|08-15-2010 01:24 AM|
Glad to see you discovered the root cause, it always worries me more when something goes wrong and you can't find a reason.
You're right, it doesn't get said enough that when you start using aftermarket parts that you have to check everything, 50% of it needs rework right out of the box. You were likely fine before the distributor was reshimmed when it was recurved, but it isn't really the fault of the guy who recurved it, he did everything right in making the distributor blueprinted and the way it should be, you just happened to get bit by tolerance stack-up all going the wrong direction in your combination of parts. Chalk it up to "live and learn". Now you know why engine builders charge what they do.
No need to reprime the oil system, it is basically full now and the pump will refill in the first couple seconds as soon as the engine is cranked on the starter.
|08-14-2010 11:31 PM|
|sqzbox||Never mind, brain fart!|
|08-14-2010 10:36 PM|
I got the distributor back and it is installed. He cleaned up the aluminum at the bottom, lubed everything, one extra shim, new gear, cap, and rotor.
Since I had the pan off, I was able to check the pump drive shaft for binding. Guess what, that was the whole problem. I never thought that taking .008" off of the heads would be enough to cause binding, but either that was the whole reason, or it was a combination of things. Live and learn I guess.
Instead of getting shims for the distributor at the intake, I just ground a tiny bit off of the pump drive shaft. It should be good enough now.
I have one question though. Since I had to remove the pump, do I need to reprime the engine before I start it?
|08-09-2010 10:38 PM|
It cranked up fine. I took the pump apart and it looked good to me. There was some VERY light wear, but nothing you could feel with your finger nail. The machine marks in the metal are still visible.
I don't know how close it was before because the wear on the teeth were exactly where you'd want it to be. I bought this distributor new when I rebuilt the engine. After this whole thing, I started looking at everything a little closer. I found that there was two gaskets stuck together, but that would have made the distributor ride a little high. The gaskets were stuck together from Mallory, because what they sent me with the distributor I used.
I can tell you that after this setback, I will be checking/rechecking the teeth wear and I will be buying shims if needed.
Honestly, this is my first ground up engine build. I've bought crate engines before and done a fair amount of engine work, but most of it is just stock replacement pieces. I have learned a lot doing this, but I think the two things I have learned most is that you can never check too much and nothing aftermarket fits like it should.
|08-09-2010 09:25 PM|
.008 may not seem like much, but if the dist was borderline before, the extra shim he put in may have sent it over the edge.
Also, you remember if there was more than one gasket on the dist when you pulled it the first time? Broke people (like me) dont buy shim kits, they stack dist gaskets to space the dist up.
And because ive been down the same road before, was the motor a little hard to crank? because if it was, you can be sure the oil pump is damaged.
|08-09-2010 06:20 PM|
Ok, I just got back from the place that recurved it. The guy that did the work said that he has never seen this type of damage this bad before. The shim and the thrust washer were all but welded to the gear. He had to use a hammer and chisel to get them apart after removing the gear. He couldn't say for sure what happened, but he thinks it's a combination of me tightening the distributor down a tiny bit more due to reusing the gasket and the fact that he DID use a shim to take up some clearance in the shaft. He said that the shim alone would not cause damage this bad unless the shaft wouldn't rotate after he was done. I know it rotated when I picked it up.
He also thinks the distributor is reusable, so I am going to have him repair it. He is going to put a new gear on with a new thrust washer and shims to take up the clearance. Then, after I get it back, he said to use the paint that you use to set up a rear end and paint the gear. Then install the distributor and turn the motor over by hand to see where the pattern is. If it needs to be adjusted, I'll have some shims to do it with. I'll also check to make sure that the oil pump drive shaft is not binding.
|08-09-2010 04:18 PM|
The thing is, if there was a problem with the internal parts, it would have been damaged within the first 250 miles...but it wasn't. The damage occured after recurving...in the 150 miles after installation. Which means either:
1. Pre-Tuner did something "different" when reinstalling the distributor, OR
2. The people who did the recurving did something to change the position of the dist. gear.
I vote for #2. If the metal tangs weren't sheared off when the dist. was first removed, it's safe to assume all the internal engine parts are correct.
|08-09-2010 01:53 PM|
|DoubleVision||I was going to say the same thing Eric did about the difference in the 400 SBC shaft, but the last time I did so many years back nobody believed me.|
|08-08-2010 09:51 PM|
|Pre-Tuner||Well, my Dad got back in town from vacation and he thinks the distributor is still usable after the bottom is cleaned up (he's a mechanic). He has some thrust washers that will work, and some shims if needed. He isn't sure what happened either, but agreed that I should take it to the place that recurved it to see what they have to say, which I will try to do tomorrow. When I reinstall it, if the oil pump shaft isn't floating, then I can grind it a little for clearance since I already have the pan off.|
|08-07-2010 02:58 PM|
As long as the dist. isn't bottomed out, there's a fairly wide leeway for where the mesh occurs on the gear itself, w/no adverse results. The pattern has to be all on the gear, not running off the top or bottom.
|08-07-2010 10:36 AM|
I did put about 250 miles on when I first got it, and then decided it needed to be recurved because I needed more initial timing. Nothing was wrong with it when I took it out, but now there is. I'm not sure what they did to it, but I imagine they wouldn't admit to it. I will definitely be talking to them. I don't know if there is an extra shim or not because I don't know what it is supposed to look like.
The intake is untouched and the block was only decked enough to make a nice sealing surface for the heads, which ended up being .008".
I have the 400 oil pump rod which is necked down. The pump is a standard volume pump, so nothing special.
It's a Mallory HEI distributor, so I would think the machining would be accurate coming from a name brand company. Especially since it started off fine.
The gear teeth didn't look like that when I pulled it at 250 miles. The wear pattern was in the center just like it should be.
|08-07-2010 04:35 AM|
I can honestly say I've never seen this happen. All the distributors, all these years...some were sloppy as hell...up-and-down and/or side-to-side...some were tight...and I've never seen this. But then...I've never had my distributor recurved. Hmmm. 0.o
|08-07-2010 03:28 AM|
|ericnova72||One thing I forgot... The 400 SBC block requires a necked down oil pump drive due to the larger main bearing bores in the block. If a pump drive shaft that is not reduced diameter is used, it will rub hard on the hole in the block and main cap that it passes through, and could well be related to your problem.|
|08-07-2010 02:02 AM|
You got off light- the damage will be limited to a distributor thrust washer, cap and rotor, probably an oil pump and a shim kit to set the distributor height/gear mesh.
The labor is another thing.
You might want to go ahead and get shims to set the distributor end play. Shims linked are for a 1/2" shaft diameter, check yours to see what it is before ordering.
The relationship of the dist. gear to the cam gear causes the dist. shaft to rise upwards- so when checking the pattern, be sure the shaft is fully up w/all clearance removed from the gear end- that is how the dist. shaft and gear is when the engine is running.
I do not believe you could have broken the tangs off an OEM thrust washer like that- the OEM piece is thick enough that I believe it would have taken out the aluminum housing first. But in any event, that dist. shaft had to have been really bound up to do what it did.
|08-07-2010 12:36 AM|
Looks like either the intake manifold is machined too low where the distributor sits(or excessive block/head milling), or the distributor housing collar is machined too high(Chinese?) and the distributor shaft is jammed hard against the oil pump drive rod bottoming everything out. I'd want to inspect the pump now too, for scoring of the end plate and end of gears.
Oil pump drive rod could be too long also, there are three lengths that all look the same to the eye but with 1/8" or so difference - standard SBC, SBC w/BBC pump(slightly shorter), and BBC(longer), but I would be looking at distributor height first for manifold ot housing problems.
Moroso sells a distributor to manifold shim kit for this reason, did you check at assembly that the pump, drive rod, and distributor all had adequate end play??
Gear appears to show distributor sitting too deep in the block also.
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