Sbf stroker doin the dynamic compression/cam timing 2step

Yeah imrunnin a four gear Thanks for figuring this for me. Sounds like its should be a good motor.

 

OK, even so, how low will the motor be bogged to when he dumps the clutch?
All I'm sayin' is that it makes no sense to me to take hp away from the top and put it on the bottom where it will be wasted. Bottom line: I would install the cam straight up.

 

Wow, informative read!!! Details, its all in the details...Maybe dumb question but since the OP plans to do street duty the cam is relatively consrvative, yes? How much more cam [and carb] for strip only and would 600hp be unrelistic?

 

You're wonderin' the same thing I'm wonderin'. I love performin' for an audience, so if you'll hang with me, I'm gonna change things up a little.....

Since the OP has presented us with a very fine short block and a decent set of heads, let's yank the juice cam out and screw a solid roller into the block and see what happens.....

393W SBF, 12.04:1 SCR, ProComp 190 aluminum heads, large-diameter, stepped-tube race headers, 1050 carb, CompCams 35-773-8 solid roller cam installed 5 degrees retarded.
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=921&sb=0

You would think since I had to retard the cam to get max results, that the motor wants more cam. Not so. I tried several other hotter grinds and lost power over this cam retarded 5 degrees. The motor likes this timing.....I think it must be a matter of velocity. More cam slowed down the velocity of the slug, resulting in a cylinder that wasn't as tightly packed.....
IO (16) BTDC
IC (58) ABDC
EO (59) BBDC
EC (21) ATDC
Intake centerline 111
Exhaust centerline 109
LSA 110

RPM....HP....TQ
2000....136....356
2500....197....414
3000....255....447
3500....318....477
4000....383....503
4500....454....530
5000....513....540
5500....544....520
6000....560....490
6500....549....443
7000....500....375

Peak volumetric efficiency 103.5% @5500 rpm's
Peak BMEP 207.0 lbs @5000 rpm's

I'm thinkin' it's time for more cylinder head. What do you like? How about AFR205, model #1450 with 58cc chambers? That'll raise the SCR a little, to 12.35:1. Speak up if you have a better choice......

 

Holy lizard shit, Batman, I guess the motor wanted more cylinder head.....
I sure hope there's a good crank and a good set of rods in the short block, not to mention valvetrain.

393W SBF, 12.35:1 SCR, 9.28:1 DCR, Air Flow Research aluminum heads, part number 1450, 2.08" intake valve, 1.60" exhaust valves, 58cc chambers, 205cc intake runners. 1050 carb on a Victor Jr. 351-W, part number 2981 (rated by Edelbrock to make power from 3500-7500), large diameter stepped-tube race headers, CompCams solid roller part number 35-773-8, retarded 4 degrees on these 0.050" numbers.....
IO (17) BTDC
IC (57) ABDC
EO (60) BBDC
EC (20) ATDC
IC 110
EC 110
LSA 110
Overlap 37 degrees

RPM....HP....TQ
2000....120....314
2500....191....401
3000....239....418
3500....298....447
4000....372....489
4500....456....532
5000....535....562
5500....600....572
6000....645....565
6500....681....550
7000....692....520
7500....700....489
8000....685....450

Peak volumetric efficiency 110.4% @6500 rpm's
Peak BMEP 219.5 lbs @5500 rpm's

I feel compelled to run a Sim with an RPM intake also (rated by Edelbrock to make power from 1500-6500).....
RPM....HP....TQ
2000....132....348
2500....193....406
3000....247....432
3500....308....463
4000....386....506
4500....471....549
5000....552....580
5500....608....580
6000....647....566
6500....668....539
7000....678....508
7500....680....476
8000....661....434

Peak volumetric efficiency 109.4% @5500 rpm's
Peak BMEP 222.8 lbs @5500 rpm's
Look at that hellacious cylinder pressure.....

I just wanted to show you guys where the breakover is between a dual-plane high-rise intake like the RPM and a single plane high-rise like the Victor Jr 351W. Up to 6000 rpm's, the dual-plane makes more power and torque. Over 6000, the single-plane takes over. Remember that when you're building your next motor. I see street motors all the time with those cheezy single-plane intakes.

OK lads, enough fun for one night.....

 

My god that's impressive. I'm at the last dribble of my budget on this rattle trap. I'm committed to run what I have HOWEVER , this will be referenced for later upgrades. Thanks a lot! Rs59

 

Put the car on a 300 lb diet and you'd be in the 8's with that motor

 

Very interesting read , very interesting indeed.....

 

I can't believe I'm gonna say this but ......that's too fast. I was thinking gettin into the tens would be awesome. .?.?.?

 

Hey, getting into the 10's WOULD be awesome.

 

I got the same static compression, but I have always used advertised duration to calculate DCR. At 106 ICL, yours comes out to 8.5. It doesn't really matter what you use, it's an estimate regardless, but I have had many builds using this as a tool, so I trust the data

A good rule of thumb is max 8.3-8.4 DCR using Pat Kelley's calculator, a tight quench, aluminum heads, all values measured, not out of the book, not running too hot, and a timing curve to match the build.

So, if this is running on race gas, you will be in good shape. If you are trying to run it on the street with pump gas, you have a little too much compression. If that is the case, I would open the chambers 2 ccs or run a .050 gasket (still plenty of quench)

As far as what the cam will do, almost always retarding a cam will gain peak HP. The question lies in the use of the car. If it is a streeter, the earlier cam timing builds vacuum and makes it easier to tune part throttle, if it is a racer, that's not as important.

I also agree that you need better heads to go real fast, but like you said, that can be pushed back for a later day.

If the motor is assembled, and its race only, I'd leave it.

 

Thanks for the info. The heads I bought were about all I had money for and are still a major step up from my iron heads. Even though they were C9 castings. I could have gone to a 205 runner but figured I wouldn't have to spin so high with 190s. Little more velocity. At least that was my thought.

 

Thank you stang,
It's like I have said before, if you build to the same calculator with every build, then you begin to get an idea of what will work and what won't. That's where you are with Pat Kelley's calculator and that's where I am with Keith Black's calculator. If you use the same one all the time, no matter whose it is, it'll work for you.

I came up with 9.09:1 DCR with the 12.04:1 SCR on the first round of calculations that I did and I agree that over 9 is questionable on pump gas, even with aluminum heads. Of course, it depends on the pump gas and how tight the squish is.

John Erb, chief engineer for KB pistons has stated that it will be better to keep the squish tight and run a little more SCR than it would be to lower the SCR with a thicker gasket. He says the motor will detonate worse with the thicker gasket. I'm a product of what I learn from others who are smarter than I am, so I have no opinion either way.

 

I'd like to throw my $.02 worth in and thank everyone who contributed to this post,as not only was it incredibly informative,but everyone was able to contribute and share knowledge,helping fellow HAMBers,without letting egos run unchecked or throwing handfuls of shit at each other like chimps at the zoo...!I guess that's because the post was all a bunch of Ford guys,and we are all above that kind of behavior...?
I have a similar combo going together for a 2700lb street/strip 4-spd car,3.70 gear,347"sbf,ProComp 210 heads w/chambers milled to 58cc,2.08/1.60 valves,owner ported,Vic jr(also fully ported),830cfm dp,and a comp solid cam (250/260 deg @.050",.568"/.592",106lsa,pn 31-609-5).
I had been a little worried until I read this thread this morning,but you guys have confirmed that I should be just fine,even a bit conservative as far as dcr for running this thing on the street on pump gas.
Once again,I just wanted to say thank you to all who contributed to this post,and to the OP:That Falcon looks like just about the most fun you could have with a car!Nice choice keeping it 4-speed!

Ps: The ProComp heads were bought years ago from a vendor who advertised them as "made is Australia".....

 

He is correct that squish or quench is more beneficial than reducing compression.

However, what I have seen is anything under .055 does fine down to about .040 (although some racers go tighter to where they will see marks on the pistons where they kiss)

The key here is that it is a wedge head with a small chamber and a relatively large quench pad and flat or inverted dome piston. Its all about moving the a/f mix around the chamber.

Small chamber, big flat areas on the piston, big flat areas on the head, you can lean toward looser quench (.055 max IMO)

If you get into BBCs with a full dish with only a quench ring around the outside of the piston, very big combustion chambers and/or a dome in the way. Things don;t move around as much at the top of the stroke.

Some 460s don't have much quench pad in the head, and open chamber 351Cs are very similar. Basically, any large or complicated chamber, tighter is better, and I shoot for for a max of about .045, but I still hate to go less than .040

So yes, better to have compression than not having movement in the chamber, but the original poster is in the ballpark even if he went .050 gasket.

Here is something else ironic, once you pass about .070, it doesn't get worse, so if you have a real deep one, like Ford truck 390s with 8:1 compression have pistons .130 down the hole and a .039 gasket, no use cutting the deck. Buy new pistons or run it, because with almost .170 quench distance there isn't a lot of movement, but anything you gain from decking won't get it better, it'll only make it difficult to bolt things together

To the original poster - Didn't mean to make it sound like your heads were a bad purchase. Most of us shy away from Procomp for quality reasons, they can be hit or miss, but they flow better than stockers and aren't all worn out! Thats a good reason right there

I just wanted to point out that the big numbers will come with a set of AFR or TFW heads that really flow some air, assuming the valvetrain, lower end, and intake/carb will support it

It never ends LOL we can spend your entire life savings if you let us

 

Yep, and mortgage the homestead.....

 

Yeah id say the pro comps were a stepping stone purchase. However im only using their casting as we put good shit in them. I wouldnt trust fully assembled ones. Great info here. Thanks to all who contributed their knowledge and time. Pwrshftr let's see some pics of that car of yours. Thanks again gents.

 

Rocketsled59:NInwould love to put some pics up,but it's an o/t ride....'66 M-word coupe done up as a vintage drag car....which I'm pretty sure it was back in the day,as it is V8/4-spd,radio&heater delete,manual drums,manual steering.
Anyway,as I am still pretty new here,and admin has made quite clear no mustangs are welcome,I am hesitant to even mention the car,even though it is every bit as period correct as a Falcon,Comet,or Fairlane of the same year.


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I'll snap some pics of the reassembly process next time I'm home (in two weeks),and pm or email them to you.All I have left to do is work the bugs out of some stuff;a header tube that hits clutch linkage,a leaky brake fitting,fix a door striker that's misaligned,and get the front end back together after the drum to disc swap.


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I think your C/R is 11.4 to 1. Here is how I calculated it, but many experts say that the formula is not correct or will not be true. I took your 168 psi and divided it by 14.7 ( atmospheric press at seal level) Like I said before, I read about this in an old car mag back in the 60"s.
And there are HAMBERS a lot more knowledge than me.