Cam Choices

[ChiefDanGeorge]

It's not agonizing, but what I don't want to end up doing is spending time/money for diminishing returns.
I can understand making sure the deck is squared, for proper head/block fitment.

I'm not with you guys who think it's "agonizing" to discuss these things.  It takes almost no energy at all.  Typing or talking or thinking about this stuff takes very little effort.  Even going out in the garage and measuring stuff is not that bad.  Agonizing is an emotional term and I don't think we're at the point being pushed to that level.  I agonize when I have a broken rib (and/or torn intercostal tissue) and 18 year old kids are asking me to keep playing pickup football with them.   I do understand and agree that we may be splitting hairs and talking about making very small gains.  Isn't that why we're here, though? 

So we're not talking about a racecar.  Does it hurt anything to try to optimize it? 

How about some more cam recommendations or questions about the combination/useage?

A big car with high gearing and a moderately sized engine might be a more difficult call than a light car with a huge engine and low gears.

JMO,

paulie

[ChiefDanGeorge]

Perhaps this is a dumb question, but why would I do this on new heads? Is there that much variation from the spec'd 72cc.

Lets make a WAG that Dan does not have a ready use competent machine shop that he can just drop off the
parts and pickup when done and swipe the CC.

Here is another cheapo way to get the same as a machine shop.
Head CC.
Get a 100 cc syringe from the drug store for 5 or 6 bucks and CC the heads on the kitchen table.
You will need a piece of plastic and a drill. The plastic must cover the head chamber.
Drill a hole in the plastic to squirt the water from the syringe in.
Smear a bit of vaseline on the head to create a seal and fill up the chamber with water from the syringe.
Head CC.

[My427stang]

Dan, many of us have seen Edelbrocks that were way off.  My own on my Mustang are 73cc, that is after being cut by Keith Craft.  I don't know what they were out of the box, they are a set of his Stage 2 heads and I bought them new, but of course to be 73 cc now, they were larger than 73cc and they are 72cc heads. FWIW, I checked mine myself and I check all of them before I assemble.  Additionally, the 396 F100 I just did, we only did a single chamber, but it was 74cc. 

Paulie got some that were 79cc if I remember right. 

The difference may or may not be significant to some, but say a 9.9:1 431, zero deck with 72 cc heads, it would be 9.64:1 with a 75 cc head, next let's add .015 of deck clearance and you have a 9.38 motor. 

Is that significant?  To me it is, even the .3 lost from the head difference is, but yes I am a bit more "mathy" then others.  I am exclusively a street torque kind of guy, and the cam and compression combo for a torquey streeter will be a bit different for a 9.9:1 motor than for a 9.3:1 motor.

So what does this mean in cam choice?  With a 9.38:1 motor, for something built for pure torque, I'd go as small as a 262 cam with a decent set of heads and a tall gear heavy car.  That cam would likely be fussy on fuel at 9.9:1 with a big car and 3.00 gears, in that case I would likely run a 272 cam.  In both cases they would work well, and the second would likely have as much if not more torque than the 1st due to the compression difference.  Bottom line, despite tweaking for compression, in both cases the parts match

Now let's talk the tougher issue... if the deck isn't square. You may have some of the 9.9:1 cylinders and some of the 9.3:1 cylinders. Which cam do you choose?  Well, probably the bigger one to make sure it isn't fussy on fuel, but in this case, although the 9.9:1 cylinders work great, the 9.3 cylinders are down on torque because of the lower compression.  Will it run well?  Sure, no skipping, no bad behavior, no nothing, but spend a couple grand on very nice parts then hit the brakes on blueprinting for a few hundred dollars?.  It's not about fitment only, it's about matching, balance, and forecasting performance.

I will say this though, after running the numbers, if you think you don't need to do the blueprinting, go with RJP's cam or Paulie's later CJ-like recommendation from Crower.  Those are conservative in terms of cylinder pressure and octane tolerance, but realize you potentially are giving up power if your motor comes in at a lower compression.

[ChiefDanGeorge]

Gotcha.
I have no problems doing the upfront work. I just can't tell what is a must do from an "I like to do this".
I have access to a good machine shop, I'm just waiting on the crank and pistons to arrive since I have to get the crank balanced.

Dan, many of us have seen Edelbrocks that were way off.  My own on my Mustang are 73cc, that is after being cut by Keith Craft.  I don't know what they were out of the box, they are a set of his Stage 2 heads and I bought them new, but of course to be 73 cc now, they were larger than 73cc and they are 72cc heads. FWIW, I checked mine myself and I check all of them before I assemble.  Additionally, the 396 F100 I just did, we only did a single chamber, but it was 74cc. 

Paulie got some that were 79cc if I remember right. 

The difference may or may not be significant to some, but say a 9.9:1 431, zero deck with 72 cc heads, it would be 9.64:1 with a 75 cc head, next let's add .015 of deck clearance and you have a 9.38 motor. 

Is that significant?  To me it is, even the .3 lost from the head difference is, but yes I am a bit more "mathy" then others.  I am exclusively a street torque kind of guy, and the cam and compression combo for a torquey streeter will be a bit different for a 9.9:1 motor than for a 9.3:1 motor.

So what does this mean in cam choice?  With a 9.38:1 motor, for something built for pure torque, I'd go as small as a 262 cam with a decent set of heads and a tall gear heavy car.  That cam would likely be fussy on fuel at 9.9:1 with a big car and 3.00 gears, in that case I would likely run a 272 cam.  In both cases they would work well, and the second would likely have as much if not more torque than the 1st due to the compression difference.  Bottom line, despite tweaking for compression, in both cases the parts match

Now let's talk the tougher issue... if the deck isn't square. You may have some of the 9.9:1 cylinders and some of the 9.3:1 cylinders. Which cam do you choose?  Well, probably the bigger one to make sure it isn't fussy on fuel, but in this case, although the 9.9:1 cylinders work great, the 9.3 cylinders are down on torque because of the lower compression.  Will it run well?  Sure, no skipping, no bad behavior, no nothing, but spend a couple grand on very nice parts then hit the brakes on blueprinting for a few hundred dollars?.  It's not about fitment only, it's about matching, balance, and forecasting performance.

I will say this though, after running the numbers, if you think you don't need to do the blueprinting, go with RJP's cam or Paulie's later CJ-like recommendation from Crower.  Those are conservative in terms of cylinder pressure and octane tolerance, but realize you potentially are giving up power if your motor comes in at a lower compression.

[ScotiaFE]

They will not be 72 cc. More like 76 cc or more.
Most of this measuring is to get to the ideal "quench" of .040".
The closer you get to that number the better your engine will run
and less chance of detonation when lugging the engine down.
Also what gas are you going to use?
The cheapest low octane crappy blend you can find or pump premium.
It makes a difference.

[ChiefDanGeorge]

Am I going to gas station hop until I find the perfect blend? No. Am I going to use the correct octane for the car, you bet!

They will not be 72 cc. More like 76 cc or more.
Most of this measuring is to get to the ideal "quench" of .040".
The closer you get to that number the better your engine will run
and less chance of detonation when lugging the engine down.
Also what gas are you going to use?
The cheapest low octane crappy blend you can find or pump premium.
It makes a difference.

[My427stang]

FWIW, my tight quench 489 at 10.7:1 compression will run and drive happily on anything, it usually gets 89 octane unless I am going to run it very hard, but even then having it dialed in right let's it run on anything.  It's EFI so I can tweak any part of the fuel curve, so a bit easier to run cheap stuff in.

My 445 in the heavier truck, with a carb, is a bit more fussy, and when I say that, all I mean is it likes mid grade or on hot days it can rattle, so I just fill it with 89 all the time.

Although some guys don't like to discuss DCR, it works pretty well for me. Just for giggles, the 489 is at 8.33 DCR with .050 quench distance and the 445 is at 8.2 DCR with .058 quench distance (fat Felpro blue head gasket).  Next time the heads are off I will swap for the small bore SCE gasket and it should work a little better, but no reason to take it apart yet.  All calcs are using PKelley's calculator and carefully measured numbers, using a different calculator or not measuring will bring different results.

The examples I gave above for your engine with the two different potential cams and compression combos were 7.98 DCR for the 9.38:1 262 combo and 8.02 DCR for the 9.9:1 272 combo.  Both would be happy with whatever mid grade is in the tank assuming the timing curve isn't crazy and the engine isn't overheating or running way too lean and are more conservative than they likely need to be, but good for a heavy car.

Tight quench, realistic compression, the right cam, and the right mixture, they run real well. 

[plovett]

I hear ya, ChiefDanGeorge.

Hey, one other question.  Again, I'm not trying to muddy the waters, but are you open to using a slightly higher rpm stall convertor?

Even a mild one, say in the 2200-2300 rpm range could make a pretty big difference in performance, and it could affect the cam choice.

paulie

[ChiefDanGeorge]

Yep, I am open to changing the converter since the motor is going to be out. Buddy that is going to help me do the build had me planning on doing that.

I hear ya, ChiefDanGeorge.

Hey, one other question.  Again, I'm not trying to muddy the waters, but are you open to using a slightly higher rpm stall convertor?

Even a mild one, say in the 2200-2300 rpm range could make a pretty big difference in performance, and it could affect the cam choice.

paulie

[wayne]

You may like a lunati high-efficiency cam i used a 10330211 in a 410 i liked it dur 262/272 lift 507/533 lsa 112/108 call and ask them.Good mpg and a ton of low end.

[plovett]

Yep, I am open to changing the converter since the motor is going to be out. Buddy that is going to help me do the build had me planning on doing that.

Man, if you put in a mild stall convertor AND found some headers........ I think it'd be a big performance increase with no downside other than cost.   

Is your engine bay the same as a Galaxie?  That would sure make things easier for headers.

paulie

[ChiefDanGeorge]

I am pretty sure it is. I've found a place that says their headers will fit here

Yep, I am open to changing the converter since the motor is going to be out. Buddy that is going to help me do the build had me planning on doing that.

Man, if you put in a mild stall convertor AND found some headers........ I think it'd be a big performance increase with no downside other than cost.   

Is your engine bay the same as a Galaxie?  That would sure make things easier for headers.

paulie

[My427stang]

FPA headers are very nice.  If you have the cash, ceramic coating will stop them from rusting and keep the engine compartment and floorboards much cooler.

BTW, for an easy reference, I'd run a stock cam with headers in your car before I ran an aftermarket cam with manifolds.  Headers make quite a difference over manifolds in most every FE, other than the few cast iron header applications from the factory

[plovett]

BTW, for an easy reference, I'd run a stock cam with headers in your car before I ran an aftermarket cam with manifolds.

Agreed!  Headers and free flowing exhaust are one of the rare win-win parts additions you can make.  Properly sized headers will make more power everywhere in the power curve. 

Most other parts are a trade off.  With a camshaft or intake manifold for instance, you are usually trading power in one range for power in another.

JMO,

paulie

[ChiefDanGeorge]

I'm skeptical of fitment until I get a set in and verify they work. Passenger side is just so close to shock tower.
I emailed the FPA guy  a while back and he said they fit.

BTW, for an easy reference, I'd run a stock cam with headers in your car before I ran an aftermarket cam with manifolds.

Agreed!  Headers and free flowing exhaust are one of the rare win-win parts additions you can make.  Properly sized headers will make more power everywhere in the power curve. 

Most other parts are a trade off.  With a camshaft or intake manifold for instance, you are usually trading power in one range for power in another.

JMO,

paulie