Engine rebuild or not? and to what extent?

[rscottm]

I have a '71 with a 260 engine with a header and Webers. I do not know if it has any internal mods. I have only seen it started and running very briefly from a gas can by the previous owner. My question is should I go ahead and have it rebuilt? I have it out of the car and have removed the exhaust and intake manifolds. One of the exhaust valves looks wet with oil while the others that I can see look dry. There is a lot of carbon build up in the exhaust ports. I do not know if hardened valve seats have been installed either.

If rebuilding, what would be recommended? Complete? Just the head?

Should I go ahead and replace the clutch while it is out too? Same question regarding water pump, front and rear main seals, oil pump?

If spending the money to rebuild, what are the thoughts on finding a 240 engine and having it rebuilt so the correct engine would be in the car? The car had extensive rust that I repaired and the floors will be noticeable because I made my own from thicker steel and made rails that run farther back than the originals. I am using an orange paint that is brighter than the original too so it will be evident that things are not original anyway so I would just like to see some thoughts on that issue.

Thanks.

[Oiluj]

260 is a fine engine, assuming it's in good shape. I'm assuming it's on a stand or mounted on a cradle. Hook it up to a 12 volt battery and do a compression test. That will tell you a lot.

[siteunseen]

I decided to rebuild mine after seeing all that carbon on the inside and grease every where on the outside. But it's project to keep me busy through the winter and not a car that I have to drive a lot. Also am replacing all the rubber bushings associated with the suspension and cleaning up the engine bay. Rings and a timing chain kit with a new oil pump and new bearings and the gaskets, everything's going to be about $800 including the suspension kit. Hopefully it will run again and already looks much better. Decisions, decisions.

[steve91tt]

If it were me, I wouldn't rebuild the engine unless there is a reason to. These engines are very durable. I would spend money on replacing cheap things that degrade with time like the water pump, gaskets, front and rear main seals. Get it running, tune it up and figure out what needs fixing.

[rcb280z]

I agree with Steve. I pulled my 280 out when it had only 91k miles because I was bored. Realized when it was apart I didn't need to do anything. But ended up having a valve job done and did a "minor" overhaul to the block because I had it out. Waste of time. Didn't change a thing. That was 25 yrs ago too. And still runs the same. That says alot about the straight six engine. As long as compression is the same across all cylinders I wouldn't worry about it. just my 2 cents. We all have our own opinions. It's what you feel is best. If you decided to let us follow the rebuild with you.

[cygnusx1]

I would NOT make a decision like that without knowing the oil pressure, and the compression. Without knowing those things, you are purely guessing.

[TomoHawk]

I've been thinking about this too. Mine knocks when you start it, telling me the main bearings are worn, and it drips coolant out of the water pump weep hole a little. Otherwise, the compression and everything but the water pump seems good. If I had the money, I'd just take it out, clean the outside thoroughly, buff/polish certain things, paint it and put on a header, and put it back in. I think I would paint the engine bay and wrap the wires too.

Edited January 10, 2012 by TomoHawk

[LeonV]

I would NOT make a decision like that without knowing the oil pressure, and the compression. Without knowing those things, you are purely guessing.

Dave and others are spot on. If you did not diagnose a problem with the engine which dictates a rebuild, then you definitely should not assume that it needs one. You will be way ahead if you take the steps to diagnose any problems with the engine before you go digging into it. It's a good idea to replace the water pump if you don't know the history of the engine, and that's a simple/cheap job, especially compared to a full-on rebuild.

I would set valve lash and check compression. If your results are good, then put in a new water pump, intake/exhaust gasket, along with any other maintenance items that need attention (gaskets, hoses, fan belt & clutch, etc.), and go drive the thing!

[rscottm]

Sound advise. Thanks. I will check compression and go from there. Hopefully, I will only be replacing the valve stem seals and water pump.

[TomoHawk]

Ok, so you want to just attach a new water pump and/or oil pump. Can you still get them?

Yes, you can. MSA has the water pump at about $40, and the oil pump is about $60, if it is in stock.

Edited January 13, 2012 by TomoHawk

[rscottm]

I did a dry compression test with it cold and no intake or exhaust manifolds. I got 120, 135, 125, 115, 125, and 125. When I poured in a little 10W30 into the 115 cylinder, it got to about 200. I have read several other posts where people had in the 120s and several with readings in the 160-170s. Any thoughts?

One thing I did not do was adjust the valves beforehand. Should I and retest?

[steve91tt]

The valve lash can effect results. I would compare cold lash on your high and low cylinders. Even If lash turns out to be the same those numbers look good to me for an engine that hasn't run for a while. Maybe someone with more experience will chime in but I expect your numbers to be better after you blow the cobwebs out of it by putting few hundred miles on it.