Ford Muscle Cars Tech Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
22 Posts
Discussion Starter #1 (Edited)
So, I was in the process of collecting parts for my budget 393w. I've acquired set of good used forged 302 pistons, some 351w truck rods, and a decent 351w block. Then I went to purchase a crank, and right before purchasing the scat 9000 cast crank, realized it used chevy diameter rod journals. Does anyone know or, or have a 393 crank that uses 2.5" ford rod journals.

Looks like about 10 years ago scat and eagle used to make such crank, but I presume due to costs it was easier for them to making rotating assemblies using the same chevy rod end on their small block rods and cranks. And maybe a bit of it also has to do with balancing/less reciprocating weight.

https://www.summitracing.com/parts/sca-9351w10 Here is the crank I am looking at, if I'm reading this correctly, that's meant for a rod with a 2.311" big end. Or am I reading that wrong, and that's the actual size of the journal, and my rod with 2.5" big end, plus the bearing thickness, and oil gap will equal 2.311"?

If not, I suppose back to the drawing board it is.
 

·
Registered
Joined
·
22 Posts
Discussion Starter #2
Never mind, that's the actual rod journal size on the crank. The rods are labeled as "rod big end" when they should be labeled as "for rod journal size". So, all is well. Please delete thread mods, feel like this will cause confusion if it is left up.
 

·
Registered
Joined
·
22 Posts
Discussion Starter #4
Absolutely, I ran the numbers before purchasing anything. Using (used) DSS 8723W-4000 393w pistons. Deck Clearance calculator comes out with 0.023" of piston recession. They're a 13cc dish piston. 60cc heads, and with a .047" compressed thickness gasket comes out to a 10:1 compression ratio. I have not purchased the head gasket yet, and will measure piston depth before I do. Wanting to keep the compression right at or slightly above 10:1 so I can still run 91. I do understand that timing/cam selection/dynamic compression plays a much larger role in detonation, but 10:1, and the new Comp Cams XE268H camshaft I have laying around collecting dust will make a pretty stout budget motor.
 

·
Registered
Joined
·
7,414 Posts
Absolutely, I ran the numbers before purchasing anything. Using (used) DSS 8723W-4000 393w pistons. Deck Clearance calculator comes out with 0.023" of piston recession. They're a 13cc dish piston. 60cc heads, and with a .047" compressed thickness gasket comes out to a 10:1 compression ratio. I have not purchased the head gasket yet, and will measure piston depth before I do. Wanting to keep the compression right at or slightly above 10:1 so I can still run 91. I do understand that timing/cam selection/dynamic compression plays a much larger role in detonation, but 10:1, and the new Comp Cams XE268H camshaft I have laying around collecting dust will make a pretty stout budget motor.
With the 268, it will have tons of low end power... and going in a heavy Galaxie with a tall gear, it could be exactly what you need! Compression might be a tad on the high side. Probably wouldn't hurt to polish the sharp edges off the pistons and combustion chamber.

Good Luck
 

·
Registered
Joined
·
22 Posts
Discussion Starter #6
With the 268, it will have tons of low end power... and going in a heavy Galaxie with a tall gear, it could be exactly what you need! Compression might be a tad on the high side. Probably wouldn't hurt to polish the sharp edges off the pistons and combustion chamber.

Good Luck
Galaxie? I wish... just a junky Ford Maverick that I'm putting too much money into haha, but that's the life. I assume you're saying to polish the sharp edges due to hot spots? I've never done that and am nervous. What would I be looking for as far as being "too sharp"? Do I just need a nice radius on all the edges?
 

·
Registered
Joined
·
7,414 Posts
Galaxie? I wish... just a junky Ford Maverick that I'm putting too much money into haha, but that's the life. I assume you're saying to polish the sharp edges due to hot spots? I've never done that and am nervous. What would I be looking for as far as being "too sharp"? Do I just need a nice radius on all the edges?
Just remove sharp edges. It doesn't take much at all.
With a Maverick, I'd use more camshaft. More camshaft would also make life easier when it comes to detonation.
What carb, intake, heads, headers, exhaust, converter and gear does the car have?
 

·
Registered
Joined
·
22 Posts
Discussion Starter #8
Well I have a fresh holley 650 double pumper I was going to use, but I have many carbs laying around. Intake, weiand 8023WND. Heads, blueprint hp9009, 2.02/1.60, 190cc. Headers, 1 3/4" long tube, 3" exhaust w/ mufflers of some sort, legality reasons, haven't purchased yet. Built C4, 2500-2800 stall, and 3.55 gears.

I contacted Comp Cams and they recommended a XE256H for low end torque, and a XE274H for less torque/more horsepower, but said the XE268H I already have would somewhat meet in the middle. I was curious as to how well the XE268H would fit, so had to call them up and have a conversation with them, always like to know what exactly is going into my engine, and why, not the "if it fits it ships" kind of person, to just throw parts at something and call it good.

But now you got me thinking about spending the extra money on more cam, would be a lot less work and time now to put the large cam in, than to have to tear it apart due to detonation, and possibly more damage to the engine due to detonation.

Dynamic compression with the XE268H was like 8.3:1, but I have absolutely no idea how that value effects detonation. Nor am I sure if that value was calculated correctly, I had just learned about dynamic compression ratio and was curious as to what it would be. So take that value with a grain of salt.
 

·
Registered
Joined
·
368 Posts
393's are awesome strokers, you're going to love it.

What heads are you planning on running?

I run a bigger cam than you're looking at and have plenty of low end power. Rear gear plays a big role in driveability.
 

·
Registered
Joined
·
22 Posts
Discussion Starter #10
393's are awesome strokers, you're going to love it.

What heads are you planning on running?

I run a bigger cam than you're looking at and have plenty of low end power. Rear gear plays a big role in driveability.
Have a pair of BluePrint HP9009 aluminum heads I picked up a while back, 190cc, 2.02/1.60 valves. Some would say they're a tad small for a 393w, but they're what I have, and should work nicely.

What cam are you running? Custom grind or off the shelf?
 

·
Registered
Joined
·
368 Posts
The heads are a tad small, but I think you'll be ok. I'm running Windsor Sr's (200cc) and they seem to work fine. I thought I was getting a deal as I picked these up off of Craigslist, but after I went through them, replacing springs and several valves, getting a valve job. I was almost in them as much as a set of AFR's or TrickFlows would have cost. Then I still have to spend several hours with the die grinder cleaning up the ports/bowls.

Anyway, I'm running a Howards Retro Roller cam - Love it.

278/284 .533/.544 lift. Used stock ford roller lifter and spider. Nice lumpy idle. Has plenty of vacuum for the brakes.

I'm getting around 15mpg with the overdrive.
 

·
Registered
Joined
·
22 Posts
Discussion Starter #12
Dang, 15mpg is pretty good. I wish I knew someone that could teach me how to port match and clean up cylinder heads. There's plenty of youtube videos, but really need some junk heads to practice on. Some day lol, might lose a bit of power due to the 190cc heads, but those are easy enough to change in car, and I already have them. I questioned doing the factory spyder retrofit, but read a lot about failures due to big cams/mostly high rpm failures, but that's a risk I don't really want to take, although thanks to you, looks like Howard's Cams makes cams for such application. Hmmm....
 
1 - 12 of 12 Posts
Top