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Discussion Starter #1
Ok y'all, I did my first post awhile back and am still battling an apparent lack of power, here's the rundown...

I swapped a 78 460 into my 86 bronco. 460 with a basic stock rebuild, other than an early 70s timing set (before they were retarded). I have a DUI distributor with 24*of mechanical advance, mild RV cam, Holley 3310 carb (dual inlet/vacuum secondaries/manual choke), weiand stealth intake, new plugs and wires, L&L headers, dual exhaust (all new). It is mated to a C6 out of an early 80s f250 (not rebuilt but checked out by a tranny shop). BW 1356 manual transfer case, 3.55 gears (my last post I had read the access code wrong) and 33x12.50 BFGs. So here's the problem...I don't feel like I'm getting the "get up and go" I should out of this setup. I just feel a general lack of power, and in 3rd gear I'm at 3k RPM at about 50 mph on flat ground. I've done basic tuning to the carb and I don't feel like my timing is dialed way back. Let me know what y'all think. Thanks.

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3k rpm at 50 sounds a bit high. My 4.10/33/C6 '92 Bronco (yes its been swapped was an E4OD) is @ 60 at 3k rpm.
I would make sure trans is good and also the torque convertor. A 2k stall convertor will wake this combo up a good bit too.
I have almost same combo in my 78, Performer Cam, Performer Intake, Stock Dizzy, 625 CFM Demon, LNL mid lengths, straight up timing set. It also has a C6 with 4.10 gears and 35's. I do not think its a race truck, however feel its about where it should be power wise. My timing goes a bit further though, I think 32 total.

Have you done a compression check or anything like that yet?
 

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Discussion Starter #3
3k rpm at 50 sounds a bit high. My 4.10/33/C6 '92 Bronco (yes its been swapped was an E4OD) is @ 60 at 3k rpm.
I would make sure trans is good and also the torque convertor. A 2k stall convertor will wake this combo up a good bit too.
I have almost same combo in my 78, Performer Cam, Performer Intake, Stock Dizzy, 625 CFM Demon, LNL mid lengths, straight up timing set. It also has a C6 with 4.10 gears and 35's. I do not think its a race truck, however feel its about where it should be power wise. My timing goes a bit further though, I think 32 total.

Have you done a compression check or anything like that yet?
Negative on the compression test

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1996 EB w/5.8 TOO much lift, 44" Mudders & 5:43-5:38's
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I'd skip base timing and make sure you get 36°-38° FULL ADVANCE and see what happens.
 

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Addicted to Junk
85 Bronco, 309ci I6 w/4bbl, np435, 4" lift, 37" Irok NDs, 4.56 w/ Detroit Locker and tru trac
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Is the DUI dizzy new? The advance plate pins are known to wear out. @AbandonedBronco had this issue with his.

My stock 96 f350 351w with stock c6, 33s, and 4.10s is at about 3000rpm at 70 mph.
 

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I have a 460 with a ZF5, NP205, 4:10 gearing. In 4th gear at 1500 she runs 40, in 5th it's 50. The ZF is so low geared that I don't really get to hit the power band on this before having to shift. I can hit 70 in 5th gear and still not be into 3500 where all the kick is. I still have to play with the timing a little. If I really want more with this setup I could change the cam.
Check out this chart. Punch in your setup and it will tell you speed/vs rpm's and tc lock. It will let you know if you're dialed in.

gearing chart
 

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Discussion Starter #7
That chart looks interesting, I'll take an in depth look here shortly. Did have a chance to play with timing today. Initial timing was at 8* haha so bumping it up definitely helped some on a short test drive! Going to play with it some more this week and into the weekend. As far as the dizzy, yep it was brand new about a year and a half ago. Thanks for the input fellas.

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Discussion Starter #8
I have a 460 with a ZF5, NP205, 4:10 gearing. In 4th gear at 1500 she runs 40, in 5th it's 50. The ZF is so low geared that I don't really get to hit the power band on this before having to shift. I can hit 70 in 5th gear and still not be into 3500 where all the kick is. I still have to play with the timing a little. If I really want more with this setup I could change the cam.
Check out this chart. Punch in your setup and it will tell you speed/vs rpm's and tc lock. It will let you know if you're dialed in.

gearing chart
So I plugged my numbers in. I'm definitely not at 79 mph at 3 Grand in third gear, which is what it says I should be at, I'm closer to 55. Anyone replaced their factory tach with aftermarket and noticed a big difference? I'm just assuming my tach is correct.

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Your tach could very well be correct. If your torque converter isn't locking, your RPMs will be much higher than what they should be. Does it feel like it's locking up? If you hit the gas while cruising, do the RPMs rise much faster than your speed?
 

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Discussion Starter #10
Your tach could very well be correct. If your torque converter isn't locking, your RPMs will be much higher than what they should be. Does it feel like it's locking up? If you hit the gas while cruising, do the RPMs rise much faster than your speed?
I have decent throttle response when I punch it when cruising. Don't C6s have non lock up converters?

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You are right about the lockup. Sorry, I was thinking about something else. However, torque converters do slip. If it is slipping excessively, that may be your problem.
 

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Discussion Starter #12
You are right about the lockup. Sorry, I was thinking about something else. However, torque converters do slip. If it is slipping excessively, that may be your problem.
This was my worry before and I took it to a tranny shop and asked that exact question and the guy said he couldn't find anything wrong. He drove it and checked everything out.

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Discussion Starter #13
I'm running a stock mechanical fuel pump, forgot to include that. You other guys with 460s doing anything like electric fuel pumps? Could that be an issue?

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You could use the brakes and throttle it up a bit to see if convertor is slipping. Not great test but easy...
I agree on the timing comments above, and that it likely could use more total timing. I am running mechanical pump with zero issues, though I did once have a supply issue due to a old cracked line sucking in air, this was very close to the connection at the tank.

Another easy thing to check is the vacuum at the modulator valve. Though this should not matter as much if you manually go threw the gears.
 

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Discussion Starter #15
I have checked vacuum, no leaks and the shop that checked everything out on the tranny got my shifts feeling as good as they've felt since I've had it.

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The way we used to check in the ol' days was to put your foot on the brake and put it in Neutral. Then shift it into Drive and see if you felt a "clunk" in the drivetrain. Shift to Neutral, then reverse and see if it clunked again. If it was smooth and you felt nothing, usually you had a bad converter.
 

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I'm not trying to be an A-hole but are you sure it's shifting into 3rd?

2nd gear with your gears and tire size might be close to 3000.
 

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Discussion Starter #18
I'm not trying to be an A-hole but are you sure it's shifting into 3rd?

2nd gear with your gears and tire size might be close to 3000.
I understand, and have questioned this myself. I'm 100% sure I'm getting into all 3 gears.

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If you manually shift, and you feel two clunks, you're getting your gears. On the timing, you have to remember, you have a big block, which does not rev as freely as a small block; even a 351W redlines at 5500, and a 302 redlines at 6000. It has a lot of mass to rotate. So, with the older-setting timing set, your base timing is 10* factory, your mechanical advance at 2500 should be between 18-22*, and your full advance at 2500 should be 38-42* once setting are made. Then road test and accelerate as hard as you can; any pinging/spark knock, you'll have to reduce timing or use higher octane fuel. I'm not familiar with DUI units, but I suspect it's just like HEI distributors, and to change mechanical timing, you change the weights; to change the vacuum advance, you change the vacuum unit.
 

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Discussion Starter #20
If you manually shift, and you feel two clunks, you're getting your gears. On the timing, you have to remember, you have a big block, which does not rev as freely as a small block; even a 351W redlines at 5500, and a 302 redlines at 6000. It has a lot of mass to rotate. So, with the older-setting timing set, your base timing is 10* factory, your mechanical advance at 2500 should be between 18-22*, and your full advance at 2500 should be 38-42* once setting are made. Then road test and accelerate as hard as you can; any pinging/spark knock, you'll have to reduce timing or use higher octane fuel. I'm not familiar with DUI units, but I suspect it's just like HEI distributors, and to change mechanical timing, you change the weights; to change the vacuum advance, you change the vacuum unit.
Great advice here. I have been tinkering some but I believe I have a bad or mismatched torque converter. Going to keep digging when I have the time and I'll report back what I find.

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