Detonation? Pre ignition?

-
If I just change out the pistons/rings/bearings, I'll just end up right back where I am. I have to fix the leaks or just change blocks. I've got a few people looking for another engine for me, and the "local" machine shop may have one in their bone yard.
 
Gotcha. I missed the crack you noted. I still think for cheap and charming you could get out of it for $7-900 rather then starting from scratch. But - it's up to you. There's something to be said for engine karma...lol.
 
Got a line on a '75 1/2 ton 360. I can use the pan and pick up from my junk one to do the swap. Bonus is that I've heard it run before buying it. Oil pressure is low (on the trucks gauge), but otherwise runs well. Should have it in the next few days.
 
Sounds good! Don't sweat the lower readings. Just make sure it goes up with rpm and is within spec.
 
Got it out and home. Looks good. Got the tranny (727) thrown in free! Should get it apart in the next few days.
 
Ok, found some time to get into this thing finally. Everything looks good, stock bores. All cylinders but one have nearly no wear (can feel a textural difference at top of bore, but no ridge), with one cylinder having enough of a ridge to catch my fingernail on. Came across a couple oddities though.
Timing gear was off one tooth, cam gear was behind the crank. It seemed to run good, started decent cold and hot. Would one tooth make any difference?
The connecting rods on the passenger side are out of order. Goes 8 2 4 6 (front to back), drivers side is fine. I take this as a sign it's been apart before. Again, does it make a difference? Should I put it back together like this since they've sort of worn together like that? Or redo it properly?
 
It's been apart - yes. Normally the rods would be remarked if they were redone but so long as the clearances were good and the orientation was right it really doesn't matter. You might be surprised at how screwed up engines can be and run acceptably. The rebuilt 360 I have for my truck had a main bearing where they used the lower half in the upper position. That cut's off oil flow to the rods that are fed by that main... Yet it ran and had some miles on it. Probably low rpm, limited use type stuff but it was run that way.
 
One tooth off timing will make a differenece in running in certain modes but not damage anything internally. Yes as above with the rods mixed around.....just don't swap caps to rods (the big ends are bored/honed with cap and rod bolted and torqued together) but you'll be fine if the rods & caps are kept together and moved around. Ridge sounds good....are your going to re-bore? If not, remove the ridge or risk a broken top ring or ring land in that bore, 'specially with new bearings.
 
I can't find any gauges to messure the bites myself, so it's off the the shop to be decreased and checked over. I guess I'll wait and see what they say. Thanks for the link, it's very informative!
 
Ok, after some setbacks with house renos, I'm back at this. Got it degreased and checked. They're going to go 30 over, but otherwise the block is good. I've ordered a 9:1 master kit, should have it by the end of the month. The machinist told me he needs the pistons to do the final boring/honing, is that right? I've never had to have a block bored before, so I'm just rolling with what these guys tell me. Once I've got it back, it's down to cam selection and carb choice. I'm going to drop this in my '83 Ram to do break in and tuning since the Duster is getting some body work slowly done.
 
Ok, I've got the cam down to two choices. Both are Summit cam kits.

SUM-K6900- 278/288 dur, .421/.444 lift, 1500-5000 rpm.

SUM-K6901- 276/288 dur, .441/.441 lift, 1800-5000 rpm.

Both claim to be a good choice for a 9:1 build, and are the same price. Which one would be better for my build? I'm going with a Thermoquad (if I'm smart enough to tune it in properly!), mostly cause I ready have one (with four others for parts),for its drivability, and for a nice stock look.
Thanks!
 
furiousgeorge said:
Ok, I've got the cam down to two choices. Both are Summit cam kits.

SUM-K6900- 278/288 dur, .421/.444 lift, 1500-5000 rpm.

SUM-K6901- 276/288 dur, .441/.441 lift, 1800-5000 rpm.

Both claim to be a good choice for a 9:1 build, and are the same price. Which one would be better for my build? I'm going with a Thermoquad (if I'm smart enough to tune it in properly!), mostly cause I ready have one (with four others for parts),for its drivability, and for a nice stock look.
Thanks!
Click to expand...

I like the 6900.
 
I would have the rod bolts replaced and recondition the rods. If the engine has been apart at least once, then the bolts have a minimum of three clamp cycles - possibly more. You shouldn't torque rod bolts more than 5 times before they can be stretched to where they may fail. By the time that you install them and check bearing clearance, then secure them, you will be at 5 clamp cycles.

If you replace the rod bolts and then recondition the rods, you can check your clearances and button up the engine and still be able to do any r&r on the engine in the future if necessary (hopefully not).

You need to recondition the rods if you replace the bolts, as it can affect the alignment of the rod and cap. A mis-aligned rod and cap can make the crank tight or even prevent it from turning if bad enough. It's best to have them reconditioned and new bolts.

http://chucker54.stores.yahoo.net/rodbolts.html
 
Ok, I'll see what the machine shop guys want to do that, thanks! I've come across a MoPar purple shaft cam P4452782, 268/276 dur .429/.444 lift, idle to 5800. This is, or is a close match to, the stock 340 hp cam I'm told. Would that be a good choice?
 
I assume the machinists want the pistons to know exactly what you are going to put in: cast, hypereutectic, or forged.... so they can be sure to get the right clearances. I would be sure to research that myself with the piston manufacturer and be in agreement with the machinist on that piston clearance.
 
Ok, I've got everything on the go with the machinist. While that's going on, I've moved onto the next thing down the list; the torque converter. I've gone with the MoPar cam I mentioned above (lots of guys I talked to recommended it), the rear end I think I'll upgrade to 3.55's, so would I need an different torque converter? If so, what should I be looking at? This is mostly going to be a street car, perhaps a blast down the track a few times just to see what it'll do, but not a race car. Would a stock converter survive?
 
You must log in or register to reply here.
-

Back
Top