You guys were dead on about my carb situation and the back firing i had going on. I had the valves adjusted like i did on my LT1 z28, tightened down 3/4 of a turn. Re-adjusted the ones 2 weeks ago on the '88 with it runing and tightened the rocker nuts down 1/4 and really changed the manorisms of the engine.




However yesterday on the way home from work while driving (@less than 1/4 throttle, slight throttle cruise) I can feel like a slight misfire or hesitation. If I gave it a little more throttle it doesn't seem to be there. About 3 miles from my house i noticed sitting a light a really loud bearing sound. Like if your alt. bearing went out only a hell of alot louder. It doesn't seen to be anything w/in the accessories. I check the crank pulley and harmonic balancer and they don't wable or anything while its running. Its not leaking water out of the WP or anything so i can't say that that bearing was done or messed up.

When I finally got home I took the distributor cap off and just wanted to make sure the mechanical advance weights we still intact and good. They were but the rotor however was missing the screws that hold it down and a piece on the side of the rotor was completely gone?!?

When I had it advanced was it advanced WAY too much throwing spark way to far in advance? Underneath it looked carbon'ed up as well??

I know its very vague, but just had to throw this out there for suggestions. Pisses me off because up till that point I had finally got the car running really good (for what it is). I had the timing alittle to far advanced to i retarded it some and had to richen up the mixture slightly.

 

Sounds like the rotor screws weren't tightened enough. You need to find them, they can't get out, perhaps were even causing your noise. New cap & rotor, properly installed, should make it good to go. Unless you really have wiped out a bearing - did your oil pressure drop any?

 

oil pressurre didn't really look any different that usual. The factory gauge has always read on the low side even when it was an L03 car. When I swapped motors I replaced it with a new one. None of my previous cars ever had a spun bearing before. I always thought a spun bearing sound more like a "knocking" kinda sound. Could a spun main bearing sound like a really loud alt or WP impeller bearing gone bad?

(The distributor, cap, rotor and plugs are also only like 2 weeks old. Plug wires were done this summer when I did the engine swap)

 

Who put these new parts on?

Have you found the rotor screws yet? I can imagine them getting in the wrong place and making a lot of noise. Among other things.

 

All the parts (cam, valve springs distributor etc.) were done by myself. I've done all this stuff before so thats why im caught off guard as to why the rotor broke on the side like it did. Yesterday after work I was in the garage working on it and found one of the rotor screws. It was sticking to one of "points" on the reluctor ring (?)

 

The pickup ring is magnetic (it's a magnetic pickup, remember). That's where it eventually got stuck after flying around inside the distributor for a while.

I'm guessing one of the screws flying around in there when it came loose is what knocked a hole in your rotor. It wouldn't just fly off, it would continue to get batted around by the spinning rotor until it eventually wedged in some uncomfortable way and then you get what you got. Buy a fresh rotor and try again. Make sure it's seated all the way before you tighten down the screws.

What kind of engine is that HEI out of? It's not a small block Chevy distributor.

 

I should've noted that the pic i posted was just one i found on the internet not my actual distributor. The distributor I have in there now is an reman one from AZ for like a '79 corvette. I was just thinking Pre-81 HEI with the best/looser advance springs. I tried like an early HEI figuring i'd have a better chance at getting better springs but from '74-80 all corvette/camaro distributor PN's were the same one.

 

Ah, that explains it.

Yes, a lot of the earlier stuff is just "one size fits all" to keep the number of different parts on the shelf to a minimum. If you want to tune it, it's a DIY proposition. The Crane advance kit is one of my favorites for a stock HEI.

 

Thanks Damon & five7kid for the responses


Assuming I don't have a spun bearing or catatrophic bottom end failure...

Im going to AZ as soon as i get outta here to get a new cap and rotor (this time i will make certain I have both screws in the rotor). I'll also order a Crane advance kit. I had one in the old distributor (not the one thats in the car now)but it was an Accel, im not crazy bout Accel's products but i didn't think it was a poorly made kit (springs or weights that is)

 

Better find that other screw as well. My guess would be it's what causing the noise you hear.

And verify no damage has been done to the metal parts in the distributor.

 

Update:

New cap and rotor. Runs good fires up and all...


The bad (bearing sound). After doing the ole' screw driver against the ear/poor mans stethescope (sp?) trick on the WP, ALT and P/S pump I put my hand between the back of the WP and the timing cover because the front of the engine is where you can hear it best. After feeling the timing cover it seems as though SOME HOW (lack of thread lock, doubt it but, never say never) one or atleast ONE of the cam sprocket bolts has worked it self loose and is rubbing up against the inside of the T/C.

Never heard of anything like this happening but oh well. It'll give me something to do on Thanksgiving break, along with painting the garage

 

You've got all sorts of "bolts unscrewing themselves" kinda problems with this thing, don't you? Hopeully the REALLY important bolts (mains, rods, etc.) are tight!

If you find the timing gear bolts have backed out make sure to use LocTite or better yet invest $2 in a timing gear lock plate for the bolts.

 

The rotor thing was my fault. I honestly didn't think that it would go anywhere, fail! The cam sprocket bolts that was done over this past summer, I had just got back from 8 months in Iraq doing convoys so I can't remember if loctite was used. Im sure it was though.

 

update:

Tore the front end of the car apart this weekend. I had, 1 broken Cam sprocket bolt, 2nd bolt was half way backed out and the 3rd one was finger tight in the cam. Threads on the second bolt were alittle goobered up, wollowing(sp?) out the bolt hole in the cam i imagine. Needless to say, a new cam is on the way along with lifters and a retaining bolt locking plate kit

 

Did you find all of those pieces?

I don't recall hearing about a cam change. I've never had cam bolts back out when torqued to spec.

 

Im just thankful that the damn thing never fell in between the timing chain and the crank sprocket.

The cam swap was done for 2 reasons...
1-I was afraid that atleast 1 of the bolt holes would be wollowed out
2-When I adjust the valves after a few hundered miles I adjusted them as per LT1 specs(i.e. set at zero lash then 3/4 of a turn). Thats what killed No. 6 cyl. Exh lifter and wipped the lobe clean(or close enough) if i had a digital cam i'd take pics.

So with all that in mind I figured screw it, if the threads are "f-ed" I already know that one lobe is toast, might as well put in the cam i originally want or one close to it. I just wish I had the dough for some decent heads. I really see no future in doing anything with factory cast '72 emissions era SBC heads

 

Glad to hear you found the (second) problem. Now don't go 180* in the oppopsote direction and over-tighten everything when you put it back together! Properly tightened and locked down with the appropriate retaining device will do just fine.

I know it's tough not to over-compensate for an earlier mistake, but try to resist the urge anyway.

Good luck with it!

 

UPDATE:

Did the cam/lifter swap and used thread lock this time on the cam sprocket bolts along with a retaining plate kit. set the timing @ 12*....WOW! in all fairness the comp i put in was a little hotter. Sounds alot louder and has a hint of that 5.0 cam sound.

One question though, when I was breaking the cam in my buddy was in the car with his foot on the gas fluctuation the RPM (2k-2.5k) and the headers wre glowing. Now as i interputed this as the engine running to lean. I adjusted the fuel mixture screws but they still remained cherry through the cam break-in. A buddy of mine says that the Edelbrock 600 on there is way to small, especially if im putting Sportmans II heads on down the road. He suggested stepping it up to a 750 or 770 cfm carb. Is that to much or about right for a 350 .040 over etc??



Drove it around today and noticed after driving it a while she had a slight knock.

So i pulled some timing and set it at 5*. I'll probably try and bump it up around 8* and see how she does with that.