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Another Stall Speed Thread...

idus25

Full Member
Joined
Oct 30, 2014
Messages
196
Loc.
St. Louis
Have the Edelbrock Performer RPM #2091 on my 302. 4:88 gears. Stock C4. Currently stock stall speed (1800ish). Bronco is not hardly what I thought it would be as far as performance. Grant it, FiTech could prob use some tuning. Edelbrock says I need no less than 2500 stall speed TC with that set-up.

Anyone tell me how that high of a stall speed will fare on the trails?
 

jckkys

Bronco Guru
Joined
Mar 15, 2012
Messages
5,196
The 1800 RPM stall speed torque converter was designed for a low RPM torque oriented engine. The Performer RPM intake is designed for high RPM. So it hurts the low (1800) RPM operation. Moving the power band up the RPM scale only works well with a long duration cam, high flow heads/exhaust, and different gears.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,835
Looking at your profile, 35" tires?

What bottom end did you bolt this kit on to? Stock dished pistons? Might be fighting a low compression ratio.

The powerband is published at 1500-6500, the 1800 should be good. Catching right at the start of the power.

What about the power are you not satisfied about? Adding more convertor will generally hurt low speed driving. The engine will be less connected at low speeds as the convertor slips more. Not going to change the top end any, a little above the stall speed it will still have the same power it has now.

What do you have for an ignition curve? Timing is easy and can do a lot. That can help a lot.

Can't really help if the compression ratio is down due to dished pistons. You are stuck with that until you redo the short block.
 
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idus25

idus25

Full Member
Joined
Oct 30, 2014
Messages
196
Loc.
St. Louis
Looking at your profile, 35" tires?

What bottom end did you bolt this kit on to? Stock dished pistons? Might be fighting a low compression ratio.

The powerband is published at 1500-6500, the 1800 should be good. Catching right at the start of the power.

What about the power are you not satisfied about? Adding more convertor will generally hurt low speed driving. The engine will be less connected at low speeds as the convertor slips more. Not going to change the top end any, a little above the stall speed it will still have the same power it has now.

What do you have for an ignition curve? Timing is easy and can do a lot. That can help a lot.

Can't really help if the compression ratio is down due to dished pistons. You are stuck with that until you redo the short block.

Thank you. I will work on the timing/tuning. Have it @ 13 initial and FiTech controlling from there. Maybe it is all it can be...Was just hoping for $2500 in engine parts, it would at least spin the tires. I have a lot to learn. Stock 1994 F150 short block referberd', no idea as to pistons.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,835
If the tires are fresh I wouldn't expect them to spin. Broncos tend to hook up pretty good.

Check if the balancer has slipped, or the wrong mix of damper and timing mark.

Another is double check you are at BTDC and not ATDC, that mistake has been made many times. Verify that the timing is actually advancing. What are you running for a distributor?
 

jckkys

Bronco Guru
Joined
Mar 15, 2012
Messages
5,196
Edelbrock may claim the intake runs at 1500 RPM, but it's very unlikely there's as good or better torque than the OE manifold below about 3000. They're great for graphs that start at 2500 RPM cause they don't do well at low RPM. The stock cam and heads won't ever get to 6500 RPM. It sounds like a recommendation by a 16 yr. old clerk in a speed shop.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,835
Edelbrock may claim the intake runs at 1500 RPM, but it's very unlikely there's as good or better torque than the OE manifold below about 3000. They're great for graphs that start at 2500 RPM cause they don't do well at low RPM. The stock cam and heads won't ever get to 6500 RPM. It sounds like a recommendation by a 16 yr. old clerk in a speed shop.

I will counter that slightly. The water brake dynos used don't have a dynamic range that can go that low. They only have so much of an RPM window. 2500 RPM is very low for a water brake that can also control loads upwards of 8000 RPM.
 
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idus25

idus25

Full Member
Joined
Oct 30, 2014
Messages
196
Loc.
St. Louis
If the tires are fresh I wouldn't expect them to spin. Broncos tend to hook up pretty good.

Check if the balancer has slipped, or the wrong mix of damper and timing mark.

Another is double check you are at BTDC and not ATDC, that mistake has been made many times. Verify that the timing is actually advancing. What are you running for a distributor?

Seasoned tires. Fresh rebuild of 302. MSD two wire (phaseable rotor), MSD 6 box.
 
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