Diputado

Hi all,

I recently bought a fairly hopped-up '65 with what I thought was a 289 (block and heads) running a late-model 302 crank, rods and pistons. This was based on the fact that the harmonic balancer has a E4TE part number, that is, a 50-oz. 302 (or 5.0) balancer. Well, after 3 months of trying to track down the guy who actually built the engine, today I found him. He told me that the ENTIRE engine is '65 289, and that he used the late model balancer because the original (28 oz) was "damaged". I then asked him what type of flywheel it had, and he told me it was a 10.5 inch flywheel from a '68 model 390 engine (also the transmission is a Top-loader from same car as the flywheel). He claims to have run this combination for nearly 2 years with no problems, and I currently have no noticeable vibration problems, either. HAS ANYONE EVER HEARD OF SUCH A COMBINATION?? I did not think you could "mix and match" these reciprocating parts with any chance of good results. Is it a sheer coincidence that the 390 flywheel "balances"with the 50-oz 302 balancer AND 289 crank and pistons???

Starfury

You can't just throw a late model 5.0 crank in a 289 block. The early block is designed for a 2-piece rear main seal; the later 5.0's use a one-piece seal.

Use of a 50oz imbalance balancer on a 289 rotating assembly would create a horrid vibration that would get worse with rpm's. You'd notice. I don't think a 390 flywheel will bolt to a 289/302, but I could be wrong. The transmission would not work without a special pilot bushing to compensate for the shorter input shaft on the FE transmission.

I vote that your "engine builder" is full of it. I bet you have a 5.0 block and rotating assembly. No idea about the flywheel. If you can get a casting number off the flywheel and block (behind the starter), and a tag number off the tranny, someone (is 2+2 GT around?) can identify them.

Diputado

Thanks for the comments, Starfury. Yeah, already confirmed that the block is definitely a '65 289 (as are heads) back a few weeks ago when replacing the intake. What's in doubt is that lower end. The dude seems "honest", at least he had no reason to lie to me, since he sold the car to someone else 2 years ago, and then later I bought it, and he wasn't liable to me for anything. On the transmission....however...he SAID it was out of a '68 Mustang with a 390 (same one where he got the flywheel), but the housing number is RUG-AE2 and the tail housing is C7OR-7A040-A. I checked a couple of websites, and according to that info, this tranny is from a '69 Mach 1 or Shelby with a 428 CJ or 429. Maybe they also came out in the '68 390..?? I don't know. Output spline count would be different, though (28 vs 31). On that line, I asked about the driveshaft, and he "said" it was standard 65-66 289 version. Rearend is a 9" out of..again, he "said"...a '69 Mustang. More questions than answers....!!

Starfury

David Kee's website supports your toploader tag code ID. Maybe the builder did use the adaptor pilot bushing. It's certainly a good tranny, similar to the close-ratio small block version I have in my '67. Like I said, the input shaft length is the main difference.

Still, you can't put a late-model 5.0 crank in an early block unless you machine the block for a one-piece rear main seal. To be sure, you'd have to inspect the rear of the block, or pull the pan and inspect the crank.

Diputado

Yeah, that's my point...I tend to think the guy is telling the truth about it having a 289 bottom end. Like I said, I specifically asked him why he used that 5.0 balancer, and he said it was because the orig. 289 balancer was damaged, and he simply replaced it with the 50-oz unit. He also said he "balanced" the crank and rods, but I didn't really dig into just exactly what he meant by "balancing". He's supposed to be looking for some papers and stuff he has at home about some of the parts he used, like the cam specs. He remembers it was a Crane cam, and he "thinks" it has .508 lift and 292 duration, but is looking for the receipt,etc. to confirm. I once had a 289 running a Crane cam with .500 lift/300 duration, and it idles and sounds the same (yeah, I know you can't go by that). Next time I talk to him, I'll dig deeper into the balancing issue. I've driven it several times, and it seems to run fine (apart from overheating!), although I do notice a very slight vibration when you're parked and rev it to around 1500-2000 rpm.