Motor is Toast - Time to Rebuild

Jeff N

Jeff N

Your Mileage May Vary
The engine that's been giving me fits for the last two years finally decided to just give it up and die. The compression test showed 30, 30, 120, 90, which probably explains the bad vibration that it developed. I'm guessing worn rings and possibly a blown head gasket for the two low cylinders. :dead:

After weighing my options, it looks like rebuilding it will probably be better than finding another motor and shipping it in. I have a buddy who is an Alfa Romeo/Ferrari/foreign exotic mechanic who's agreed to rebuild it for me. I've just got to pull it and take it to him.

At this point, I'm looking for suggestions for what I should do on a slim budget while I'm in there. A performance cam is a possibility, but not sure which would be a good option. Any other input would be appreciated. Also any suggestions to help make dropping and installing the engine easier, since I've never done it before.

:help:
 
Gee, there's an open-ended question. The only way you'd get more responses on this list is if you asked which color was best. ;-)

Knowing the year and current specification of your car would be a big help. Your avatar seems to be a 1300 car but assuming that's what you're working on would be a leap of faith. It'd also help to know how you currently use the car, how you plan to use the car, and what other mods (if any) have been done.

The more you tell us the better targeted the advice will be.

///Mike
 
More info

Sorry, I guess that would help.

76 1300 stock with a new 34 DAT carb. The car will mainly be used for pleasure, no daily driver or track use planned.

As far as suggestions, I'm looking not as much as what mods to do, although some are fine, but I guess more of what are the worst wear points that I should go ahead and replace while I'm in there- seals, bearings, etc. I'm not a gearhead when it comes to motors, which is why my buddy is doing the work. I don't think he specificially knows these motors, however, so I'm looking for input as to what to pay attention to in the rebuild. Budget is definately a consideration, unfortunately, so I can't go too wild.

Jeff
 
The good news is that there's not all that much to worry about in either a 1300 or 1500 engine. The X motors are pretty decent designs to begin with so there's not really anything that's an absolute must to replace or upgrade in a stock rebuild-- other than worn or broken parts, of course.

In my experience the biggest wear item in 1300s is the rings. Back when I used to work on these cars regularly I'd see motors where the bearings looked like they'd go another 200k, but the rings were toast. Other than that the little engines will go forever if you take care of them.

But that kind of leads to the bad news, which is that your compression numbers are indicative of something worse than just a tired engine. I hope whatever is wrong can be solved without a huge investment but if it turns out you find that major components of the engine need to be replaced it may well be less expensive to find another engine to rebuild than it would be to buy a bunch of brand new parts for this one. For example, if you find one or more broken pistons it be less expensive to freshen up another engine than it would be to buy a new set of slugs-- assuming you could find a decent rebuild candidate at market rates (i.e. cheap). Just something to keep in mind.

In any event, for your stated purposes I'd suggest focusing more on making the long block absolutely right than I would buying any go-fast parts. I'd rather have a well built engine than something haphazardly thrown together and topped off with a trick cam. After all, you can always add the cam later.

But that's putting the cart before the horse(power). The first thing to do is either find out why the compression numbers are so awful or find a better candidate for a rebuild. You'll be in a much better position to plan once you know what you're dealing with.

But I will throw a few parting thoughts at you-- if there is room in the budget for a complete balance job I'd do it. If there's bucks left over I'd try to find a way to lighten the flywheel, or buy one that's already been lightened. And as part of the rebuilding process I'd have the block and head surfaced enough to bring the compression ratio up about a point. We can provide further input here when you get to that point.

Past that it's really just a matter of doing the stuff that you'd do to any engine during a rebuild. I don't think there's anything in an X motor that will catch out a really decent engine guy, even if he's never seen the innards of an Italian motor before. It's all about taking your time, measuring, checking, remeasuring, and rechecking. If your engine guy isn't sure about something the answer can probably be found in the archives, or by asking here.

Once again, at the risk of sounding alarmist or overly negative, the compression numbers you posted are pretty bad. If you're confident of them and happen to know where there's a 1300 engine in a known condition (even if it needs a rebuild) you might consider starting there. Hope I'm wrong, but just an idea...

Oh, and as to engine removal, there's tons in the archives. Well worth the effort to check it out. No doubt somebody will offer up some more detail but the short answer is : support motor, disconnect everything, lift car off of motor. ;-)

HTH and good luck,

///Mike
 
There is a evil bay sell who has new std size 1300cc piston sets for $100.00 as BIN. Aftermarket, but should be OK for a stockish build.

http://cgi.ebay.com/ebaymotors/1966...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories


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Jeff N said:
Sorry, I guess that would help.

76 1300 stock with a new 34 DAT carb. The car will mainly be used for pleasure, no daily driver or track use planned.

As far as suggestions, I'm looking not as much as what mods to do, although some are fine, but I guess more of what are the worst wear points that I should go ahead and replace while I'm in there- seals, bearings, etc. I'm not a gearhead when it comes to motors, which is why my buddy is doing the work. I don't think he specificially knows these motors, however, so I'm looking for input as to what to pay attention to in the rebuild. Budget is definately a consideration, unfortunately, so I can't go too wild.

Jeff
Click to expand...
 
I saw those pistons, along with some others with cutouts to make them non-interference. Hoping that it only needs rings, but I guess we'll see when we get in there. It looks like that between Matt and Ebay I can pretty much easily get what ever I'll need.
 
Actually, I'm hoping you have a blown head gasket between #1 and #2.

If the compression is that low due to rings you may well wind up needing oversized pistons.

///Mike
 
Blown head gasket is what I was thinking, based on both cylinders having the same reading, while the other two were significantsly different. Blow by had always been an issue, so I knew the rings were at least worn, then the vibration started, so I figured I'd lost at least one cylinder. The fact that two are similarly low makes me think head gasket.

I'm out of town this week, so it will be next week before I can get started.
 
I just found a 1500 motor close by that I can pick up fairly cheap. Worth it for the upgrade? My understanding is that the 1500 is pretty much a straight bolt on to the 4 speed tranny, is that correct?
 
The deck height is different...

so you will need some kind of extension on the exhaust system to take up the extra half inch or so.

Also, (doing this from memory) you may have problems with the starter - the 1500 starter doesn't engage the 1300 ring gear properly or some such thing. As I recall, the formula was to keep as a single package the clutch, pressure plate, flywheel and ring gear and starter. That is, use all the 1500 stuff, or all the 1300 stuff, but don't interchange. I'm no expert here, but there have been some good posts in the archive recently so do some searching.

Pete
 
Adding to what ///Mike already said...

You did not mention HOW the engine was failing or giving you trouble (overheating, missing, hard to start???)... and did not state if you did a WET compression test to see if it was just the possibly the valves OR the rings.

If there is no OBVIOUS signs of trouble... why not do a WET compression test and post those numbers also...

Lastly, I agree (as I find more and more often I do...) with Mike's philosophy that if you were thinking of just adding a performance cam it will not do much unless there were bigger valves, more carbs and a free flow exhaust system to go with it. Since you seem to want a weekend crusier, a rather fine running STOCK engine would seem to be a better fit for YOU and your BUDGET.

I agree with the engine balancing and a lightened AND rebalanced flywheel also... and do not forget to replace the clutch, pressure plate and T/O bearing while its out. Stock replacements are more than adequate for the power output.

Also... Best to "drop" the engine AND trans as one unit by lifting the body using the rear bumper brackets and a sling. More on this if ya need details...
 
IMHO... a bigger OOPS would be...

... buying that 1500 and NOT rebuilding it before installing it.

There is probably a good reason its for sale for cheap...

But... the 1500 would be a nice upgrade... and like Pete said, the starter, flywheel and clutch componants would need to be mixed and matched to accomodate. A better upgrade would be a 5 speed trans also, then the half-shafts and A arms etc. would need to be swapped also.

It never ends...
 
I think I'm coming down on the side of just rebuilding the 1300 I've got, assuming the block is OK. At this point, the "why" of what went wrong probably isn't really of primary importance, other than knowing what needs to be replaced, since the engine's getting torn down anyway. I'm sure the problem will probably become evident when it gets opened up. I replaced the stock carb several months ago with a new DAT 34, which was billed as a little peppy-er carb, to help solve some rough running/power problems. I'm also planning on getting an electronic ignition unit to help upgrade a little.

One question I've always had is about lightening the flywheel. I'm always seeing references to having it done, but don't understand how losing a couple pounds from it will have much of an affect on performance. Can most competent machine shops do this as well as balance it? As I've said, I'm mechanically inclined, just not technically inclined when it comes to engines.
 
Jeff N said:
One question I've always had is about lightening the flywheel. I'm always seeing references to having it done, but don't understand how losing a couple pounds from it will have much of an affect on performance. Can most competent machine shops do this as well as balance it? As I've said, I'm mechanically inclined, just not technically inclined when it comes to engines.
Click to expand...

A very simple way to view it is

Force = Mass(acceleration)

This gives you two ways of increasing your acceleration, increase the amount of force or decrease your mass.

Now its far more complicated then that obviously, but that gives you an idea on how the rotational mass influences acceleration. Then add in how gearing works, and that few pounds now becomes far more as far as the motor is concerned.
 
I got started on pulling the motor tonight, draining and disconnecting everything. When I pulled the oil plug I was greeted by a stream of thick chocolate milk! Guess that answers one question. The follow-up will be whether the head gasket blew or if something cracked. :shock:

I'll be praying for the head gasket option.
 
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