more gas engine trouble.

[Jackman]

When you had the carb rebuilt did you set the float to the correct level? Maybe you have it set so that its not delivering enough fuel at the higher rpms? Maybe the float is one of the old type and saturated...thus giving too much fuel and boggin the engine down.

Just a thought..

 

[67hat34c]

Mike, we are re checking all the ignition. did not have spare cap and did not feel like pulling off of other motor. got frustrated and buttoned it back up and made other easy repairs. installed new faucet in head, it was true bolt off bolt on replacement and did not need to change a thing. note original faucet, 40yrs old. nothing is ever that easy.

Jackman, carb is most likely not an issue other than the slow speed air mixture adjustments. found all spark plugs dirty-dry black. except #5 and it was perfectly clean as if running way way too lean but that cant be possible with a carburated engine, no way to run one cyl too lean via carburator. also it is not running out of gas, doesnt speed up then die back.

i get 3900 on that motor and no more. no back fire,no misfire, no vibration, just wont do anymore.

could not find a cap even at speed shops, automotive Mallory YL cap has a hole in the side of it and no gasket so could not use it. so i just ordered one.

I doubt the cam shaft issue but who knows. i can tell you that i adjusted the valves 2 different times and i know for a fact that they were all working, just dont know if they were opening up the same amount.

If i left a rag in there, i would guess it would have been sucked into the valve by now and would have shown up on compression test not to mention the noise of the valve not closing all the way.

 

[Ross]

Have'nt seen any one suggest a vac test on the intake. There should be a pipe plug you can hook a vac guage and run the eng at idle.Guage should read stedy at idle and when you throttle up to about 2 grand.If it drops then you have a leak in the intake.If you got the intake gasket kit aftermarket they might be slightly differant.GM did many changes to heads and intakes hance engine mods like marc 1,2,3,4,5 and so on.Good luck

 

[Maynard Rupp]

The key here is that everything looks good except #5. Please swap the caps, it just isn't that hard to do. If the cap is OK and the plug is firing in the air, start the engine at night with no lights anywhere. look at the cap and wires while that engine is running to see if you see errant sparking. Next is to make sure that intake valve is opening. I presume you checked all the cylinder's compression. Did #5 come to the same value with the same # of cranks as the rest? Next remove that side's valve cover. Lay a ruler on top of all the rocker arm studs to make sure that none are pulling out. Simple fix if one is. I would sure suspect #5. Are the keepers on that valve spring's retainer? Is the rocker arm cracked or worn? Is the 1/2 ball below the rocker nut OK and not in upside down? Has the pushrod worn a hole in the rocker arm? Re-check the valve lash on #5. Remember these are not rocket engines!!!

 

[67hat34c]

Not that i have a trained eye but i inspected each and every part before installing. i cleaned each one individually, looked at wear surfaces and reinstalled.

I have video of this side of the engine running, on my cell phone, and all look good, of course it is on a 2" screen. Will go out at lunch today and get a usb cable to hook to the phone and computer and down load it. will e mail it to maynard

Intake gaskets are of course aftermarket, Felpro. they lined up perfectly, would suspect we would feel and hear a leak big enough to cause this problem also if it was sucking air from inside then would the plug not get oily?

I will however take some wd and spray along the gasket line and see what happens.

Hay maynard dont you need to come down and visit your boat this weekend?

 

[Jackman]

I don't think the aftermarket kits come with the blockoff plates for the exhaust crossover that runs underneath the carb. If this was not installed the exhaust may have burnt through the intake gasket causing a vacuum leak in one of the adjacent intake ports. Something to look into. Look at your intake and inspect for burnt paint near the choke area and opposite side of that.

 

[67hat34c]

kit did come with restrictor plate, i did not install this. metal plate with .5" hole in it. we have manifold choke so thought it needed the heat.