[VinnieVega]

Hey guys, I was recently given a 1969 327 (618 block) and I'd like to rebuild it as a 302 that will eventually find its way into a 1969 z28. I plan on making 450HP at max with this motor, looking as factory as possible with an offy cross ram intake, and fuelie heads. Right now my main concern is which crank shaft I should be using because I do have the medium journal block, and its hard to locate a medium journal forged 3.000" crank. My options are a nodular iron 4.3 crank that has been modified to fit the 2 piece seal ($225) or Use a small journal forged steel 283 crank with bearing spacers (I believe these are the ones http://www.race-mart.com/items/products/callies/list42.htm) for a total of 175+ the cost of a redone 283 crank. I could also use the eagle forged crank that will drop right in but thats around $600, and I think is a bit over kill for this application. Old timers / pros WHAT SHOULD I DO!

 

[VinnieVega]

A medium journal 327 crankshaft is quite rare also. You may be able to use it as a bargaining chip for a 302 crankshaft.

Now that you mention it I guess it is pretty rare.

 

[VinnieVega]

First off, I would not used bearing spacers. Its done but there are heat transfer problems doing this.

Second, if you are going for a custom crank , why not go for a forged drop in assembly and get it done right the first time. These nodular cranks are good and do live well but the choice is there and yours to make for a few dollars more.

Third, are your sure your block will not need line boring? Now is the time to think about all this .

Ok, spacers are out of the question in that case, I was kind of suspicious of them in the first place.

Even though its a very clean motor The block is defiantly getting completely redone, Line bored and punched out, as well as what ever else it needs. These are added costs that make budgeting the parts a little bit harder. I need to call the machine shop that I have picked out fairly soon (Its in NY and I live in NC) and get a price on all of it.

I know that all the orignal 302's came with forged steel cranks. I cant say that im a complete and total purest because I'm not starting with a numbers matching z/28 but I do like to keep things as original as possible. The difference is about $300-350 to use the eagle, minus the cost of the spare parts I wont be using on this motor and it seems pretty reasonable, and the piece of mind being able to say that I have forged internals makes it seem cheap at the price at the end of the day.

 

[VinnieVega]

I'm not a fan of bearing spacers for the same reason Don states, the heat transfer is critical into the mainwebs. However a lot of guys run them with no issues, many on this site and maybe they'll chime in with why they like them.

If you do go with spacers there is only one manufacturer that I would even consider, King. They make their spacers from hardened steel tube and not modified main bearings. Comp Cams, Jegs, Summit, Manley and all others are simply soft modified main bearing with the full grove running through them. The groove serves absolutely no purpose on a spacer, but verifies that you are dealing with a very cheap excuse of a spacer.

The Eagle crank would be a good way to go. I also like Chris (Smits 67) idea of a small journal build. It's easy to find the parts and it's the least expensive and least troublesome way to go. Just use good SJ rods, which there aren't many as most SJ rods were inferior in strength and quality (small cross section beam, very little material on the big ends and very small diameter bolts) other than 67 SJ rods or aftermarket.

We'll the reason I want to use this block is because it shares the same casting as a 1969 302, so it adds a little flare to what I'm trying to get done. Also this block was given to me in pretty excellent condition, It would be hard to find an even older block in such good shape.

 

[VinnieVega]

If it isnt the numbers motor for the car,why not build it better internally?A forged 350 crank would rev just as hard as the 302 and make more power.Since you are even looking into non original setups like main spacers,it is obvious that you arent looking for something that can be torn down and be confirmed as 100% original.Do justice for the Z/28 name,and make it as fast as possible by making your date/casting correct 302 into a bigger and badder monster then the factory ever did.Even if it were torn down,it is just as believeable to a future buyer that and original 302 was rebuilt as a 350 as it would be to belive that an orginal 302 was rebuilt with main spacers an a 283 crank.

Good luck.

Im not interested in a 350, I have a 357 built in my garage right now that should make over 400hp. I have a 1970 Chevelle SS with a 402 bored .030 over that makes plenty of torque. I want to build a 302, Im not saying that I want to trick anyone into believing its an original DZ motor. I just want something different. The z/28 name is justified in its own right, and thats with the 302.

 

[VinnieVega]

I was going to leave it up to my machinist to help me decide on what pistons to run, I was thinking 10.3-10.5, with a set of 64cc chamber heads. Currently I have 461s that I'm thinking about using but I'm still searching for some cheap 186/401 cores. I don't think that flat tops will give me that with the heads that I want to run. What pistons should I use in that case? I'm also looking into the 140 cam. From what I read GM offered it in a package with the cross ram intake and headers, so I was under the impression that it would be a good cam to use for this engine but I've also read on these forums that its not such a great cam to use with lower than 12:1 CR. I'm not looking for a huge lopey cam, just something mild.

 

[VinnieVega]

One word of advice if you plan on running a manual trans, I assume with the short stroke you are, be very picky on your flywheel selection. This is no place to save $$ you'll need a very good quality flywheel to spin it high without worrying about it failing. I'd also run a scattershield. I've seen what happens when the flywheels fail and come through the floor with GM aluminum bellhousings. The flywheel I pulled out of my 68 scared me pretty bad when I saw all the stress cracks propogating in it. It was an uncontained failure waiting to happen. Same for one I pulled out of my 69Z and that car with it's 302 saw 8K plus all the time, but also had a scattershield, the 68 did not. It only had the 621 aluminum bellhousing. Just stay safe!

Thanks for the advice! I'll run the scatter sheild :thumbsup:

 

[VinnieVega]

Vinnie for what it's worth TRW thick spacer main bearings are MS3110P for SJ crank in MJ block and MS3063 for MJ crank in a 400 block. There are others who make these bearings, but they are all around $200 a set.

Ok, thanks but I think I'm going to just buy the eagle crank to avoid any of the problems mentioned earlier. It will end up costing me another 200-250 to go with the steel forged MJ crank brand new over a 40 year old turned SJ crank.