Rebuilding my first 360

Woody Long

I'd like some help and advice on how I should tackle this job.

First off it's a AMC 360 out of a 81 Wagoneer (my 81 flew apart). The Po has already completed the Oiling Mod

I'm kinda ristricted now and have to keep the smog on till after final inspection and a later propane conversion.

My first impressions were weary. I noticed alot of carbon build in the combustion chamber and on the piston. There is a .019" gap between the piston and the cylinder wall.

I still need to pull the botom end out and check for play.

My intenet for this block is to power my Wagonner, she'll have 4.10's on 35's being pushed by a 727 and NP208.

What kind of parts and modifications should I be looking for to produce a good HP and Torque engine. Should the fact be taken in account that I'm in the blistering cold of Canada? Today the temp is -33 Celsius (-27 Fahrenheit) and a whopping -40 with the windchill. Should I do something special to my engine to ensure I won't wreck it from cold starting. I've noticed there is already 2 block heaters installed and run off a power inverter (I think) Would more block heaters be bad?

I have ordered the BJ builsd an AMC book for reference because that Haynes book of mine is a little worse for wear.

jeepsr4ever

BJ's book is a good book to start with...some good info in there. Like any engine build the first thing you want to do is establish your bore size before ordering anything else. Maybe we should do this step by step. Hot tanking, new cam bearings (with a smaller hole provision) possibly a bore and hone. We may want to lok at the budget that you are using for this build as you may not need/afford forged pistons.

Woody Long

I got a quote for $2045 for a rebuild, but all that means is stock stuff. I'd like to keep the price down if at all possible, maybe $1500 including macheing and parts. Are forged pistons worth it? I've heard both sides of the story, but those are from suppliers. With forged pistons would running really hot or cold affect them?

jeepsr4ever

forged pistons dont change as much thermally as cast pistons. You may want to run cast where you are living but it doesnt seem that extreme compared to where we are at in MN. That seems a little expensive. You can get a awesome rebuild kit from northernautoparts.com and a great oiling systems form Bulltear and get the general work done to the engine and assemble yourself.....but wait we are talking canadian money arent we...

Woody Long

Sorry, all the prices I'm talking about are in Canuck Bucks.

So as it sits, last night was a whopping -47 C or -53 F. Working in the garage was less than comfortable. All my tools had frost on them and the block also had frost on it.

After warming the garage up I started on pulling the block apart. I got a drop sheet to catch all the extra oil and coolant when I turn the block over. But before I turned it over I noticed something on one of the pistons.....Took a better look, though it was a scoring mark. But how would a score mark be in the center of the piston? An old tooth brush a rag and some gas revealed something I've never seen.......................................

Does this mean these are 0.030" Over Pistons? I tried measuring the bore size and came up with 4.101? I could be wrong and measured it wrong or just can't read the caliper...it was like the second time I've used it in 2 years.

I turned the block over and proceeded to remove the oil pan.....this PO had used a cork gasket and RVT out of the wazoo! Using a putty knife and deadblow hammer it took me 1/2 hour to get that crapper off. Next I noticed this.

Am I off or is this another oiling type of mod? Or would it be used for balancing?

Soon after the pan was off I realized that the block had already been rebuilt. I found stamping all over the place.

What should be my next course of action? I need the block tanked and Magna Fluxed. Should I pull the pistons and crank or let an engine shop do that?

As things are now I'm stumped till the weather turns a little warmer and I have some answers.

jeepsr4ever

It loks almost like the #7 rod is mismatched. 30 on a piston like that usually means .030 over and with a bore of 4.101 it sounds at least .020 over. You might want to double check that measurement. 360 (5.9L), bore 4.08 x stroke 3.44 1970-71, 245 hp @ 4400 rpm, 365 ft/lb @ 2400 rpm, 2V, 8.5:1 1970-71, 290 hp @ 4800 rpm, 395 ft/lb @ 3200 rpm, 4V, 10.0:1 1972-74, 175 hp @ 4400 rpm, 285 ft/lb @ 2400 rpm, 2V, 8.5:1 1972-73, 195 hp @ 4400 rpm, 295 ft/lb @ 2900 rpm, 4V, 8.5:1 1974, 220 hp @ 4400 rpm, 315 ft/lb @ 3100 rpm, 4V, 8.5:1 w/dual exhaust 1975-78, 140 hp @ 3300 rpm, 251 ft/lb @ 1600 rpm, 2V, 8.25:1 1975-76, 180 hp @ 3600 rpm, 280 ft/lb @ 2800 rpm, 4V, 8.25:1 1977-91, 155 hp @ 3200 rpm, 280 ft/lb @ 1500 rpm, 2V, 8.25:1 Jeep only

Woody Long

I'll give the measurements a check later. What would cause so much carbon build in the cylinder head's like mine have? (see first post)

jeepsr4ever

usually carbon buildup like that is caused by valve seal wear and/or ring wear

tufcj

A .030 360 block would measure 4.110, so maybe you just read the caliper wrong. Everything else looks like factory markings. There were letters stamped on the webs near the mains for piston selection when assembled at the factory. The hole on the crank counterweight is for balance. Pop the main and rod caps and look on the backside of the bearings, they will have just a part # if standard, or will be marked .010, .020. or .030 if the crank has ever been turned. Carbon build up could be bad rings, valve seals, or just running with a poorly tuned carb or incorrect timing. The 360 in my CJ came to me with about 85,000 miles on the clock. We measured the cylinders and they were still in spec for taper and out of round. We honed the walls, had the crank turned .010/.010, put new rings and bearings on the stock pistons and rods (did have the rods re-sized). Definitely replace the cam bearings too. I put on 291C (1970) heads that were ported and polished. It's running great, and has another 50K since the rebuild. Still only uses about 1/2 quart of oil between 3000 mile changes. I have a 60K original mile 401 sitting in the garage, but I can't justify the swap because the 360 is just so dependable. Bob tufcj

Woody Long

I just received "BJ Builds and AMC"!! Looks great. I read through some of it last night before I pulled the pistions out. Question though. Is is supppose to be tight taking the pistons out? I checked and there was no lip on the cylinder, but it was tough to get the pistons to pop out. I ended up for 2 or 3 of them pushing them out with the end of a wodden hammer. I did notice that there was burnt oil on the underside of the piston, common? I did read the caliper wrong it is 4.11". From just feel and visual inspection I didn't see any wall scoring or distortion. That's good. Now I need to take the crank and cam out, then check all the bearings, or should I replace all of them?

tufcj

It's normal for the pistons to be snug, just means the rings are doing their job. A bit of discoloration on the bottom of the piston is normal too, that's probably one of the hottest places inside the engine when it's running. As long as you have it apart, replace all the bearings, cam, main, rod. You will need to buy or rent the tool for cam bearings, it's impossible to do without the tool. If there's no ring ridge at the top of the cylinder, you should be able to just hone it, and install new rings. If the crank is clean, you may get away with just polishing the journals there too. Sounds like you got one that will rebuild fairly easily. :t: :t: Bob tufcj

Woody Long

Well I came to the decision to get someone to rebuild my 360 for $1850CDN ($1500US). I'm getting the heads polished too. Before he picks it up I'll port the intake and exhaust.....how do I do it? I heard of making the ports line up then matching them??? I could be way off. What should I do? Any input on what to get done extra?