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What's an "interference" engine?
Do I really have to replace my timing belt?

you came from: Master List > Engines

These two questions get answered in the same section, because they relate to the same problem.

There are automobile engines of non-interference design, but you won't find many Honda products using them. A non-interference engine is one in which the pistons go up and down in their own private space, and the valves open and close in their own private space. You can turn such engines over with the cam disconnected from the crankshaft and it won't do any harm.

Interference engines however, depend on accurate timing for their operation. The piston coming up the bore occupies space at the top of its rise that was a millisecond before occupied by an open valve. Worse, in some dual overhead cam engines, an opening intake valve occupies part of the space just vacated a millisecond earlier by a closing exhaust valve. So what keeps all these parts from colliding? Your timing belt, that's what! If that sucker breaks, or even jumps a tooth, you've got big expensive trouble, almost instantly. At 8,000 rpm your pistons are going up and down the cylinder bores 133 times a second! If they encounter still-open valves because the timing belt just slipped or broke, they'll bend the valve over like a clinched nail into the soft aluminum of the head, busting themselves into pieces in the process!

There are engines out there that are technically non-interference, but once a bit of carbon builds up on the piston top and valves, they become interference. That's how close the tolerances can be.

So the bottom line here is change your timing belt when your service manual says you should do so, or pay some mechanic muy dinero to put your engine back together. As a mechanic friend of mine used to quip about such repairs, "It was a peach-basket case!". His implication was that the owner had to pick up his engine parts off half a mile of road and bring them into the shop in a peach basket. If you don't want to be a peach-basket case, change your timing belt when you're s'posed to!

For most older Hondas the change interval is every 90,000 miles (144,000 km) or every 72 months (6 years) whichever comes first. From about 1998 up, the interval was increased to 105,000 miles (168,000 km) or 84 months (7 years). These figures are for OEM belts. Aftermarket belts may not be made as well or last as long.


Can I put a VTEC head on my plain vanilla Honda engine?
you came from: Master List > Engines

Apparently it can be done with some engines. We haven't compiled a list of which engines will stand for this radical hot-rodding, but you might find some during a search for web pages put up by performance shops like this one:
http://www.prospeedpower.com/


What's the best way to make sure I get my new timing belt on right?
you came from: Master List > Engines

OK, so you've got that dang pulley bolt undone, and the new timing belt in place, and now you've got an uneasy feeling that maybe you're out a tooth one way or the other, even though you followed the shop manual's instructions exactly. Well here's a better way that I've seen suggested in the newsgroup (but I can't remember by who).

Before removing the old belt, make a mark on the side of the belt and on each pulley with a dab of paint or even some typist's whiteout. Then after the old belt is off, lay it beside the new one and copy the marks exactly on the new one. Now you know for sure where things line up!

For a detailed presentation, complete with pictures, of a timing belt change on an Integra engine, look here:
http://timingbelt.soben.com/

Note that the 2nd generation Integra's B18A1 has tiny holes in the camshaft bearing caps and camshafts near the timing belt pulleys. After the engine has been turned to TDC on the #1 cylinder, you can slip a couple of 13/64" (or 5mm) drill bits into these holes, which then conveniently keep the camshafts from turning when the belt has been removed. It's worth checking for such a feature on your car.
Warning: DO NOT use these holes to hold the engine still as you wrestle with the crank bolt. ONLY use them once the crank bolt is off. If you put rods in the cam holes to keep the engine from turning while loosening the crank bolt, you will do grave damage to your camshafts and bearings.


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