tuning woes

[D575]

That should probably be stickied, great write up.

 

[moparbob498]

Engines I've built in the past I adjusted the spring tension in the vacum dashpot to work with what the engine idle vacum was making and it seemed to work pretty well for me.. after you get your initial base timing set (no vacum hooked up) and then plug vacum to it I've seen @ 52* timing until throttle is. Raised & it backed down to 32* - manifold vacum dropped & mechanical. Is in. Took a lot of reading and hands on tinkering to get it to what the engine wants & responds well to....I even used the EGR valve to get more timing & better performance + a couple more mpg's with todays sucky gas..my dad runs the 590. Ran the 654 mini express in my coronet (was a daily driver) but I just used my mechanical advance with that set up...does anyone remember the emission dual pick up. Distributors? If your crafty you can run that set up...with the flip of a switch you power of the one pick up & power other pick up..I think it retards the timing 4* or 6* degrees...its been years since I ran that set up..you also need to use the shaft & weights from a mech. Adv type dist as the dual pick up is a emission style dist. Sorry for goin off topic a bit just thought i'd throw some hopefully useful info out there...personally I still like my OLD Mallory dual point dizzy with mech. Adv.(car ran 10.80's with it as well as my MSD. Dizzy)

 

[moparbob75]

ok so let me clear this up just a bit, edelbrock says most advance runs on ported vacuum, (most to them dont include mopars) i have my dist hooked up to the passenger side (ported vacuum) and it runs like crap when i hammer on it, so i need to run the drivers side manifold vaccum?

 

[moparbob498]

Yes...you want ported manifold vacum hooked to your vacum adv. You should also use a vacum gauge to see what vacum your engine is making at idle..& then use one of those hand pump vacum jobbies to see how much vacum it takes to activate your vacum pod (on your dist) and if need be you can adjust the tension in your vac pod (small allen wrench) to meet your engines idle vacum ..it would be. Dead on then..good luck & tinker with it as your performance & mpg's will go up .. that's a plus in my book

 

[coloradodave]

The reason Edelbrock says to use 'ported vacuum' is because their products are usually going on newer cars with smog control and emissions standards that have to be met. Our cars, at least the pre-smog ones, use 'full manifold vacuum'.

 

[Elvad]

Timing your Big Block comes down to one major point, accuracy. The first thing you need to do is verify TDC. These old dampeners have a 40+ year old dried out old rubber ring that breaks and slips, moving the factory timing marks to unusable locations and you guys are trying to use them...We have told you guys over an over again to verify TDC with a positive stop indicator and/or a dial indicator and yet you still wonder why you can't time your engine correctly....Todays gas SUCKS. Timing is more critical than ever with this useless fuel. You need to go back to the basics of engine building. You can build an engine that screams on this crap they call gas today, you just need to read the directions... ... ...!