Budget 302 Build

I measured all the journals on the crank in 2 spots 90* apart, and got 2.122 on the rod journals and 2.249 on the mains, measured the whole crank twice. This does not tell anything about any warpage though. All the bearing 1/2 s in the block looked ok. Could these caps be too short? Seems unlikely to get 2 side-by-side like that. I am going to set up my dial gauge to see if I can detect any run-out. This is the first tear down I have ever done, so thinking all this stuff through, and practicing measuring skills is the main learning curve.

GT40 heads have bigger ports and valves.....probably optimum for for this....but I got some junk I ported and they flow decent for tiny valve stuff. The intakes are flowing 47 cfm at .050, and I want to build this motor with a small chamber and tight quench to allow this low lift potential to fill the chamber during overlap. There are some builders out there that consider this phase of the intake stroke to be the most critical for good cylinder fill, so everything is going to be aimed at that. I will even mess with tuning my collectors when the time comes. My junkyard 302 has GT40 heads, and it runs very good for what it is....and those heads were milled .040 to get in the neighborhood of 9.9:1, has a .035 quench, and runs without detonation on 87 octane. I do not drive it on hot days, and it has a 160 thermostat, so I may be cheating a bit with that claim. But I did lug it on a hill, next to a fence, with passenger window down, and heard nothing.

 

I cannot detect any runnout on those two crank journals. If I put new bearings in, and torqued it with plastigauge in the spots of wear, and in the block side, and found the cap side to be too close (tight), would I suspect a cap that was too short? Or would that have worn out both bearing halves and not just the cap side?

 

What did the same #3 & #4 bearings look like on the block, where they worn down to copper too? Do you know the mileage on the 71 Torino block? I gather you have the "how to rebuild your Small-Block Ford" by Tom Monroe and checked the runout via page 61?
David

 

lol....I have the lame book by George Reid. all the main bearing 1/2 s in the block were good. I layed the crank in the block and put dial indicator on each journal, and spun it slowly by hand. The needle did not move on any of them. I will have to google it to see if there is a more recommended method. The pistons that had the damage on top were 2, 4, and 6, with 6 being the one pictured, 4 being less damaged, and 2 having "lighter" damage. 2 and 6 are both on the side of # 3 main bearing, and #4 piston and #6 are on each side of main #4. Is the damage from detonation? Mileage is unknown, but the block appears to have never been rebuilt. Second pic is rod bearing on # 6, all 8 of them are down to copper, but this one is the worst.

 

How you checked the crank is basically how Tom Monroe does in his book, if you are within .004" all is good for you "budget" build, would "chamfer" the oil holes, then give it a good cleaning.....
As for the block, once you check out the bores and so long as there is no "ridge", you mentioned there is still cross hatch, so again for your build, a good deglazing/honing should be fine. Pistons probably not worth saving, you mentioned about getting a new set anyways, chamfer all oil holes and good cleaning.
I gather you will be checking the rods too and if necessary getting them honed or reconditioned?
Are you going to have anything magnafluxed? What about boiling the block? Have fun with your build!
David

 

Just started reading this. Pistons .040" down in the hole, with an early 302 block and stock pistons? The only time I've seen anything close to that was a 289 that was redone with cheap "rebuilder special" piston.

With squish/quench distance that large I can see why the piston tops look like they do. How do the backs of the bearings look? Detonation will often pound the backs of the upper rod bearing insert and the lower main bearing insert (cap).

I've found that depending what heads and pistons you run you can get away with larger piston-to-head clearance if the heads and pistons have lager squish/quench pads.

Personally I'm more a fan of running big heads (within reason) and a small cam to control the flow. Don't let the heads or intake be a restriction. For the street a high lift, short duration cam with high LSA like an EFI cam works good. It might run out of breath at 4500 rpm but below that it'll pull hard.

 

What's the casting date on the block? Have partial VIN stamped into pad behind intake? Engine assembly date stamped into LF of block where timing cover meets?

D1 blocks were used into 1972 and due to reduced compression, had .029 less milled off deck. That also includes D2 blocks used into '73. I believe pistons were changed in '74, normal deck height returned.

 

D4 block used from 74-77 had a .023 higher deck height than blocks before and after.

 

OMG!!! You mean I waited till Dec 30 to screw up a otherwise perfect year???

How was compression reduced in the '72/'73 models?

 

Lol...all the engines that come over my house to play are weird. Part# D1OE-6015-AA with a 1B18 cast very nearby. 1B22A stamped near timing cover. 1K182960 stamped on top near back edge. I slid a 289 rod and piston (with the rings removed) down a hole and tightened up the cap, and that was .038 above deck. The pin height on that piston was 1.620, so a 1.585 piston in that hole with the 289 rod would be .003 above deck. I discovered that 289 pistons do not clear a 302 crank, but that the 289 rods will fix my deck dilemma with a rebuilder piston. I also slid that piston backwards down every hole until the skirt was at the midway point to see if it fit loosely anywhere. That skirt was 4.000 inches, and had zero wear. all 8 original 289 pistons are flawless....but they dont fit!!!

 

I have heard it said that a good flowing head gets the cylinder filled without the extra duration....and a poor flowing head takes longer and needs the duration. The heads I am using flow 176 CFM @ .4, 178 @ .5, and 179 @ .6 . I found someone with a real flow bench in my area, and @ .05, .10, .15, .20, these heads flow as good as most aftermarket heads, and better than some. I will give away flow at high lift, but get some of it back at both ends.....and who knows, when the piston is hovering in the bottom of the intake stroke and the intake charge finally gets to catch up against a closing intake valve, I have something that flows 47 cfm at .050 lift. It is my winter time science experiment!

 

Mill .035 off the 289 pistons & go for it. Yeah that'd probably require balancing.

The flat top, 5.0 HO LSC engine in the T-Bird had the pistons approx .003 out of the hole. With Trick Flow heads & cam, a awesome runner. Would run low 13s all day long, weight with me 3760.

 

Define "Cheap" rebuild? And what is the purpose of this engine anyway? Sounds like you're trying to build a "claimer" engine for a dirt track race.
Any ridge in the bores might/will break new rings when you start pushing the pistons higher up. END OF GAME

 

Didn't know that myself until I was putting together a 347 stroker one time with a D4 block and pistons were down in the hole. Looked it up. I had to pay more money out to get the block decked again that I wasn't planning on. Leave it to Ford to make odd ball changes.

 

That is a good point, and I did not consider it. The ridge is almost non existent. It can barely be felt with a finger pad, but I cannot feel it with a fingernail. I was planning on honing it with a stone type hone, but even that minimal ridge should probably go away.....otherwise the top ring will be climbing over it alot. The learning curve on that might deal me trouble.