# 350 Small Block Timing



## The1965Ghost (Feb 25, 2010)

My 350 has a cam installed to give it the loping idle and I'm having some real problems with timing. I've searched the stock factory timing and tried it to get closer but with that cam, it doesn't use the stock timing setting.
What settings can I try? Has anyone had experience timing with performance cams? I've read stock is 6 to 8 BTDC, and with a cam at 4. I do know that there might be different times for different cams. :sigh: Are there any other timing tricks to timing an engine? I've heard about a vacuum gauge trick. Any pointers? Any help is appreciated. :grin:


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## SABL (Jul 4, 2008)

Not recommended but I never used factory settings on any of my older SB Chevies. I always advanced the timing to the best idle when the engine was warmed up........then tried to restart and notice if the engine "kicked back". From that point I retarded the timing until the engine started smoothly with no kicking back. IMO factory specs (on the older SB's) are too conservative.....and I never lost an engine due to timing issues.


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## The1965Ghost (Feb 25, 2010)

I don't know exactly what you mean by kick back, but I notice that sometimes my engine will start right up at some timing setting, and others it'll take awhile and when cranking, its not a smooth continuous crank. I wish I could show you what I mean. It'll crank then kinda slow down or stop suddenly, then crank more. I could try your idea since I really do not have any other way of timing it. I'm having trouble.


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## SABL (Jul 4, 2008)

If it is a sudden violent type of stop that is working hard against the starter it may mean that the timing is too far advanced. The engine should turn smoothly with a fully charged battery. Keep the dist clamp bolt just tight enough so you can turn the dist by hand and only tighten it fully after timing has been accomplished. Going by memory, your dist will turn clockwise.....if your starter *suddenly* stops (even just briefly) it means the timing is too far advanced. Rotate the dist clockwise to retard the timing.....only in small increments (about 1/4"). Rev the engine and note the throttle response.....it should be rather "snappy". Shut it down and attempt another restart......if the starter suddenly stops again, repeat the process and retard the timing further. Repeat until the starter operates smoothly and the engine starts with little effort. Again, check throttle response.....it should never seem sluggish. 

Next is the load test........quick acceleration or holding the brake while giving the engine some gas. You should never hear "spiking" (pre-detonation) which will sound like the engine is rattling. That can be caused by the timing being too far advanced *or* octane deficiency. Octane requirements are determined by compression ratio and not timing.....bad timing can present the same symptoms but using too low of an octane will never be cured by any adjustments to engine timing and still have the engine run as it should.

Let's get down to what you have. What year engine and what is the compression ratio?? After thinking over what I have typed so far, and especially the preceding paragraph, if you have a high compression engine it will never start easily (after it reaches operating temperature) unless you are using the correct octane.


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## The1965Ghost (Feb 25, 2010)

SABL said:


> Let's get down to what you have. What year engine and what is the compression ratio?? After thinking over what I have typed so far, and especially the preceding paragraph, if you have a high compression engine it will never start easily (after it reaches operating temperature) unless you are using the correct octane.


Well, to start with now I know why it suddenly wants to stop briefly when cranking. I thought I had some kind of severe engine problem with something stopping it from turning or some sort. I'll go back out there and check it out again. At times it did crank smoothly and start right up! RIGHT up too. Maybe once I get it there again, I'll continue from there. I notice that my idle isn't steady either. I want to get it around 800 or so RPM. It seems to want to stall though. It only idles at around 1200 RPM. and anyway, when I check my RPMs, they vary. Its not steady. 1000 RPM to 1200 RPM ect. It's frustrating. I'm pretty new at it. I'll check what it does under load later. 

Now about the year... It's fairly unknown... but sure seems to be around the 72-75 or 78 range. Seems to be an earlier year. About the compression ratio, Uh, totally clueless. Maybe if I research the short style water pump 350s of the 70s could tell me anything? It's not that modified. Just the cam. And the intake manifold I put in and the conversion to the long water pump, changing the crank shaft pulley and everything.


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## The1965Ghost (Feb 25, 2010)

And at first start it refuses to idle. Only will idle after I gun the engine a bit. Frustrating. Must have to do with the choke system on my rochester


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## kjms1 (Jun 4, 2010)

depending on the cam the timing will have to be advanced more ... a spec sheet that came with the cam will tell you ... is it a RV cam or a towing cam or a racing cam

try abut 12 or 14 deg timing or hook up a vacuum gauge and move the timing till you get the best reading remember the bigger the cam the less vacuum the engine will produce ... when we installed a big cam we use to put offset timing pins (chevy) or offset key ways for the crank (ford) to help the performance & torque ... 2 4 or 6 deg ... but now they use multi index timing gear to achive the same results

this time of year the choke does very little check to see when you start it does the choke pull off open the butterfly a 1/4 in or so


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## The1965Ghost (Feb 25, 2010)

I'm not sure about the type of cam. It produces a good lope though, or it should. If I can get this engine to idle. The cam was purchased and installed years ago. I don't have a spec sheet or know what exactly the cam is. :sigh: I guess I'll experiment the timing. The choke seems disengaged, but I'm confused because it won't idle until I stomp on it a few times. I thought maybe it was some kind of choke adjustment screw that controls the choke idle, and maybe it was too low?


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