Cam shaft question

[knuckleharley]

The one topic I have never seen has been did the factory ever change the cam profiles over the years - car, trucks, industrial, per years made and obviously the application?

 

Is that info avail. anywhere?"

 

I'm sure they did because if you got anything more than 14 MPG on a 292 Ford Y-Block in a car back in 56 you spent a lot of time rolling downhill. By 1969 I was driving a full-sized 1960 Ford custom 300 tudor with a 2brl 292 and 3 speed with no overdrive,and getting 21 MPG on the highway without even trying. And it seemed to make more power than the earlier 292's,also. Yet it ran fine on regular gas and idled smoothly. Probably increased compression and a much better distributor had a little something to do with that,but I'd be surprised if the cam grinds hadn't changed,too.

 

I'd almost be willing to bet it can be found on sites that cater to restorers and in factory literature.

 

Edited January 20, 2014 by knuckleharley

[Scruffy49]

One more time, THE hot rod L6 shopping list...

 

Block: any 230

 

Head: alloy or stock cast iron milled .060-.125"

 

Crankshaft: 1955 or newer

 

Camshaft: stock 1957-60, regrind specs from Howard or Isky via your favorite cam company

 

Induction: 1957-60 intake and 2bbl carb, dual 1bbl intake

 

Exhaust: split manifold or headers, with a Smithy or similar muffler

 

Distributor: 1951 to 1960, with removable plug tunable vacuum advance, 4 degrees initial to 36 degrees total advance

 

Porting: match block and manifold passages, do not waste time/money relieving, polish the combustion chamber instead

 

Oil system: oil groove in mains 3x as wide and 2x as deep as stock; 1/4" spacer behind oil relief valve spring; rotor type oil pump

 

Match starter, bellhousing and flywheel. In other words, if you run a truck bellhousing and starter from an original 218, use the truck 218 flywheel as well. Ditto with cars, starter ring gear change between 1956 and 1957, so 56 back is fine, and 57-60 is fine, but don't try to mix and match a 55 starter with a 57-60 flywheel. You WILL break something expensive.

 

Specs from David Pollock, from Don Bunn and Tom Brownell's Dodge Pickups History and Restoration Guide 1918-1971, Motorbooks International, 1991 edition. ISBN 0-87938-491-3

[martybose]

Okay, I'm good with most of your list, but why the 1955 or newer crankshaft?  What's different?

 

Marty, curiously ........

[Scruffy49]

Okay, I'm good with most of your list, but why the 1955 or newer crankshaft?  What's different?

 

Marty, curiously ........

 

He doesn't specify why. And I have no idea, other than metallurgy. I'd guess, and that is ALL it is, a guess, that the 55 up is forged instead of cast.

[Dodgeb4ya]

Aren't the 218/230 cranks forged? I thought they were.

Sure am glad I don't have to be concerned with all these custom mods! I never have and never will be close to blowing a flat head . I drive em nice and easy!

Edited January 20, 2014 by Dodgeb4ya

[james curl]

If you only use a reground camshaft ground for more torque and keep the original rear end ratio you have not accomplished much, but if you change the rear to a lower numerical ratio to reduce engine rpm at the same speed then it should allow you to cruse with less strain on the engine.  I am running a 3.55:1 rear end and have no trouble taking off in second gear, I have a cam reground for more torque. The engine is modified to take advantage of the cam.

[DJ194950]

Vintage power wagon co. sells a "high performance" cam with new higher pressure valve springs for $300. Has more lift and duration according to their catalog. NO SPECS GIVEN, NOR comparison to a stock spec.

Call them?

 

Just for info, saw it is past searches of their parts.

 

Doug

[Frank Elder]

I have only seen one engine where the block was relieved as pictured below. I was told this engine was used on a circle racer but I do not know how well it did. It is my opinion that the relief cuts would do more harm than good due to the loss of compression ratio.

 

What exactly are relief cuts supposed to accomplish...why would this be done if the factory didn't think the motor needed it?

[martybose]

What exactly are relief cuts supposed to accomplish...why would this be done if the factory didn't think the motor needed it?

They are supposed to give the bore more space to breathe through; sort of the flathead equivalent of porting the head.  The downside is that it reduces the compression ratio, which partially (or totally??) reduces anything you gained ......

 

Marty

[knuckleharley]

What exactly are relief cuts supposed to accomplish...why would this be done if the factory didn't think the motor needed it?

I'm not automotive engineer,but my best guess is to provide a smoother flame front for the combustion gases to reach the exhaust valve.

 

The factory didn't do it because it's only a benefit at very high RPM's for racing applications. Another guess of mine is it would actually reduce performance in street engines. Kinda like a high rise open plenum intake on a V-6 or V-8 street engine. They work  great above 3 or 4 thousand RPM,but below those speeds you can practically see gas dripping from the tailpipes. 

[greg g]

something to do with a Beach Boys song lyric about hot rodded Ford Flathead engines.   However Stock ford valves were shrouded by the block design. Intake and exhaust charges needed to climb a little hill to get into the combustion chambers.  Stock Mopar valves open directly into the combustion chamber.  So the conventional wisdom was to relieve this extra ramp on Ford engines to make the path more like the Mopar design.  Although it does decrease the effectiveness of any milling of the head.  Additionally the with the Ford engine's convoluted exhaust path, I don't think any easing of the path the relief might have gained it was lost in the distance from the valve to the port.

 

 

[Frank Elder]

Thank you for the answers fellas.

[Ricky Luke]

Another reason for getting a brand new cam is if the old cam is heavily worn or been ground sometime in the past, there may not be enough metal to lift the valves the full height.

 

Also, the later cams benefit from new metals and profile experiments. My dad's 1929 Plymouth cam is very pointy - valves snap open and shut quickly with little overlap which doesn't allow the exhaust to be completly scavenged from the cylinder.

 

Rick

[knuckleharley]

Another reason for getting a brand new cam is if the old cam is heavily worn or been ground sometime in the past, there may not be enough metal to lift the valves the full height.

 

Also, the later cams benefit from new metals and profile experiments. My dad's 1929 Plymouth cam is very pointy - valves snap open and shut quickly with little overlap which doesn't allow the exhaust to be completly scavenged from the cylinder.

 

Rick

That's really not a problem. Lobes can be welded up and then ground to any profile you like. Even broken cams and crankshafts can be welded back together and then ground back down to any cam profile or bearing specs you like. Not to mention tappets.

 

Sometimes this is your only valid option. When I was rebuilding a 1953 Ford "Golden Jubilee" tractor I discovered the cam was flat and even the tappets were trashed. I couldn't find a NOS cam anywhere,and the used ones I found were running over 300 bucks without lifters/tappets.

 

I discovered Delta Cams and they sent me a rebuilt one for $39.95 plus shipping and core charge. I also bought all "new" (welded,reground,and heat treated) tappets from them for just a few bucks each.  This was maybe 15 years ago,so don't expect $39.95 prices on rebuild cams today.

 

Ended up having to do with same with my 58 Rambler with the 194 OHV 6.

 

BTW,I used to work at Power Engineering out in Denver. That is a company that specializes in rebuilding cranks and cams for industrial use. Some of the lathes in there will spin cranks and cams 16 feet long.  We got in cranks and cams from all over the world to re-manufacture and return to the customer. If cams and cranks that big and heavy can be welded up and reground to stock,doing it to a automotive cam or crank represents no  problem.

[Lumpy]

That relieving is quite commonly done on flathead motorcycle engines, and it works, that's a fact. You do have to mill the head and up the compression that you lose, and be careful that the valves don't then hit the head. If they do you can relieve the valve pockets in the heads, without losing too much compression. It does all work out, and does work.

However, it's very-super-extremely labor intensive so you don't usually see it on a six cylinder engine. It has to be done so that all the chamber volumes remain the same...a lot of time and hard work. Having to do it to only two cylinders, as in a motorcycle engine, makes it a bit more feasible, and more common. It does produce a large gain in breathing. I can't imagine the time it would take to do it to a flathead eight cylinder!

As far as cams, OHV's and flatheads are very different animals. Flatheads make a lot of low end torque, and really not much HP. Increased overlap will bleed off low end torque, and a flathead won't see enough RPM to make up for the loss. Really on a flathead cam, the most reasonable thing is to increase valve lift, and call it good. You really can't apply much OHV cam tech or theory to flathead cams. And there are a lot of other dynamics that are quite "different".

Using flathead motorcycle engines again as an example, when modifying cams, the overlap is usually left alone, (and a motorcycle factory cam will be pretty "hot" in specs to begin with, but not "hot" compared to the same size and type of OHV engine) and most of the work is put into getting more lift, and then modifying the valves, stems, and springs to stay alive, and usually trying to make the valve train lighter.

I saw a figure of 9.0:1 for compression. Was that a typo? To the best of my knowledge, around 7.0:1, or a tiny bit more, is about the limit for a flathead that would be driven on the street. ??? Just curious.

ken

Edited January 25, 2014 by Lumpy

[Scruffy49]

1959 stock 230 compression ratio was 8:1, and the guy in the Bunn book says you can run as high as 10.5:1 in an L6 (expect head gasket issues).

[Ricky Luke]

That's really not a problem. Lobes can be welded up and then ground to any profile you like. Even broken cams and crankshafts can be welded back together and then ground back down to any cam profile or bearing specs you like. Not to mention tappets.

 

Sometimes this is your only valid option.

I agree, but it's expensive. If there's no other option, then yes.

 

Rick

[TodFitch]

1959 stock 230 compression ratio was 8:1, and the guy in the Bunn book says you can run as high as 10.5:1 in an L6 (expect head gasket issues).

I recall reading in my parent's old 1963 edition of the Encyclopedia Britannica that above a 8:1 compression ratio on an L-Head engine breathing/flow difficulties outweighed any gains one might have from the increased compression ration.

 

Thus the demise of the L-head engines was due to the availability of gasoline with an octane rating high enough to to make compression ratios higher than 8:1 feasible.

 

But it also seems, if that article was correct and my memory of it correct, that going above 8:1 compression when modifying an old engine is just trading off one limitation for another with no real gains and as pointed out adding other areas of possible failure like the head gaskets.

[Lumpy]

Well, no offense intended, but I'll have to respectfully agree to disagree with the guy in the Bunn book. The art of modifying flathead motorcycles is still alive and well, and really no one goes over a 8.0:1 compression, and really the compression of choice for an engine that you will enjoy driving is 7.0 or 7.5:1. Flathead motorcycles were raced quite extensively, for many years, with full factory backing and the highest compression achieved was right around 9.0:1. These were all out racing motors, running mostly at WOT, and using aluminum cylinder heads.

I'm not saying a L6 would not run with 10.0:1 compression, but I think, just my opinion, that the disadvantages would far outweigh the gain. I don't think it would run well, I think the timing would be so far retarded that it really would not make much power. I think the thermal dynamics just make it pretty impossible. However...just my opinion.

I am close or at 8.0:1 on my L6, and it runs great, but I really can't run regular gas, and I usually add some octane booster. I can afford to do that because I don't drive it year around...but still, I'd say it's on the ragged edge of what actually "works".

Sometimes there is a confusion between static, and dynamic compression. If you take an engine with a static compression of 10.0:1, and have enough overlap/duration, that can bring the dynamic, or "real" compression much lower. On a small block V8, using a cam with a lot of duration, you might have to run 11.0:1 static compression to achieve 9 or 10.0:1 dynamic compression. The problem here is that if you do that with a low revving engine that produces it's power (torque) at low rpm, such as a L6, you don't gain anything...you bleed off your power, but can't gain it back on the upper end.

So, theorhetically, (sp), you could run 10.0:1 on a L6, but you would have to have enough overlap to bleed that back down to 8.0:1, and then you wouldn't have your low end torque, nor the ability to rev it high enough to make any hp. In my opinion, 8.0:1 is the highest you want to go, and 7.5:1 is probably better.

Did that make sense?

I could be wrong. !!! IF so, I'll stand corrected!

ken

[austinsailor]

If I ever get mine assembled I'll find out. It should be about 10:1 with a pretty long duration cam.  Course, all it'll cost me is a different head if it goes south, so it's not too big a deal.

 

Gene

[knuckleharley]

I agree, but it's expensive. If there's no other option, then yes.

 

Rick

If your cam is just worn flat,it is cheaper to send it to Delta Cams and have them rebuild it to any specs you wish than it is to buy a NOS stock cam.

 

Don't forget to buy tappets while you are at it.