I've build a bunch of sbc in the past, but on this last one, I decided not to build my own and bought a new vanilla GM Goodwrench SBC 350 Crate engine. Bought a new replacement balancer for it also. Got it all installed. Ran it through its break-in period and wanted to start tuning afterward. Started like I always do with a Vacuum gauge at operating temp. Has good steady vacuum in the 20" range. But for giggles, I hooked up my timing light. Expected to see the slash on the balancer around 12deg give or take. But when the dial was zeroed I saw no slash. In fact it wasn't until I turned the dial to just past 60deg when the slash came into the 0deg range on the timing tab. Thought my timing light must be bad, so I tried another one. Same thing. I have heard of, but never seen when a balancer separates and the outside gets clocked differently, but this is a brand new one and when inspected it didn't look like there had been and separation in the rubber between them. Also the only load on the pulleys is the alternator and water pump. So I would find it hard to believe that this is the case. I have never seen an SBC do this before, wondering if anybody else has. Am I missing something that I've never seen in other sbcs? It's not that big of a deal since it seems to be running good, could be better if I could get this edelbrock carb tuned out right (I'm a holley guy). Just very weird. The other thing that I am not used to is the incredibly high oil pressure these new crate engines have. Mine is at 60psi at idle. It worries a fella, but in talking with others, I have heard that this is somewhat normal for these crate engines. I just hope my rear main seal stays together.
what did you buy for harmonic balancer? i wonder if you got one for a timing pointer behind the water pump. where is your pointer? take the center retaining bolt out , then feel for the keyway groove....approximately how many degrees away is the mark on the outer ring?
I will check the 12 position. Makes sense it would be there since the tab is the older style located below and outside of the water pump passage on the driver's side (early style). Between 12 o'clock and the tab should be pretty close to 60deg. What SBCs had the under the pump tab? I haven't come across any, all I have ever had is the driver's side tab style. The balancer was a CL purchase with very little detail. Thanks.
I have to recheck it. When I first fired it off I set the slash at 0 and when I fired it off I thought to myself "man I have sure had to turn this dizzy quite a bit to get it fired", at that point I ignored it and went to my vaccuum gauge. So I am guessing it probably is not at TDC.
Check your #1 TDC and see where your balancer is. You can get timing tape to mark it according to your pointer. There were 2 rather involved discussions going on about timing a SBC before the new HAMB came online. Try a search.
sounds like a mismatched balancer and timing cover. Best bet would be to use a through the #1 spark plug hole piston stop to find true TDC then see where the mark on the balancer ends up
1987-on, and a lot of late crate stuff have the tab at 12-o'clock. Balancers from than era will fit fine, but time straight-up.
yep. Just checked. Slash on balancer is showing up at 12 o'clock. Must be mismatched tab and balancer. Guess that explains that. I don't normally use the the tab much anyway. I normally tune by ear and vacuum gauge, so I'm not gonna worry about it. But good to know since I have never come across it myself before. Makes sense since I usually only use pre-1986 SBCs.Thanks for the replies.
Mismatched tab and balancer happened on my early 283 build. A check with the dial indicator to get true TDC showed the marks to be 10 degrees off. Filled to wrong mark on the balancer and cut a new mark in the right spot.
^Yep. I've been through this too. It took me a while to figure out. Like you, I had never heard of a SBC balancer with the marks at 12:00, until then. I remarked the balancer and all is well.
The top paragraph here explains it: http://static.speedwaymotors.com/pdf/PPDamperNotes.pdf SBF's also have 3 different timing mark locations.Professional Products was proactive and made their balancers with all 3 sets of marks on both SBC's and SBF's.
its not just the sbc's either the BBC gen 5/6 motors they moved the tabs to get around the cast ancillery supports , they have 2 marks one on top drivers side and one on the drivers side down under by the ps pump
Had the same thing happen to me on the BBC I stuffed in my Falcon. Had an ugly balancer, so I got a replacement and put it on before installing the new engine. Did a TDC check, and the mark was way off! Not knowing what was wrong, I pulled it back off and double checked everything. Everything looked perfect, so I reinstalled the balancer and put a stick on timing tape on the balancer at corrected TDC. Later I found out about the various balancer used on BBC engines, which answered my question.
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