VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1933-1936 rebuilt engine to tight

I always start a fresh engine and run it at a very fast idle untill it reaches operating temp. Then run for 15 more minutes.
Shut down and re-torque the head bolts. Then I drive them. When I reach for the key they start.

Chevy 1937

Would you explain how re-torquing the head bolts after running for a short time helps a rebuilt engine start better? This forum is a great place to learn for those of us who lack the mechanic's skills many folks have here. Thanks ahead for the continued lesson.

Retorquing the head bolts is done to compress the head gasket farther and has nothing to do with starting. This is done to prevent coolant leaks. The old "thick" head gaskets could compress a bit.
The steel shim head gasket used for 8 Cyl. engines back then did not require retorqing.....and most of the new conventional gasket does not require it. Probably best to follow the instructions made by the gasket maker. That being said I would still retorque the head once later due to the age and etc. of the head.
When new the new car prep guy would retorque the head and adjust the valves. For the 1000 mile inspection that would be done again. Chevrolet recommended retorqing the head with easn tune-up.

It doesn't help it start! It's just the proper thing to do. No engine should be TIGHT after a rebuild that the proper 6 volt will not turn it over. If so, it should be gone through to see what is wrong.

I know it's a hassle but I would add a couple thousandths of shims under the rods and mains, run it a while then pull down the caps and see where the wear is. I still have a good set of babbit scrapers but who knows what I'm talking about or even how many still know the technique? Babbit bearings on small engines should be set up properly if you want to do it the right way and not have problems 5 thousand miles down the road (or less.....). The boring bar sets up the mains, not the rods. Get them too tight and you risk rubbing out the material due to high friction; then you will wish you had done it right in the first palce.

Chev 1937 - I understand the reason for torquing the head after a rebuild, but the way I understood your post made me think there was some connection to starting the motor which I could not understand.

Part of the problem is the 75 year old starter just dosen't perform the was it did when new. That along with batterycables that are not up to par plus "not the best" connections along the way.....and new rings sliding on a dry cylinder wall, all add up to a tight engine not turning over.

Thanks for everyone's input--this thread certainly seems to have ellicted opinions! We're hoping to try starting the car this coming weekend--will see what happens. It is set up pretty tight, but we plastigauged all the main and rod bearing surfaces and assembled with engine lube. If I recall correctly we set the clearances at 2 thousandths or a little more on the mains--between 1 and 2 on the rods. NOS (GM)rods and NOS (GM) crankshaft.

NOS and NORS later-style insert main bearings were used, so line-boring wasn't necessary. I'm hoping these aren't an issue--these seem to be rare as hen's teeth so a complete set of three was put together from 2 GM bearings and 1 aftermarket. Theoretically the should all be the same--but I've had other NORS parts that weren't exactly like the NOS.

One area I'm concerned with is the valve guides--the machinist got those a little tight and I'm hoping that a valve doesn't stick after getting hot, bending a push rod. Some of the piston pins are tight, too. The set of NORS aluminum pistons I had didn't come with the wrist pins, so the machinist fit a set.

Will also re-torque the headbolts after running. That advice I was familiar with.

How crucial is it to prime the oil pump? I thought that since everything is well coated with engine assembly lube and these things were low pressure anyway that this might not be necessary. Any thoughts?

I'll provide an update once more is known.

P.S. My brother's Model A F*** was very tight when he rebuilt it-but it now runs very well.

I would definitely prime the engine, spray the valves/guides with Marvel Mystery Oil, and crank over for a while with the plugs out before trying to start.

Is this Marvel Mystery Oil available in Canada? I've never seen it or heard of it outside of this forum. Looks like it is almost indispensable.

Just use ATF (automatic transmission fluid) instead. It is nearly the same, much less costly and available everywhere. I use ATF even though I have some MMO. Use it as aftershave.

It is not necessary to prime the oil pump. What I do is leave the plugs out and spin the engine over with the starter. After the engine is runnning the presure will be up right away.

I'll agree with Gene on the older splish splash sling and dippy-do engines gets a major part of the lower works luberication from the rotation of the crankshaft and rods.

An update: good and semi-bad news.

The good--engine running great except for heating issues. When the spark plugs were removed, the starter would barely turn over the engine. With spark plugs in, not a chance. We towed the car around the yard in second gear(with spark plugs out) for a few laps with my brother's Farmall A.

Then put the spark plugs in and the starter was able to turn the engine over and it fired right up. Ran it for about 10 minutes and it got hot, so shut it down. After cooling, it was again too tight for the starter to spin. So hooked it back up to the Farmall A and did a tow start. Let it run again for about 10 minutes or so--got hot again and shut down. After cooling, it was able to turn with the starter and has ever since. Good oil pressure as well--for what little these carried.

But it still wants to overheat when sitting still. I don't have it road worthy yet (see semi-bad news below), so not able to drive to see if will stay cool with air moving over the radiator. I'm hoping that as it breaks in, the heating tendency will abate. Also, the timing is a guess right now--we forgot to bring the timing light so it may be advanced too much. And the cylinders have been bored to .060 over--I hope that the heating is NOT being caused by the oversize bores. Any thoughts--is .060 too much?

Brand new, NOS, flushed and inspected radiator and block cleaned out--so shouldn't be due to the cooling system. I did put in a Gano filter (because I thought there still might be some rust flakes in the block and wanted to catch those before they got into the radiator--my brother thinks the Gano filter could be restricting the flow-but I would think the thermostat would restrict far more). If still wants to get hot, I'll take out the thermostat for awhile.

The semi-bad news and why not on the road: I had put new brake cylinders and hoses on the back and we then bled the system. After pulling the car into my Dad's garage, heard this "glorp" and a whole bunch brake fluid was puked out onto the nice clean floor. Found the steel brake line from the master cylinder to the tee block had sprung a leak--and I apparently have been very lucky it didn't happen long before. Someone (before I got the car in 1983 and it's been a regular driver) had soldered up a hole in the line--it looks like the speedometer cable had worn a hole in the line! The solder gave way. So will need to replace this line--front rubber hoses are fairly new and other steel lines look good.

And the tail light sockets now have shorts in them (original wiring), so got to rewire that before getting on the road. Next is hook up the headlights (my brother put in a new wiring harness for me), put the hood back on, and should be ready to go!

Thanks again for everyones input!

In warm weather it is not that unusual for a newly rebuilt engine to over heat when the car is not moving, When you do run it pull out the hand throttle so the idle is quite fast.
You could also place a box fan in front of the grille.

If the timing is too retarded it will overheat, don't ruin your new job so watch the temp closely.

I see you are not a member of the VCCA. You are strongly urged to join so you can receive many benefits from this site and the club newsmagazine.

Sorry that my profile doesn't indicate it, but I've been a member of the VCCA since the mid-1980's (don't remember exactly when, but shortly after I got the car in 1983). I don't have my card in my wallet presently (guess I'm not a card carrying member), or could otherwise give the member number and update the profile. I'll try not to be a "lurker" on the forum and should make more of an effort to contribute.

I've always appreciated everyone's help and Gene has been of great assistance. The Tech Tips in the G&D have always been appreaciated and I hope Gene and others are able to continue.

Best regards,
--Joel

Actually, I just looked at my profile and it does have my member number. How do I indicate membership for the forum?

I looked at your profile and your Chevy Chatter II member number is 2522, and your VCCA membership number is 30031.

1936chev.
If you go to .. My Stuff on the header bar above. click on Edit Profile, and then go to "group images to display" Tick in the adjacent box and it will allow the VCCA member blue oval Icon to be diplayed under your user name with your posts.

Jack,

Thanks for the instructions--updated and even added an avatar of the 36.
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In warm weather it is not that unusual for a newly rebuilt engine to over heat when the car is not moving, When you do run it pull out the hand throttle so the idle is quite fast.
You could also place a box fan in front of the grille.
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Chevgene

Gene,

Appreciate the input. Yep, I've been running at a fast idle, and for awhile had a big shop fan in front of the car. As long as the fan was going the car stayed nice and cool. And timing could be a contributing factor--will set the timing before running again.

A quick update: The car has been driven almost 200 miles now and doing well (except for some old gas causing the carb needle/seat to stick closed) . As long as on the move and not on too prolonged of a pull (we live in the Appalachians...), it doesn't overheat. But one concern: It didn't seem to have as much power as should. Plenty of torque at low RPMs, but not much for acceleration.

I'm going to re-adjust the valves while hot(set with a pretty big gap cold for rebuild). Using a timing light, the timing was set with the ball on the pointer. But by using the octane adjustment on the distributor, advancing two degrees gave it a good bit more power. Would it hurt to try advancing it a little more?

No, not at all. You can probably go six or eight degrees more advanced. You will have to experiment and see what the best setting would be.

Also, adjust your valves to the correct spec. and never run a new engine on old gas.

Exactly ...and I think by "experiment" you mean "You can leave the timing light in the tool box ", do you not ?