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Old 10-13-2010, 06:39 AM
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Symptoms after Heads Installed

I installed replacement heads on my 350 last night. They are rebuilt heads from a 327, double humps.

The engine starts but it idles high. My guess on this is that I need to make sure the dist is installed at TDC for pist #1 then adjust timing. I can even screw the carb idle screw out all the way and it doesn't reduce the idle.

I am also hearing a tapping sound around #2 cyl. I will recheck the last and make sure there is no slack on the rocker.

What else should I be looking at?
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Old 10-13-2010, 08:12 AM
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vacuum leak?
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Old 10-13-2010, 10:45 AM
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What carb do you have?

Did it do this before the swap?

How does the engine run? is it steady, not missing or anything?

How does she start up, buck the starter? do you need to give it lots of throttle to get it going or can you fire it up without depressing pedal?

Advancing timing will cause a higher idle rpm but turning the idle screw all the way out should still cause the engine to stop unless the carb is running on 2 much of the secondary circuit or the primaries are still open somehow.

Yes vacuum leak can increase idle speeds

What is the base timing set at?, TDC verification and the damper/pointer being in sync with TDC is important, double check it. Do you run a vacuum advance dist, are the dist mechanisms (weights, vacuum adv) working free and properly?

The base timing setting is dictated in part by the cam type, so if you are going to get the base timing set right then consider the cam as one of many determining factors for your BTDC number.

What cam is in there? are the heads/springs/lift/rockers setup for the cam?
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Old 10-13-2010, 12:29 PM
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Assuming that the other things mentioned are ok I would look at the bracket that holds the throttle linkage. Could it be holding the throttle open? Is it mounted in the same spot as before? Same intake? That would also explain why the idle screws have no effect.
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Old 10-13-2010, 12:31 PM
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http://www.crankshaftcoalition.com/w...al_vacuum_leak
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Old 10-13-2010, 12:38 PM
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What carb? Possible the secondary side is open, or vac leak, bound linkage, ect.......
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Old 10-13-2010, 01:48 PM
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The carb is a Holley 700 CFM.
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Old 10-13-2010, 01:58 PM
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I have never used the propane technique. Where can you purchase the small canisters with the nozzle?
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Old 10-13-2010, 04:25 PM
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Check at your local hardware, plumbing supply store, Home Depot, HomeBase, Harbor Freight, etc. Here are some online sources.....
http://www.brandsplace.com/0246-bnzul2317.html
http://www.technologylk.com/crl-prop...htm?src=nextag
http://www.toolup.com/bernzomatic_ul...torch-kit.aspx
http://compare.ebay.com/like/2004774...Types&var=sbar
http://compare.ebay.com/like/2804832...Types&var=sbar
http://compare.ebay.com/like/1404625...Types&var=sbar
http://compare.ebay.com/like/1604815...Types&var=sbar
http://compare.ebay.com/like/1704683...Types&var=sbar
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Old 10-13-2010, 05:45 PM
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Starting is hard. It sounds like timing advance with higher compression. Retarding does not seem to work well for it either. The throttle linkage looks good and unchanged. Idle is rough. The springs on the heads are the same as the ones I took off. Stock size of 1.25 with no shims. Max lift on XE CAM is .488. The heads I removed were rebuilt 305 heads, these are rebuilt 327 heads so the chamber is only slightly larger. It didn't have these issues before the change. Heads were torques correctly as was the manifold. Dist is a vacuum advance with new hose.

Valve lash was set by ringing tdc for #1, setting it, rotate 90, set #8, etc. The sound I here sounds like it is coming from #2 area.

My plan of attic is the following.
1. tdc for #1. Remove dist and rotate oil pump so that rotated will align to #1 when dropped in. Set dist to original marks before removal.Damper mark shoul be advanced of tdc marking.
2. Check valve lash again.
3. With engine running check for vacuum leaks with propane.

What do you think?
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Old 10-15-2010, 11:36 AM
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Yesterday I removed the dist and reset it and timing from scratch. It start great and runs. I hear a ticking sound but I think it is an exhaust leak so I picked up new gaskets. I still think there is a vacuum leak as well that I will find.
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Old 10-15-2010, 08:44 PM
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Tonight I advanced the timing a little more and the bog went away so I don't think it has a vac leak, I just had my initial timing too low.

The only thing left now is that ticking sound. I ran the engine with the valve cover off and it looks to me like it is one of the rockers making the noise. I set the lash again but the noise is still there.

The car is idling higher than I like still. Advancing the timing has everything running great. When I adjust the idle screw out it does not lower it any more but if I push the arm forward it idles it down. I think I need to put a vacuum gauge on the carb and adjust the odle mix screws to see where everything is.
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Old 10-15-2010, 09:00 PM
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Check to see if you can close the Secondary butterflies any. That's usually what keeps them from idling down further. Don't press on the linkage hard.

On Holleys I think you have to unbolt the Carb & adjust them from bottom or maybe a screwdriver with a 90* bend.
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