Engine: Where'd the term "still tight" come from ?

[Mike Van Veghten]

I've seen and heard this term for many years...up to reading a post here today.
I don't have many miles on it yet, "the engine's still tight".

Where'd it come from?

If much of ANYTHING wears early on to "loosen" an engine, the engine will have a short ugly life. Anytime since replaceable bearings, this statement is pure myth.

Things that may...loosen...

Rod bearings to crank, hopefully very slowly.
Main bearings to crank, hopefully very slowly.
Pistons to bore's, hopefully very slowly.
Rings to bores, hopefully very slowly.
Rings to pistons, hopefully very slowly.
Wrist pins to pistons or rods, no.
Cam to bearings, hopefully very slowly.
Timing chain, hopefully very slowly.
Lifters to bores, hopefully very slowly.
Oil pump gears (gerotor disc) to housing, hopefully very slowly.
Rocker arms to pivots, hopefully very slowly.
Rocker arms to push rods/valves, adjustable.
Push rods, see above.
Distributor drive to cam, hopefully very slowly.
Points to rubbing block, (old term), adjustable.
Various thrust bearings/surfaces, hopefully very slowly.

What have I missed that may..."loosen" in a short period of time ?
Beside piston ring break-in, (which isn't really measurably loosening !), nothing should "loosen", hopefully for a very long time.

OR...is this another ancient carryover comment like using the word "rim" when actually meaning wheel. At one time, changing a tire, actually did mean, changing a "rim" with the tire, leaving the spokes and hub on the axle. But this hasn't been so for...well, many, MANY years, but for some reason, some people don't either understand the difference or refuse to give up the 80 year old terms.

Just curious ?

Mike

[tsenecal]

I think the term "tight" meant new rings running against a new honed cylinder, or crosshatch. Until they break in and "seat" there is a little extra friction. I agree on the rest of the items, The bearings should have all been checked with plastigage, for a proper fit, and ring gaps checked in each bore, with the ends filed if needed.

[wittsend]

Referring to the last paragraph in #1.

Yes, and I see it more here at the SDC than on any other car related web site I frequent (sorry but it is a valid observation). It must have something to do with the predominant location and age of the forum users. There seems to be a real "I've just walked into Floyd's barber shop..., like I do every day" way of conversing for some people. I've been tempted to tally up a months worth of Forum Subject lines like, "What do you think?," "Will it work?" "Could be" etc. and ask how one would search out an answer with Subject lines like that.

Ever have someone call you and when you answer they say, "Are you there?" Like..., WHAT, you didn't hear me say "Hello"??? Well if we follow the theory you presented of old terms lingering the very first phone call was, "Watson, are you there." So, there you go.

I'd be curious to know what term you would use for an engine that isn't yet (and here we go..., where did this term come from) "broken in?" Because as you point out about loosen, we don't want anything broken either.

[doofus]

I think that term can be lumped in with terms like "Center Head" (Intake Manifold) or "Hogs Head" (Bell Housing). seems to depend on where in the country you hail from. when heard you should nod wisely and look studious, or burst out laughting. Doofus

[nvonada]

OK, I happen to know this one. Back in the days of poured babbitt bearings our intrepid forefathers would pour new bearings in place. The ideal technique was to cast the new bearings using a shaft a little smaller than the journal you were aiming for. Then you could use a reamer the same diameter as the journal to ream out the new bearing to the right diameter. Shadetree mechanics did not tend to have the right reamer so they would coat the bearings in Prussian blue (or paint if you did not have that), then shave the high spots on the bearings down by hand. Shaving too much was fatal so the final bearing would be not very flat. So they would shim the bearing blocks or rod ends so the bearing was too tight (just enough so the engine would turn) and hope that the bearing would wear smooth to about the right clearance. Your engine was literally "tight" while the bearings were wearing in. This was probably a lot more noticeable when you had to hand-crank the engine...

Nathan

[christophe]

OK, I happen to know this one. Back in the days of poured babbitt bearings our intrepid forefathers would pour new bearings in place. The ideal technique was to cast the new bearings using a shaft a little smaller than the journal you were aiming for. Then you could use a reamer the same diameter as the journal to ream out the new bearing to the right diameter. Shadetree mechanics did not tend to have the right reamer so they would coat the bearings in Prussian blue (or paint if you did not have that), then shave the high spots on the bearings down by hand. Shaving too much was fatal so the final bearing would be not very flat. So they would shim the bearing blocks or rod ends so the bearing was too tight (just enough so the engine would turn) and hope that the bearing would wear smooth to about the right clearance. Your engine was literally "tight" while the bearings were wearing in. This was probably a lot more noticeable when you had to hand-crank the engine...

Nathan

I was just about to tell the same. I heard stories from truck drivers who started their careers in the 30's. Upon delivery of a newly refurbished engine, it was not uncommon for them to have to stop when they felt that the engine was a still a little stiff. Then, they dropped the pan and made the required adjustments on the hottest bearings. I have the utmost respect for these men. With a maximum top speed of 35 mph (less, sometimes) they could only achieve an average speed of 20 mph. It was a strenuous job.

[52hawk]

Yes,years ago I watched a very well known engine builder 'shave' a rod bearing with a pocket knife.

[christophe]

Here is an assortment of the tools used to "massage" babbitted bearings.

[greyben]

I would suggest that the term breaking in carries over from the days when it was common to "break" a horse to be ridden or worked. It was certainly a common term as far back as I remember (1950s). Studebaker owner's manuals more appropriately referred to it as a run in period. A tight engine was an appropriate term for the times. Engines tended to run hot until the initial seating of the rings. Also in the days of poured bearings it was common to fit them tight initially so as to allow them to have more time to become loose which could occur in a few thousand miles. If engines went from tight to loose it might seem obvious that the tighter a new or rebuilt engine was the longer it would last. Both terms seem more intuitive than terms such as facebook and tweet.

[Dwain G.]

I think it can have two meanings depending on the circumstances:
1. Not worn, all clearances nearly as new, good engine.
2. Engine just overhauled and starter doesn't crank the engine very well.
This last one I remember from when us kids used to hang around cafes/diners. Once in a while someone would ask us to give him a push because the engine was just overhauled and 'still a little tight'. This seemed to be mostly on Chevy sixes with the shimmed bearing caps.

[JoeHall]

I am told modern motors do not come with a break in period, and are ready for a coast to coast trip, on the super slab, right off the show room floor. Further, they will continue to run, "like new" for hundreds of thousands of miles, use very little, oil, need few if any repairs, etc..

OTOH, vehicles of the 50s-70s, were to be kept at low, varied speeds for the first 50 miles, then an oil change, then below 50-60 MPH for the next 500 miles, then another oil change, then drive as usual. They burn extra oil during break in, and will need repairs from time throughout their lifespan, which is usually about 100,000 miles. A motor of the same era is treated similarly today, after a rebuild, maybe even more so, i.e. initial run-in procedures for cam break in, if using flat tappet lifters (not called for in the 50s-70s). The reason for the above procedures with vintage motors is due to technology and standards; moving/mating parts really do need time to, "bed in", and friction/heat will lessen with miles. Anyone who has ever fired up a newly rebuilt motor has probably noticed how quickly they heat up, and how quickly they stop turning when the key is shut off. Compared to a motor with 20,000 miles or so, which is less prone to rapid heat up, and sort of spins to a stop when the ignition key is turned off.

Call it conceptual semantics, old technology versus new, or whatever. But to me, a newly rebuilt, 50s-60s era motor is, "still tight" if it heats up quicker, stops turning quickly when ignition is turned off, and leaks less oil, but pushes a little extra oil past the rings. They tend to remain tight for the first 5000 to 20,000 miles or so, but unfortunately loosen up as miles tick by. By 100,000 miles, most are in need of another rebuild.

So my conception of the term, "still tight" still applies, to Studebakers, and any other freshly rebuilt or extremely low mileage motor, over 50 years old.

[BILT4ME]

I have one of those tools and have never known what it REALLY was.... (The second one from the top)

Here is an assortment of the tools used to "massage" babbitted bearings.

[6hk71400]

Tom McCahill in his test of the 1956 Golden Hawk referred to the engine in the car as still tight. Packard engines back then as far as I know, were built with extremely high tolerances.

In remembering new cars, my granddad had just bought a new 1960 Pontiac Catalina when my great grandmother passed and had to drive to New Mexico. It was rough trip as the speeds had to vary so many miles under 50 mph, then 60. I do remember after the break in period that car would fly down the road and not use oil. in 1966, dad bought in August a Chrysler Newport. Asking about breaking, sales manager said not to go over 110! He later said just vary the speed.

After my first car, 55 speedster was rebuilt, mechanic advised break in period and change the oil after about 300 miles. Since the car was driven around town, kept the speed low. After break in, found out way she could do in overdrive.

Bob Miles
Tucson AZ

[PackardV8]

FWIW, there were some bad old parts in the good old days which did make for a tight engine when new.

Tom McCahill in his test of the 1956 Golden Hawk referred to the engine in the car as still tight. Packard engines back then as far as I know, were built with extremely high tolerances.

Minor point of order, but 'extremely high tolerances' means a wide variation is permissible. It is probable 'extremely tight tolerances' is what was meant, which means very little variation permissible. And yes, Packard V8s had each piston individually, tightly, fitted to each cylinder - proof of superior craftsmanship, right? Wrong, they had to do it that way because the machines honing the cylinders and those making the pistons were not capable of holding exact tolerances. At least Packard tried to compensate for variations by measuring each finished bore and stamping a letter code below each cylinder. Each piston was measured and put in a box with a letter code corresponding to which cylinder it would fit with .0005"-.0025" clearance. Ford just specified looser tolerances and let the assembly line run ragged.

Packard also used a heavier, stiffer, deeper K-wall ring where GM and Ford used a D-wall.

Piston rings, back in the bad old days, and even today's Champion repops, use wide, stiff cast iron rings which don't conform well to the cylinder until they've had some miles and heat cycles to make them fit the bores.

Today's engines have much thinner, more flexible moly coated rings mated to a precision honed cylinder, don't require any break-in miles.

On my latest high-performance Packard V8, I ordered the custom forged pistons machined for 1/16" moly rings.

Today's pistons are designed by finite element analysis, with the pistons cast and machined on CNC machinery, having complex inner and outer shapes so the clearance begins exactly where it should be and stays that way hot or cold. Thus they don't need any break in miles to scuff of the tight spots.

Joe Hall will remember back in the day, Egge Machine reproduction pistons for the Packard V8 had to be fitted with .003"- .004" clearance or they'd be too tight and the engine would run hot. Today's Egge's are much better made.


jack vines

[jnormanh]

I am told modern motors do not come with a break in period, and are ready for a coast to coast trip, on the super slab, right off the show room floor. Further, they will continue to run, "like new" for hundreds of thousands of miles, use very little, oil, need few if any repairs, etc..

You're correct, modern engines are ready-to-run the day you buy the car, and, with reasonable care will run a few hundred thousand miles.

They are better designed.

They are manufactured to more precise tolerances.

They are made of better materials.

They do not run leaded gasoline which causes wear and corrosion.

Modern oils are better.

Fuel mixtures are more precise.

Cooling is better. Most have oil coolers, and all have adequate radiators.

And there are fewer design and manufacturing screw-ups. In this regard , remember the 1958 332 ci Fords which were assembled and sold with camshafts which, due to a manufacturing error, were shipped with camshafts which had not been heat-treated. They all fell apart at 30K miles. And Ford said: "Too f'ing bad, the warranty ran out at 12K."