I think I'll just quit!

[scamper]

Went to the boat this morning, reset the plugs to .35. Checked the wires one more time, placed the distributor on the correct time, started the engine. Same as before, backfire until 1000 rpm and the miss. With the new exhaust manifold I can now take the valve cover off with the flex drive so off came the valve cover. All looked ok. The rocker nuts all looked to be in about the same depth on the studs. Decided to just turn the engine over to see if anything obvious showed up. Hit the key and WHAM an explosion that lifted two of the hatch covers off. The whole boat rocked. The two main hatches had been open all morning so I knew I didn’t have an engine room explosion. Looked where the covers were knocked off and saw the muffler or what was left of it. It’s one of those can looking things about 18” in diameter and 20” tall, not like an inline. The whole top was blown off taking the hatch covers with it. Don’t know where the gas in the muffler came from. This probably was the lowest point for me in the last couple of months. I have tried to do everything suggested to me by ya’ll and thought sure the end was in sight. Now I will replace the muffler and guess call a mechanic to see if he can do anything. I tried to get a mechanic when I found out the lifters weren’t just stuck. Matter of fact called two. Neither showed up and that is when I decided to try this myself, with the help of this board of course. The thing is a lot of effort has been put into this project, both by myself, and all you good people that have given your know how and advice to make sure I could complete this. I really, really distain failure, and to be beaten that close, or at least I think it was that close just tears me up. I did want to see this through.

 

[Buttanic]

Re: I think I'll just quit!

Scamper, what do you mean by you placed the distributor in the correct time. You have to use a timing light with the engine running to time it correctly. Did you do this? Idealy the timing and the valves should be set with the engine running. I believe your problem is either<br />incorrect timing or valve ajustment. Sound like you need help from a good mechanic if you are not completly sure of what you are doing.<br /><br />Buttanic

 

[scamper]

Re: I think I'll just quit!

Both valves closed on no.1, timing mark dtc. Pull no.1 plug, rotate distributor till plug fires. Leave distributor there and replace plug. Did I miss something?

 

[Buttanic]

Re: I think I'll just quit!

Which way did you rotate the distributor. It needs to be rotated the opposite direction that the rotor turns which would be counter clockwise.<br />The plug fires when the points open <br />but if you rotated it the wrong way the plug would still fire but it would fire at the wrong time.<br /><br />Buttanic

 

[snapperbait]

Re: I think I'll just quit!

Scamper... Know how you feel...<br /><br />Curious about the brand of muffler?... Sounds like a "lift" type muffler, some of which are'nt made to withstand a backfire and can explode like yours did if the engine backfires..<br /><br />About the backfire... Is it backfireing out of the carb, or poping out the exhaust, or maybe both?<br /><br />I feel as if it's one of two posibilities... Timing may be off a tooth or two on the gear, or maybe 180 degrees out of sinc...<br /><br />If your sure the timing is correct, I'd say you have some rocker arms that are'nt adjusted correctly, leaving the valves open just slightly durring ignition...<br /><br />Oh! Never quit!...

 

[rodbolt]

Re: I think I'll just quit!

hello<br /> man I feel sorry that I cannot hear it. if it runs at all its very close, cannot run at all 180 out.the fact that the muffler blew tells me that large amounts of unburned fuel is going out the exhaust. test the compression to rukle out a valve not closing. if the compression is good then you need to use a timing light . I dont think its a big timing issue. I think you have a valve misadjusted or a stuck lifter plunger<br /> good luck and keep posting

 

[LubeDude]

Re: I think I'll just quit!

Run it past us how you set the valves?<br /><br />I think you have a tight exhaust valve!<br /><br />LubeDude

 

[johnkc]

Re: I think I'll just quit!

scamper ,glad your here to tell us the story.

 

[Hunky Dory]

Re: I think I'll just quit!

So there I was cursing and hollering when I spotted my problem hiding in the skirts of my ever lovin assumptions – come to think of it, that’s where the last one was too!<br /><br />This recollection leads me to ask: Are you numbering your cylinders correctly? Does your distributor cap connect as you think? Are your parts clean and sound? Is there no carbon tracking from previous use? Are you using the correct rotor? How do you know?<br /><br />I've just come in the middle of the movie but it would seem that you have a timing problem pure and simple. You are either not firing one or more cylinders or you are shooting them off out of sequence (mixing). Either way, carbureted gas mixture is being pumped into the exhaust system. Not good; blows up in the wrong place.<br /><br />What can mix cylinders? Incorrect firing order; (way) late timing, cracked or dirty distributor cap; crack, grease, tip-damage, carbon tracks or incorrect rotor; bad distributor cap button; bad plug, plug-wire or plug-wire terminator; or even corrosion in the cap's plug-wire connectors. <br /><br />In the pre-electronic era a bad condensor, a shorted or missing ballast resister or bouncing points must be added to the list. Not to mention loose connections, especially the points-wire.<br /><br />Do you have one of those caps that internally routes the spark to the opposite side to make the wire harness neater? When I look at engine pictures I often see unfamiliar caps on chevies. I wouldn't assume I knew how mine worked until I metered it out.<br /><br />Hang in there, it’s in a boat but it’s still just an engine…

 

[FreeBeeTony]

Re: I think I'll just quit!

scamper, I just read your other post. I recently rebuilt my Mercruiser IL6 165 and I set the valves as you did (by the manual) and they were way too tight. I would recheck the valve adjustment when the engine is running.

 

[kenimpzoom]

Re: I think I'll just quit!

scamper,<br /><br />I would definately do the compression check, it will tell you if the valves are too tight.<br /><br />Of course first things first you will have to fix the muffler before trying to fire it up again.<br /><br />Ken

 

[scamper]

Re: I think I'll just quit!

The muffler was the uplift type. Didn’t look at it very close after the explosion, did see what looked like the top of the thing lying back there. The rest of it still looks to be in place, just sorta threw the hatches in the general direction of where they came from and left. Could have bought a 34’ sea ray cheap yesterday afternoon. Now have had second thoughts and the thing is not going to whip me no matter how many times I have to ask you for help. Before I blew the da** thing up I took the valve cover off cause I believe you guys, that it has to be a valve. Did everything the way I was told to, but I must of tightened a couple too tight. Going this weekend. First rattle out of the box will be a compression test. I know I will find it but in case I don’t I’ll be back here with hat in hand for more advice. One thing, I did have the head reworked the bill showed they did a valve job, resurfaced the head .006, 8 guides bronze 3/8, 8 intake guides 3/8 bronze and 8 exhaust guides 3/8 bronze and pressure test. Anything there? By the way it was backfiring out the carb so definitely an intake but I didn’t think it was backfiring through the exhaust. Guess I was wrong there huh?

 

[rodbolt]

Re: I think I'll just quit!

hello<br /> scamper.<br /> it takes some care to adjust the rockers on the chevrolet engine. its very simple but exacting. the object is to have about .05-.100 lifter preload with the lifter on the cam heel. it can be done by turning the engine over just once but it leaves room for error. I have not adjusted a chevy rocker with the engine running in over 20 years, no need to. makes a mess<br /> makes it stink and smoke. if you insure the cylinder is at TDC on compression stroke(intake just closed) and tighten the nut up until all slack is removed giving a zero lash then 3/4 turn more it will place the lifter plunger in almost the center of its travlel/. but you must insure the lifter plunger collapses or it jacks the valve open and holds it there. do not go by how many threads are showing. that can be meaningless.when we blue printed engines we never went by turning the nut we always used a dail indicator on the lifter plunger. lets make sure the valve train is ok and then we can go look at ign.<br /> Good luck and keep posting