You don't need to rebalance anything when buying new pistons for a 302. I've built many a motor with new pistons and nothing done as far as balancing goes. And unless that 93 motor was mistreated, chances are it doesn't need new pistons. If there's no ridge at the tops of the bores and the cross hatching is still visible, all you need to do is run a ball hone through the bores and re ring it. Ditto on the crank, many times nothing's needed there either as long as the journals are nice shiny and smooth.
You guys are missing that the '93 block has already been rebored .030 and he has mentioned buying pistons for it...
...and a lot of ...if it doesn't need this or doesn't need that going on here. "sucked in" is a good description of what can happen to an engine build. when you get done, a little more and you could have had a "crate motor"...
Ok, it's been hot tanked and bored ? What's that got to do with it ? Other than the fact that a block should never be bored without the pistons in hand to match them to the bore, it really has no bearing on what needs to be done now. I would still go forward with the roller block and crank. Top it with the GT 40 heads and use the cam that came with it, augment the cam's lift with a set of 1.7 rockers, that'll make a snappy, fuel efficient combo when topped with the intake he listed and a 500-600 cfm vacuum secondary carb.
I think his point is I don't have the option of using the stock pistons in that block any longer. I realize now that you should have the pistons when you bore the block, but unfortunately the machine shop I was working with suggested the bore and never said anything about having the pistons. I'm just hoping that it's a little under and can be adjusted to fit whatever I get. Are there decent full roller rockers that will fit the stock mounting, or do I need to look at having the heads modified for screw-in studs? If doing that I wonder if it would be worth having the heads shaved a bit to reduce the chamber size a few CCs.
You don't need stud mount rockers, a set of Crane 1.7 Energizer (pedestal mount)rockers will bolt right up. These are the same as those made for Ford for the GT40 motors in the Stangs. Or find a used set of those too. These things last forever. I've got one set in my 96 E150's roller 351. This is the 4th or 5th engine I've had this set in, after buying them secondhand with 100K miles on them. You can mill the GT40 heads up to .040 before running into intake fitment issues. Just be sure before that the set you have aren't off a Stang GT40 motor. These were milled at the factory to reduce the chambers to 60 ccs for the Stangs. A .040 mill gets the chambers to around 58 ccs from the nominal 64 ccs they had when cast. I've built one motor this way, stock roller short block, GT40 heads, Cobra rockers, F4TE roller cam (this is the pickup cam with specs of 256/266 advertised duration, .445/.473 lift with 1.7 rockers, the Cobra cam has a .479 lift with 270/270 duration) Topped with a Ford A321 intake (this is the old Cobra high rise dual plane) and a Holley 570 Street Avenger. This motor was blast to drive around town in an 89 Ranger backed with a Toploader 4 speed and 3.73 rear. Very fuel efficient, smooth idle, smooth powerband from idle to 6 grand. Lotsa torque to spin the 275's out back with a trac loc rear. 18 mpg in the ranger on the highway without OD.
I'm pretty sure they're off an Explorer. I didn't measure every chamber, but the two I measured on each head were 65 cc. Here are a couple sets of rockers I found on Summit. I don't know if the proform are any good. Both sets are on sale. Proform 66878 http://www.summitracing.com/parts/pro-66878/overview/make/ford Ford Racing M-6564-A50 http://www.summitracing.com/parts/fms-m-6564-a50/overview/make/ford
Go with the Ford rockers, that's a no brainer to me. Reason I recommend full roller 1.7's is Ford found a 15 hp increase using them. Some is from the ratio increase, but most is from the frictional loss in the roller trunions, they found the oil temps dropped some too. I'd buy new pushrods too (6.25") The roller cam pushrods don't get rotated in service and after a 100,000 miles or so the rocker ends get a somewhat wedge shape worn into the rocker ends
Update: So upon a suggestion from my step-father I went to NAPA's website and searched for local stores that offered machining services. I called the closest one and was informed that the man who used to run their machine shop had retired and they no longer offered those services. What I did end up getting was the name and phone number for the shop they used to send things to that were beyond their capabilities. I called them up yesterday and took them the GT40 heads and the '93 crank. Some moisture had gotten to one of the heads so it needs some attention. I'm having them inspect the crankshaft and measure all the bearing surfaces so I know what I've got there. They're going to de-rust the heads and oil everything up and replace valve seals if needed as they've sat on the shelf for about 4 years dry. Then they're shaving them down 0.020" to bring them closer to my stock chamber size. In the mean-time I've rebuilt the stock carburetor and dusted off the Maverick. After the rebuild it still runs really rough. I need to go through all the adjustments on the carburetor. The biggest problem is that when you press the accelerator, it stumbles and usually stalls. This is really bad when the engine is cold. I've noticed that the distributor that is in the car now only has a single vacuum connection. The diagrams for this year show two connections. Currently the port on the intake is plugged and the single distributor port is connected to the base of the carburetor. Is this correct, or is there some other way it should be connected? The other thing I've found is that there is a lot of moisture in the exhaust which concerns me. It still sounds like there's a misfire. I'm not really sure what the best way to sort that out is.
When cold out condensation is very noticeable to the point of usually leaving a puddle under the tailpipe, unless it's loosing coolant a non issue... Don't worry about the back connection on the dist, only retards timing... Front one connects to ported vacuum on carb(someone will say different but is how Ford connected all their vacuum advances prior to emissions)... If the carb rebuild is correct, it should run fairly good with the idle adjustments backed out 1½ turns... Use a vacuum gauge to set carb for highest reading when adjusting, if it's unsteady or pointer has the "shakes" there is likely compression issues(burned valve, head gasket, broken piston ring, etc) that needs to be checked with a compression gauge... More often than not ignition issue causes rough engine, could need plugs and/or wires, a bad carb can foul plugs...
You're also likely dealing with points ignition here too (unless someone has converted it to electronic) seeing that you're listing a 71 Maverick in your sig. Points need to be adjusted with a dwell meter for the best operation, the gap setting is a starting point, not where it needs to be when you set it with a dwell. The erratic running could be due to worn points. Just me but I'd convert it to electronic and toss the points in the dust bin in case there's a Nuclear war. As with what Krazy already said, the distributor vacuum hose goes to the ported nipple on the carb (above the throttle blades) not to the nipple at the base. This way the vacuum adds timing to the engine as the throttle is opened, with it at the base, it's advance is "all in" all the time.
