I would like to rebuild my 78 engine in the near future. It has about 150k miles on it and runs well, oil pressure is good. My reasoning is that parts will be harder to get as time passes, high mileage & I plan to keep the car for a long time. The heads will get rebuilt completely. My question concerns the bottom end. Barring excessive piston wear, should I be ok with replacing the bearings & not turning the crank & replacing the rings? I plan to lightly hone the cylinders, but not bore them out unless really needed. If needed, are there any special things to know about boring the cyilinders on the 16 valve engine? (I really don't want to buy a new set of pistons, though). I'm not trying to half butt this. I'm trying to get a feel for how much machining is really needed. I also understand that you don't know until you look, but what is typical on a running engine?

Thanks.

 

You need to do some basic research. First off, the cylinder bores don't get honed at all. Getting the manuals is a good start:

http://www.cannell.co.uk/Manuals.htm

Once the engine is apart you'll know what needs to be done.

 

Scott, there's no reason to rebuild this motor. Truly. If you're concerned about parts availabilty, buy the parts and store them on the shelf, not in a motor that doesn't need them.

 

I wouldn't rebuild it if I were you. The engine is just warming up! I would get some headers, redo the exhaust, add some euro cams. You could do the heads if you wanted, put some larger valves in and port. Another option would be to just find a euro top end, evrything from a euro CIS and swap over. I believe the euro CIS was 80 to 83 and that will be corrected if I am wrong!

I would also buy a 85/86 block, keep the car running and enjoy it. Refreshen the 5.0L block and when you need a short block you will have one ready to go. The 5.0L bottom end should get you to around 300rwhp!

Cams and exhaust took my car from 219 to 265hp! Heads should be worth another 20 easy!

 

+1 - Put the parts on the shelf, and drive it like you stole it. Read lots of Rennlist in the meantime, then if it actually blows up, rebuild it.

 

if your engine is running good then dont fix something thats not broken .
I dont think your going to have to worry about engine parts/
if you wanted another engine to rebuild then there is one for sale in Colorado springs for 750.00. it runs .
Rebuild this one and swap it out if your engine ever stops.
Check Craigslist

 

SCOTTY WE NEED MORE POWER!

 

Yep, let those sleeping dogs ....... you know! best advice is to find the 85 short block and when its time to rebuild or you ned more power, you bolt it up. all you would need is to re-ring a 85 short block, with new bearings and stick it in when you want to upgrade to about 260rwhp. (290rwhp with just cams heads and euro intake stuff)

 

I guess you guys just aren't real Car Guys.

 

throw some NOS on it until it blows.

 

Check back with us when you have over 300,000 miles on that motor. Or if you must take one apart hit Mark A up about an old 4.5.... $500 should get you a core to take apart and rebuild with the ability to DRIVE your car until it NEEDS a motor.

 

I was racing my 150k motor, with its ONLY problem, a headgasket leak that filled the center valley with water. with barrs stop leak, i raced another full season with very little leaking. Upon pulling the engine to do the hybrid, the block was perfect. dont know how much the rings were sealing, but the walls were perfect. I only pulled it to do the heads and or the hybrid conversion.
as Jim says, running to 300k miles . there will be plenty that goes wrong before then, that is unrelated to the block.

mk

 

Well, oklee doklee. I'm a fan of "if it ain't broke..." Sounds like these things go forever. I appreciate the advise & will do as suggested. A follow on question, please. It keeps wanting to run rich. I tweak the fuel control a bit leaner, but then it goes rich again in a few days. Not really rich, just enough that it doesn't run at its best. I've got an O2 air/fuel meter on it which confirms this. The warm up regulator is a rebuilt one a couple years ago. The fuel injection manifold is also a rebuilt one a couple years ago. A vacuum leak should make it run lean - correct? Haven't found one yet. Any other ideas, please? Thanks for all of your inputs.

 

I agree about letting it lie. In the mean time you can be watching ebay (or here) for a good deal on parts prices. Your big expenses will be rings and a gasket kit, so keep an eye out and snag 'em when you can.

 

Scott3n:

The easy tweaking that most folks do on CIS is the screw between the airflow metering pancake flap and the plunger in the fuel metering unit. That has a measurable effect at idle and just off-idle, but the effect slowly diisappears as load and airflow get up a bit. If you are seeing it get rich at normal driving loads, you probably want to g back and start at basic control pressures again. You'll want to buy or borrow a set of good CIS pressure gauges and fittings. Then confirm the operation of the warm-up regulator and the metering unit. The WSM has the target values. There's also a great book on CIS by Probst (sp?) that is really the bible for any serious diagnosis and/or refurb work in the main components. The symptom you describe would steer me to the gauges first, and basic control pressure set at the metering unit with shims.