BOSS 302 Rod Length Question

[FED 387]

its my understanding that Ford connecting rods are the following lengths
289---5.1550 in
302----5.090 in
Boss 302---5.150 in
you obviously must have the correct piston pin location to be legal

[astikhossw]

How did a inline valve head become legal for use over a canted valve boss 302 head with the big intake and exhaust valves and why use a inline over a Boss head in super stock.

[SSDiv6]

Originally Posted by astikhossw

How did a inline valve head become legal for use over a canted valve boss 302 head with the big intake and exhaust valves and why use a inline over a Boss head in super stock.

It is an obvious typo by NHRA.
They assumed the Boss 302 engine is a Windsor engine.
It should be the same head as the Cleveland engine; Edelbrock 61607.

[magnumv8]

since the Edelbrock # 61607 is an acceptable S/SS replacement head for the '71 351 Cleveland, if it was submitted to be used as a legal replacement for the earlier Cleveland motors it might be accepted for them also......it never hurts to ask.....

D L Rambo......Stk 1300

[FireSale]

Originally Posted by SSDiv6

It is an obvious typo by NHRA.
They assumed the Boss 302 engine is a Windsor engine.
It should be the same head as the Cleveland engine; Edelbrock 61607.

Maybe, but they got the rod length right in the 69 blueprint and the Accepted Parts list right. They have 289/BOSS 302 with 5.155 rods and 302 (Windsor) with 5.090 rods. I have a parts interchange book that supports the rod lengths I listed.

Should have read it cover to cover before I started this thing. Live and learn.

The BOSS 302 block is an accepted replacement for S/Stock. With the true BOSS (tunnel port?) heads hard to find, my guess is that NHRA approved the AFR head for BOSS 302 builds to allow access to the mechanical cam and big carb that was on the stock BOSS 302 in 69 and 70. You could build an almost BOSS 68 Mustang and run it in S/S, not GT.

But then that's too logical...

I'm currently researching everything I can find on the 68 Cougar to make sure the Holley carb they list isn't a typo. That's a 390 carb, and I need to verify that it was available on the 302 Windsor 68 Cougar.

Now I know why t here are so many bracket cars at the track these days. Just build it and race. Box or No Box. Nothing complicated like c.c. ing heads or micing a throttle bore.

Dale

[Bill Harris]

Wow, there is a lot of incorrect information out there on this particular engine.

The 69/70 Boss 302 was not a tunnel port engine. The 302 tunnel port is a completely different head than the Boss 302 and was only used for Trans-Am racing in the late 60's. It was not very successful and it's failure to perform led to the development of the Boss 302 engine for Trans-Am racing.

As I stated earlier, the Boss 302 was a Windsor 302 block with heads that were essentially the same as the high performance Cleveland heads; canted valves and huge valves and ports. They were not true Cleveland heads since the water jackets were different between the Windsor and Cleveland engines. Magnumv8 suggested that the Edelbrock 61607 head should be a replacement for the 69/70 Boss 302 and that is not correct. If you tried to put a Cleveland head on a Windsor block you would have major issues with water passages. The Cleveland feeds water to the radiator from the heads through the block while the Windsor feeds water to the radiator from the heads through the intake manifold. While the Cleveland heads will physically bolt onto a Windsor block, they won't work without modification to the water passages. Ford actually published instructions on how to modify Cleveland heads to work on Windsor block as far back as 1969 (Muscle Parts Catalog). The modification is not trivial as it involves blocking water passages on the head surface and drilling water passage holes in the intake manifold surface. It can be done, but it isn't pretty.

Bottom line is that if you want to run a 69/70 Boss 302 combination, the only real head to use is the OEM C9ZE-A iron head which are very rare. If you are a purist, the NHRA specs are actually wrong on the valve size as the '69 heads had a larger intake valve than the '70 but NHRA says they are the same size at 2.235". The '70 head was actually in the 2.16" range.

There is a ton of information on the 69/70 Boss 302s on various websites. The important thing to note on this forum is that the Boss 302 was developed to compete in Trans-Am road racing, not for drag racing, and the engine has never been particularly good in drag race format. I think it has potential, but the massive ports argue for massive RPM which introduces its own problems.

When Ford brought out the "Boss 302" block, it added confusion to the whole mess. The original 69/70 Boss 302 block was unique in that it had four bolt mains and more material in the crank web than the usual 289//302 block. The re-issue of a Boss 302 block, which is really just a beefed up 8.2" deck small block casting was a nice addition to the racing world, but building a small block Ford engine using a "Boss 302" block doesn't make the engine a Boss 302.

[FireSale]

Bill: Thanks.

The reason I bought the, um, Ford Racing Replacement 302 block was out of frustration in finding a quality 302 block that I could trust. The 4 bolt mains and extra material were the selling point for me. I knew I could take this block and build several engines, including what NHRA called a BOSS 302. I have a Chilton book that covers 68 Mustang and Cougar and the Cougar did run a 302 (not BOSS) with a Holley, but they claim it was a 4160. When I can be sure of the carb specs, my engine will be the 230 hp Cougar. It has a larger carb than the 68 Mustang 302/230hp.

Dale

[Hans Olsson]

Originally Posted by Bill Harris

This is not true. The inline aftermarket heads are listed as acceptable for Boss 302 engine in SS for 1970.

I stand corrected, thanks Bill.

[Bill Harris]

The 68 302 with the Holley is legitimate and is a good combination. Based on the parts you already have it would certainly be the best way to go. As someone already noted, Nick Morris ran this engine in SSGT for several years and it was a stout runner. He has since switched to the 2010 352CJ in his Mustang, but he and his dad probably know the 68 engine as well as anyone out there.

[Bill Harris]

Originally Posted by Hans Olsson

I stand corrected, thanks Bill.

What I find even more odd about this particular situation for the 1970 Boss is that while the classification guide shows that the inline head is legal there is actually a horsepower adjustment for the engine in SS when using aftermarket heads. It went to 305 HP on Jan 1 2012. That either says that someone actually built such a thing and went fast invoking an AHFS hit (highly doubtful) or the NHRA just slapped some number on it for the hell of it.

IMHO it is just flat out wrong to have the "&&" on that engine at all.