Where's the Timing Tab go? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Zonaman · 09-22-2005, 06:07 PM

With a little help form this board (Thanks!), I figured out that I have one of those post 1986 "Hencho en Mexico" crate 350's. Where's the timing tab supposed to be on the that, top or side?

Thanks.

matthufham · 09-22-2005, 06:23 PM

top, does made in mexico make a difference?

Zonaman · 09-22-2005, 06:28 PM

Quote:

Originally Posted by matthufham

top, does made in mexico make a difference?

From what I can gather, they had some quality issues early on when GM started down there. However, today they're supposed to be very good quality blocks. Somewhat thinner than older castings but supposed to be beefed up with a higher nickel content.

byrd · 09-22-2005, 07:38 PM

I've got one of the mexican blocks and the tab is on the side, but I thought the difference is long or short water pump. If you have a short pump, the tab has to be on the side as you coundn't see it from the top. My .02 Randy

Zonaman · 09-22-2005, 08:58 PM

I've got the long and I got mine on top. I timed it with a vacuum guage. Trouble is, when I hit it with the strobe it reads BTDC off the scale. Seems to run fine. A bit of knocking on hard excelleration. Premium gas seems to help. A little better since I figured out what the right spark plugs were.

Tx Firefighter · 09-22-2005, 10:11 PM

The crate engines come with two timing tabs. One is for the 6 and a whatever inch balancer and the other is for the 8 inch balancer. Use whichever is appropriate. Once you get the balancer installed, it will be obvious which tab is needed.

Zonaman · 09-22-2005, 10:35 PM

Thanks Tx, Now I remember , when I got the tab, hadn't figured out what year engine I had. I had a 6 3/4" balancer and I wound up with the tab at the 12 o'clock position as opposed to the 2 o'clock. Nevertheless, using a vacuum guage, the 0 mark on the balancer is way to the left- like 10 o'clock. Am I missing something here or was I right to go with the vacuum guage as the best way to set it ?

Tx Firefighter · 09-22-2005, 11:04 PM

Your balancer may have slipped if the engine runs properly, but the timing marks are wacky. The rubber gets old and allows the internal balancer hub to slip in relation to the outer ring.

byrd · 09-23-2005, 06:32 AM

I had the same problem, put a new harmonic balancer on and it fixed the timing issue. Randy

09-22-2005, 06:07 PM	#1
Zonaman Registered User Join Date: May 2004 Location: Chandler, AZ Posts: 519	Where's the Timing Tab go? With a little help form this board (Thanks!), I figured out that I have one of those post 1986 "Hencho en Mexico" crate 350's. Where's the timing tab supposed to be on the that, top or side? Thanks. __________________ 69 C-10 LWB, 350, 700r4, 3.73 posi-traction, front disc brakes. Built for the desert- She can take the heat! Vivat Rex Chevus!

09-22-2005, 08:58 PM	#5
Zonaman Registered User Join Date: May 2004 Location: Chandler, AZ Posts: 519	I've got the long and I got mine on top. I timed it with a vacuum guage. Trouble is, when I hit it with the strobe it reads BTDC off the scale. Seems to run fine. A bit of knocking on hard excelleration. Premium gas seems to help. A little better since I figured out what the right spark plugs were. __________________ 69 C-10 LWB, 350, 700r4, 3.73 posi-traction, front disc brakes. Built for the desert- She can take the heat! Vivat Rex Chevus! Last edited by Zonaman; 09-22-2005 at 10:37 PM.

09-22-2005, 10:11 PM	#6
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	The crate engines come with two timing tabs. One is for the 6 and a whatever inch balancer and the other is for the 8 inch balancer. Use whichever is appropriate. Once you get the balancer installed, it will be obvious which tab is needed. __________________ I'm on the Instagram- @Gearhead_Kevin

09-22-2005, 10:35 PM	#7
Zonaman Registered User Join Date: May 2004 Location: Chandler, AZ Posts: 519	Thanks Tx, Now I remember , when I got the tab, hadn't figured out what year engine I had. I had a 6 3/4" balancer and I wound up with the tab at the 12 o'clock position as opposed to the 2 o'clock. Nevertheless, using a vacuum guage, the 0 mark on the balancer is way to the left- like 10 o'clock. Am I missing something here or was I right to go with the vacuum guage as the best way to set it ? __________________ 69 C-10 LWB, 350, 700r4, 3.73 posi-traction, front disc brakes. Built for the desert- She can take the heat! Vivat Rex Chevus! Last edited by Zonaman; 09-22-2005 at 10:39 PM.

09-22-2005, 11:04 PM	#8
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	Your balancer may have slipped if the engine runs properly, but the timing marks are wacky. The rubber gets old and allows the internal balancer hub to slip in relation to the outer ring. __________________ I'm on the Instagram- @Gearhead_Kevin

09-22-2005, 06:23 PM	#2
matthufham Registered User Join Date: Feb 2005 Location: Carl Junction, Missouri Posts: 2,061	top, does made in mexico make a difference?

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