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The all Mighty Cam - Flathead Style


timkingsbury

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As suggested by Captain Fred in his blog entry on his 1940 Plymouth build, he wanted something done on cams.

 

Well, that can be quite a topic, and while you can find all kinds of article on the "inter-web" on how cams work in an engine, my
goal is to put a Flathead Mopar slant on the topic.

 

Of course as my Grandfather used to say, an engine is nothing more and a large vacuum pump. Your cam turns lifting up intake
valves, as pistons are being turned by a crank and that creates a vacuum. The vacuum sucks in whatever is near by into the engine.
The cam turns a little further, closing the intake valve, we "light a candle" to whatever is in then in the cylinder and after what we hope is a controlled explosion, the cam turns a little further lifting exhaust valves and those pistons coming up push out whatever is left out of the engine..

 

In the V8 world a great deal of people used to think that making power, aside from the "no replacement for displacement" concept was putting in a wild cam. As time went by in the racing world, while the cam was important, we know it is the heads that are a much bigger factor to the V8 world. Sure superchargers or turbo chargers, trying to jam more stuff into the cylinder and the type of fuel you use for your controlled explosion also became a big factor, but in the world of cam vs heads it is the heads that lead that world.

 

In the flathead Mopar world, fuel isn't entering via the heads, and so it is definitely a cam that leads this world over the heads.

 

Next lets talk about stock lift and duration and even there, Chrysler Corporation made a huge number of cam profiles so the second I toss this out here, its easy for someone to say - "my stock cam is different" and yes I know that.

 

But in high level terms, a cam has two major factors and a few lesser factors. Lift and most of the p15-d24s were a 375 lift
and then duration. Lift is how high the cam lifts the valve from its closed position, and duration is the degrees of the 360 degree circle that it keeps those valves open. In other terms how high we lift the valves and for how long we keep them open, whether intake or exhaust valves.

 

Again high level - you are limited by how high you can lift the valves in a flathead by the head. Lift the valve too high and it hits the head. On the duration side, there becomes a point where you have kept the valves open too long and it starts to effect the actual vacuum level in your engine. Remember again, a big vacuum pump. as we open and keep open valves we loose the seal on the vacuum. Of course we do that because we want to get and fuel and air mixture into the engine.

 

The change in duration also does things to the torque curve on your engine, but that is a whole different level of the discussion and I am trying to keep this more on the basic side.

 

Again in general if we keep the intake valves open longer and lift the intake valves higher, we get the opportunity to get more fuel/air into the engine. More fuel and air, and yes, clearly effected by the compression ratio, the more "bang" when we ignite the mixture with the spark plug firing.

 

Now, in the cause and effect department, generally as we raise up the valves higher (aka the lift) and hold those valves open longer (increased duration) we tend to change the rpm idle and things become what most of us call "lumpy". In the good old mopar v8 days of the 1970s I am sure lots remember pulling up to the lights with a guy running a "cammed up" motor and it was idling rough, shaking, coughing an weezing and yes that was also how the timing was set, but it was the duration of the cam that was causing that. When the light turned green and they hammered it, assuming the timing was set correctly, the goal was for that high lift cam to allow for a lot more fuel to get into the engine dramatically raising the RPM and turning the lumpy idling engine into a smooth running race engine.

 

Yes I am isolating and slanting this entire discussion towards cams, when timing can also be a huge factor. No better example being when Big Daddy Don Garlitz was forced to use a 426 hemi after they actually ran out of 392 hemis. He couldn't get the 426 to run as well, and out of frustration he advanced the timing way way beyond what anyone would have thought would work. In fact Don often tells the story that he intended to blow the "blanking" thing up. But as the engine rev'd up that advanced timing suddenly brought out the inner Monster of the 426 Hemi and all of a sudden the 392 Hemi was obsolete in Don's mind!

 

Back to our cams and remembering that the generation of car cams we are talking about were 375 lift. There are two school of thoughts on creating high performance cams. 1st is to raise the lift gradually and some pretty famous high performance cams raise the lift to 380 an and then increase the duration to 242 degrees. The 2nd is to raise the lift up as extreme as we can and also increase the duration. in the 1950s a pretty famous performance cam used a 400 lift. and 250 degrees of duration.

 

The other factor without diving into the details to much, is what I call the split. A great deal of cams have the intakes open and the exhaust close at exact same time, but some use a split. So for example an Esky 3/4 miles cam the intake opens intake valves at 20 degrees and closes them at 50 degrees and the exhaust opens at 57 degrees and closes at 13 degrees.

 

The Schroller full race cam - again a stock car racing - Higher lift and increased duration the Intake - has the intake valves open at 18 degrees and closes at 54 degree. The exhaust opens at 54 degrees and closes at 18 degrees.

 

If you are using a turbo or a blower, you often want a period of time (number of degrees) in which the intake is close and the exhaust hasn't yet opened, or visaversa.

 

The age old question is of course - so how much lift can I have before the engine sounds like it is misfiring. Almost always visions
of those 1970 v8 engines coughing and wheezing are the reason for thing that. In reality the flathead just doesn't really act like a great deal of those badly timed, over cammed engines.. lol The reality is in the flathead world it is more a case of the rpm rises at idle than it is about it sounding like the 1970;s v8.

 

Of course most want a cam that sounds like it is rock stock, idles like the engine isn't running, but then they want a Top Fuel Monster to come alive when they hit the throttle. That becomes a delicate balance and is always a compromise.

 

So lets talk extreme. Maybe there is a wilder cam out there, but if there is we have never seen it. Ill keep the origins of this cam a little bit of a mystery, but the cam we use in the Velociraptor is the most extreme cam we know of. I chuckle these days as this phrase that seems to be in vogue again, but decades ago my Grandfather used to refer to a car that had this cam as "The Hot Mess Express".

 

Today we call if the AoK Velociraptor Grind . It is tough to get it to idle below 2000 rpm and we have with a ton of work have
actually gotten our dragster to idle around 1800 rpm. It will wind up to North of 7200 rpm. You can run an engine on alcohol and will need 3 carbs and need to shift to 6 exhaust pipes for at least 42", to get it to run properly. Its lift is are you ready, 446 and its duration is 280 degrees. At this point we definitely have issues with vacuum and it would be extremely rough at idle, thus increasing the RPM just
to get it to idle. For those that figure that isn't possible, by reply is gather up and bring all the cash you can find, because I am happy to say - "How much would you like to bet!".

 

Here us a link to 3 videos of the Worlds Fastest Dinasour

 

 

 

Now from the extreme, to lets say a mid-50s truck cam which topped out around 3600 rpm, becomes the topic where many recipe's for
performance have been made. Some by Chrysler Corporation for everything from cars, to boats, to combines and even Massey Harris 101 Super tractors powered by Chrysler Flatheads. The later were built for high torque and low rpm, which is great for plowing a field, but achieving a high way speed, not so much!

 

Today I think we have a catalogue of around 25 cam profiles. Of those we have cam patterns that we use , made for about 6 or 7 cams and of those, the number drops down to 3 or 4 for most engine builds. I think right now among the Kingsbury motorized items we have 14 different cams in use. In the Asche fleet of motorized items I am going to say they have 7 different cam profiles. The major difference, lol, yes I have more junk... I have a marine version, several truck versions, a combine, a water pump, a welder, a compressor which actually uses 4 cylinders to run the engine and 2 cylinders to make air, and an engine that used to be in a certain motorcycle.. lol.. Oh and I have an actual cam from a tank engine, but it isn't in an engine. I could make a pattern if someone ever needed one !

 


For Fred's engine, we used what many call an Esky 3/4 race cam. The 3/4 stands for stock car racing on a 3/4 mile long track.

 

This is what I today call, a fairly mild cam and we likely sell the most of these. I suspect part of that reason is as I talked about earlier, that people think back to those lumpy, poorly idling v8 engines with wild cams.. The .380 lift cam is going to give Fred 4500 rpm quickly. Its been around a long time and has a quicker rev over stock and was used historically for stock car racing. As you can likely figure out by reading this thread so far, we likely sell the most of these because most guys think they want power..... but..... they want to start it and not hear the engine running or running like a sewing machine. Tons of guys call this cam a race cam.. For me, its far from that. The tech side = 242 degrees of duration and .380 lift

 

Finally I will end the cam conversation for now, with the cam I am using in my 1949 Plymouth. It is what I call a little lumpy but still very much streetable and no, it is nothing like a 1970s over cammed v8 with bad or good timing..

 

lol but it is definitely aggressive, with a .435 lift and 258 degrees of duration. This cam was developed from tweeking a full race cam through the 1950s and 1960s and was what Harry Hein #90 (NASCAR hall of fame) used at the end of his career. Harry who is still alive would be the uncle of one George Asche Jr. The intake valves open at 20 degrees and close at 58 degrees, while the exhaust opens at 58 degrees and close at 20 degrees.

 

Here it is in my 1949, when it was started for the very first time, so its not tuned and its running 47" straight pipes out of the headers. It is a bored our 265 ci  25 1/2" Canadian big block flathead 

 

 

And here is the same cam in a 230 ci USA 23 1/2" small block 

 

 

I hope that helps a little Fred, without confusing things too much!

 

Now what is in that Engine of yours, I can not confirm or deny what was originally put in the engine is what is in it now.. Who knows what happens in the middle of the night in George's shop... Only the shadow, or in this case the 1929 Desoto knows for sure.. lol

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Without revealing any AoK secrets can you give us an idea of what cams you have available for sale and that the costs are ? Can you tell me if there was any difference in Big Hub and Small Hub cams ?  Do you guys have cam blanks or do you under cut and regrind the cams ?

 

Danny

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Without revealing any AoK secrets can you give us an idea of what cams you have available for sale and that the costs are ? Can you tell me if there was any difference in Big Hub and Small Hub cams ?  Do you guys have cam blanks or do you under cut and regrind the cams ?

 

Danny

Hi Danny -  I would be happy to do that and to be honest, if guys can get the cams ground themselves I am  ok with that.  Prices of cams is something that is in a little bit of a flux at the moment.   Guys want new cams but don't send back their old cams and  the cost of getting cams, especially big block cams has risen a great deal.   I can tell you a few guys we wholesale cams to are about to crank their prices because we just cant do them for what we could.  So right now, your talking $300 + shipping for any cam we do, and we will take $50 off if you send us your old cam. That is the price right now, and really is dependant upon what everything costs us. 

 

Now small hub cams are 1" and that is the size of the hubs one every small block or big block from 1936 (and likely prior on small blocks) up until 1951 for the big blocks.  The small blocks I am told it is around that time. They changed to a 1 1/8" hub on the cam and the reason was you actually could break a cam. They saw it will bigger trucks used for dump trucks or plow trucks.

 

Unless you really hard on the engine, and by that I mean rev-ing it hard, changing gears and dumping the clutch your likely never ever going to have an issue.  If it is straight rev, you can rev the engine to any level and the cam will be find, its the changing gears and dumping the clutch at high rev, that sees the torque

do damage.   I don't know of anyone that has ever broke a big hub cam, nor has my partner in crime George. Hope that helps and I will put something together on cam profiles beyond what I did above ..  soon !

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Ok Danny - 

 

I covered the 380  and 435 lift cams

 

Next the ½ mile  “1023”-  this was a stock car cam or the modified .375 increasing duration instead of lift  which will give you a little more rev, so the 5000 rpm range. It was for  quick bursts coming out of the corners at stock car tracks.  Barely idles at 1000rpm

 

tech specs  -  intake opens at 20 degrees and closes at 50 degrees, and exhaust opens at 57 degrees and closes at 13 degrees,   Duration .250 and lift is .375

 

 

Next one -  Modified Scholler full race cam. Higher lift and increased duration cam which was use for drag racing in the later 50s and early 60s. your starting to get a little lumpy at idle, it will idle down but you need a fresh rebuild as this is the point where your starting to test the limits of a flathead. This is a modified version of the famous Scholler  full race cam -  stock car racing and drag racing -  Higher lift and increased duration (Intake - open at 18 degrees, closes at 54 degree. Exhaust opens at 54 degrees and closes at 18 degrees -  duration is 252 and lift is 400

 

Next one - 430 -   Briggs and Stratton – Tractor Pull Grind was born out of looking at cams from different manufactures and believe it or not Briggs and Statton made a high lift higher torque cam. This was born from using other performance mopar  cams and the briggs and Stratton cam. Its an extreme lift cam, with big  torque pattern at slightly higher rev than a stock mopar truck cam.  It is here where the engine modification has an effect on engine vacuum, Its 430 lift and 247 degrees of duration

,

 

And the last one being the the AoK Velociraptor Grind cam.. Its 446 lift and 280 degrees of duration and there is a little more to the cam than that but there is the main attractions. This cam, we have a licence agreement that needs to be signed  and notarized before we will sell you one, and it covers exactly who is using it, for what and has a non-disclosure agreement to it.  There would be very few that would

ever want this cam, and those that do, well usually we wont sell them one.. lol

 

Hope that helps.

 

Tim

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Thanks Tim -  Thank you for all the information. I don't think I will be needing a Raptor cam, or a tractor pulling cam although one of those cams that you have in your Plymouth might be in the future. If I am following your correctly the cam patterns are available on both the USA and Canadian block engines?

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thanks for writing this down! :)

 

so, 242 degrees of duration and .380 lift on the 3/4 cam...

do you also have the intake and exhaust valves opening and closing degrees?

just curious...

 

i'll test drive this one for a while and see where it gets me.

but i have  a feeling it will be wild enough for me ;)

lots of traveling and very little racing on my schedule.

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Hi Fred -  yes that is correct. I don't have those off the top of my head. Its a cam that almost every performance place has so I never bothered checking it with a degree wheel. I can do it if you want it.

 

In terms of wild enough, well, that was what you wanted so that is what is in it.. lol..   Its all personal preference.  We have cars with 40 -50,000  miles using the .435 cam  which is what is in my car. Its got more HP in it and I prefer it out on the highway where I am definitely keeping up with traffic.   I don't do much racing, but then I also don't take too much **** at the lights from 350 chevy's and any of the vintage lead-sleds that figure they will blow me off the road across the lights.

 

I think you will be very happy with your setup I really will. Now if you happen to find yourself

in our neck of the woods as they say,  and come for a ride in something with a 435 cam in it, you

may get the itch for a little more.. lol..  In which case, your engine is build for it. as is any nice fresh built mopar flathead.

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Since I have been asked by a few for specifications for some of our more popular cam grinds,  or in a couple of cases, people are curious as to what

the specifications are, here they are....     While a lot hide behind names of the cam they sell, honestly,  happy to hand out the cam details.  If you can

find a computerized cam grinder you should be able to cut any of these from the detail...    so as my Grandfather would say -  knock yourself out!

 

1)    .380 - Mild and we likely sell the most of these. It would be a .380 lift cam which is going to give you 4500 rpm. It’s closest comparison would be to the Isky 3/4 mile cam. It’s been around a long time and has a quicker rev over stock. It was historically for stock car racing.  For most guys this is where George steers them, because most guys think they want power.. but they want to start their car  and not hear it running.  Tons of guys call this cam a race cam..  It’s far from that.  The tech side =  242 duration and .380 lift

 

2)    400 -   Higher lift and increased duration cam,  which was use for drag racing in the later 50s and early 60s. Your starting to get a little lumpy at idle, it will idle down but you need a fresh rebuild as this is the point where your starting to test the limits of a flathead This is a modified  version of the Scholler full race cam -  stock car racing -  Higher lift and increased duration (Intake - open at 18 degrees, closes at 54 degree. Exhaust opens at 54 degrees and closes at 18 degrees -  duration is 252 and lift is 400

 

 

3)    435  - Tim’s 49 Plymouth & Harry Heins #90 cam.  It is a little lumpy and still streetable, but it is definitely aggressive, with a .435 lift,so it will crank to over 6000rpm.  This was a cam was developed from tweaking a full race cam from the 1950s and 1960s and was what Harry Hein #90 used at the end of his career. Harry is in the NASCAR hall of fame and George's uncle.  Tech info - intake open 20 degrees closes at 58,  exhaust opens at 58 and closes at 20 degrees.  258 duration .435 lift

 

 

 

4)    375 ½ mile  “1023”-  this was a stock car cam or the modified .375 cam  increasing duration instead of lift,  which will give you a more rev taking you to the  6000-6500 rpm range. It was for quick bursts coming out of the corners at stock car tracks.  Barely idles at 1000rpm. Not for  street use although it has been used by some on the street.. aka  Harry Hein’s personal car. It was designed for use on ½ mile and longer tracks. tech specs  -  intake opens at 20 degrees and closes at 50 degrees, and exhaust opens at 57  degrees and closes at 13 degrees,   Duration .250 and lift is .375. Stock lift (which is 375) and played with the duration and the intake and exhaust opening. If you ever decide to go blower, this isn't a bad cam.

 

 

5)    430 -   Briggs and Stratton – Tractor Pull Grind was born out of looking at cams from different manufactures and believe it or not Briggs and Stratton made a high lift higher torque cam. Thus was born from using other performance Mopar  cams and the Briggs and Stratton cam. Its an extreme lift cam, with big  torque pattern at slightly higher rev than a stock Mopar truck cam.  It is here where the engine modification has an effect on engine vacuum. 320 duration 430 lift. This cam would likely be questionable to putting it on the street.

 

6)    446 – This  is the most extreme cam likely ever made for a Flathead Mopar -  We call if the AoK Velociraptor Grind .  It is tough to get it to idle below 22-2300 rpm, and we have with a ton of work gotten our dragster to idle around 2000 rpm. It will rev to 7200 + rpm and we have tossed almost 1500 cfm of carburation at it.  You can run an engine on alcohol and will need 3 carbs and need to shift to 6 exhaust pipes for at least 42” and if it’s going into an exhaust system it will need to be large duals after the 42”s  of 1 ½’ pipes. Tech  info - intake opens 30 degrees and closes at 70 degrees, and exhaust opens at 70 and  closes at 30 degrees,  280 duration and 446 lift

 

If your running 3,4,5 or 6 -  you may want to print yourself off this bumper sticker!

surgeon general bumper sticker.png

Edited by timkingsbury
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Hi Tim - I have one of the "380" cams and was wondering if you have a cam intake degree centerline specification for it. I got in the habit of checking centerlines on any engine build I do many years ago. Eventually I intend to install this cam in a 230 which will be hot rodded.

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