Another day of great fun... maybe not so much. WTH?!
 

So, I had been enjoying the fact that my engine ran so much better after replacing the intake gaskets and such. Key word, "had."

Yesterday, I stopped at home on the way back to the office, and thought it would be nice to hear the boat running before heading back in to work. Hooked up the water, uncovered her real quick, then went to start her. I got about two revolutions, she backfired out of the blower (did that once the day before... figured maybe a timing issue that I'd get to before going out). Tried to turn her over again, then just grinding. Lots of grinding. As in a jammed starter. Immediately, I feared that maybe I had hydrolocked the engine. Not sure why I thought that, it was just the first thing that came to mind. I pulled all the plugs, and no water. Not even a peep.

I got in there today and sure enough the starter was busted. The nose was broken off and I recovered the broken piece inside the engine cover. i broke out a breaker bar, and to my horror found I couldn't turn the engine. It was jammed. I couldn't turn it in reverse much either (maybe a 1/8-1/4 inch). Fast forward two hours later, after yanking the blower belt and the drive (neither of of which helped), I was able to get her to turn again. Could something have jammed it within the housing?

The question then is... what broke it? Did it kickback and bust it, or did something else jam it? What could jam in a kickback? And she definitely backfired. I'm almost positive that it was the catalyst to the whole thing.

I plan to put another starter on it, then run a compression test to make sure nothing went south.

Seems that I'm cursed or something.

Anyone else encountered something like this?

I wouldn't rule out a valve train issue.

Like a valve hanging open?

Timing chain jumped, piston hit intake valve, incorrect valve adjustment, igntion timing issue, valve stuck in guide, broken rocker arm, just throwing stuff out there.

One thing I learned a long time ago when it comes to roots blower engines.

Pump throttle, return throttle to idle, then crank engine over. I never crank blower motors over with the throttles wide open, like I see so many do with N/A carb engines trying to get them to start.

Not suggesting thats what the problem was, but just throwing that out there.

I hear ya Joe.

I never hold her open to start. I give two or three pumps, let her sit, then start cranking. Usually, no issues.

I guess I'll start looking at the valvetrain.

I'm a firm believer in the KISS principle. Starter rolls twice, backfire blows up starter, starter crap falls inside housing or got caught between the teeth, won't roll over. My first thought is some chunk of metal wedged against the flywheel and held it enough you couldn't turn it with a breaker. AS you messed with it, the little chunk of crap fell out. New starter, compression check it, all good, fire it up. (If it's something else it will let you know quickly) X2 on MT's starting procedure.

I've only run blowers on a car, but something to keep in mind possibly. My blower intake has spring loaded burst panels on it to relieve pressure in case it backfires so the rotors and engine don't feel the shock (hopefully). Marine engines often don't have burst panels because of the explosion risk boats have so blower and engine absorb the shock. That's why marine blowers commonly use a serp type belt because it will slip before something breaks (hopefully). Running a coggeg Gilmer style belt that can't slip combined with no burst panels could potentially cause an issue.

That's what I do with NA motors, that's just good practice, catch the engine with the throttle. Only time I ever hold something to the moon is when it's my buddies rx8 so it doesn't flood when cold....

Thanks for the note. I'm running a 16-rib serpentine belt.

I wasn't sure what you had but figured I'd put it out there anyway. Maybe someone with more blower experience disagrees but it might help someone.

Like others said, the broken piece off the starter was the cause of the jam. Ive had that happen before. You would be amazed how small of a piece it takes to jam the flywheel when turning over by hand. The other problem was not knowing where the timing is.

Going to get to putting her back together now.... I thought that I had found all the pieces, but probably not.

Regarding timing, I was pretty sure I was close. I marked everything before taking it all apart. I guess I shouldn't have assumed.

An update will be coming a little later today.

Thanks guys!

Ended up working on trailer lighting for a good part of the day, but got to it after dinner. The valvetrain is good, no issues seen. I couldn't get the starter done because of some issues with the old one that I had laying around. Headed to West Marine here in a minute to go get a new one.

While we were at it, checked the alignment (which ended up being spot on... all from setting the engine with an angle finder and forklift... I was quite impressed), got the drive back on, and everything else together.

I'll put in the starter this afternoon, then do a compression test for good measure, and we should be good to from there.

** Update **

Figured out why she was backfiring. Also verified that timing was not the issue. In fact, I was just about on the money.

Anyway...

The backfiring through the intake is happening on number one. Why? Because the lifter pumped and won't bleed down. Going through the adjustment, I get the exhaust valve open, then go to adjust. I take out the slack then give it an eighth of a turn. Roll her over to TDC, put air to the cylinder, and it comes out of the blower. Backing off the rocker seals the cylinder tight... tight enough to roll the engine backward.

WTH?

Anyone run into this and have a fix that doesn't require taking the blower and intake off... again?

I forget tom, are those flat tappets?

When you are adjusting the lash, is the lifter plunger depressing, or the valve itself opening? You sure the lifter isn't collapsed and bottomed out?

1/8th of a turn on a hydraulic isn't enough preload imo. Not that thats your problem, but......

Joe,

The cam is a Bob M 525 EFI copy, and I'm using Comp 854S-16 lifters. I cannot see the lifter because it's hidden by the cylinder head casting. I'll go out in a minute and use my bore scope to see if the lifter is indeed collapsed or just solid stacked.

1/8 preload was just for testing... these lifters require a half turn for preload (.030-.040).

Bad lifter... or bad installation. Either way, it's collapsed. Great.

Let me just add, I've done plenty of these in the past, and with this exception, had not had one go bad like this. I spun the polylocks done until there wasn't any up and down slack, then half a turn. I guess this one was a bad apple.

Going back to my other thread about ignition... my thought now is that I was chasing the ignition problem as well as the hanging intake valve. The module was definitely bad (corrosion coming through the pins), but I think the new ignition helped mask some things. My thinking is that when the engine warmed up good, the lifter would try to pump up, negating preload, and holding the valve open.

My guess is a bad check valve in the lifter. I'll take it apart for curiosity's sake when I'm done repairing.

I ordered two pairs of replacements last night. I'm going to replace the bad lifter, examine and adjust the entire vlavetrain, and hope to have her back together by the weekend.

It seems like I've been hearing a lot about bad lifters lately. I was watching a show on the idiot box where they were in a nascar engine room and they've got fancy shmancy machine microscope just for checking the lifters. The reject rate was ridiculous.

Is it possible that the ignition backfire traumatized the lifter?

My next setup will be solid rollers.

Good job Tom, it's been a crazy year with these builds so far! I'm curious to see what you find when you open it up.

I haven't gotten the lifter out yet... only viewed via a bore scope, but the lifter was adjusted this way, and from what I can see, the plunger is about a 1/4-inch down in the body. The backfire didn't cause this. It's the reverse.

I readjusted all the valves back in November after the initial dyno session/run in the boat (I had an intake that was clacking on number 5). I adjusted number one per the instructions that came with the lifters, and thought nothing of it. I'll be looking at all of them when I get it torn down.

I have four lifters coming, and I'm hoping I do not find any other issues. They're all coming out for inspection. I should have ordered another set of lifters all together (something other than Comp... well... except for their new short travel lifters... I hear they're actually pretty good), but then that would have required new pushrods because of seat height differences. My geometry is good (per wear patterns), and if I can get these to work, then I'll be happy.

Joe, I actually have a set of Crower solid rollers coming for this as a backup. They're the lifters that were originally used with the engine that my heads were on (468 Chevy). I have the pushrods and everything. Would only be a matter or determining the proper lash with the hydraulic profile. The duration would drop a little, but RPM would be extended. I'm not sure that I would want to go down that road, but it's an interesting approach.

One thing though, my Comp 953 springs are definitely on the edge of working with these lifters. Comp recommended them for the cam using my 854 lifters, but mentioned that they were really meant for a solid roller.

In my not so educated opinion, I do not think the springs are beating the lifters to death... I think I have a couple of bad apples maybe.

Got everything apart during lunch. I'm getting good at taking this thing apart quickly... great! Anyway... All the lifters look good with the exception of the number one intake's lifter. The cup is down in the lifter a quarter inch and if I invert it, the cup will come almost to the retainer. Safe to say that something let go in that one.

I'll starter prepping for new gaskets tonight sometime. Hope to have her all back together Friday evening.

I'd put the solid lifters in the engine.

A friend just went through this BS with a set of comp came hydraulic lifters and switched out to solids.

Anyone know the lash settings for this cam? Merc 525 EFI or Crane 741? Iron block, aluminum heads?

Thanks!

Well, it's fubar.

New starter, two new pairs of roller lifters, went through the valve train, but didn't do compression test because I thought I found the smoking gun. Started her up, backfired for a second then ran rather rough. 5 inches of vac at idle. Seems okay when you rev but very lazy to do it. Thinking I have a burned intake valve, bad head gasket, or who the heck knows!

I should have checked compression.

An hour of dyno time plus maybe three hours of easy run time in the boat... is that enough time to waste a valve or a seat? I'm really upset about this.

tom,if the tuneup is wrong,espically on a supercharged engine the exhaust valves& seats can develope a bad seal in a hurry.i am not saying that is your issue but it sure is a possibility.

Backfires are all out of the intake. Nothing out of the exhaust side, and this thing is fat.

I'll dig into some after I'm done being pissed off at it. I'm not ruling out a spark plug wire issue.

Not sure how good of a wrench you are, but given your frustration it may be a good idea to take it to a pro and alleviate some headaches through $. I have had a rough go of it myself this year...have a beer, step back and let it go for a while.

Thanks JRider. I'm my own wrench, and pretty decent at it, if I must say.

I need to re-evaluate some things here, and apply deductive reason. A compression/leak-down test will tell all. I have the equipment to do it so not a big deal.

I need to step back and have that beer, then get into it.

On a related note... the pops only happen on the intake. The engine ran okay outside of the random pop pop pop that would disable being able to start the engine. I thought that I got rid of that with the new distributor.... she ran well!

I changed the intake gaskets (three times now) and this is what I've got.... a fast-spinning motor on the starter that randomly pops through the intake, then runs and idles fine, but seems lazy. Hitting her hard on the throttle makes her rev; no pop. Timing is set at 30-31 degrees locked.

What am I chasing?

Sure you have the cam installed correctly, timing wise.

I'd check that intake valve,,it may be tight in the valve guide.

Running lean?

I had a similar issue with my old 454 years ago - idled fine, albeit a little rich, ran OK at cruising speed, but under load or full throttle would backfire through carb. Compression test revealed one low cylinder. Pulled head and found that I had blown a chunk off the ringland through detonation, and that chunk had hung up in the intake valve and knocked a 1/8" hunk off of it. Hope this is not your issue.

I'll yank it apart tomorrow... could be a valve adjustment. Either way, an intake valve isn't quite shutting.

More to come!

Guess I need to rethink my wrenching abilities....

I thought for sure that my firing order was correct. In fact I was so sure about it that even today I didn't go about double checking before tearing into everything. I went through everything on the odd side of the engine (all cylinder tight), then went to the even side. Looked at the wiring (after getting the valve covers off and backing off all the rockers), I found that numbers 2 and 4 were swapped. Dammit!! All cylinders were tight on the even side too. Oh well, at least I was able to test everything.

Trust but verify!! Sometimes it's the littlest of things that mess up the works. In my case, I was rushing to fire it up because I had to be at an after-hours work function.

Now I'm waiting out some thunderstorms so I can put her back together.

Question... I see conflicting information on how to set the preload on Comp lifters. I've always used a 1/4-1/2 a turn from zero lash. The instructions from Comp say 1-full turn, but there are some other instructions state 1/4 and 1/2 and 3/4. The lifters are Comp 854s-16 High Energy roller lifter (retrofit). What's the general concensus?

Up to one full turn, where ever you feel most comfortable. I usually go 1/2-3/4 so plenty of margin on either side.

Exhaust just starts to open - adjust intake
Intake just about closed - adjust exhaust