diff --git a/lib/services/block/index.js b/lib/services/block/index.js
index 20ffc810..12b60c41 100644
--- a/lib/services/block/index.js
+++ b/lib/services/block/index.js
@@ -26,7 +26,8 @@ var BlockService = function(options) {
 
   this.GENESIS_HASH = constants.BITCOIN_GENESIS_HASH[this.node.network];
   this._initialSync = false;
-  this._serviceIniting = false;
+  this._processingBlock = false;
+
   this._blocksInQueue = 0;
   this._recentBlockHashesCount = options.recentBlockHashesCount || 1000; // block service won't reorg past this point
   this._recentBlockHashes = new LRU(this._recentBlockHashesCount);
@@ -522,17 +523,19 @@ BlockService.prototype.onHeaders = function(callback) {
 
   var self = this;
 
-  // at this point, we need to ensure the block header is in a very specific state
-  // 1. we should have no listeners of any kind that could cause side effects
-  // 2. we should have no pending events, yet to be fired, after this routine yields
-
+  // if this service is waiting on block-related callbacks to be fired in the event loop,
+  // then we need to wait for the _processingBlock flag to be set to false.
+  // when this flag is false, we know we aren't waiting on any new blocks or historical blocks
+  // that we asked for, but not yet received
   self._initialSync = true;
-  self._serviceIniting = true;
 
-  self._removeAllSubscriptions();
-
-  // this should ensure that any handlers, yet to be fired, will fire
-  setImmediate(function() {
+  // a heavy block could take a really long time to index
+  async.retry({ interval: 1000, times: 100 }, function(next) {
+    return next(self._processingBlock);
+  }, function(err) {
+    if (err) {
+      return callback(err);
+    }
     self._onHeaders(callback);
   });
 
@@ -542,8 +545,6 @@ BlockService.prototype._onHeaders = function(callback) {
 
   var self = this;
 
-  self._serviceIniting = false;
-
   // check whether or not we need build a new tip (unlikely)
   self._resetTip(function(err) {
 
@@ -560,6 +561,8 @@ BlockService.prototype._onHeaders = function(callback) {
 
     }, function() {
 
+      self._removeAllSubscriptions();
+
       // check to see if our current tip matches what the header service has.
       // if this is a reorg during our initial block sync, it is especially important
       // to see if we've synced past where the reorg/fork took place.
@@ -571,6 +574,7 @@ BlockService.prototype._onHeaders = function(callback) {
 
         // we've checked the tip, handled any reorg for ourselves, and we are ready to
         // sync any new blocks that might exist after our tip
+        self._reorging = false;
         self._startSync();
 
         // once we start syncing, we can call back to the header service, so that it can
@@ -832,19 +836,24 @@ BlockService.prototype._onBlock = function(block, callback) {
 
   var self = this;
 
-  if (self._reorging || self._serviceIniting) {
+  if (self._reorging) {
+    self._processingBlock = false;
     return callback();
   }
 
+  self._processingBlock = true;
+
   self._getBlock(block.rhash(), function(err, _block) {
 
     if(err) {
+      self._processingBlock = false;
       return self._handleError(err);
     }
 
     if (_block) {
+      self._processingBlock = false;
       log.debug('Block Service: not syncing, block already in database.');
-      return setImmediate(callback);
+      return callback();
     }
 
     self._processBlock(block, callback);
@@ -857,6 +866,7 @@ BlockService.prototype._processBlock = function(block, callback) {
   var self = this;
 
   if (self.node.stopping) {
+    self._processingBlock = false;
     return callback();
   }
 
@@ -873,6 +883,7 @@ BlockService.prototype._processBlock = function(block, callback) {
   // we will have a chance to clear out our block queue, check our tip,
   // discover where to reorg to, reorg all the services that rely on
   // blocks and sync from there.
+  self._processingBlock = false;
   return callback();
 
 };
@@ -895,17 +906,26 @@ BlockService.prototype._saveBlock = function(block, callback) {
   }, function(err, ops) {
 
     if (err) {
+      self._processingBlock = false;
       return callback(err);
     }
 
     self._db.batch(_.compact(_.flattenDeep(ops)), function(err) {
 
       if (err) {
+        self._processingBlock = false;
         return callback(err);
       }
 
       self._recentBlockHashes.set(block.rhash(), bcoin.util.revHex(block.prevBlock));
-      self._setTip({ hash: block.rhash(), height: self._tip.height + 1 }, callback);
+      self._setTip({ hash: block.rhash(), height: block.__height }, function(err) {
+        if (err) {
+          self._processingBlock = false;
+          return callback(err);
+        }
+        self._processingBlock = false;
+        callback();
+      });
 
     });
   });
@@ -924,6 +944,7 @@ BlockService.prototype._syncBlock = function(block) {
   clearTimeout(self._getBlocksTimer);
 
   if (self._lastBlockSaved === block.rhash()) {
+    self._processingBlock = false;
     return;
   }
 
@@ -991,10 +1012,6 @@ BlockService.prototype._onSynced = function() {
     clearInterval(this._reportInterval);
   }
 
-  if (this._serviceIniting) {
-    return;
-  }
-
   self._logProgress();
   self._initialSync = false;
   self._startBlockSubscription();
@@ -1024,19 +1041,23 @@ BlockService.prototype._sync = function() {
 
   var self = this;
 
-  if (self.node.stopping) {
+  if (self.node.stopping || self._reorging) {
     return;
   }
 
+  self._processingBlock = true;
+
   log.debug('Block Service: querying header service for next block using tip: ' + self._tip.hash);
 
   self._header.getEndHash(self._tip, self._readAheadBlockCount, function(err, targetHash, endHash) {
 
     if(err) {
+      self._processingBlock = false;
       return self._handleError(err);
     }
 
     if (!targetHash && !endHash) {
+      self._processingBlock = false;
       return self.emit('synced');
     }
 
@@ -1048,7 +1069,11 @@ BlockService.prototype._sync = function() {
     // then we must assume we've reorg'ed very shortly after
     // we made this call and we should re-compute where we are
     self._getBlocksTimer = setTimeout(function() {
-      self.emit('next block');
+      log.debug('Block Service: block timeout, emitting for next block');
+      self._processingBlock = false;
+      if (!self._reorging) {
+        self.emit('next block');
+      }
     }, 5000);
 
     self._getBlocksTimer.unref();