The Stovebolt Site Forums The Shop Area Engine Shop Some 50 years ago

In high school I had a .060"over '59 261 motor in a '54 Chevy, and a good six cylinder buddy had a '57 .060 235 in his '57 chevy both had their stock cams.

The buddy wanted to try out my "Corvette" cam, so we swapped out cams (see what can happen with idle hands). We swapped cams and lifters. My solids went into his 235 and his hydraulics went into my 261.

The reason for this post is: BOTH CARS THEN BEGAN TO SMOKE LIKE THEY HAD RUBBER BANDS FOR RINGS!! The question is WHY??? After about a week we both were dying to swap back, and when we did both engines went back into their normal happy smokeless lives. He couldnt stand the noisey lifters and the smoke, and I couldnt stand the smoke either (but I did like the quiet hydraulics-sounded like a new car!)

Why, and what, caused these cars to smoke? They each ran fine with no big performance changes (at least none for me!). Cams were installed correctly on their correct marks, both cars were Texas cars with regular road draft tubes-of course no smog stuff.
The smoke did come out the tail pipes (both had split manifolds and dual exhaust and so all pipes did it) You could rev them up at a light and the fire trucks would come running with lights and sirens (almost)!

Any ideas-surely no one else was dumb enough to do this thing too?

Neat question. I'd think that the excess oil would be coming from the topend but with both engines reacting the same I dunno
I'll be watching to see if anyone nails it

Good thought about too much oil at top end possibly flooding the guides and getting into combustion chambers - but why on both motors?

We were just two mechanically talented bozos that didn't know about whether each block had any special drilling to be able to run the hydraulics or not--just did it- it did fit-so start it up!

As you know (but, this is being posed for others):

The 1957 235 motor came with hydraulic lifters. Presumably it should work with the 261 mechanical/solid lifters and cam.

The 1959 261 motor came with mechanical/solid lifters. That block was supposedly drilled for working with hydraulic lifters.

As with a lot of these mystery's there is usually a missing piece.
In most cases something else was done inadvertently, like both cars filled up with gas at the same time, same place, with bad gas.
I can not come up with a logical explanation, but I will keep working on it.

Is it possible the difference in the cam spec's for a Hydraulic vrs Solid lifter would be enough to allow the overlap needed to get there?

found this on the tri 5. a NHRA spec from the time...
123 235 .015 1880/1505 294/312 Outer Only
136 235 .015 1880/1505 400/400 Outer Only
155 235 .015 1880/1505 405/414 Outer & Inner
162 265 .015 Flat 1725/1505 334/334 Outer Only H
162 265 .015 Flat 1725/1505 334/334 Outer Only M
180 265 .015 Flat 1725/1505 334/334 Outer Only H
180 265 .015 Flat 1725/1505 336/343 Outer Only M
195 265 .015 Flat 1725/1505 404/413 Outer w Damper

H Hyd lifter cam specs
M Man Lifter cam specs

dont understand what I'm looking at, like in the case of the top line maybe its:
123 ('55 stick hp?) 235(engine?) .015(Dunno)1880/1505(dunno) 294?312?(Lifts @cam?) Outer Only(valve spring configuration?) could it be at .015" lift you have 1880 somethings? This is some way of checking the cam while its still in the motor, but some of the units are unknown to me.

The list seems to be the complete '55 Chevy lineup with 123 hp 235 motor std shift motor
136 235 P.G. motor
155 235 Corvette six
162 265 P.G. V8 motor hyd
162 265 std shift V8 motor mech
180 265 P.G. V8 power pak motor hyd
180 265 stick shift V8 power motor mech
195 265 Corvette V8 motor

Just cannot understand the 1880/1505, must be some sort of units of duration. help

Labels(meanings?) for the first line of 235 "data" are shown below
(taken from the NHRA Technical Specifications for 1955 Chevrolet car engines)

123 hp
235 displ
.015 Deck Cl
1880/1505 Valves
294/312 Cam-Lift
Outer Only Springs

How/why would these be pertinent is trying to figure out a question regarding a 1957 235 car engine (cam/lifters) and a 1959 261 truck engine (cam/lifters)?

Well that was simple! And to answer your question,
beats me, I didn't know what i was reading, and dunno what overlap would have to do with oil smoke. Both cams are quite tame, and smooth idling.

It cannot be a function of the piston rings. The only other way excessive oil could be entering combustion chambers is by way of flooded valve guides. Both seem impossible to be changed by merely switching cams and their attendant lifters/pushrods.

Keyword may be "flooded"- what could cause excess oil to appear at head when the only apparant difference was solids and hydraulic lifters. If I remember right, the oil to the head comes thru a passage in the head from the lifter gallery and then thru the rocker arm shaft on these engines. What and how would the different lifters change things that were happening in the lifter's oil gallery?

I cant remember back that far if the lifters had any "grooves" or different external drillings--but once the hydros "fill up" they should not have any different oiling requirements than the solids.

And as stated when everything went back to normal when all pieces were returned to their proper homes.

I saw my buddy 10 years ago at out high school's 40th reunion and we still couldn't figure it out--my opening statement to him was "Harvey, are you still messing with six cylinders?" He said "Yeah!" So I said "yeah, what 'cha got now?", He said "...a Porsche!". ahem

The mechanical tappets changed in late 1957/1958. Earlier mechanical tappets should not be used in the later engines. Maybe Pre '68 Dave will know if the earlier hydraulic tappet design is OK in the later block. The later mechanical tappet design in the earlier block might allow easier oil flow around the tappets.

Still no answer/explanation.

The earlier hydraulic lifters use the same oiling design as later. The main difference would be the material they are made of to match the early steel cams or the later cast cams.

And here is what the 1958 Truck shop manual says.

Caution: Do not install early 1957 mechanincal tappets in 1958
six cylinder truck engines. 1958 mechanical tappets have a annulus around the lifter body for passage of oil to the rocker shaft assembly as shown in Figure 15. The use of a mechanical tappet without the annulus would block the flow of oil to the rocker arm shaft assembly.
-------------
So at least for the one engine that had this situation going for it, the blocked oil would be more inforce blowing past the lifters, bearings etc and on to the crank and then likely overwheming the oil control for the piston rings, (yeah you'd think the pressure regulator would offset it). Thus causing the extra oil consumption and the smoke. At least its a theory.

'dis is heavy-could be true, since we only did it for a week we didn't notice any rocker arm or shaft problems-had a blocked passage once that required an external oil line to the head on the original 235 and didn't notice what was happening 'til the rockers actually squeaked (high school kids really do know it all dont they? almost like today's)

The "situation" that I referred-to regarding lifter design, and that truckolet quoted , is the information half-way down this page. That information is for mechanical lifters from earlier engines being used in the later engines. The lifters being put into the later engine in edski's scenario are hydraulic lifters.

Here is an earlier hydraulic lifter...ar ring) that is warned as being needed.

Most likely the lifters are not the cause of the smoking (from both engines)?

edski,

Wait to hear from Dave on this, but that common shade-tree technique for getting more oil to the rocker-arm might deprive the lifters of some lubrication-pressure (that would probably be more critical for the hydraulic lifters).

I have slower-than-dirt dial up internet. I can see the end of the "wire" from here about an eight mile away-everytime I dig it up and pull on it -they catch me!!
So checking out link's different head pictures is a slow business for me, but it seems we are getting close. More specifically, my car (the '54 with the '59 261) ran the stock '54 235 head with all its unmodified components-oil lines included. The popular aftermarket "external oiling kit" was used on the original 235, but removed when the head was placed on the "fresh" 261- While on the old 235 it had the "sqeaky rockers" prevously mentioned. Several new rockers were replaced and new shafts were used at the time the external oiler was added.

The buddie's '57 235 was as stock as can be other than a split manifold, and drilled main jet. Matter of fact it would run right with my 261 (blush) catching me at top end of low and then second gears, third gear outcome was only a function of length of race--for me the shorter the better. The reasoning for his smoking condition,will require some thinking as we dont know if perhaps he had an early, or a late '57.

Final question-are we in agreement that its a good bet the oil causing the smoke was probably coming from the overly oiled valve guides? Overly oiled either by different plumbing, or perhaps by the misused lifters?

And finally, thanks to everyone for a little enlightenment on a 50 year old "puzzlement" Whew!