Disadvantages of a reground cam

[Ross/Kzoo]

After reading a different thread about cams I started wondering what the disadvantages were to the reground cam. The advantage would probably be price. Also what are the advantages and disadvantages of a reground cam?

[Dave in MN]

Originally Posted by Ross/Kzoo

After reading a different thread about cams I started wondering what the disadvantages were to the reground cam. The advantage would probably be price. Also what are the advantages and disadvantages of a reground cam?

Disadvantages of a reground cam: When compared to a newly manufactured
1) Worn bearing surfaces creating a loose fit between the block
2) Worn distributor drive gear teeth causing sloppy distributor timing
3) More duration when ground to restore lift (changed ...thanks Marco!)

Advantages of a reground cam: When compared to a newly manufactured
1) Less cost

Disadvantages of a reground cam: When compared to an unrestored original
1) You really need to measure the overall lift of the original cam and compare it to the specs of a reground. A really good original could be as good as a reground cam if the lift is very close because the duration will be better.

Advantages of a reground cam: When compared to an unrestored original
1) The lift will be back to spec but again, you need to measure all aspects of one cam to the other.

If you have more than .004" clearance between the block and the cam journals, you could notice a nock.

[bykerlad]

Great answer to K zoo`s question,i too are now just a little bit wiser thanks ...ken

[Ross/Kzoo]

Thanks for the very complete reply. I'm not there yet but I when the time comes I want to know what direction to go.

[Marco Tahtaras]

Originally Posted by Dave in MN

Disadvantages of a reground cam: When compared to a newly manufactured
1) Worn bearing surfaces creating a loose fit between the block
2) Worn distributor drive gear teeth causing sloppy distributor timing
3) Less duration when ground to restore lift

Advantages of a reground cam: When compared to a newly manufactured
1) Less cost

Disadvantages of a reground cam: When compared to an unrestored original
1) You really need to measure the overall lift of the original cam and compare it to the specs of a reground. A really good original could be as good as a reground cam if the lift is very close because the duration will be better.

Advantages of a reground cam: When compared to an unrestored original
1) The lift will be back to spec but again, you need to measure all aspects of one cam to the other.

If you have more than .004" clearance between the block and the cam journals, you could notice a nock.

That should be: 3) More duration when ground to restore lift

[BRENT in 10-uh-C]

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One other thing to add to this list is something that Bill Stipe, James Rogers, and I have discussed in our chats, is that all reground cams on the market are not equal in quality either. If one is truly concerned with performance, then a degree wheel and a dial indicator should be used on all four tappets to verify lobe uniformity between each valve not only in lift, but in valve timing. Just as Marco pointed out, less duration is what is needed to get the 'I' valve closed faster so it can start building static compression on the compression stroke. Hypothetically having one lobe ground where it opens & closes later in relationship to the others will potentially not allow it to build as much compression in that cylinder as compared to the others, thus creating a cylinder imbalance. Think about how this can affect the smoothness and the overall power of the engine.

.

[Jim Brierley]

Any disadvantage would be very negligible in a 40 HP Model A. Advantages are price and availability. Most re-grinders suggest a minimum diameter on the bearings, the center main wears the most.

[Charlie Stephens]

Another advantage to a new cam from Bill Stipe is that you can order one with an oversize center bearing and bore your block to match. When I went through this years ago I had the center cam bearing metal sprayed to build it up. Check your block for wear in the center cam bearing (which is the block itself). Just one of the small details that will result in a better engine

Charlie Stephens

[JoeWay]

Originally Posted by Charlie Stephens

Another advantage to a new cam from Bill Stipe is that you can order one with an oversize center bearing and bore your block to match. When I went through this years ago I had the center cam bearing metal sprayed to build it up. Check your block for wear in the center cam bearing (which is the block itself). Just one of the small details that will result in a better engine

Charlie Stephens

Very true, but you must have at least two larger bearing journals--the front bore must be as large as the center journal or you can't get the cam into the block. Might as well do all three. Or have the block bored for standard-ID cam bearings instead of oversized cam journals.

Joe

[Kevin in NJ]

Isn't it amazing the only bearing in the A that is pressurized, the center cam bearing, and it is more worn then the ends.

While we are on the cam bearing discussion, how about some details from experience.

What is considered too worn, actual dimensions, and the best ways to measure the block? When can one expect extra noise from loose cam bearings?

Some added details would help others learn how to evaluate their blocks.

I have to admit I am just learning the techniques for high accuracy measuring. My brother has been helping me. I have learned the low quality inside snap gauges may be made of brass and will not be accurate. I have some Central Machinery steel gauges, I got them recently cheap, that do an adequate job. The Starrett tools are much better.

[Richard Lorenz]

Some of you machinists can make go-no go gauges be turning a bar with step increments of a thousandth or two.

[Don S]

I have a Stipe regrind "touring " cam. I have often wondered whether or not I made the right choice for my application.The engine has new cam bearings,Brumfield 5.9 head,standard valves,but new style with keepers,counterbalanced crankshaft,bearing shells. I encounter lots of long hills on tours,shifting made easier with a F150 tranny which I love.I think it should pull better on the hills. Any thoughts?

[1931 flamingo]

Many diff tranny ratios. What ratio in the rear end?
Paul in CT

[Benson]

Originally Posted by Don S

I have a Stipe regrind "touring " cam. I have often wondered whether or not I made the right choice for my application.The engine has new cam bearings,Brumfield 5.9 head,standard valves,but new style with keepers,counterbalanced crankshaft,bearing shells. I encounter lots of long hills on tours,shifting made easier with a F150 tranny which I love.I think it should pull better on the hills. Any thoughts?

That is what I noticed also.

I drove several Model A engines with original (un-reground) cams for 40,000 miles, 50 years ago. All engines have been installed in the same Sport Coupe. These were well worn engines. The only modification to all of these engines was a head "with the large B" (5.2 ratio).

These old engines would pull hills at low RPM (Added to clearify: 35 to 40 MPH in 3rd gear) MUCH better than my present rebuilt Model B engine with the reground cam. The reground cam engine has to be run at a higher RPM to pull most hills ... down shifting or getting a running start to keep RPMs high enough.

A reground cam with its longer duration will raise the max torque and HP to a higher RPM and from the torque curves I seen, will result in a much more narrow RPM range where the max torque occurs.

Instead of having good flat torque curve over a wide RPM range starting at low RPM like the stock cam, the regrind cam has a sharp peak over a limited range and at a higher RPM.

As a result it is necessary to have a 4.11 rearend and to shift more frequently (hard to do with a 3 speed!) in order to keep within the narrow RPM range where the engine has enough torque to pull a hill.

Maybe these reground cams work at sealevel. But at 6000 feet and above they do not seem to work too well on steep mountain roads where there are curves, switch backs and motor homes that slow you down on a regular basis.

[Jim Brierley]

Everything is a compromise! Touring cams give more power but at a slightly higher RPM, with slightly less torque at low speeds. You may be lugging the engine on hills if you are in OD. High performance cams are even worse at low speeds, but more than make up for it at high RPM's provided you have more carburetion. Compression helps all across the spectrum.

[Don S]

Sorry for the long response time. The rear end is standard 3.78 to 1.The tranny is a 4 speed with 4th being 26% od. I have a good matching set of 4.11 gears,but not sure if it is worth the work of the RE and Re.Thanks for your input

[James Rogers]

Originally Posted by Jim Brierley

Everything is a compromise! Touring cams give more power but at a slightly higher RPM, with slightly less torque at low speeds. You may be lugging the engine on hills if you are in OD. High performance cams are even worse at low speeds, but more than make up for it at high RPM's provided you have more carburetion. Compression helps all across the spectrum.

Jim, suppose you take a standard available reground cam and advance the valve timing by, let's say 7 degrees, how would that affect bottom end and hill climbing in a standard rebuild.

[Bill Stipe]

There seems to be a lot of talk about cam problems but no one really talks about the numbers and facts, timing, lift, etc.
I notice many reground cams are not timed correctly for a stock engine when I degree them on my engine stand. They generally have the intake opening too soon and closing late losing the static pressure for these low compression engines.

I Ask the guys here on this web site and the regrinders out there what timing they have for opening and closing seat to seat both intake and exhaust. My guess would be most don't know because they never degree the cam when they installed it and the regrinders don't know ether or more likely will not tell you because they don't want you to check there work.

It seems when ever a person is not getting the performance they feel there engine should deliver the cams are the first thing to blame. And they may be correct but you need to know the facts first.

With that said ask your regrinder what valve timing he is going to grind on your cam.
Ask for valve lift, lobe separation, and openings and closing of the exhaust and intake.

Then if you want to get deeper in to it ask him what degree of intensity he has on that regrind?
If he can not answer all your questions move on to a different grinder because he does not know CAMS!!!!!

He is selling you something you most likey will regret installing.

Happy motoring!!

Bill Stipe

www.stipemachine.com

[Don S]

This thread kinda got away from the original question. I got the touring cam from Bill Stipe,complete with the technical information He provided. With the engine described in my earlier post,is the touring cam the best option,or should the 3.78 rear gears be changed to 4.11,or better carburation?Highway speed is no problem,it is just that long hills will slow her down to 30-35 or so in 3rd gear. Thanks again

[Jim Brierley]

James Rogers, the theory is that an advanced cam will provide more low-end power while a retarded cam will provide more at the top end. I usually set them "straight-up", with equal overlap. I suspect all engine types are different and only dyno or other testing would really tell you. Bill Stipe does a lot of dyno work and is usually willing to share his findings.

[BRENT in 10-uh-C]

Originally Posted by Don S

This thread kinda got away from the original question. I got the touring cam from Bill Stipe,complete with the technical information He provided. With the engine described in my earlier post,is the touring cam the best option,or should the 3.78 rear gears be changed to 4.11,or better carburation?Highway speed is no problem,it is just that long hills will slow her down to 30-35 or so in 3rd gear. Thanks again

Happens a lot around here ...and it seems like more so here lately. It's all good though!!


.

[Bob Johnson]

I have been doing some investigating of camshafts. I was curious about what regrinds were in certain cars. I built a tool that allows me to measure the lift curves without removing the head. Here are graphs of camshaft lifts for two cars that I measured. The one labeled Regrind #1 was in a car that was lacking power. The one labeled Regrind #2 was in a car which ran very well. Regrind #2 show that to get more lift the duration is increased. Regrind #1 indicates a possible worn lobe and a slight shift of the valve timing.

Bob

[john in illinois]

Don S I have about the same setup as you. Touring,inserted,balanced engine. Stock Zenith carb. ,3.78 gears ,F 150 OD trans, 23 or 26 %.

The engine was built with an unknown touring regrind cam. I had the engine apart,so I decided to put in a new Stipe 330 cam,Which Bill told me would be a good torque cam for overdrive. Boy what a difference that made. It pulled better at all speeds. I was going to put a Weber carb on it and decided that I didn't need it after the cam.

I went to Montana last summer and crossed the Rockies at Helena,6500 ft.
I was able to maintain 40-45 mph in third . I only had to shift to 2cnd one time to get over the top of a hill without lugging.

I think 4.11 gears would make all the lower gears too low in the 4speed. More power would help a lot. If you don't want to change cam,a Weber or some other carb set up might help hill climbing. Good luck,each A engine seems different to tune.

[Don S]

Some numbers regarding the reground cam from Bill.
Intake---Max cam lift--.304 Duration at .016, lash 241deg,cam duration at.050 209Deg
Exhaust numbers are the same except the lash ,which is 241 deg.
Lobe center line is 112 Deg
Exhaust is set up for 10deg btdc and 52deg abdc
Intake is set up for 8 deg atdc and 53 bbdc
Some numbers for the crunchers out there.Comments?

[Don S]

THanks John,it sounds as though we do similar touring trips.I am not ready to tear down my engine at this point as it is running quite well except for the hills.Did you change your valve size with the engine apart?

[Bill Stipe]

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Don, Sorry your having troubles. I will post a dyno test of an engine I think is similar to yours accept you have a 5.9 head and I assume an A carb. The 5.9 head should give you about 2 to 3 HP more acording to tests I have done.
Also on your OD 150 tranny I have the same one in my truck and bought from Dave Wilton years ago and I made sure I purchased the one with the smallest jump in 4th gear over drive the other 2 chioces are too tall to pull with the Model A engine. Also if you are pulling a hill you need to pull out of over drive and run straight through in high gear, you should be able to run 45 to 50 mph yet in third gear. I guess I don't know how steep of a hill you are talking and how long the hill is but you only have about 54 to 57 HP at 2400 rpm and the torque drops off at higher RPMs.

Ford Motor 40 HP @ 2200 RPM and 128 Ft LB @ 1000 RPM
Bill Stipe

www.stipemachine.com

[Don S]

Thanks Bill,I may leave it in 4th a bit too long on occasion. Some of the hills are several miles long,some with swichbacks. I am running a Zenith carb,with only the spark arrestor,no real filter,should breathe ok. Ive run this thread long enough,thanks for your suggestions.

[Smitty]

What does a cam with worn bearing surfaces sound like?

[Purdy Swoft]

I don't see any disadvantage with the reground cams that I run in two of my model A's. It all depends on the cam core and the person that grinds the cam.It is a must to talk with whoever grinds the cam. The cam grinder will give you the specs that are necessary for the core and what other mods may be needed for the desired effect. Compression, gear ratio, carburetion and lifter choice will be the most important consideration. I run a regrind in my roadster with a 317 lift and the duration is 252- 255. I don't have the other specs in front of me now, but the roadster or the speedster have power, pretty much like a modern car. I don't live in mountainous country but there is some pretty good hills and I can accelerate going up any of them. My Super Winfield 3/4 race cams also idle good and will still chick ah lunk with the spark retarded. The 3/4 cams won't idle quite as low as a stock cam with a heavy flywheel , but still idle good. I run 3.78 gears and the original three speed transmission. and I have never needed to down shift on any hill.

[john in illinois]

Don,my engine does have larger intake valves.

[Don S]

Thanks John,larger valves will help. Purdy,you are probably running a downdraft carb? I am trying to stay stock looking for licence purposes

[Purdy Swoft]

Don, no down draft for me. I'm running a vintage Trojan dual updraft manifold with model B carbs. Its not like it came from the factory look but was a period correct accessory. The car looks mostly original, otherwise.