More progress on the motor. Had a brief set-back on the timing chain set-up. I had a new, unused set up that was supposed to be the "early style" but the fuel pump eccentric wouldn't clear the front cover. There's like 4 different front covers & I have one of each type, it wouldn't work with any of them so it must be a later type for use with an electric pump, thus no eccentric needed. Call Jeg's, wait a couple days. Not unhappy to get an actual roller-chain set up with some cam degreeing capability anyhow. Changing the cam timing makes the valves open & close sooner (cam advanced) or later (cam retarded) this will move the power band up (cam retarded) or down (cam advanced) the rev range somewhat. I'm installing this one straight up (and yes, I did turn the motor after I installed it correctly, but before this pic was taken.) but may experiment later.
Putting the front cover & water pump on is pretty straight forward aside from locating the proper bolts from the the pile. Copper gaskets discussed further on.
On to the heads: Along with most of everything else that's going on the motor, I got these when I bought somebody else's unfinished project 5 or 6 years ago. They are stock heads, by the numbers they could either have came on a 302 or a 351. The only difference would be the size of the valves. The heads have had fairly extensive exhaust porting done along with some basic intake clean-up. May sound backwards to chevy people (I actually don't know) but limited exhast flow has always been the small-block ford's bigger issue. They've got new valves installed, they're the larger 351 size. Swapping 351 heads onto a 289 or 302 was the standard upgrade until the early nineties when more aftermarket heads started being made. The one bummer about these is the large combustion chamber, I measured them (by filling them with a measured amount of liquid) at 68cc. With the standard valve cut-outs on the pistons, the unmodified deck clearance of about .035 and a standard .048" head gasket, I'd have a compression ratio of 7.95:1 Basically, this was the deciding factor in whether to tear the short block apart or not. I do want to run 87 octane, so I don't need or want high compression, but there's not a lot of sense in bolting the fun parts I've got onto a motor with that low of compression. So more compression was needed. I'm pretty convinced that the best way to increase compression while warding off detonation is minimizing quench (or "squish") clearance. Quench clearance is the distance between the piston and the head, the narrow red space on the left side of this illustration:
a larger space invites detonation as it leaves a lot of mixture under high pressure far away from the ignition source. Minimizing quench also promotes turbulence in the combustion chamber, which speeds up the burn process. This has an added benefit of requiring less ignition advance to fully burn, further guarding against detonation. The one drawback to a faster burn is slightly increased emissions. Which does matter to me, but you can't have everything and a guy has to have his priorities. So having the block decked until my clearance is .009" and using a .032" gasket, I get a compression ratio of 8.68:1, a little shy of my prefered target (9:1) but a whole lot better than in the 7's. Should be no worries whatsoever with 87 octane. The gaskets I also had lying around, they're pure copper & generally aren't used without O-ringing the head or block. I've talked to a couple people who use them without o-ringing & I talked to SCE (the manufacturer) they said use some Yamabond sealer & be sure to double & triple check torques after the first couple warm-up/cool-downs & I should be fine. hope so. The gamble is worth saving $100-$150 on custom thin gaskets so long as I don't end up stranded in the middle of the desert. Ok, heads on:
.
Again, I'm a bit further along but I'm as tired of typing as you are of reading this boring stuff, so I'll spare you for now.
Here's something for the ladies for valentines day:
Putting the front cover & water pump on is pretty straight forward aside from locating the proper bolts from the the pile. Copper gaskets discussed further on.
On to the heads: Along with most of everything else that's going on the motor, I got these when I bought somebody else's unfinished project 5 or 6 years ago. They are stock heads, by the numbers they could either have came on a 302 or a 351. The only difference would be the size of the valves. The heads have had fairly extensive exhaust porting done along with some basic intake clean-up. May sound backwards to chevy people (I actually don't know) but limited exhast flow has always been the small-block ford's bigger issue. They've got new valves installed, they're the larger 351 size. Swapping 351 heads onto a 289 or 302 was the standard upgrade until the early nineties when more aftermarket heads started being made. The one bummer about these is the large combustion chamber, I measured them (by filling them with a measured amount of liquid) at 68cc. With the standard valve cut-outs on the pistons, the unmodified deck clearance of about .035 and a standard .048" head gasket, I'd have a compression ratio of 7.95:1 Basically, this was the deciding factor in whether to tear the short block apart or not. I do want to run 87 octane, so I don't need or want high compression, but there's not a lot of sense in bolting the fun parts I've got onto a motor with that low of compression. So more compression was needed. I'm pretty convinced that the best way to increase compression while warding off detonation is minimizing quench (or "squish") clearance. Quench clearance is the distance between the piston and the head, the narrow red space on the left side of this illustration:
a larger space invites detonation as it leaves a lot of mixture under high pressure far away from the ignition source. Minimizing quench also promotes turbulence in the combustion chamber, which speeds up the burn process. This has an added benefit of requiring less ignition advance to fully burn, further guarding against detonation. The one drawback to a faster burn is slightly increased emissions. Which does matter to me, but you can't have everything and a guy has to have his priorities. So having the block decked until my clearance is .009" and using a .032" gasket, I get a compression ratio of 8.68:1, a little shy of my prefered target (9:1) but a whole lot better than in the 7's. Should be no worries whatsoever with 87 octane. The gaskets I also had lying around, they're pure copper & generally aren't used without O-ringing the head or block. I've talked to a couple people who use them without o-ringing & I talked to SCE (the manufacturer) they said use some Yamabond sealer & be sure to double & triple check torques after the first couple warm-up/cool-downs & I should be fine. hope so. The gamble is worth saving $100-$150 on custom thin gaskets so long as I don't end up stranded in the middle of the desert. Ok, heads on:
. Again, I'm a bit further along but I'm as tired of typing as you are of reading this boring stuff, so I'll spare you for now.
Here's something for the ladies for valentines day:
VIEW 5 of 5 COMMENTS
The study goes for another few months, and I could drop out at any time, but I want to be a good guinea pig and do my part for science. These people are giving me free medical attention, after all. The potency is set at the beginning of the study, goes by weight (I'm apparently getting 1 gram of the stuff since the prednisone has me up to 260 lbs now). The study drug, abatacept, appears to be having a cumulative effect: My joints aren't swollen like they were a year ago (though that may be the prednisone, too). The bone erosion is still there, I just hope the connective tissue starts growing back.
Hey, got that Frod running yet?