CJS

Putting stock WCFB dual quads back on a stock 283 220 hp engine. The best, most admired carb man on this board told me to get a dual point none-vacuum adv. distributor like it came with factory stock. Or a modern Mallory, Crane, Petronix non-vacuum distributor would work also.

He said the vacuum advance is just too slow to react and the engine will have poor throttle response or even a bog with the vacuum advance.

Could someone explain this to me? I am currently running 14 deg. initial (vac. disconnected), with 15 more centrifugal in by 3000rpm ( I know I need to recurve it to get this in sooner!), and also 22 vacuum on top of this, for 51 total at cruise.

How will non-vacuum advance or dual points help this with the 2x4's?

Coves4me

Your comments confuse me, also. My experience of 40 years working on carbed cars tells me that the introduction of a vacuum advance distributor will improve driveability, increase gas mileage and allow the engine to run cooler. All of my experiences with non-vacuum advance cars have been with highly-modified engines that were never meant to run at normal in-town speeds or conditions.

I have a 283, 245-HP car withn 2 WCFB's and I'm planning on running a more contemporary single-point vacuum advance distributor rather than the dual point non-vac set-up. Perhaps the gentleman you refer to will chime in with supporting facts in favor of the use of the original distributor.

L78racer

chris, i have run it both ways. both ran very well no complaints.
as Coves4me states, i've gotten better fuel economy and it runs cooler with the vacuum advance.
i have mine connected to manifold vacuum off the rear carb. i use an Accel adjustable can i got from Summit.
my current distributor has a Crane electronic conversion from Summit. it has the built in adjustable rev limiter. curve kit also.
i run 36-38 deg total advance without the can hooked up. i have around 6-8 deg dialed into the can.
motor is a .060 283 with a Lunati "097 version" camshaft. 4spd. 4.11 gear
i've drag raced it alot (13.50 @ 102mph on street tires). and it's street driven alot too.
my dual point had a Pertronix kit. same spark curve. worked great too.
driveability was good with either setup.
paul

plaidside

I have been running your same setup for about two years. I first put the correct dual point unit in and it ran fine. Then I installed a single point distributor with a vacuum advance and the idle became smoother and it helped with cooling.
I would never change back.
I hid the vac can under the shielding so at first glance it looks stock.

L78racer

nice job. looks good.

JohnZ

Plaidside has an excellent setup - that's what I'd recommend; anyone who tells you vacuum advance isn't necessary simply doesn't understand ignition systems or spark timing. The only reason the 1x4's had vacuum advance in those days and the 2x4's didn't was that the advance can wouldn't fit behind the rear carb and under the upper ignition shield. The 891-style dual-point non-vacuum advance bowl-type distributors disappeared when 2x4's did.

devildog

I ran my 283/270 2x4WCFBs with factory dual point ignition (mechanical advance) for 37 years. last year I put in the little Petronix plate and electronic modual in the distributor body.

Looks original and took about 20 minutes.

I runs a liitle better and avoid adjusting those dual points to +/- 1 @33 degree.

It was Petronix part 1183.

I set at advance 15 degree and it is FAST response upto 35-38 degrees.

65ZR1

I have a 283 using the duntov cam and a 245 hp dual quad setup. I ran the original dual point distributor then changed it to an MSD unit with vacuum advance. I would never go back. The car is much smoother, gets better mileage and does run cooler. I also found since you can unscrew the idle speed screw ( the vacuum advance raises the idle rpm) the care doesnt "load" up as much. Initial timing for me is 14 degrees.

Plasticman

Running a 355 CID SBC with dual Carter AFBs (500 CFM each) on an Offenhauser intake. Initially had a dual point dist. with points and no vac. Changed over to a tuned single point dist. with an adjustable vac. can (Crane). Since I have a Sun Machine, I can dial my dist. in perfectly. The current single set of points do not float way on up past my redline, and I would also never go back. The better idle quality and cooler running are attributes that I know are real (with the vac. can). Bog / poor throttle response are unknown to this engine!

I do not understand your "expert's" comments concerning throttle response with a vac. can. A vac. can is a pretty quick responding device! I have never seen a bog caused by a vac. can.

Plasticman

DZAUTO

I have a SB400 with a modified FI unit in my 56. For many years, I ran a 62, non-vac FI dist and just never was quite satisfied with street performance. A few years ago I installed a 65 FI dist with vac advance. It turned the engine into a totally different machine on the street.

JohnZ

Just another "mechanic" who doesn't understand what vacuum advance is, how it works, what it does (and doesn't do), or why it's necessary; he needs to read my "Timing 101" paper . "Bog" has absolutely nothing to do with vacuum advance - it's a carb tuning issue.

CJS

Thank you Gentlemen! It will be the vacuum advance for me. It is a 57 Belair with the 2x4 added to a single 4 bbl. engine, so it not a show car anymore! I just like it to look mainly period and run great. I drive it everyday in good weather.