Vortec Test

[John_S]

Re: Vortec Test

Tony,<br /><br />Was the cam checked to make sure none of the lobes have worn? I have seen a few posts were this has been an issue, especially for flat style hyd lifters. (not sure what you have) I believe the lobes are one of the main areas to be concerned with, on dry start-up. I pulled the distributer, to use a drill to pump oil through motor, prior to first start in a year and a half. Not sure if a bad lifter, would cause this issue, as well. The cam/lifters might be the next major thing to check, after the compression/leakdown test.<br /><br />As far as the advance timing, you might have an issue with that with the vortec heads, but it would not have been the same issue prior to install. Being a 350 mag, you probably have a V8-24S advance curve. It brings in 24 degrees of advance, at a rather aggressive profile. The V8-22A has 22 degrees of advance, at a much less agressive profile. You could try retarding the initial advance, a few degrees, to try to elliminate it from causing the high rpm miss, but I doubt this is causing that much of an impact. <br /><br />I believe you went with an Edelbrock 1409, which according to many posts, should be relatively close in its tuning for your engine. ie, outside of idle mixture, idle speed adjustment, and choke, which should have been set during install. Most likely, if the jetting and rods need adjustment, it is because the out of the box settings are slightly rich, ie black plugs. Both the advance tweeking and the carb final tuning adjustments need to be done, but the "real" offending issue needs to found first. <br /><br />Need any more opinions? Anyway, we all have one, if not more. I hope this can get resolved this month, before the NY boating season, gets into full swing. Your iBoats friends are pulling for ya.

 

[paulie0735]

Re: Vortec Test

Tony, (everybody) if the engine starts at the turn of the key and will idle nicely and the engine will rev out ok when there is not load on it than i think at this point its fair to say that the cam lobes are fine, the valves are not sticking. if an engine starts to drop a cylinder under load than I’m back to electric’s. Do you have access to a decent timing light? if so I would like to know what the distributor is doing when the miss develops. for what its worth, I ain't giving up on this, i was not a big supporter of the mods you have done but you don't deserve this result. hang in there mate, we will get you through this. Also I think its worth getting the old heads crack tested, i suggest you take them to a head shop and tell them what has happened. I just want to be sure we are not still dealing with the initial problem of sucking water into the engine, hate to say it but the symptoms sound the same. Also what test are you doing to isolate the problem cylinder when the engine is breaking down under load?

 

[FreeBeeTony]

Re: Vortec Test

Thanks for the votes of confidence...........<br /><br />I am trying to get in touch with a reputable mechanic that will come to the boat and go for a ride.<br /><br />John_S.......it has the roller cam/lifters, I'm pretty sure the timing is advancing OK (I tried a different module with no change in performance) and, I tried changing the initial timing with no change. Yes, went with the Edelbrock 1409, idles smooth, does not appear to be running rich.<br /><br />Paulie.......I am with you (I think) that the cam/valves are OK because of the way it idles. I am going to verify that the I am loosing the #2 cylinder again and then with the aid of a timing light I am going to check for spark under load.<br /><br />Being that the problem (loosing a cylinder) has moved from #3 to #2 I am thinking that maybe it's something as simple as sticky lifters and they aren't showing up until higher RPM under a load. I pumped about a quart of oil out last night and added a quart of Marvel Mystery Oil. Wouldn't that be a kick in the A$$!

 

[John_S]

Re: Vortec Test

FWIW, my logic with the cam, was if the lobes are worn, you would not be getting the lift/duration you need. ie like running a much smaller cam. Also, the posts I remember seeing on people that had bad lobes, their issues generally showed up at the upper rpm, not at idle.

 

[FreeBeeTony]

Re: Vortec Test

Can I measure the lift of the cam by measuring the travel of the rocker arm on the push rod side?<br /><br />How far off would it have to be to cause this problem?

 

[KaGee]

Re: Vortec Test

Seems to me Tony, that if it were your cam, the same cylinder would be misfiring as before your rebuild/update.<br /><br />If #2 was truly misfiring and you were still ingesting antifreeze, #2 plug should look funny. If it were missing from ignition or fuel mixture, you should also be able to see something there on the plug. <br /><br /> Read Here <br /><br /> Another read

 

[rodbolt]

Re: Vortec Test

seems. coulda.<br /> woulda<br /> same words. <br /> I prefer a word called verified.<br /> like I said there are only a few things that can cause an uncontained explosion from the carb shutters.<br />this is not rocket science. but it does require a certain amount of test equipment and a knowledge of what is going on in the motor and why.

 

[FreeBeeTony]

Re: Vortec Test

I have the vacuum/pressure gauge, compression gauge, timing light, multimeter and am trying to get the leak down test equipment.<br /><br />Probably won't be able to get to it until the w/e.......and Sunday is mother's day!<br /><br />So what would you suggest first rodbolt?

 

[John_S]

Re: Vortec Test

Tony, I checked a few manuals, and did not find any that use the dial indicator on the rocker arm. All had rocker arm removed, and measured with a rod off lifter socket or off push rod. You would need to use a degree wheel if you want to measure duration. Procedures are in the Merc manual, but didn't find any in Seloc.

 

[paulie0735]

Re: Vortec Test

John, I hear ya mate and I don't disagree, just trying to eliminate the obvious things before somebody convinces him to pull the cam out! <br /><br />Tony, I’m still trying to stay focused on your original problem, if you want me to back out than just say the word…. In the mean time; Do you remember what condition the head gaskets were in when you removed the old heads, any sign of leaking from the water passages into the cylinder? <br />If you still have the old gaskets and the heads can you post some hi-res pics please? If you feel like it try this: Get some masking tape and stick about 18 inches down on a clean smooth surface, with a making pen rule a line on the tape every ¼ inch for the full length, now stick the tape around the harmonic balancer, start the engine and put some load on it with the timing light on the no.2 plug lead, we’re looking for an irregular spark pattern when its starts to break down, if its regular despite the fact the engine starts to run rough than do the same with each plug lead, if they all look like they are getting a smooth advance curve despite the engine breaking down than I think we can say the spark and spark timing is ok. Might sound dumb but have you moved the plugs around? <br /><br />IMO if the cam lobes are worn bad enough for the engine to breakdown severely at the same rpm every time than they are gunna effect its idle quality in fact its normally a rough idle that alerts me to worn cam lobes in the first place, that said they can also cause unusual pressure waves in the inlet manifold causing some cylinders to run lean and drop out at various rpm’s. It could be a lot of different little things combining into one big symptom, anything from a poorly sealed inlet manifold, worn cam lobe(s), carb fuel circuitry blockages to an incorrect coil or a even a cracked block or a dozen other things. Sticky lifters are usually just that, sticky and I have never come across one as regular as Tony’s they also normally come with increased tappet noise or bent push rods. It will be interesting to see the results of the leakdown, compression and spark tests.

 

[lilmandavis]

Re: Vortec Test

i dont think its the cam either especially since hes got the roller lifters! but the stock vortec heads do come with weak valve springs. might have good compression on start up but at wot there might be a weaker spring on that cylinder. they come with usually 80 lb springs. great for a stock cam but the marine cams are generally a little more agressive. if a valve isnt lapped in right which these things come off production lines with some snow pea building them. i think a valve is either floating or it needs to be lapped. ive put vortecs on old blocks. different push rods, roller lifters, 1.5-1 rockers, new springs from summit, and a good lap job at least, i cut three angles on my valves. ive had that problem before and its the valves. gas was spewing out the carb at about 4grand. changed springs after i figured out they were weak. then relapped the valves. if you got a big cam, you must machine off the valve seal risers and get new offset keepers. but you shouldnt have that big of a cam in a boat..if he said it only back fired a time or two its got ta be the spring on that cylinder floating. if it was an electrical i think it would do it before 3800

 

[lilmandavis]

Re: Vortec Test

yeah do what paulie says check the plugs and make sure its advancing pretty smooth and not shuttering at wot. what did you mean by the condition of the top of the piston?

 

[paulie0735]

Re: Vortec Test

I think i missed the bit about a 'roller cam' Tony please confirm!! If so where did this engine originate from, ****!!! a million more questions now...... Tony please tell me this engine was running fine for many years before this original problem showed up.............

 

[I/O WALDO]

Re: Vortec Test

Ignition

 

[KaGee]

Re: Vortec Test

Paulie, <br /><br />Tony posted this This Link above. It's when he tore down last August.<br /><br />He also posted the link that we all followed then... Read Here

 

[rodbolt]

Re: Vortec Test

I agree mostly with paulie<br /> if its a mechanical failure it wont come and go.<br /> you can measure valvelift at about any point on the valvetrain.<br /> as long as the reference point stays the same. I usually use the gasket rail on the head.<br />compare all the ex and all the intakes to each other.<br /> instead of tape on the balancer I will bring each piston up to TDC and make a mark and cyl number on the balancer.<br /> its time consuming but it is what it is.<br /> my specialty is contracting with local marinas to solve issues they cannot.<br /> its rare I change oil anymore.<br />sticky lifters is rather a myth. kinda like a jumped tooth on the timing chain. I hear a lot of it but never see it.<br /> usually if the stick once they are stuck.<br /> the "roller" lifters in the vortec are hydrualic just like the old flat tappet ones were.<br />they have a bleed orifice and a plunger like they have had since the 50's.<br />most techs cant explain how and why they work anyway.<br />if you suspect weak valve springs there is a tool that can be used with a dial or arm type torque wrench to test them in place.<br />its a spring, no voodoo or black magic, it is either good or bad but wont shift back and forth.<br /> like I tell ya, ya got 8 tiny motors that share a common crank and a common induction system.<br /> treat each cyl as such and it makes it easier.<br />dont shotgun or splatter test.<br /> confirm or eliminate each subsystem<br />if you suspect #2 has a missfire then make a mark on the balancer corresponing to #2 at TDC and use a timing light to watch it. if any other of the 7 marks show up or the #2 mark is not steadyyour on the right path, <br /> like I say its time consuming but simple.

 

[FreeBeeTony]

Re: Vortec Test

That's a great idea robolt, marking the damper for each cylinder at TDC.........I will try that.<br /><br />Guess I will try this first. Hopefully sometime the w/e.

 

[Buttanic]

Re: Vortec Test

Measure the diameter of your balancer and go to the auto parts store and ask for a timing tape for that diameter. Follow the instructions and stick it on the balancer. They have marks every 90 degrees. A V8 fires every 90 degrees so it takes two revolutions of the crnkshaft to fire all 8 cylinders.

 

[rodbolt]

Re: Vortec Test

babylon. use numbers not just marks, its quick easy and permanant. try to get that tape on in a boat then try to make it stay. I use magic marker or white fingernail polish depending on the paint color. my timing light also has an advance function so I can cheachk the advance curve of each.<br /> if your advance is mechanical they have no choice. if its electrical advance you will find the odd one that does not advance correctly.<br /> I use a DVA meter on the primary and a Kv tester on the plug wires. once I confirm the ign system is ok and confirmed the engine mechanical systems are ok that mostly leaves induction.<br /> like I say its not hard just sometimes time consuming.<br /> it will help if you make a list of anything that can create a burn in the intake tract and go confirm or eliminate it.

 

[FreeBeeTony]

Re: Vortec Test

Use a DVA on the primary? You mean on the coil? The 12v on the coil?<br /><br />Kv tester (kilovolt tester?) on the plug wires? You mean remove a plug and measure the voltage at the end of the wire? This is not a constant voltage obviously......how do you measure this? Can you use an oscilliscope? How much voltage are we talking about?<br /><br />Advance is electronic.....Thunderbolt IV.<br /><br />So if the V8 fires every 90* then 2 plugs will fire at each mark.<br /><br />So my plan is to put the marks on the damper, test for the dead cylinder under load then check for spark on that cylinder using the timing light.<br /><br />Will also check the primary voltage on the coil under load.<br /><br />Sound OK?