BTDC Changes
Junior User
Joined: Jun 2000
Posts: 73
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BTDC Changes
the stock btcu for my truck is 3 degrees. now i have been advised to bump it up to 8. my question is what the difference would be in this change? i have an 400 cui '80 f-150 4x4 ranger explorer. it's getting around 8 mpg and is slow to accelerate but has great power. will this change increase mpg or decrease power. please give me your input and suggestions. thanks.
Posting Guru
Joined: Jun 1999
Posts: 1,100
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From: Durham
BTDC Changes
Wow, I wasn't aware that any of the older V-8s had a recommended 3 degrees BTDC. I've got an '82 351W and I run my around 6-8 when towing (better torque, less HP) and then bump it to about 12 for normal street driving (better HP and gas mileage). Most of the small block V-8s are recommended to run at around 10 BTDC. For max hp, keep advancing your timing until it just starts to ping under load (acceleration) then back off 1-2 degrees. You should end up in the 12-15 BTDC range and that will give you max HP, max performance, and max mileage.
'82 F150 2WD w/351W (orig 300 I6)
Slik
'82 F150 2WD w/351W (orig 300 I6)
Slik
New User
Joined: Jul 2001
Posts: 13
Likes: 0
BTDC Changes
I have to agree with slikness about 10 BTDC as standard. One other caution... your harmonic balancer may have shifted, yes it does happen. The only way to be sure is a diagnostic scope. Once the correct time is set with diagnostic analyzer, you can mark your balancer to keep it there. I have run across this more than once.
