Vortec Test

[FreeBeeTony]

Not quite what I had in mind.........<br /><br />Slowly bought up the throttle, backfired through the carb and lost power. I backed off the throttle, seemed to idle ok. Tried again, same result. tried again and seemed to clear out. Thought maybe a clog in the carb?<br /><br />Was able to throttle up to ~3600RPM, seemed strong, then it almost made the same noise as the original problem except now at a higher RPM and an occasional backfire through the carb.<br /><br />I am going to take it out again and run the test I did at the end of last season to see if I am still loosing a cylinder.<br /><br />Hope the backfire indicates something else. I am also going to change the fuel filter.

 

[Don S]

Re: Vortec Test

See you guys, I'm headed for Iraq where it's safe.

 

[Bondo]

Re: Vortec Test

Book an extra room at the Bagdad Hilton,........ I'll meet ya There........ <br /><br />I want the 1 with the Big Red Target in the window...............

 

[FreeBeeTony]

Re: Vortec Test

This is nuF%$^&*(ing believable!!<br /><br />Now it looks like I am loosing #2 cylinder.<br /><br />I was afraid of a cracked block, but why would the problem move to the other bank? Last time it was #3 cylinder.<br /><br />What do you guys suggest now? Besides putiing a for sale sign on it.<br /><br />I am really at a loss here.<br /><br />Backfire is gone?<br /><br />I'm going to take some pills and take a nap.

 

[FreeBeeTony]

Re: Vortec Test

Are you guys giving up?

 

[Don S]

Re: Vortec Test

You have a thread on every part of your engine from last year when you were attempting to troubleshoot this problem. Before you found the real cause you pulled the engine to work on the heads, and cam and other feel good items. But you never found the root cause of your problem.<br />Search your old posts on the ignition, fuel, exhaust, and vacuum, drive ratio's and other problems associated with this project. All the questions were asked, and re-asked and answered several times. Somewhere in all that is your answer of what you actually checked and what you assumed to be correct. Now, you have to do it all over again and hopefully you find the problem.<br /><br />

 

[FreeBeeTony]

Re: Vortec Test

But it defintely seems like I am loosing a cylinder. <br /><br />When this miss appears and I short circuit the spark plug cylinder #2 I do not get a change in engine performance.<br /><br />New fuel pump and carb. Oil is clean and not over filled. Exhaust is not restricted. Vacuum varies between 19-20 at idle.<br /><br />I am really stumpted and feel like s^%t.

 

[rodbolt]

Re: Vortec Test

seems<br /> coulda<br /> woulda.<br /> maybe<br /> why dont ya buy the book I have posted about, read the thing and teach yourself ?<br />it aint hard.<br /> the motor is a suck,squeeze bang and blow. everything else bolted to it just helps make it go.<br /> your making this incredibly hard on yourself by your absolute refuasal to lean why the pistons move and what subsystems are involved in keeping them moving.

 

[FreeBeeTony]

Re: Vortec Test

rodbolt, I am not refusing to do anything......<br /><br />I think I have a pretty good basic understanding of the workings of an engine......<br /><br />What book are you talking about?<br /><br />Here is the latest:<br /><br />At the dock I checked the vacuum again, varies between 19-20 at idle.<br /><br />According to this site , it reacts normally when the throttle is opened and closed rapidly.<br /><br />However, if the throttle is opened and closed rapidly 3-4 times it starts to "sputter" out of the carb, fuel is acutally "spraying" out of the top of the carb and not being sucked in when in the open position. What would cause this?<br /><br />Please don't get frustrated with me. There is no one more frustrated than myself right now.

 

[KaGee]

Re: Vortec Test

I feel for ya Tony.

 

[lilmandavis]

Re: Vortec Test

timing gear a tooth off? did you tear the engine apart? is timing correct? valve leaking, floating? leak down test? sticky valve, bent pushrod? bad pickup? dwell? preignition?

 

[FreeBeeTony]

Re: Vortec Test

Replaced the heads and intake manifold.<br />Didn't disturb the cam or timing gears. Is there a way I can tell if I am off a tooth other than removing the cover?<br /><br />Timing is correct. Don't think the valves would be leaking as the heads are brand new. Checked all the push rods when I had the heads off.

 

[paulie0735]

Re: Vortec Test

Tony, perhaps its time to go back to your original problem, I know you have changed heads but what was it that made you think all this work was necessary, can you describe your original problem.

 

[John_S]

Re: Vortec Test

Tony,<br /><br />Not what I was expecting to find in your post <br /><br />At this point, I think everyone needs a refresher on what is new in your engine, what is not. Also, what has been done since it was buttoned up. What was checked last year, prior to the parts changes.

 

[FreeBeeTony]

Re: Vortec Test

OK.........<br /><br />At ~3200RPM the engine develops a miss (I originally descrdibed it as bogging down)<br /><br />I replaced the fuel pump, carb, ran it off a seperate tank, replaced the coil, cap, rotor, sensor and plugs and wires. Even tried a different ignition module.<br /><br />At the end of last season I discovered that I was loosing the #3 cylinder by shorting out each plug at the distributor when the miss occured.<br /><br />I removed the heads and it looked as though I was ingesting coolant in the #5 cylinder . Thought was either the head was cracked or I had a bad head gasket.<br /><br />Decided to replace the head with new vortec's.....and here I am. Except now I am loosing the #2 cylinder.

 

[lilmandavis]

Re: Vortec Test

hmmm. i tried to put vortec heads on a older style block in my buddies car a few months ago. i couldnt get it to wind out. beware of "new" stuff these days. any time i get something "new". i tear it apart and plastigauge, check for warpage, dissasemble the heads, check for valve shaft clearence, make sure and cut in the seats with three angles. in fact i have to go down to a boat i put a long block in and replace a "new" lifter. and in fact on that motor, there were two sticky valves and when i lapped the valves there were three that werent seating right... so much for new stuff... but i never got my buddies car to run right with the new vortec heads. anything over 3000 rpms and it just spat and sputtered. tried everything and ended up goin with regular style heads.

 

[lilmandavis]

Re: Vortec Test

im thinkin its the valves or cam what generation is the block? is it a vortec block? its more likley the valves. need to make sure that cylinder has spark do a compression check. do the leakdown. take the heads in to a private machine shop and pay to have a "good" valve job done. have them check for sticky valves. have them cut three angles on em. unless you have the tools.

 

[rodbolt]

Re: Vortec Test

ok, first you have to purchase some test eqiupment.<br /> you will need a fuel vacum/pressure guage, a timing light and a Kv tester. a DVA meter will be very handy as well.<br /> you will need the correct service manual(s) for the engine and subsystems being serviced.<br />the vortec heads flow more air,did you rejet the carb to compensate? its all about getting a 14/1 air fuel ratio into the combustion chamber and sealing the chamber and sparking it at the correct time. a water leak from the manifold/riser will create a backfire as well.<br />the book info.<br />motor <br /> auto engines and electrical systems 7th edition. <br /> its avalible used from amazon.<br />read it study it and be able to ansew the questions at the end of each chapter and you will amaze yourself, I have had my copy since 77.

 

[Bondo]

Re: Vortec Test

Are you guys giving up? <br />I am really stumpted and feel like s^%t. <br />I feel for ya Tony.<br />Tony,<br />Not what I was expecting to find in your post

I wouldn't Jump Ship on ya Tony,........<br />But,..... I Am as Baffled,+ Depressed as You are about this.........<br />Totally Out of Ideas at the moment.............

 

[Bt Doctur]

Re: Vortec Test

what are the compression readings on all cyl. taken with the carb wide open?<br />popping back thru the manifold sounds like a sticky/tuliped/ not seating intake valve.