Technical Cams that will not work well with a auto trans?

I guess I should not take my anger out on the cam,the builder has gotten karma and out of business.

 

The four "C"s

Cam / Compression / Converter / Carb

Have you degree'd the cam. You can shift a cam "down" the RPM range by advancing it .
On my BBC we advanced the cam 5° to help it pull off the corners

 

If you want a torque, install your cam with 4-6* advance even a stock one.
My son was working for Don Johanson and learned to grind cams for him. He was building a 350 to go in his 54 GMC pickup. We bought everything from PAW ( remember them) and he ground his own “RV” cam. I suspect is was 260* or so. He assembled the engine and put a stock 350 TH behind it with 3.25 in the 9” he also installed. He told me he thought it should feel way better than it did. I asked him more about the cam but I don’t think he really understood what I meant on degreeing it during installation as I wasn’t there for everything he did. One Saturday I told him I was going to advance it. By the time he got up and wanted to start I told him to put the water pump back on and finish it as I was done. I had bought a button kit, took it apart, removed the cam gear, drilled it, added a 4* button, and put the cover on.
He finished it and took it out for a test ride….when he came back he told me he had a new truck and couldn’t believe the difference.
Like said above …. Everything needs to work together.

 

With a cam and carb when in doubt go smaller. When I was in high school Chevy guys would buy a 097 cam and not replace the valve springs and wonder why the car slowed down. A case of 6000 RPM cam and 4000 RPM valve springs

 

Very true. When I worked in an auto parts store that sold a fair amount of speed equipment, I spent more time talking people OUT of buying a certain camshaft than into it. If you allowed most customers to go with their first choice, they would have been very disappointed, unless all they wanted to do was impress the kids at the ice cream stand with their choppy idle.

 

Advancing the cam timing is a great point !
Many cam grinders "build-in" advance in the cam timing (even when the installer puts the cam in dot-to-dot... it's advanced 4-6 degrees) BUT some don't !
Even if they do...you can advance it another 4-6* to gain some low end torque (while losing some top end torque)
You just need to measure piston to exhaust valve clearance....since the exhaust valve is closing later and the piston "will-be-chasing-the-closing valve !
My sbf (306 cu. in) has a cam with 230-236@050 duration.... LSA 108*...460-ish Lift. 6* advanced
By 2000RPM it has smoothed out by.... 3000RPM it's pinning you in the seat all the way to 6000 RPM!
It has an idle like the old Duntov Corvette cam (or just a touch rougher).
This same cam in a 351 'should' behave behind fine for you..(even with a stock convertor.)
Try advancing it 4-6* and see what happens......
6sally6

 

I don't understand wouldn't advancing the cam cause the Exhaust to close earlier and the intake that would have piston issues.

 

Advancing it will open both valves earlier, and close them later.

 

^^^^^^ Doesn't advancing the cam move ALL event's earlier in the cycle? ^^^^^^

 

If you have a given cam lobe and you advance the opening of the valve wouldn't it follow that the closeing would also be earlier.

 

Maybe I have it wrong, but advance or retard, it will open and close as it does, designed to do based on the "grind". Difference will be when the charge is brought in and exhausted out in relation to the piston up or down. But it will not change the relationship to when and when. I could be wrong but that's my understanding.

I'm of the belief this falls into my eat a Hoagie Theory.
Speed at which you can chew and swallow is directly related to mass x hunger + allowable cc. volume / stroke =rate of swallow. If you got a better theory I'm all ears.

 

Back in the ‘097 cam era Chevy only had one spring whether you had a 185 horse 283 or the 283 horse fuel injected engine and that followed through to the ‘63 360 horse f.i. engine that still used the ‘097 cam. In fact it was the over the counter, off road Z/28 ‘140 cam that used the ‘142 spring, the so-called “brown spring” because they were dipped in brown paint. The early springs and even the Z/28’s were 90#’s on the seat and the ‘142 was 110#’s.
It may have been a tired engine or just a sluggish advance curve or bad tune on a carb that caused the poor performance.

 

32 has 302 with X grind , 1.7 roller rockers , C4 and v6 converter , you know it’s there but it’s very drivable , the hot rod thump is for sure present

 

In the 60s I worked in big auto machine shop my job was mostly cylinder heads A good percentage of used valve springs were down at checking height. https://www.kobelco.co.jp/english/ktr/pdf/ktr_26/021-025.pdf

 

A long duration cam, combined with a tight LSA of 108 or under will usually result in a pretty lopey, high rpm cam, regardless of lift. And a cam with lots of lift will help a shorter duration cam breath better. Start getting wide LSA around 112-114 and your cam will make better low end power.
But what a small displacement engine needs for a cam isn't applicable to large displacement cams as the larger engines have enough extra torque to not be so boggy on the low rpm range with a bigger cam. I personally like cams with as much lift as the build and piston selection will allow. And I prefer LSA to be down around 109-110 for a mostly street driven combo. And durations over 290 for a street built engine are not what I want, unless I planned the engine for street/strip use, and then I might get a little over 290 duration.
Of course all this still depends on the weight of the car, trans, converter, and gear ratio. I have identical rear gears, tires, and automatics with similar converter stall speed in my lightweight Austin gasser, and my heavyweight '39 Chev gasser. But the engines started as 350 Chevs, but are built completely different due to the over 1000 lb. weight difference.

 

Oops, thinking cap misplaced on that one, doh!

 

I agree that a fairly narrow lobe separation angle, let's say 110 or less, is going to give more overlap and therefore rougher idle than wider LSA. Advancing a cam does give better low end. That's an easy crutch for a bigger cam running on the street. I think also why some cam suppliers grind advanced into the cam, so even installed straight up provides better street driving. Enables to run a longer duration cam.

But the real reason for the OP's problem is really the mismatched torque converter. Not whether the cam LSA or installed advanced or not. To smaller extent, the weight and rear gear of the OP's car are not matched to the cam either.

 

Not always. The OP's problem is could be mismatched cam for compression.
So the cylinder pressure and torque is less.

This is a problem when idiots put the biggest cam off the shelf into a stock low compression engine. [and it is worse than before]

Advancing the cam closes the exhaust valve earlier, [and opens the intake earlier] so there is less flow at dwell.
An advanced cam is more prone to "8 stroking" at idle [exhaust charge going out the intake] giving the rough idle, but it will be more responsive down low but run out of breath at higher rpm.

The opposite also applies.
In Formula Ford racing with a stock blueprinted 1600 Kent engine [rated at 68 hp] they are getting 115hp at 7000 rpm with a 5° retarded stock GT cam.

 

Too tight of a converter will cause a big drop in rpm when the trans is put into gear. When my brother got a cam for his truck he got some bad advice, there was about a 500 rpm drop when it was put into gear, requiring an unusually high idle rpm in neutral. Shifting into gear was uncomfortably harsh and drivability wasn’t all that great. When he passed away and I inherited the truck, one of the first things I did was to install an Edelbrock RV cam with .500 lift, 218/228 @ .050 and a 114 LSA. It totally changed how it runs and drives, idle vastly improved and it has gobs of torque from off idle to around 5000 rpm and still has a healthy rumble. RPM drop is minimal when you put it into gear.

Bottom line, the more aggressive the camshaft profile, the more important having the right combo becomes…

 

Just wondering when I read " does not work well" what that actually means ,how each individual interprets that , how much variation there would be in individual descriptions ??
I'd bet there'd be a lot of difference ... Newer vehicles have turned driving into something that most folks don't have or feel the need , to think about the mechanics ,what's going on, any longer ..

 

You are correct but not many guys on the street drive at high rpm that’s why my suggestion is advancing one. Just makes a street engine more fun where it’s driven the most.

 

It did not seem to have much of a RPM drop when put into gear and yes it is a lower compression engine.

 

Mismatched torque converter, too tall rear gears, and a heavy car. It's all of these, not just one.

 

I told the dipshit that built the engine what kind of vehicle it was going in and the gears it had and was expecting a engine that would work with what I have but got the opposite.

 

Jeff ,is your 351w a roller or flat tappet engine?
What heads ?
What Intake and carb are you running? [You need a dual plane for your expectations]

The easiest thing to do is change the whole cam to a known spec.
It would cost less than $200 to reprogram the behavior of the engine

You need a "rock crawler" cam and a small carb [390cfm vac secondary Holley 0-8007]

Here's a good spec cam for $120 [but you will need a new set of lifters]
https://jamsionline.com/ford-sbf-v8...48-472-lift-cam-camshaft-302-ho-82-85-mc1775/

Pair that with a small vac secondary carb.


I build a 283 with similar manners [I wanted it to be docile like a diesel engine, because of the 3 speed column in the city]

 

I have never even tried putting a camshaft in an automatic transmission!

LSA has a big effect on dynamic compression.

If all else are equal:

If you take a high-compression engine and put a narrow LSA cam in it, it will bleed off some of that compression.

If you put a wide LSA cam in a low-compression engine, it will "hold on to" more of the compression.

Get just that angle alone wrong, and you might have a super unhappy engine.

 

For every street engine that I spec, I have the cam advanced anywhere from 3-6º. Mostly that depends on the number of cylinders, and if there is advance built in.

People have told me that this will cause the engine to lose horsepower at higher RPM.

I could care less. If you are really missing a few horsepower above 4,500rpm, you are likely not doing something that you should be doing on the street.

I drive an inline-6 that is a low-RPM torque monster. Once the rains stop, and I have more time for testing, I am going to start experimenting with taller gears to get the RPM down.

 

Everything matters when selecting a cam but the big three are vehicle weight, convertor stall speed, and rear gear ratio. The major cam companies usually have a tech line that can help with your selection. Summit Racing also has a tech line that can help. Nothing hurts performance like the wrong cam

 

Flat tappet and E7 heads,it got a stock cam from a 92 351 short block I had in the garage and rums more like I wanted. I am going to get a Y block togather to replace the 351 and use the 351 for another project,I would like to tear down the 351 to check it over before using again since I heard horror stories about the builder after I picked up the engine and surprised it lasted as long as it did.

 

This will kind of a blanket statement about cam specs but hundreds of thousands aftermarket cams have been installed by us back yard mechanics and engine builders alike without ever knowing its setting on advanced, retarded, or straight up.
If you don’t ask the grinder if it has anything either way and you don’t get out the degree wheel, mag base dial indicators, and pointer you will never know. I’ll guarantee it’s not when you’re changing in the car.
Some engines (supposedly exactly the same) always seemed to run better than others and it was probably the cam setting.
If you’re lucky enough to have an engine with a cam gear button kit you are fine but if not you are stuck with what you got. When the gear companies gave us crank gears with options it got a little easier.