timing help needed - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**68350** · 01-08-2008, 03:28 PM

what is the timing supposed to be set at for a 1970 402? has hei. thanks

dave2953 · 01-08-2008, 04:39 PM

I think it's 4*, but hopefully someone else will chime in to confirm this.

**El Jay** · 01-08-2008, 04:41 PM

I'm sitting here w/ a "Chilton's" on my lap & it's not showing a '70 w/ HEI.
W/ a point distributor it's 8B.
Later models w/ an HEI, are shown as 2, 4, 8B, depending upon the engine
(400, 402, 427) & whether it was CA, or non-CA.

I dunno if I helped you or hurted you.

Maybe somebody else can do more better.

**VetteVet** · 01-08-2008, 08:27 PM

GM did not use HEI until late 74 and beginning in 1975 just about everything went to HEI
Time it to 1975 specs and you should be good.

**68350** · 01-08-2008, 08:36 PM

I knew it wasn't original, I was just adding that info cause I *think* it matters. The HEI was in it when I bought it, so I assumed it ran just fine. Please see my other post, that's what this question was a predecessor(sp?) to. thanks

**El Jay** · 01-08-2008, 09:04 PM

I just relooked @ the books.
4 B should work just fine.

You can always fine tune it from there.

**VetteVet** · 01-08-2008, 09:21 PM

check here for help.
http://www.lbfun.com/Corvette/Tech/v...20Problems.pdf

GMC Jim · 01-08-2008, 10:15 PM

Use the specs for the 1970 402 as outlined in GM shop manual. Time the distributor to the engine !!!... Change spark plug gap to .045 for better spark characteristics, Centrifugal and vacuum advance should be reset to the engine specs at the RPM's indicated by the GM manual. The proper timing ( both centrifugal and vacuum ) makes all the difference of performance and gas milege economy!!!

01-08-2008, 03:28 PM	#1
68350 Senior Member Join Date: Jan 2002 Location: Williston, ND Posts: 2,999	timing help needed what is the timing supposed to be set at for a 1970 402? has hei. thanks __________________ 68 Chevy CST/10, 50th Anniversary, 327/th400, 373 posi, buckets 68 GMC Shortbox Stepside, 402/th400, Tilt, Tach, Bucket Seats, 3.08 Positraction 69 Chevy Camaro SS, 383, 4 speed, positraction 70 Chevy El Camino SS396, Triple Black, 454/th400, Tach 70 Chevy Shortbox Stepside 4x4, 350/th350, Tilt, Tach, Cab Lights, Bumper Guards, Tow Hooks 70 Chevy 3/4 Longbox, 350/auto, 70k, SURVIVOR 71 Chevy Blazer, CST, 350/auto 71 GMC Sierra K2500, 454, 4 speed, 4.10 posi, 37s 71 Custom/30, Open Road, 350/th400, tilt 72 Chevy Shortbox Fleetside, 496 Stroker/th400, Tilt, Tach, Bucket Seats, 3.42 Posi 72 GMC Sierra Grande 2500. 427/th400, tilt, a/c, tool and stowage, buckets/console, 3.54 posi

01-08-2008, 04:39 PM	#2
dave2953 Dave's not here, man Join Date: Jun 2004 Location: Winder, Georgia Posts: 2,000	Re: timing help needed I think it's 4*, but hopefully someone else will chime in to confirm this. __________________ - 2014 VW Jetta - 2015 VW Jetta - 1966 Ford F-250

01-08-2008, 04:41 PM	#3
El Jay Gone to greener pastures Join Date: May 2007 Location: Gateway to the Delta Posts: 7,354	Re: timing help needed I'm sitting here w/ a "Chilton's" on my lap & it's not showing a '70 w/ HEI. W/ a point distributor it's 8B. Later models w/ an HEI, are shown as 2, 4, 8B, depending upon the engine (400, 402, 427) & whether it was CA, or non-CA. I dunno if I helped you or hurted you. Maybe somebody else can do more better.

01-08-2008, 08:27 PM	#4
VetteVet Msgt USAF Ret Join Date: Jan 2005 Location: Kalamazoo, Michigan Posts: 8,718	Re: timing help needed GM did not use HEI until late 74 and beginning in 1975 just about everything went to HEI Time it to 1975 specs and you should be good. __________________ VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative.

01-08-2008, 08:36 PM	#5
68350 Senior Member Join Date: Jan 2002 Location: Williston, ND Posts: 2,999	Re: timing help needed I knew it wasn't original, I was just adding that info cause I think it matters. The HEI was in it when I bought it, so I assumed it ran just fine. Please see my other post, that's what this question was a predecessor(sp?) to. thanks __________________ 68 Chevy CST/10, 50th Anniversary, 327/th400, 373 posi, buckets 68 GMC Shortbox Stepside, 402/th400, Tilt, Tach, Bucket Seats, 3.08 Positraction 69 Chevy Camaro SS, 383, 4 speed, positraction 70 Chevy El Camino SS396, Triple Black, 454/th400, Tach 70 Chevy Shortbox Stepside 4x4, 350/th350, Tilt, Tach, Cab Lights, Bumper Guards, Tow Hooks 70 Chevy 3/4 Longbox, 350/auto, 70k, SURVIVOR 71 Chevy Blazer, CST, 350/auto 71 GMC Sierra K2500, 454, 4 speed, 4.10 posi, 37s 71 Custom/30, Open Road, 350/th400, tilt 72 Chevy Shortbox Fleetside, 496 Stroker/th400, Tilt, Tach, Bucket Seats, 3.42 Posi 72 GMC Sierra Grande 2500. 427/th400, tilt, a/c, tool and stowage, buckets/console, 3.54 posi

01-08-2008, 09:04 PM	#6
El Jay Gone to greener pastures Join Date: May 2007 Location: Gateway to the Delta Posts: 7,354	Re: timing help needed I just relooked @ the books. 4 B should work just fine. You can always fine tune it from there.

01-08-2008, 09:21 PM	#7
VetteVet Msgt USAF Ret Join Date: Jan 2005 Location: Kalamazoo, Michigan Posts: 8,718	Re: timing help needed check here for help. http://www.lbfun.com/Corvette/Tech/v...20Problems.pdf __________________ VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative.

01-08-2008, 10:15 PM	#8
GMC Jim Senior Member Join Date: Dec 2002 Location: Portland, Oregon Posts: 901	Re: timing help needed Use the specs for the 1970 402 as outlined in GM shop manual. Time the distributor to the engine !!!... Change spark plug gap to .045 for better spark characteristics, Centrifugal and vacuum advance should be reset to the engine specs at the RPM's indicated by the GM manual. The proper timing ( both centrifugal and vacuum ) makes all the difference of performance and gas milege economy!!! __________________ '71 GMC;fleetside;PB/PS/AC/CC/402 Eng./Custom Paint/110,000act miles/3 fuel tanks(52gal).



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