289 Crank in a modern 5.0 block?

chuckbrandt · #1 (**permalink**) 04-01-2003, 11:51 AM

Does anyone know if I can put a 289 crank into a modern '86-up 302 block? My concern would be the one piece rear main seal - are all the cranks dimensionally the same?

My 289 broke it's cam and may have trashed the part of the block the cam bearings go into, so I'm thinking of a std bore block I stuff my other guts into.

Thanks for any advise,

Chuck Brandt

Rick Parker · #2 (**permalink**) 04-05-2003, 10:13 PM

If you want to maintain originality just get a core block from a volume engine rebuilder and go from there? They are also on Ebay quite regularly, or if you want a small increase use a run of the mill 302 shortblock. Most other parts are interchangeable.
The 302 bore is the same but the rods in a 289 are longer, the same length was used in the Boss 302 to improve rod angle on the 302 stroke (3.0" vs 2.87).

Rick

Excaliber · #3 (**permalink**) 04-05-2003, 10:44 PM

Hmmm,,,,interesting question. Is the 302 bigger bore, longer stroke or a combination? Either way, your crank or pistons won't fit.

One big advantage the 302 block had was a deeper cylinder wall/skirt area. This kept the pistons from "rattling" around at high rpm, making the engine more stable. So the design of the block was NOT just bigger is better, it's stronger too.

Ernie

Satanpez · #4 (**permalink**) 04-06-2003, 12:28 AM

Excaliber, can you show that any 302 ACTUALLY had the deeper cylinder wall?

I've read somewhere (I believe Dave Williams webpage on the net) that the 302 blocks weren't actually built that way. They WERE somewhat designed like that as drawings of the block in 1967 showed the 302 should have a deeper skirt. But actually measuring countless blocks showed that 302 and 289 blocks were the same.

I'm not an engine builder so I haven't measured any myself, but have read that it's a common myth.

The bore is the same, the stroke is different.

-steve in nj-

I hope this post makes sense as I'm half asleep.

Satanpez · #5 (**permalink**) 04-06-2003, 12:29 AM

Oh yeah, and different year 302 blocks are supposed to be better. I believe earlier (67 through early 70's) and then mid 80s+

-steve in nj-

Excaliber · #6 (**permalink**) 04-06-2003, 12:35 AM

I do know the modification was to address the piston slap problem. Longer bore would make the problem worse without a redesign of the piston skirt or bottom of the cylinder. So the mystery remains exactly what the difference is.

Ernie

chuckbrandt · #7 (**permalink**) 04-06-2003, 06:04 AM

It turns out my 289 block was okay afterall, but a very strange thing happened. I had found thin pieces of cam bearing lying around loose (and the cam had broken) so I assumed the cam had been grinding into the block. In fact, I found some bearing material in all the cam bearings when I got it all torn apart. My only conclusion is that one of the cam bearings "de-laminated" itself. The silver layer came off the copper looking layer! Can you believe that? Anyway, thanks for the input.

CDB

Excaliber · #8 (**permalink**) 04-06-2003, 10:46 AM

Ha ha, what do you mean never mind? Now we got a real mystery going! What caused the failure? Oil starvation? Age? Dig a little deeper here!

Ernie

Rick Parker · #9 (**permalink**) 04-06-2003, 01:01 PM

aaaaaaarrrrrrrrrrgggggggghhhhhh

and a 427 SO in the bio ????

wasssupppp?

Rick.....

chuckbrandt · #10 (**permalink**) 04-06-2003, 03:06 PM

Hey Fellas,
I didn't necessarily say the 289 was for or in a cobra. I just thought someone would know the answer to the 289 crank in a 302 roller block question.

The 289 is in my '67 galaxie that I inherited from my Dad. It has supposedly only 50K miles on it, and looking at the internals of the engine I tend to believe that. Recently it ate it's timing chain gear (old style aluminum with nylon). During that event the camshaft broke. And a couple of valves smacked pistons. I don't think it was a lubrication issue, everything else looks so good in the engine. The crank is nearly perfect and even the cam chunks look good. But this whole cam bearing coming apart is a new one on me.

The 427 SO is a pile of parts sitting in my office (mostly NOS) that will go in my cobra when it comes. Besides the Galaxie I have a '66 F-100 and a '74 Bronco. My game is trying to keep them all running spending less each month than my wifes car payment.

Anyway, that's all I know about that.

Chuck

Excaliber · #11 (**permalink**) 04-06-2003, 03:20 PM

My daddy used to say, in reference to cars:

"If miles don't get you, age will".
Like that camshaft gear. The plastic gets old and hard and cracks eaily. Typically you "loose" one in the morning at your house. The engine is cold, not in perect tune, it misfires just a "little" and BAM, there goes the gear!

The cam bearing wear is also indicative of "time" and lots of "cold starts" over the life of the motor. Most engine wear occurs on "startup". The outer surface of the cam bearings were just deterorating from "age". I'm kinda surprised the cam broke though, don't know what to make of that!

"Elementary Dr. Watson......"

Sherlock

chuckbrandt · #12 (**permalink**) 04-07-2003, 05:48 AM

Yes, I knew all about those nylon / aluminum cam gears and a good steward should have replaced them when I first got the car. But I blew it.

The cam breaking really threw me too. I just had not heard of it. In fact when I first tried to repair the car, I just put in a timing set and close it back up. It wasn't until I tried to start it that I noticed anything wrong.

Actually it might be a chicken and egg thing. Because the break was just in front of the second journal the cam could have tipped up loosening the timing chain to start the teeth shelling on the cam gear. The 3rd journal is the one that the bearing delaminated on, a chunk of it could have gotten wedged tightening up the back part of the cam. I think cams are pretty hard and brittle aren't they? I should also mention it is a manual trans car, so the engine continued to turn over for a few seconds until I realized what had happened.

CDB