The Stovebolt Site Forums The Shop Area Engine Shop Max speed for original enclosed driveline with a 235

OK, since my speedo hasn't worked for years, I threw a tach on the steering column and had
my wife follow me telling me how fast I was going. At 2,000-2.100 rpms I was traveling at 50
mph. What is the maximum rpm or mph I can safely travel at with my current driveline combo
without blowing up or out something ? The tranny is a 4 banger on the floor.

Full pressure 235 or dipper?

The long stroke engine is your weak link. If you have a full-pressure 235 cruising rpm is best kept under 3,000 rpm. The faster you turn these engines, the shorter their lifespan. The rods will stretch at high rpm. A brief spin at higher rpm won't do much damage, it's the prolonged stretches that will fatigue your rods. They are made to cruise at the 2,000 to 2,500 rpm range.

If the engine is a stock 1950 with babbitt rods the "official governed" rpm from Chevrolet is 3200rpm. This is what Chevrolet would set the RPO Governors at for fleet usage to keep the rod bearings from wallowing out too much and needing frequent "shimming". In addition, the dipper/trough/squirt oiling system was A-Ok at 3200 rpm.

Peak horsepower was often given in the 3200-3400rpm range in sales liturature with a lot of caution made by Chevrolet for exceeding 3600rpms for extended periods.

Tachometers were very rare in the early 1950's Chevy trucks as they often had to be mechanically driven. Todays electric tachs are super for preserving the life of your engine; helps you keep the rpms under 3600.

FOR MORE INFORMATION SEE THIS SITES FORUM:
VCCA

My 235 is a late 58-63 series. What is meant by full pressure or dipper ? I think I'm more
concerned with the rear end's capacity ? Just listening to the engine, I'd be sweating if
I traveled at 2,500 rpms. It sounds pretty happy just cruzin at 2,000+.

Thanks

The pre-54 235's had a splash oil system (dippers).

A good idea would be to "search" this site for topics dealing with the various ways of determining the exact year of your engine. Once you know the year, you can get specs for torque, horsepower, and of course the factory recommended rpm's.

The topic of full pressure versus low pressure is also covered on the stovebolt site with a "search".
In general the common "concept" of full pressure being better than low pressure is a FALSE one. "Full pressure" Chev truck engines occured around late 1953 and were available in 1954. The "full psi" oiling system basically included a new passageway in the crank rod journal to provide oil from the new oil pump, thru the crankshaft, and under pump pressure to the rod bearings. The OIL GAUGE would READ a much higher psi than the old system and thus the term "high pressure".

In the old so-called "low pressure" system the oil to the lower engine was provided in a 4-Way method. 1) The oil pump to the mains at full psi 2) Dippers to scoop oil to the rods at low rpm 3) Squirt nozzles to hit the dipper scoops at higher rpms and 4) Splash from the dippers/squirts to lube the cylinder walls & wrist pins. This system would READ a lower psi on-the-gauge BUT IT WAS NOT an inferior or bogus system.
The FLOW of oil to the rod bearings was VERY high and the centrifical force of the oil on the rod bearings that had been squirted into the rods was extremely HIGH in psi! The so called "low pressure/high flow" system was excellent for the 216 and 235 engines, it wasn't really lower pressure where it was critical!!!! It was super for the babbitt bearings and kept many a stovebolt running into the 21st Century. (It was also quite expensive for Chevrolet to produce)

BUT in the mid 1950's the race for more horsepower ment a race for more rpms' and the old dipper/trough/squirt system could not keep providing good engine lube at the 4000+ rpm range. The expensive scoops/troughs/squirts could not keep up at higher 4000+ rpms and GM switched over to the oiling type system they had for the GM trucks. The need for hydraulic lifters in Chevy cars also spelled doom for the old 235 oiling as better oil routes were needed to get oil to the hydraulic lifters. New use of "oil filters" also became popular by mid 1950's and the filters caused a need for consistantly higher psi to overcome the resistance of flow thru the filter media. Combine all this with an expensive production cost and GOOD-BYE faithful old dippers/troughs/squirts ...aka "low pressure".

Your rear end is very robust and should handle high rpms (3000+ range) better than your old engine. The truck rear ends were often used in the 1960's for street racing on cars to get a lower rear axel ratio and provide a very tough rear end.

Maybe the whine in the rear end at speeds above 2500 rpm is a call to have the rear end checked out. You can lower the rpm's by switching to taller diameter rear tires. But maybe your rearend neads to be opened and examined: clearances checked; look for an imbalance in the drive train??

FOR MORE INFORMATION SEE THIS SITE:
Vintage Chevy Forum

I was just going to mention that too. You hear your rear end? I hear nothing from the tranny or the rear end at any speed. In the lower gears there is a small whining that I think is normal.

It is engine RPM that limits me from going faster. I think I cruise at 50 but have hit 55+ pulling into traffic, but just don't like all those RPM'S for sustained periods.

I saw your truck the other day and your tires are much taller than mine so I am probably doing a few more RPM than you at 50mph.

lil' johnny

great post.

FINALLY!
A posting by someone that knows what he's talking about when it comes to the 216 and early 235 oiling system! This system was great on a stock engine and not abused. I changed my '52 coupe engine to a late 235 because I knew I wouldn't leave it stock--NOT because the 216 was defective in any way. I grew up with and built numerous Chevy 216 engines and NEVER had a thrown rod or broken crank--this with the idiocy of a 16 year-old kid abusing them!! So please quit badmouthing these engines if you never had any experience with them (and I suspect that most of this board is too young to have any). No, they won't take 4500 rpm for long, but they weren't designed to! Hell, you couldn't stop them at 55 mph anyway! If you're going to "soup it up" then go with a '54 or later 235.

Tony,
It's not that I hear anything from either the tranny or rearend. I just dont know what my speed limitations are based upon the hardware that I'm running. After reading the various replies, I guess I'm not so worried about the rear end. Tranny ? runs like a champ. So it sounds like the engine is the guy I should look after. I'm going to do a compression test this weekend just to see how I'm doing. I'm also going to try and get my gas gauge working.

Tony,
It's not that I hear anything from either the tranny or rearend. I just dont know what my speed limitations are based upon the hardware that I'm running. After reading the various replies, I guess I'm not so worried about the rear end. Tranny ? runs like a champ. So it sounds like the engine is the guy I should look after. I'm going to do a compression test this weekend just to see how I'm doing. I'm also going to try and get my gas gauge working.

CMayna,

Your concern for the well-being of your engine is encouraging.

When I started driving my Grandad's 1954 Chevy 3/4 ton at age 17, I knew that it had a 4.57 rear, but really didn't know what that meant in terms of driveability, so I forced her down the road at 55-60 mph, not knowing how fast the engine was revving (didn't own a tach then!), just noticing that it sure sounded "busy" on the other side of that firewall! :rolleyes:
When it began to require a quart of oil every 100 miles and rods were beginning to rattle, it slowly dawned on me that perhaps I was pushing the vehicle beyond reasonable limits for sustained driving.
This was with a later 235, BTW.

Now, almost 20 years later, I don't have a hard answer for you as to "redline", but, I have had & driven many other pre-1960 vehicles, and particularly on long-stroke engines, don't like to spin 'em more than 2,500 rpms for extended periods.

Now, some of the guys might suggest that I'm selling the 235 a bit short here, and perhaps a meticulously re-built 235 will withstand more "revvage" than 2,500, but I'd say that the average unrestored or partially restored engine should probably be treatd with some respect, if we want to prolong its life.

If you were doing 50 mph @ 2000-2100 rpm, that's not bad.
I let my "ears" be my guide, for the most part; if the engine is sounding "taxed", I back off the gas.
Not very scientific, but I don't like old "undersquare" engines trying to "scream" like ninja-bikes!Bad things will happen!

Think of it this way, in 1950, there weren't many places where you could drive faster than 50 mph, legally.

My 2 cents.

Frank,
Not to swell your head too much but your advise from experience, is exactly what I've been after. I cannot agree anymore than what you have said. I feel pretty safe at 2k+ rpm especially with 16x7.50 tires. I would have a problem (maybe even lose some sleep) if I ran my truck at 2.5k rpm's. It's all in the sound. My 235 has been extremely faithful to me for the past few years just due to me listening to her. Now that I've installed a tach, I now visually know when to back off.

I truly appreciate your comments.
Craig

Craig,

It must be sign that I've owned too many vehicles when I can't remember them all at one sitting!

I also had a 1950 Chevrolet Fleetline 4-dr, with a 216 & 3-speed. I'm pretty sure it had a 4.1 rear in it, at least it seamed like it was geared similar to the 1/2 ton trucks.

The car was much less abused than my Grandad's truck, and as long as I didn't push it past 50, it seemed happy.
Sold it several years ago, and of course, now I wish I had not!

Now that we've determined our "limitations",the challenge is to find enough "blue highways" (U.S. & WPA state roads) that get us where we want to go, so that we don't get squashed doing 50 on the Interstates!

Thanks to all for your help. Since I have an enclosed driveline '53 in my '50 1/2 ton, I cannot
watch the driveline spin around. Was there a standard gear ratio issued for this year driveline? Or what other method would someone suggest dealing with enclosed drivelines?

The trucks had 4.11's from the factory.A few years ago we drove out to the Wendall show as usual but this time a friend followed us out there.It's a 300 mile one way trip.Our 51 has a 59 235 with 3.40 gears,. We cruise at 60-65 mph pulling a travel trailer.The other guy had a stock drivetrain 54 Chevy 1/2 ton. he didn't seem to worry about the engine reving up .We lost track of each other 50 miles into the trip and I didn't see him again until we were 50 miles from getting there and my friend blasted by at 70 mph. He said he had a problem and drove the whole way at 65-70 mph to catch up.He drove the 300 miles back at 70 mph also.With the stock gearing ,his engine was running 3200 rpm anyway.This was in a truck that no one knew the internal condition of the engine.I wouldn't run high rpm like that on a trip but his engine is still running today.