BOSS 302 Rod Length Question
 

I'm building up a crate BOSS 302 block (the accepted S/SS one) for GT in my 68 Mustang coupe. I want to claim the BOSS 302 from either 69 or 70, but NHRA has issues with rod length. On the 69 blueprint, the BOSS is listed with a 5.155 rod length while the standard 302 has a 5.090. Turn to the 70 blueprint and only 5.090 is listed for 302 with no seperate BOSS up on the top. The 290HP blueprint specs are the same on both pages, so the BOSS engine is mentioned for both years but not named in 70.

"Independent Research" tells me that both the 69 and 70 BOSS 302s had 5.155 rods, so I assume NHRA made an office mistake and omitted the rod length info for the 70 BOSS from the blueprint.

Being the smart *** I am I had decided to build using the easier to find 5.090 rods and present the blueprint to NHRA if they ever called me on it, but after the $1000 fine deal in Ennis, I'm rethinking my strategy...:o

Here are my options as I see it:

A) Build as I had intended with a QF 780 carb and bracket race it this season. Rebuild with 5.155 rods over the winter and go GT/ next year. I don't have a trailer, so I will only sit out two or three Lucas Oil races.

B) Switch to flat top pistons and a Holley dash number carb, claim the 68 260HP Cougar engine and run GT/ this year. Would have to wait for the pistons.

C) Build as intended and claim the 1970 290HP 302 (with no reference to BOSS) like the blueprint says and take my chances with the NHRA tech guys.

Any thoughts on this? And yes, this is a rookie mistake...

Dale

Re: BOSS 302 Rod Length Question
 

69& 70 Bosss did use the longer 289 length rods, so to use the shorter rod with Boss configuration pistons would require custom Non legal pin height pistons to get the deck height in spec.
By the way, what "crate" motor does NHRA have accepted for S/S?

Re: BOSS 302 Rod Length Question
 

If you check the accepted rod and piston list it shows the 289 boss 302 with the same height.You are going to change the heads if you go to a 302 non boss right.

Re: BOSS 302 Rod Length Question
 

Rory: Not motor, block. The Accepted replacement block for the 302 Ford is the BOSS block M-6010 legal in S and S/S.

astikhossw: AFR 1399 58cc heads. Accepted replacement for Super Stock.

The rod/piston combo is the issue for me.

5.090+flat top= 302/230hp(Mustang) or 260hp(cougar) in GT
5.155+domes=BOSS 302/290 or 305hp in GT

My 090 rods are really nice Crowers and my domes are middle of the road Keith Black.

EDIT: With GT based off the heaviest car available for the year, that's 3001 lbs. for the 68 Mustang. With the HP ratings of the motors I can build, it works out like this:
290hp: GT/EA
305hp: GT/DA
230hp: GT/KA
260hp: GT/HA

The K and H builds are at the top of their weight breaks and E and D are mid or low. BOSS is looking more like a hard sell.

Dale

Re: BOSS 302 Rod Length Question
 

You just built a great bracket racing engine.
Even if there is a misprint in the blueprint sheet, building the engine to that spec will get you thrown out.
All Boss 302 engines have the 5.15" length rod.
They were also stick shift, no automatics were ever built.

Re: BOSS 302 Rod Length Question
 

I'm a little confused. If you are going to use the AFR heads it will never be a Boss 302. The Boss 302 heads are what make a Boss a Boss and there are no aftermarket versions of the Boss head. The NHRA classification guide does indicate with the && notation that the AFR1399 head is acceptable on the 302/290, but that makes absolutely no sense and is an error IMHO. All the aftermarket Windsor SBF heads are inline valve heads while the Boss 302 heads are canted valves. The Boss was essentially a 302 Windsor with small chamber, large valve Cleveland heads. Claiming a Boss 302 with an inline head is just wrong, heresy in fact. Finding real Boss 302 heads will set you back a bundle.

That being said, since you are talking about SS or SSGT, if this abomination is really legal the only thing you will gain over the 302/230 combination is the 780 Holley carb and some compression since you can use a domed piston. But in any case, it damn sure isn't a Boss 302!

Re: BOSS 302 Rod Length Question
 

All Boss 302 in the NHRA guide uses canted valve heads.
295 hp rating in GT.
Shipping weight for a´68 Mustang 428 hardtop is 3241 pounds.
GT/F at 3267 pounds.

Re: BOSS 302 Rod Length Question
 

OOPs 3369 for the convertible. Thought it was the heaviest 302. It's the heaviest gas engine offering of that model and year.

That puts the 302/260 Cougar engine at the bottom of GT/J close enough to move to GT/KA.

I think bracket racing what I have with a Holly 600 that would be legal on the 260 hp Cougar for this season and switching the pistons to flat tops over the Winter for GT next year is the best way to go. Carb specs for the 260 Cougar are 1563 1563 1250 1313 the Holly 80540-1 is a 600cfm carb with a throttle bore of 1563 and a venturi of 1229.

EDIT: The 68 Cougar 302 is 230 HP, but does have the Holley carb.That puts it at GT/MA with the heavy body weight of the convertible. The actual car, 68 coupe 302 is 2874. That's 495 lbs lighter than it's classification factor. Is that right? This is favorable, yes?

Dale

Re: BOSS 302 Rod Length Question
 

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

Re: BOSS 302 Rod Length Question
 

I think Nick Morris from Div 3 ran the 68 302 4 bbl combo a few years ago with the AFR aluminum head in GT/MA