Vacum advance or mechanical and vacum or mechanical secondaries? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

chevybill · 09-14-2005, 10:57 AM

Hey everybody,

I will soon be buying a distributor and carb for my 96 vortec motor.
I am considering going mechanical advance and mechanical secondaries for the dist and carb.

Please give opinions, good and bad, just want a very simple look with few rubber hoses as possible. Just after reliable, powerful daily use truck

Thanks

DTerry · 09-14-2005, 11:38 AM

You really don't give enough info here to recommend anything. What has been done to the bottom end and heads? Will you be running headers? Stock intake? What tranny?

That said, assuming a pretty stock engine with headers and auto, I probably go something like this:
- Pertronix distributor with a slow advance $150-$200.
- Holley 650 or so. Rule of thumb has always been machanical secondaries with a manual trans, vacuum with an auto. However, I don't think that's necessarily a good choice. Depends on variables above.

chevybill · 09-14-2005, 11:54 AM

Sorry about the lack of details,

If I can find headers, I will put them on. Engine is a stock 98 chevy tahoe and I am running my original 3 speed manual tranny. (truck was a 6cyl and 3 manual originally).

Going for simplicity and dependability.

About headers, I plan on running the engine in the 6cyl position, so I will need the smaller distributor cap set up. If I can't find headers that work I will use the stock manifolds.

Thanks for your response

motocrosschump · 09-14-2005, 11:58 AM

you will have to build a Pivot ball plate.

Not too hard tho.

chevybill · 09-14-2005, 12:58 PM

tell me more about this pivot ball plate, if you can.

neonlarry · 09-14-2005, 02:26 PM

If you want better fuel mileage go vacuum otherwise mechanical will work. Just make sure if you go mechanical you have the distributor curved(preferably on a dyno) for your truck\engine combo.

jimfulco · 09-15-2005, 01:50 AM

I'd say use vacuum advance if at all possible. It will make the engine run a little smoother at idle, and it will get better gas mileage.

Don't forget to get the melonized distributor gear so it will be compatible with the roller cam.

http://www.sdpc2000.com/catalog/924/...butor-Gear.htm

chevybill · 09-15-2005, 10:14 AM

thanks for that link, i will make sure i get the melonized gear for the distributor.

chevybill · 09-15-2005, 10:13 PM

how about some input about the carb- mechanical or vaccum secondaries?

09-14-2005, 10:57 AM	#1
chevybill Senior Member Join Date: Oct 2004 Location: calhoun city ms Posts: 940	Vacum advance or mechanical and vacum or mechanical secondaries? Hey everybody, I will soon be buying a distributor and carb for my 96 vortec motor. I am considering going mechanical advance and mechanical secondaries for the dist and carb. Please give opinions, good and bad, just want a very simple look with few rubber hoses as possible. Just after reliable, powerful daily use truck Thanks __________________ ongoing 1970 c 10 lwb 1994 z-28 few mods.-owned since new 1978 vette silver/grey 25th anniv. paint

09-14-2005, 11:38 AM	#2
DTerry '70 GMC C-25 LWB Join Date: Oct 2004 Location: Binghamton, N.Y. Posts: 273	You really don't give enough info here to recommend anything. What has been done to the bottom end and heads? Will you be running headers? Stock intake? What tranny? That said, assuming a pretty stock engine with headers and auto, I probably go something like this: - Pertronix distributor with a slow advance $150-$200. - Holley 650 or so. Rule of thumb has always been machanical secondaries with a manual trans, vacuum with an auto. However, I don't think that's necessarily a good choice. Depends on variables above. __________________ 1970 GMC C-25 LWB (middle of frame up) 5-7 drop with 3in drop spindles, flip kit with blocks and still keeping the 3/4 ton. Shaved drip rails and marker lights, rear roll pan, cowl induction hood. 1987 Camaro z28 350, vortec 305 heads. 10:1 comp, t5 trans. Street terrrorizer. 1988 Monte Carlo (Super Stock ashpalt race car) My Truck

09-14-2005, 11:54 AM	#3
chevybill Senior Member Join Date: Oct 2004 Location: calhoun city ms Posts: 940	Sorry about the lack of details, If I can find headers, I will put them on. Engine is a stock 98 chevy tahoe and I am running my original 3 speed manual tranny. (truck was a 6cyl and 3 manual originally). Going for simplicity and dependability. About headers, I plan on running the engine in the 6cyl position, so I will need the smaller distributor cap set up. If I can't find headers that work I will use the stock manifolds. Thanks for your response __________________ ongoing 1970 c 10 lwb 1994 z-28 few mods.-owned since new 1978 vette silver/grey 25th anniv. paint

09-14-2005, 11:58 AM	#4
motocrosschump Registered User Join Date: May 2005 Location: Texarkana, AR 71854 Posts: 397	you will have to build a Pivot ball plate. Not too hard tho. __________________ 2006 Titan SE Crew Cab Daily Driver 2005 Mazda Tribute (Wifes car) 1969 C10 SWB 350/3 Fleet "Max" 1969 Chevelle 2 door 350/3

09-14-2005, 12:58 PM	#5
chevybill Senior Member Join Date: Oct 2004 Location: calhoun city ms Posts: 940	tell me more about this pivot ball plate, if you can. __________________ ongoing 1970 c 10 lwb 1994 z-28 few mods.-owned since new 1978 vette silver/grey 25th anniv. paint

09-14-2005, 02:26 PM	#6
neonlarry Registered User Join Date: Feb 2002 Location: Vacaville, CA Posts: 2,745	If you want better fuel mileage go vacuum otherwise mechanical will work. Just make sure if you go mechanical you have the distributor curved(preferably on a dyno) for your truck\engine combo. __________________ 70 C/10 Light Red 350/TH350, HEI, Duals w/40 series Flows, 91 seat, LED taillights 99 Pontiac S/C GTP, SLP Ram Air hood, GMPP Konis & springs 95 Neon ACR, MP PCM, AFX UDP, 3.0 CAI

09-15-2005, 01:50 AM	#7
jimfulco Registered User Join Date: May 2003 Location: Shreveport LA Posts: 3,170	I'd say use vacuum advance if at all possible. It will make the engine run a little smoother at idle, and it will get better gas mileage. Don't forget to get the melonized distributor gear so it will be compatible with the roller cam. http://www.sdpc2000.com/catalog/924/...butor-Gear.htm Last edited by jimfulco; 09-15-2005 at 01:51 AM.

09-15-2005, 10:14 AM	#8
chevybill Senior Member Join Date: Oct 2004 Location: calhoun city ms Posts: 940	thanks for that link, i will make sure i get the melonized gear for the distributor. __________________ ongoing 1970 c 10 lwb 1994 z-28 few mods.-owned since new 1978 vette silver/grey 25th anniv. paint

09-15-2005, 10:13 PM	#9
chevybill Senior Member Join Date: Oct 2004 Location: calhoun city ms Posts: 940	how about some input about the carb- mechanical or vaccum secondaries? __________________ ongoing 1970 c 10 lwb 1994 z-28 few mods.-owned since new 1978 vette silver/grey 25th anniv. paint



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