Magna Owners Of Texas

Public Forums => The Garage => Topic started by: Ingramml on November 02, 2012, 06:26:42 PM

Title: Vacuum pressure
Post by: Ingramml on November 02, 2012, 06:26:42 PM
I recently had my carbs synced and cleaned. The guy who did the works says I have a problem with my vacuum pressure. He says the normal level is 20 and I am at level 4. I am wondering what could cause that. I have to to the valve adjustment tonight and they may some of the problem but I have the feeling it is something else. Could there be a gasket problem somewhere?
Title: Re: Vacuum pressure
Post by: Ingramml on November 03, 2012, 08:12:26 PM
i will be tearing into my bike for the next couple of weeks. I plan to do a small video series to get some feed back from those who can help.
Title: Re: Vacuum pressure
Post by: ttooee on November 03, 2012, 08:27:34 PM
Check the rubber boots that connect the carbruators to the engine heads. Also check all the vacuum hoses and replace as required.
To check for vacuum leaks spray carburators cleaner to the area that you think the leak is while the engine is idling. If there is a vacuum leak the engine will smooth out for a few second. If the engine still runs rough then look for leak in another location.
Title: Re: Vacuum pressure
Post by: Ingramml on November 07, 2012, 08:56:28 PM
I have need to adjust my valves for a while. I was hoping to that would help a little. I opened the valve cover and noticed the adjustment screws were missing. I have done some reading and I believe that would be a oil burning and possible compression problem. Doe any one else have any comments about that.
Title: Re: Vacuum pressure
Post by: TLRam1 on November 08, 2012, 12:31:23 AM
That's a problem alright.

On the ones that I have manually adjusted there is a slot on the adjusting screw (I call the tappet) and a locking nut to tighten the whole mess down after adjustment. I am not familiar with the style you are working on, post up a photo of what is a proper fitted valve with the adjustment apparatus on top, maybe someone can help looking at both photos.
Title: Re: Vacuum pressure
Post by: Ingramml on November 08, 2012, 07:32:37 PM
I have added a picture of what the valves adjustment screws look like when they are seated. I don't believe there are adjusted correctly. I am going to remove my engine tonight. I assume the missing screw is in since the head some where.
Title: Re: Vacuum pressure
Post by: Jigger on November 09, 2012, 04:37:34 AM
What happened to the cam ? Those are some nasty gouges. I'm wondering if that missing adjustement screw came loose and got fragmented.
Title: Re: Vacuum pressure
Post by: Ingramml on November 09, 2012, 11:26:35 AM
I dont remember what it looked like before. That could have very well happened. I a going to remove the cylinder heads tonight to see if I can find that other adjustment screw.
Title: Re: Vacuum pressure
Post by: Ingramml on November 09, 2012, 08:52:27 PM
I have all but removed the head of my 1st and 2nd cylinder. I was hoping to find the adjustment screw in there. There is a good chance that it is in the crank case. I am wondering if anyone has any advice dealing with how worth it it will be to remove the engine and check the crank case or just replace the screw and move on? I am unsure what the screws are made of so I don't know about internal damage. I also would like to know if I can do a compression test with out the valve covers on? My valves being so far out of spec have been the majority of the problem.
Title: Re: Vacuum pressure
Post by: TLRam1 on November 09, 2012, 09:18:02 PM
Okay, that looks like it should and familiar, other than your cam looks like it seized up or has been mentioned is that the lost screw.

Do your other cams look the same as this one?

Would I look for the screw in the crankcase, if I knew that was not the screw on the cam, for me yes. But I would try diligently to get it out of the oil drain hole first.

If that is not the screw on the cam and it did run hot or w/o oil taking apart the bottom end in inevitable. 
Title: Re: Vacuum pressure
Post by: Ingramml on November 10, 2012, 10:55:28 AM
I found my other adjust screw. I had to take apart my entire cam to find it. I found the nut stuck by one of the valves. I think it was stopping my first cylinder valve form closing which would give me some compression problems. I am going to fit it all together and compression test the thing.
Title: Re: Vacuum pressure
Post by: TLRam1 on November 11, 2012, 12:42:42 AM
Keep us updated so we can see your progress.
Title: Re: Vacuum pressure
Post by: Greg Cothern on November 11, 2012, 01:06:44 PM
3rd gen Magna's DO NOT have adjustable "rockers" as you would think from older designs.  They have a shim under bucket design, meaning to adjust you put a different thickness shim under the bucket to raise or lower etc.
With that said, I have seen many folks, against my recommendations, spend big money to have them checked, and only seen one or two that were "adjusted" and truth be told, so minor you will/would never see a difference in fuel economy or power etc........
If its running good, gets good fuel economy on avarage, then leave it alone!  Spend you time and money on something that counts.