Proper stall converter- do I need a steeper stall?

[jc74868]

Running 2400. Wondering if 2800-3000 would wake up my engine and be better suited to my setup. This is a street truck. Mainly just for fun, but I don't want my driveability and highway cruising to suffer too much

I have a '78 SWB C10 (approximately 3500 lbs)

Running a new Blueprint 430HP/450 torque  roller cam/roller rocker, big valve 383, new 700R4 transmission (1 wire lockup, constant pressure valvebody) with an FTI 2400 stall (2400 is what was recommended by my engine manufacturer), 3.73 rear gears.

I am really not impressed with this engine.  Doesn't really have much better takeoff than I did with the previous mild 350 (650 Holley, Edelbrock Performer, headers)/stock converter in the stock 700R4 that I ditched. It ran great, lots of tire smoking power.

This current setup does run good, sounds good, but definitely not the tire roasting beast I was expecting from a hopped up 383 stroker. Slightly more oomph at take off, but not much.

 **on a slightly different note, I have also noticed my RPMs in 4th gear are way higher than previously. With the old 700R4 & a factory type lockup system in place, it seems like I was cruising at about 1500 RPM at 70mph. Now it's closer to 2500RPM at 70mph...I'm assuming this has something to do with the higher stall, different lockup system, possibly something to do with the constant pressure valve?** I can live with that. I really want a more bombastic takeoff though.

Below are the full specs on my engine, including cam specs. I have switched their Edelbrock 7101 Performer RPM intake to an Edelbrock 7501 RPM AirGap and their Holley 750cfm to an Edelbrock 800cfm AVS II and running long tube headers in to Flowmasters.


BP38313CTC1D
ROTATING ASSEMBLY:
New BluePrint Cast steel crankshaft
3.750" Stroke
OEM type 5.700" connecting rods w/ 150,000 psi bolts
Hypereutectic pistons
External Front/ External Rear
CYLINDER HEADS:
BluePrint Aluminum Cylinder Heads - H8002K
64cc chamber
2.02" intake/1.60" exhaust valves
195cc intake/75cc exhaust runners
CAM SPECS:
Cam Type: Roller
.528 Intake .536 Exhaust
221 Intake / 226 Exhaust duration
@.050 - 110 degree lobe separation

[Stewart G Griffin]

This is just my totally inexperienced and uneducated opinion:

The cam is not too wild for a 383 at all.   Thus, no, you don't need  a higher stall converter and in fact the one you have now might even be too high.  (even though blueprint engines knows a lot more than me....).


Do they have the hp/tq curves posted anywhere?

[jc74868]

https://cdn.shopify.com/s/files/1/2160/9839/products/BP38313CTC1D-dyno-chart_1903x.jpg?v=1580245640

[jc74868]

https://cdn.shopify.com/s/files/1/2160/9839/products/BP38313CTC1D-dyno-chart_1903x.jpg?v=1580245640

https://cdn.shopify.com/s/files/1/2160/9839/products/BP38313CTC1D-dyno-chart_1903x.jpg?v=1580245640

[jc74868]

This is just my totally inexperienced and uneducated opinion:

The cam is not too wild for a 383 at all.   Thus, no, you don't need  a higher stall converter and in fact the one you have now might even be too high.  (even though blueprint engines knows a lot more than me....).


Do they have the hp/tq curves posted anywhere?

Sorry for posting this multiple times. Was trying to reply to you, but posted incorrectly and can't delete it. Here's the link to their HP/TQ chart:
https://cdn.shopify.com/s/files/1/2160/9839/products/BP38313CTC1D-dyno-chart_1903x.jpg?v=1580245640

[Stewart G Griffin]

Does it idle ok in gear?

[jc74868]

I believe so.  Seems like about what I'm used to

[Stewart G Griffin]

You're sure you have 3.73?

[jc74868]

The original WAS 3.73, but a gear shattered and I changed out the entire differential years ago. I could swear that  I went with the same ratio. I'm pretty sure about that.  I'll  double check on that, because that would throw the entire equation off

[jc74868]

Well, you were on to something. I jacked up one side and check the ratio... I got barely over 3 driveshaft turns... It's somewhere in the 3.08-3.21 range. Definitely not the 3.73 I thought I was buying. I'm on the hunt for a 3.73 rear now and will double check before buying

The original WAS 3.73, but a gear shattered and I changed out the entire differential years ago. I could swear that  I went with the same ratio. I'm pretty sure about that.  I'll  double check on that, because that would throw the entire equation off

[Stewart G Griffin]

If you really want to roast 'em and since you have OD, we may want to consider 4:11 or even 4:56.    You should still have good rpms on the  highway.

[JohnnyPopper]

What size tires are you turning?

[FlatBlack77]

I wouldnt hesitate to go deep to at least 4:11s like Stewart said. It would really wake it up

[jc74868]

What size tires are you turning?

275 60 15

[jc74868]

I wouldnt hesitate to go deep to at least 4:11s like Stewart said. It would really wake it up

I just ran across a complete rear end with 4.10 gears. I really thought about it, but I've already thrown down on a new 3.73 ring and pinion I got a really good deal on. Got a new Yukon ring and pinion, pinion bearing, new seal and gasket for 130 bucks. Seemed like a good deal to me.  What I've got under it right now is an '85 or '86 10 bolt 3.08 that came out of a Suburban. I'd still like to go back with a 12 bolt C10 rear one of these days so it'd be closer to stock and maybe a little stronger