Boss 302 crankshaft question

Mark Worthington · 04-21-04, 10:49 PM

I have an opportunity to buy a Boss 302 crankshaft for $100 (maybe a little less). This is a forged steel crankshaft good for as many horsepower and RPM as I would dare put into it. I am told it is in new, unused condition. Here's the catch - the rod journals have been turned to Chevy size (2.100 inches). As I understand it, these journals are slighhtly under-sized (stock 302 rod journals are 2.123"), but that rods are available (e.g. Crower Sportsman for $570).

I guess this effectively increases (slightly) the rod length (which improves rod ratio which is a good thing) and also results in slightly improved friction characteristics due to the smaller journal diameter and bearing area.

Aside from the oddball rods needed, are there any other problems with this crank? Any reason I should stay away for $100?

Kevin M · 04-21-04, 11:00 PM

If it uses Chevy Rods, then it uses Chevy Pins which means new pins and of course it will need new pistons. If you are building the motor from scratch, this won't matter.

You have a lot of choices with rod lengths for Chevys. 5.400" would be reasonable for this motor. Just make sure your piston supplier is told about all of this.

By the way, a lot of aftermarket Ford cranks are made for Chevy rods these days. It is not at all unusual.

Kevin

VICTOR A · 04-21-04, 11:05 PM

I am using a Boss 302 crank shaft in my engine. My unit is a NOS piece I have had from my owning a Boss 302 and always buying spare parts. I am using a Explorer Roller Block with the one piece rear main seal, so I cut off the flange by the seal surface on the crank and also installed a stainless speedy sleave where the rear main seal rides as the Boss Crank has slight grooves cut in the seal area because they used a rope seal on some. The Neoprene seal (one piece or two piece) works better with the grooves covered. I am using standard Ford dimention crank. I would have the crank magnafluxed and also ringit with a small hammer, as many of the Boss stuff was run pretty hard and they are 34-35 yrs. old [img]/ubbthreads/images/graemlins/smile.gif[/img]

Vic

Mark Worthington · 04-21-04, 11:27 PM

Well, this would be an opportunistic purchase for that long-rod aluminum-block 321 (4.125" bore by 3.000" stroke) that I can see myself building a few years down the road. Except I've been thinking about doing it with a flat-plane crank in an effort to get that Ferrari sound! [img]/ubbthreads/images/graemlins/laugh.gif[/img] So, yeah, I could assemble the pieces over time. Vic, can you describe the "hammer test?"

Kevin M · 04-21-04, 11:39 PM

Mark,

Metallurgy has come a long way in 40 years. 4340 today is much better steel than it was in the 1960s. If you are planning this for an engine with a $4,000 block that you intend to go all out on. You can get stronger cranks made today. There is not a lot of nostalgia value in it being a real Boss 302 crank if it needs Chevy rods. If you are going to put it in an engine like that, I would seriously consider a high quality new crank instead.

Kevin

Rick Muck- Mark IV · 04-22-04, 08:10 AM

If you don't want it, I will take it.....and I'll go $105.00 so you can have some profit!

Rick [img]/ubbthreads/images/graemlins/grin.gif[/img]

VICTOR A · 04-22-04, 08:43 AM

The hammer test consists of taping each crank cheek with a small hammer (usally a ballpein) and the crank should ring like a bell, a suspect crank will produce a light thud or clunk sound. I have read that some of the old time racers (Garlits etc. ) believed more in this than magafluxing. If you plan on building a high buck engine I would surely use a crank made from modern materials and get som the benifits of knife edging, etc. I was fortunate with my crank as it was new in the box and I just made the mods as I described, and by the way my engine runs fine.

Vic [img]/ubbthreads/images/graemlins/cool.gif[/img]

VICTOR A · 04-22-04, 08:48 AM

Here is a pix ofmy engine with the Boss Crank installed.

Vic

Gary Gibbs · 04-22-04, 11:13 AM

Does the Boss crank use Cleveland sized mains of Windsor sized mains?

Kevin M · 04-22-04, 12:27 PM

The Boss 302 was used in the 302 block, not the Windsor or Cleveland 351 blocks. It uses 302 (2.25") Mains.

Kevin

scott · 04-23-04, 10:31 AM

If my memory serves me well, the 1969 boss cranks were somehow different than the 1970 boss cranks...could be a cross drilling issue or perhaps something else. I do recall the '69 cranks being more desirable but could not tell you if the forging numbers were different. Anyone else know?