Engine guys i need your help
Thread Starter
Melting Slicks
Joined: Jul 2006
Posts: 2,373
Likes: 6
From: Baltimore MD
Engine guys i need your help
Guys ive been noticing a small drop in engine vaccum at idle,it reads about 8 on the gauge and it use to be about 15,but when i rev it up to about a 1000 rpms the vacuum goes up to about 20.Do i have a problem here?the engine does run good ,I did change to a bigger cam too ,would this have anything to do with it . Valves seem to be adjusted ,i know this can cause the problem.The engine starts right up and idles the way its suppose to.The vaccum drop just puzzles me.
Thread Starter
Melting Slicks
Joined: Jul 2006
Posts: 2,373
Likes: 6
From: Baltimore MD
The cam duration,maybe, but it seems to have lowered in vacuum during this cam. and the rings i thought about ,but why would vaccum go back up to normal when i rev it up a little , from, 700 to a little over a 1000 rpms,and if i remember correctly the vacuum gauge needle didnot jump around or fluctuate any,it stayed steady at low rpms and higher rpms.i think this means rings are ok .Also i put total seal rings in , but i know that doesnt mean anything if the rings didnt seat.
i dont know. any ideas ,im fishing here 
i dont know. any ideas ,im fishing here
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
The cam duration,maybe, but it seems to have lowered in vacuum during this cam. and the rings i thought about ,but why would vaccum go back up to normal when i rev it up a little , from, 700 to a little over a 1000 rpms,and if i remember correctly the vacuum gauge needle didnot jump around or fluctuate any,it stayed steady at low rpms and higher rpms.i think this means rings are ok .Also i put total seal rings in , but i know that doesnt mean anything if the rings didnt seat. i dont know. any ideas ,im fishing here
i dont know. any ideas ,im fishing here I'm sorry if it sounds like I'm being sarcastic, but could you clarify this statement? I have no idea what you are trying to say here.
Scott
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Scott
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Melting Slicks
Joined: Mar 2002
Posts: 2,164
Likes: 7
From: Beringen
The cam duration,maybe, but it seems to have lowered in vacuum during this cam. and the rings i thought about ,but why would vaccum go back up to normal when i rev it up a little , from, 700 to a little over a 1000 rpms,and if i remember correctly the vacuum gauge needle didnot jump around or fluctuate any,it stayed steady at low rpms and higher rpms.i think this means rings are ok .Also i put total seal rings in , but i know that doesnt mean anything if the rings didnt seat. i dont know. any ideas ,im fishing here
i dont know. any ideas ,im fishing here I had the same thing happening on a new motor of mine (see one of my threads about machineshops). Turned out that the block was not plate honed as was requested and the rings didn't seal anymore when warmed up. (maybe you should measure vacuumreading between being cold and warm for verification reasons). Anyway, the cullpritt was not only the rings not sealing, but either due to fuel washing off the oil or the oil getting burned off because of large blow by, caused the pistons to scuff. This was after only 20 minutes of initial break in.
BTW : i'm by no means an engine expert. However i do think you need to check some things. Some of those checks, like a compression test can be easily preformed by you. If necessary get you oil analysed. This doesn't cost much and prevents you from having to take your engine apart to check.
Last edited by Belgian1979vette; Sep 12, 2011 at 03:22 AM.
Thread Starter
Melting Slicks
Joined: Jul 2006
Posts: 2,373
Likes: 6
From: Baltimore MD
Thanks for the replys guys.The vaccum lose was with the new cam,it was alright at the beginning and as i drove it for a while i noticed the the vaccum was going down on idle,but when i rev it up to about 1000 rpms , in neutral the vaccum goes up to normal between 15 to 20. there are no vaccum leaks,everything is new,and timing is on.im kinda thinking it might be the rings not seating,i broke the engine in on a engine stand and i guess i should have done it on the road to put a load on it. 
The engine has alot of power to it 
But a blower will give any engine power.
The engine has alot of power to it But a blower will give any engine power.
Last edited by Billysvette; Sep 12, 2011 at 06:54 PM.
