Cam choices for a 512 build

[cdr]

Well I run a 518 trans in my car, 512 cid, 4050 lb with me, I drive my car almost every day, hydro roller 255,258 @ .050, 3.54 gear 4000k lock up converter, AC, can lock up the converter & be smooth @ 1800 rpm, it took a LOT of tuning to get it there, have not done any track tuning, 1 easy pass short shifting 1750 DA, 11.33 @ 121 on MT Drag Radials, car was as it is drivin on the street, full exhaust, air filter ect. car is a BLAST on the street.

This is a great example of the HR working well.   What are the lobes or lobe specs?  What are you shifting at?  What is your idle rpm and vacuum. I would think the 255@0.050 would be have a bit of rumpity rump.

I have not mapped out the lobes, on that run I shifted @ 5500, I will be going back to the track in October & hopefully do some tuning, a lot depends on my health at that time & not having a roll bar, idle RPM is 1100 in neutral vacuum is @ 7 ish & drops to about 3,4 in gear, it is not smooth @ idle LOL.
 

[cdr]

https://youtu.be/c4jgbv98adY

[Challenger340]

https://youtu.be/c4jgbv98adY

THAT Car runs fantastic Charlie, you should be proud  

How do you find the Pwr Brakes with 7" at idle and 3" or 4" in Gear ? Did you add a vacuum canister ?

[cdr]

https://youtu.be/c4jgbv98adY

THAT Car runs fantastic Charlie, you should be proud  

How do you find the Pwr Brakes with 7" at idle and 3" or 4" in Gear ? Did you add a vacuum canister ?

Thanks Bob, no power brakes, disc in front,drum rear, stops great. I am in no way recommending my cam to anybody, just showing what I have made work for my street car.

[Paul G]

Did you read what I poster regarding overlap?  This is your general measure of idle and low speed characteristics.

I did, and have been doing some reading on overlap. LSA on the wider side will will loose a little torque but move torque higher in the rpm range, broaden the power band, and will improve idle and ease of tuning. An acceptable trade off for a street engine.

[BSB67]

Did you read what I poster regarding overlap?  This is your general measure of idle and low speed characteristics.

I did, and have been doing some reading on overlap. LSA on the wider side will will loose a little torque but move torque higher in the rpm range, broaden the power band, and will improve idle and ease of tuning. An acceptable trade off for a street engine.

Good.  If you are planning to have a hand in picking your cam, consider some reading/research on:
1) why hydraulic cam 0.050" don't equal solid cam 0.050"
2) relative cam rates by using advertised timing (seat timing), 0.050", 0.200" and lift.

[BSB67]

Well I run a 518 trans in my car, 512 cid, 4050 lb with me, I drive my car almost every day, hydro roller 255,258 @ .050, 3.54 gear 4000k lock up converter, AC, can lock up the converter & be smooth @ 1800 rpm, it took a LOT of tuning to get it there, have not done any track tuning, 1 easy pass short shifting 1750 DA, 11.33 @ 121 on MT Drag Radials, car was as it is drivin on the street, full exhaust, air filter ect. car is a BLAST on the street.

This is a great example of the HR working well.   What are the lobes or lobe specs?  What are you shifting at?  What is your idle rpm and vacuum. I would think the 255@0.050 would be have a bit of rumpity rump.

I have not mapped out the lobes, on that run I shifted @ 5500, I will be going back to the track in October & hopefully do some tuning, a lot depends on my health at that time & not having a roll bar, idle RPM is 1100 in neutral vacuum is @ 7 ish & drops to about 3,4 in gear, it is not smooth @ idle LOL.
 

Dave has always held his cam lobes specs close.  I don't think I've ever seen seat/advertised numbers, or 0.200" numbers.

Comparing my motor and your motor is probably the best example of completely opposite cams make about the same power.

[flyinlow]

Paul, sorry I am not trying to hi jack your tread , but it is interesting reading and  I end up with more questions.

I was thinking SFT lifters  are the lightest, HFT, SR, and finally HR lifter are the heaviest ? How much of the valve springs work  is due to lifter weight?

It was mentioned SFT cams wipe more often. Why?


1

[c00nhunterjoe]

Are we counting individual roller lifters or the pair with link bars? Flat tappets are wiping more frequently due to recycled junk metal, oil quality, and improper breakin.

[Challenger340]

https://youtu.be/c4jgbv98adY

THAT Car runs fantastic Charlie, you should be proud  

How do you find the Pwr Brakes with 7" at idle and 3" or 4" in Gear ? Did you add a vacuum canister ?

Thanks Bob, no power brakes, disc in front,drum rear, stops great. I am in no way recommending my cam to anybody, just showing what I have made work for my street car.

Well IMO,
your build and the work you've done should be an example of how it's done, Thanks for sharing with others !

So I'm guessing you run the 1-1/16" Big Bore Master Cylinder ?
They do indeed work great, and saves a lot of hassles with Vacuum BS and Big Cams.... Smart !    Like I said, some pretty damn fine examples.

[BSB67]

It was mentioned SFT cams wipe more often. Why?

If it is my post you are referring to, that's not really what I said.  I was comparing the SFT to a HR.  Is your question why does a SFT have a higher risk of wiping a lobe verses a HR?

[flyinlow]

SFT seam to have a higher fail rate from what I read or hear. I have no data from a builder or manufacturer to substantiate this.

For an engine like Paul wants with a HR set up to run with the lifter compressed to close to being a solid lifter and no lifter bore bushings, will the cam and lifters go the distance ? At least 50k. preferably 100k.+ miles.

Does the bar between the lifters on a roller lifter actually keep the lifter aligned or is it a back up in case you float the lifter?

[BLK 68 R/T]

The bar keeps the lifters from turning in the bore. It's game over if they turn since the wheel will no longer roll.

[BSB67]

SFT seam to have a higher fail rate from what I read or hear.

For an engine like Paul wants with a HR set up to run with the lifter compressed to close to being a solid lifter and no lifter bore bushings, will the cam and lifters go the distance ? At least 50k. preferably 100k.+ miles.

Does the bar between the lifters on a roller lifter actually keep the lifter aligned or is it a back up in case you float the lifter?

Again, your question is not clear.  Relative to what?  Generally speaking, today, all FT cams seem to have increased rate of failure than in the past, and over rollers cams for a variety of reasons. The specific reasons are regularly debated on various forums but seldom fully agreed upon.

The rate of SFT cams is probably higher than HFT simply because generally the lobes are more aggressive and spring pressures higher.

Rational HR cam with a high quality lifter should go the distance.

As mentioned the bar is for alignment.

[c00nhunterjoe]

One of the earliest production performance v8s to have roller cams stock would be the 5.0 mustang. They go hundreds of thousands of miles without failure. It comes down to the profile you pick as to what has to be done maintenance wise. Keep the spring pressures mild and it will last, go more high performance and you will be replacing parts more often- valve springs will wear and fail before a lifter in most cases.

[PRH]

Comparing my motor and your motor is probably the best example of completely opposite cams make about the same power.

Not to be argumentative...... and it's kinda off topic to boot.....but......

I think if you dyno tested Russ's motor with manifolds vs Charlie's motor with headers......back to back on the same dyno, I'd expect there to be somewhere around 50hp difference........ maybe more.

In either motor, I'd expect Russ's cam to work better with the manifolds, and Charlie's cam to work better with headers.
And, the difference in power between manifolds or headers, in either motor, would be greater with Charlie's cam.

[BSB67]

I think if you dyno tested Russ's motor with manifolds vs Charlie's motor with headers......back to back on the same dyno, I'd expect there to be somewhere around 50hp difference........ maybe more.

Maybe.  That's why I prefer to race cars.  

In either motor, I'd expect Russ's cam to work better with the manifolds, and Charlie's cam to work better with headers.

Absolutely.  And that is somewhat the point for the OP to consider, considering his goals.

And, the difference in power between manifolds or headers, in either motor, would be greater with Charlie's cam.

Not sure what you mean by this.  But if you put Charlie's cam in my motor with manifolds, it will be down 50 HP.

[cdr]

I think if you dyno tested Russ's motor with manifolds vs Charlie's motor with headers......back to back on the same dyno, I'd expect there to be somewhere around 50hp difference........ maybe more.

Maybe.  That's why I prefer to race cars.  

In either motor, I'd expect Russ's cam to work better with the manifolds, and Charlie's cam to work better with headers.

Absolutely.  And that is somewhat the point for the OP to consider, considering his goals.

And, the difference in power between manifolds or headers, in either motor, would be greater with Charlie's cam.

Not sure what you mean by this.  But if you put Charlie's cam in my motor with manifolds, it will be down 50 HP.

Russ's combo shows that you can make AWESOME power with stock exhaust manifolds , be very steetable & fast as heck !!!

[PRH]

I mean...... if you tested both cams in either motor, with both manifolds and headers, you would see a bigger spread in power between the manifolds and headers with Charlie's cam.

What would have been a fun test was talking one of the FAST builds I had on the dyno....... then added headers...... then added a more traditional cam.

Ultimately the goal is making the car go fast.
But as an engine builder I rarely have any control over what happens with the motor after it leaves my shop.
So, it's easier........ and more accurate for me to compare motors to each other that I've tested on the dyno.
Those numbers are apples to apples.

Sometimes the stars align and it all comes together.
I sold a set of heads and a cam(and guided him through the rest of the combo.....gears, converter, carb, etc) to a customer who was looking to run low 10's in his street/strip car.
I got a call today that he went 10.01@132 through the mufflers.

[BSB67]

After getting pretty close to a couple of HP machine shops owners, it became clear that there is a disconnect between what they do, and what happens to their builds when they leave the shop.  Definate missing links.  Good, skilled customers and their feedback are key to piecing together the complete picture.  Heck, even driving skill is a factor.

If the goal is the highest peak HP on a dyno w/ open headers you cannot beat a big ole duration cam on a 108 installed at 104.  Probably a 10 million dyno sheets out there to prove it.  Slap in a 4200 stall, and its a bracket racer's dream combo.

However the highest peak power motor is not necessarily the highest average power motor, although it usually is.  But the spread in average power might be much smaller than the spread in peak powers suggests.  

My cam is both smaller in duration, and much larger in LSA, so the lower peak power is predictable.

If Charlie and I switched torque converters, I would probably pick up 1 - 2 mph, and he would probably lose 1 - 2 mph.