The more you break them in, the better they work.
Soon I'll be able to set the total timing, then, I can go downtown and Charm Some Snakes!!

By the way what kind of timing values are you guys running? Are you around 6-7 degrees?

 

base timing meens NOTHING if your talkin about a carbed car.

It all depends on the capacity of the vac can in your distributor. You want to be at 38* total timing WOT, even if that means your base timing is low... anything over 38* will not help you.

The ideal situation is to get a fully adjustable vac can like mine (made by Crane). You also need to get a curve kit consisting of weights with more travel and some lighter springs.

This way you can custom taylor your ignition curve.


You want to be in the 12 to 20* base timing range, and have the mechanical and vacuum account for the rest to give you a total of 38*. If you have a stock can, setting your base at 20* will put you WAY over the edge... Some of the hardcores disable vacuum advance entirely. This is not recommended nor is it necessary.

 

we got a trick kit full of various springs and that for the carb, and one for the distributor. I know that with a manual tranny I shouldn't be running a vac sec. carb anyways, but thats what i got. my secondaries, even with the lightest spring don't open till pretty late, like 5000-5500rpm.

Paul gave me a vacuum reserve canister, but I don't think that'll help my carb, just my brakes.

 

Woah... you're gettin your shizzles mixed up with your nizzles....

What kind of carb are you talking about?

With a Q-bog the secondaries are adjusted by a set screw... no need for springs.

What you need is an adjustable vacuum advance canister. You put lighter springs in your distributor to get the mechanical advance to come in sooner.

You are also going to need a timing light and a tape to degree the damper. Put the light on, and WOT the engine. Turn the distributor until you get 38* total.

Forget about screwing around with base timing... and listening for ping. The ping and crank back is a total amature method of setting timing... Not suitable for racing.

 

be careful playing with that set screw on the q-jets.......

i know all about how easy that little spring breaks...jason knows what i am talking about

 

It's a Holley 750 VacSec.
I have no idea about timing, the vaccumm or the rest of that stuff, my old man and the guy that set up my engine is taking car of that stuff.

So I wouldn't know the difference between shizzles or nizzles.

 

lol that's for real... If you hear a click while you're turning it.... just get a new carb it'll be easier

 

Tell them you want 38* total advance. This is important.

 

Cool! Thanks.

I think I'll put the rest of the remaining clicks on tomorrow. Then get him to do it sometime after he's done work this week.

 

I always thought vacuum advance came in over mechanical advance, which is what is controlled by the base timing + advance timing available from the slots on the arms inside the distributor (sorry for lack of technical terms). All the spring and weight kits do is alter the rate at which the timing starts in the rpm range, and when full timing is reached. To increase total timing, you must either alter base timing, or grind out the slots that limit the 'swing' travel the advance weights. Some motors might not be able to handle 12 degrees initial, so to get 38 total, opening up the slots would be the only way to get that much.

Vacuum advance is only used at part throttle, since there is little vacuum at WOT. An adjustable can will work (I had one on my 85) if you have problems with pinging under light throttle situations. I had problems with my car on really hot days, or when under heavy load (going up hill). I got the adjustable can and reduced the amount of timing the vacuum added (I think 16-18 degrees is stock), and it worked very well.

 

Sorry this is a little late but KEVIN you are absolutely right.

CRUZN BRUZR vac secondary carbs are much more streetable, easier to set up & much better on gas. I run a 770 Street Avenger vac secondary on my Z. I also have a 750 double pump 4150 that i took off to run my vac secondary.

Timing is very important, escpecially total timing as Jay explained. Generally you'd like to be between 34-38 deg. The higher the total, the more likely you'll be prone to pinging.

Personally, IMO of course, i wouldnt let your engine builder rotate my tire after all the BS & stupidity he has put you through.

Now a vacuum canister (adjustable) is worth the $40 it costs. It enables you to have a smoother & quicker response at part throttle, as well as increases fuel mileage dramatically. Vacuum advance although, does not have anything to do with total timing. It is only existant under part throttle/higher vacuum conditions.

The weights/springs do control your advance curve & at which particular RPM your total advance comes on. Being a stick car, you could prob get away with 2800 & maybe 2600 rpm total if you have some steep gears. But i would keep it for 2800-3000. The center peice in the distributor in which the weights fall on controls your total advance. You can grind this to achieve more/less advance.

Anyways Dave i told you when you want to get that car going, dont hesitate to call. You'll see a very big improvement with maybe 1/2 hrs of tuning.

Good Luck & "keep it tight eh!"

 

Listen to da man!

 

Not to be disagreeable- but the term 'total timing' has been confused.

For some unknown reason- most manufacturers have referred to 'total timing' as being initial+mechanical- not initial+mechanical+vacuum (many drag-only cars do NOT use a vacuum advance system as it can be disrupted/inconsistent too easily).

TOTAL timing- initial+mechanical+vacuum should be in the range of 46-52 degrees on a typical 350.

Just to give people an idea of 'proof' (using stock parts): initial- 8*, mechanical will add anywhere from 16-22 degrees depending on weights/springs, vacuum an additional 18-24 degrees depending on can installed.

Now add up the minimum and maximum ranges with initial staying at 8*: 8+16+18=42*, 8+22+24=54*- these numbers are Total timing as you and I would think about it. TOTAL timing of 34-38 degrees would be far far far too retarded to work correctly.

 

ERIC2NDGEN,

At WOT there is no vacuum. Therefore "vac advance" doesnt exist.

Yes, cruise timing with a vac advance can can be upwards of 45 degrees.

Total timing @ WOT is not the same because the vacuum advance is bypassed(due to 0 vacuum = 0 advance) and the centrifical/mechanical takes over.

This is why you set your total timing between 34-38 with the vac can disconnected.

 

Yes- that makes sense (maybe I should have though about it for a bit longer).

I just wanted to be sure that no one was confused with the wording of 'total' in the example.

Call me slow- but if someone says 'total' I would tend to think 'total' from the point of view when all mechanical is in and vacuum adv. is at maximum (i.e. stabilized) once mechanical is in.