Cam/gear selection for 393w

A

afterglow

Member
Jul 2, 2006
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6
#1
I'm in the process of putting together a parts list for a planned 393w stroker build. Here's the pertinent info:

393w
9.5 CR
AFR 185/61cc
Weiand Stealth intake
750cfm vacuum secondary
built C6
~2500RPM TC
1-5/8" Hooker Comp longtubes
2-1/2" Magnaflow X-pipes
9" Detroit Truetrac rear
25.8" tires
subframe connectors (welded)
CalTracs

The car is being built purely for street....mostly local roads and very minimal highway. I'm limited to 9.5CR because of bad gas in the area. Emphasis is on torque at low-to-mid RPMs.

I've been fiddling around with the Desktop Dyno and the best cam I could come up with is the CompCams XE274H (274/286, .519/.523). Anything else you can suggest?? Will the ~2500RPM TC be fine??

I also need suggestions on what rear gears to run. With the new build, something like 3.5 perhaps?? Remember....very little highway and only 30-40 miles at a time.
 
#4
overall i like the combination you have selected, including the cam. i would suggest a built AOD instead of the C6 as you will have less parasitic loss, and you get the overdrive as well. if you dont, or cant get an AOD, then a C4 would be a better choice, again less parasitic loss and lighter weight.

as for the subframe connectors, good starting point. tie them in to the rocker panels, and build a center cage much like total control products. this will make any suspension modifications you choose much more effective.
 
#7
Yeah, sounds petty good as you have it. Should make 450hp without a problem. What does the Desktop Dyno say?
Click to expand...

Desktop Dyno says 434hp@5500rpm/456lb.ft@4500rpm.

Why don't you go ahead and do a 408. It wouldn't cost much more and maybe no more if you're buying new rods for the 393. What car is it going in?
Click to expand...

Going with the 408 would mean bumping up to the AFR205s with the smaller 58cc chambers. I've tried various combinations but can't get the CR I want...they're either too high or much too low. It would also mean upgrading a lot of stuff I already have....

The car is a 69 Mach 1.
 
#8
danny clemens said:
Why don't you go ahead and do a 408. It wouldn't cost much more and maybe no more if you're buying new rods for the 393. What car is it going in?
Click to expand...

393 is dirt cheap compared to 408.

393 only needs a crank.
The 408 cannot be built without a kit or buying a kit's worth of parts.

393 uses inexpensive, off the shelf 302 pistons. You even save money here because 302 pistons are generally cheaper than the 351 pistons you would buy if you didn't stroke the engine.
393 uses stock 351w rods. No money spent.
393 crank is inexpensive... if you don't stroke your 351, you will still need to spend money to refresh the crank.

It's almost a shame not to stroke a 351 to 393 even on a simple rebuild.


I want to know what car he is dealing with too...
What tranny came in the car?

I like the combo for the most part.
Personally I see a 393 being able to use a little more header.
Even with a 1.75" primary, it won't lose torque and will make good power.

Let's see if I can remember header theory correctly... ;)
Tube diameter determines power curve, tube length determines where the curve starts.
Point being, tube diameter is too often over thought and underdone, while folks ignore the far more important (low rpm speaking) tube length.
A big tube will make more power with the 393 cubes. If you want the low end torque enhanced like you say, then go for the longest tube you can find.
 
#9
afterglow said:
The car is a 69 Mach 1.
Click to expand...

Gears would depend alot as well on what tranny you decide.
If the car came with a C4 or FMX, I would go back with a well built C4 or AOD.
That is just my opinion...
The C6 just eats up alot of power just turning.
If it came with a C6, and I had it waiting to go in, that is the only way I would use a C6.

C4 I'd use at least 3.50s, but lean hard to 3.70s.
C6 I'd go up to at least 3.70s, but maybe as high as 3.89 or 3.91.

AOD could use 4.11s easy and still cruise nice.
 
#10
ratio411 said:
Gears would depend alot as well on what tranny you decide.
If the car came with a C4 or FMX, I would go back with a well built C4 or AOD.
That is just my opinion...
The C6 just eats up alot of power just turning.
If it came with a C6, and I had it waiting to go in, that is the only way I would use a C6.

C4 I'd use at least 3.50s, but lean hard to 3.70s.
C6 I'd go up to at least 3.70s, but maybe as high as 3.89 or 3.91.

AOD could use 4.11s easy and still cruise nice.
Click to expand...

The car came with a C6 which is why I'd really like to stay with that....I don't wanna mess around with having to source a C4 and getting the right bellhousing, crossmember and shifter linkage.

How much power does the C6 consume compared to the C4??
 
#11
ratio411 said:
393 uses inexpensive, off the shelf 302 pistons. You even save money here because 302 pistons are generally cheaper than the 351 pistons you would buy if you didn't stroke the engine.
393 uses stock 351w rods. No money spent.
393 crank is inexpensive... if you don't stroke your 351, you will still need to spend money to refresh the crank.
Click to expand...

I think that will all go out the window when you buy 302 pistons with a big dish. When you increase the displacement from 302 to 393 compression sky rockets. He will need a piston with 20+ cc dish. It is not a simple "off the shelf" 302 piston. If it is off the shelf it will be a blower or turbo piston which are not cheap. If you want 10.5:1 cr then you point is semi valid. The prices for performance pistons are pretty close for most applications including strokers.

Stock rods cost money too. Stroking increases piston speed which puts more strain on the rod bolts. Add ARP's and resizing and it starts adding up. Aftermarket rods with good bolts already installed are not enough extra to justify using stocker IMO.

Crank is a wash. 408 and 393 cranks are the same price.

Most kits give you a price break. Piecing together parts individually adds up to more than a kit price.
 
#12
brianj5600 said:
I think that will all go out the window when you buy 302 pistons with a big dish. When you increase the displacement from 302 to 393 compression sky rockets. He will need a piston with 20+ cc dish. It is not a simple "off the shelf" 302 piston. If it is off the shelf it will be a blower or turbo piston which are not cheap.
Click to expand...

The cubic inches are not going up that much.
Neither is compression.
Yes, compression is going up some, but a monster dish is not needed.

The stock rods are fine unless you are planning to run the rpms through the roof.
351s have strong rods... As for the bolts, I would never build a Ford and not use ARP bolts. Personally I wouldn't build an engine and not polish the rods myself.

Like any stroker, or even stock rebuild, the builder should know what they are doing and plan properly.
 
#13
When you go from 302ci to 393ci, you have increased displacement a lot. The original poster needs 9.5cr. With 61cc heads, 0 deck, .039 gasket and 3.85 stroke the calculator I used said he needs 25cc dish. Plug those same numbers in with a 302 stroke it comes out to 7.6cr. I wanted to build a stroker with a turbo and I found out it is hard to get low compression with a stroker. I have -27cc pistons in my 357 with the same heads and got it down to 8.8:1. There are numerous CR calculators on the net, try one for yourself.
 
#14
brianj5600 said:
When you go from 302ci to 393ci, you have increased displacement a lot. The original poster needs 9.5cr. With 61cc heads, 0 deck, .039 gasket and 3.85 stroke the calculator I used said he needs 25cc dish. Plug those same numbers in with a 302 stroke it comes out to 7.6cr. I wanted to build a stroker with a turbo and I found out it is hard to get low compression with a stroker. I have -27cc pistons in my 357 with the same heads and got it down to 8.8:1. There are numerous CR calculators on the net, try one for yourself.
Click to expand...

Correct me if I am wrong, but IIRC the 393 using stock rods and 302 pistons doesn't have anywhere near .000" deck clearance.
Also, .039" is a bit on the thin side for an SBF head gasket.

Edit:
Sorry.
Got this thread mixed up with the other 351w thread.
This one is using AFR heads.:bang:


All of that together can make a big difference. It comes back to what I said about someone rebuilding an engine at all better be able to plan it out.

Don't get me wrong, I am not arguing to be an a$$, I am just pointing out the need to plan and be flexible. To some extent your comments are just highlighting that point.
 
#15
Just did the math...
A 302 piston with 3.85" stroke and stock rods, 351 block, will sit .023" in the hole.


Edit:
With stock type eyebrow flat tops, I get:
60cc heads= 10.3
64cc heads= 9.9

I don't know the common dish cc for a 302, but I would guess it would drop each of those 1.0...
That's 9.3 or 8.9 with a standard dish 302 piston.
 
#18
The original poster is worried about poor gas quality. If I was worried about poor gas quality, I would not run the pistons in the hole with a thick gasket. I would shoot for .040" piston to head clearance or less. Fel-pro blues come in .039" and .041" thickness depending on if you want steel or copper ring.
 
#19
I've got to jump in on this one.

Had a 351W needing a rebuild, tore it down and the crank needed to be turned and rods cleaned up too. Looking for around 400 easy hp, keep in mind this is not a race car.
So my machinest says why don't you just stroke it to 393, use cheap 302 pistons and the cost of the crank & new rods w/ARP rod bolts is barely anymore $$ than the machine work to clean up what you've got. Keep in mind the replacement rods are exactly the same length as the factory 351 rods.
He was right... So far.

Bored it .020 over, got a rebuild kit, but couldn't find a good 302 piston in the dish I needed.
Part of the problem is that the replacement rods are bushed, set up for floating pins not pressed, and the overbore of 0.020 (did that so I can get at least one more rebuild out of it).
I need about 12 to 18cc dish piston, hard to find in a good and economical stock piston. Ended up with a Hypereutectic Keith Black piston w/12cc dish (I've got 64cc heads), measured the pistons to be 0.017 in the hole, had the block decked so the pistons are now 0.005 in the hole, using a 0.039" gasket (very common), and I'm at about 10.4 CR. Thats fine this is where I wanted to be.

Problems:
The pistons were expensive for Hyp.'s, mostly because of the needs stated above.
AND to balance the assembly they needed to add Mallory metal, apparently very common with 393w setups, nobody ever mentions that, $300 alone.

Then I looked at the kits you can get for a 408W, I could have had the same setup but with FORGED pistons for about the same price. Now I say the 408W is the obvious choice.

393W setup
Hyp Pistons $240
3.85" stroke crank $250
New rods w/ARP bolts $250
Balance $300
Total $1040

408W kit $1000, pretty common price, inlcudes
FORGED PISTONS
Same quality crank
Same quality rods with 3/8" ARP bolts
and comes with rod, main bearings, & moly rings (subtract about $90 from price for comparison)
Balance $150
Total $1060
 
#20
Dbiscayne said:
New rods w/ARP bolts $250...
Click to expand...

The idea behind the 393w for street use is to use the stock rods!
Why, oh why, did you buy new rods that were the exact same length as stock???
You can't count the cost of ARP bolts, they are needed on any Ford build!
You also can't count the cost of those pistons because there are stock 302 pistons with healthy dishes and if you had used stock rods, you wouldn't of had the expense of floating pins.
Also, if the 393 crank needs balancing, how do you figure the 408 crank wouldn't need the same expense???

I understand the 408 is a killer combo, and not badly priced, but if you aren't racing and just want a strong street runner, the stock rod 393 is cool.
 
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