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Discussion Starter #1
Looking for peoples ideas on what is a safe number for final timing on a BBC, I'm currently running 20 static and have a final of 38/40 at around 4000/4500rpm. There is no noticeable detonation when driven on the street, but I'm concerned it may detonate when driven down the strip! Always interested in everyones ideas!

Cheers

Pinko351

PS, For those that may have read my post many weeks ago, about it bogging of the line. We fixed that by fitting a fuel regulator (fixed the ruff idle after the burn out) and to fix the bog of the line we inflated the slicks to reduce traction. I know this sounds strange but as many may have guessed the converter stall was too low, therefore the engine was bogging down as if was launching well below it's torque range. We have now fitted a 3500rpm stall and will be testing this at the strip tomorrow night.
 

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Hates: Liver. Loves: Diesel
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5,659 Posts
Safe final timing is very subjective. Total timing for best power usually occurs around 38*, but if you have a different combo it might affect it.

More specs?
 

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Discussion Starter #3
Engine specs

540ci
Holley 750DP
single plan weiland manifold
Alloy heads (brand ?)
scat crank/rods
roller solid cam with roller rockers
MSD6
10.5 compression
turbo 400 full manual
4.11 9inch mini spool

Currently running 600hp on the engine dyno

Not my car, but help out alot. Current best ET 12.3 and getting faster every meet. Looking for high 11s next run!!

Not really looking for a right or wrong number for final timing, just a feel for what people think or are running them selves.

Cheers
 

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Glad To Be Here
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2,240 Posts
Pinko351 said:
Looking for peoples ideas on what is a safe number for final timing on a BBC, I'm currently running 20 static and have a final of 38/40 at around 4000/4500rpm.
Your 38/40 Total Mechanical Timing (initial plus the built in distributor mechanical advance) is OK but you should be reaching that figure between 2500-3000 RPM and not get any higher as the RPM exceeds 3000. Do not exceed 40 degrees of mechanical timing. This does not include any increase that is accomplished by the vacuum advance.
 

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Hammer and a torch
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Might find on the track with the proper curve to make the timing come in to full advance at the 2500-3000rpm mark and a total timing of just 32-34 degrees that big inch BBC will pickup better on the top end... With more compression it would do so even with only 30-32 degrees and your headgaskets will live longer too... :thumbup:
 

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I run a total of 34*, all in by 2,500 RPM. I think my initial is about 15*. The total is more important. I would just worry about the total and let the initial fall as it may. All timing should be in at your crusing RPM, that may differ from mine depending on your set-up. (ie rear end, manifold, cam)
 

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Discussion Starter #7
update

thanks for all replies all good info.

A couple of things to note there is no vacuum advance and the cars primary use is for the strip. The dizy is currently running standard MSD specs which I believe are 20 degrees mech at 4000rpm which matches what the timing light was telling me.

We got to run it at the strip and found it came off the line a lot harder then in the past however it run out of fuel at the top of the track, only reving to 4000 RPM, we removed the fuel regulator but still only made power to 5000rpm. So I decided to back off the static timing to what we had run in the past. However as I have found in the past it is near impossible to adjust the timing when the car is hot. As a result I broke the dizy cap trying to move the dizy!

So we are now in the process of upgrading the fuel reg and up sizing fuel line from the tank. I also want to fit weaker springs in the dizy to bring the mechanical advance in earlier.

Cheers
Pinko
 
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