest of the main bearings interchange and I have heard of people using the later rear main, but I don't know if its a smart idea or not.  I don't know if the narrower rear main bearing would be an issue with rear main oil leakage.

 

Bill