I heard that Boss 302 Mustang heads came with 2.23 or 2.19 intake valve. If this is true than when you talk to a company about some heads they recommend something like 1.90 or 2.02 intake valve & say anything bigger would be overkill. I was thinking about Edelbrock Victor Jr's or AFR's. Both company's say the Jr's & 205 would br to much. What do you guys think?
Lonnie your right. It is a Cleveland style head, difference is water ports on the heads for the intake manifold.
These are the specs: Eagle 302 assembly with 9.1 compression, 600 holley, Air Gap RPM, Cam is a 268,276 duration with .500 lift on both sides & 108 lobe sep, GT40 iron heads with a small amount of port work done by a buddy. Worked fine both I want more power. I was told that a good set of heads with 1.7 rockers or stoker kit would be the best way to go. Both would be around the $1300 range. Is this true? What heads are good?
Your cam is not all that wild but will perform in the upper rpm range where head selection to match, is important for best overall power. Staying 302, AFR 165 for street use would be fine. AFR 185 if you were going to wind over 6500. Note that the 165/185 heads have the same exhaust port configuration unless ported. Only the intake is sized differently. Strokeing would be the same thing. It makes your cam act milder so AFR 185 would be fine. Only a serious hi rpm engine would benifit from AFR 205 or 225 level heads. When going the stroker route a 750 carb could be used in a light car. These are ways of looking at an engine combination so you have to settle on what level of performance you want and build for it baseD on the capability of the componants. Boss style heads are not real throttle responsive for street use unless you run real deep rear gears to keep the rpm/airflow up due to the large runner/valve sizes.
Boss 302 heads do have canted valves, BIG canted valves BUT not all Boss 302 Mustangs has Boss 302 engines. Be sure to inspect the heads before you buy - Boss 302 heads are exactly like standard 302 heads as far as water passages and oil returns go but they have screw-in studs, larger ports and larger valves that are angled. The important water passage is the one on the ends of the head where the intake water crossover is. If that one is there then you can do a bolt on to any 302.\ PaulS
I have to disagree with PaulS True Boss 302 Mustangs were built in 1969 and 1970 and all of them came from the factory with the canted valve Boss 302 engine. In the later years there were Mustangs produced with a Boss Graphic package that were simply Mustang GT's with a Graphics package and came with an EFI 302 HO like the rest of the GT's. The Boss 302 heads are nothing like standard 302 heads. They have canted valves completely different intake and exhaust ports. They do share the same cylinder head bolt pattern but will require a Boss 302 style intake as well as the correct headers or exhaust manifolds. This is not a simple bolt on. You can modify the 351 Cleveland heads to put on a 302 but it still requires the unique (expensive) pieces to go along with it. IMO with the vast offering of heads available for a 302 why bother unless you already have all the parts.
i had a friend in high school tell me he was going to change his 302 into a BOSS 302 by putting 351w heads on his 302w block. the BOSS series were a different block from the windsor. much like the 351c or 351m blocks compared to the windsor. i would suspect that the boss heads would cost a great deal more also..
So it was a 351 head on a 302 block. That's why the valve's were so big. Is this why the engine was stout or is that why the GT350 beat it. The heads were more of a con than a pro. What company make good street heads. Brodix, Edelbrock, AFR, etc for miy little set up? Will the alum. heads make a big difference of my iron GT40 heads?
the boss 302 engine started to come alive about 6,000 rpm, which was where the factory rev limiter kicked in. so that was the first thing you disconnected. since this engine wouldnt push water down hill, the second year was when the wide ratio 10 bolt toploader came out with the lower 1st gear to help with standing starts. the valves really were too big. i built one for modified prod class (D). fun ride. let the clutch go at 8,000 and shift at around 9,500. some guys with better head work and titanium valves were going about 10,500.
You have GT40 heads, yet you are looking to make power with new heads... I don't think that just changing your heads is going to give you noticable power. Especially going up in valve size. You are just setting yourself up for losing low end power and needing more gear. That is one thing you don't mention: What gear are you running? You might have plenty of power, but don't have the gear to manifest it properly. Dave Btw: Boss 302s were Cleveland headed (slight water revision). They had 2.24"/1.71" valves in 69. In 70 they dropped to 2.19/1.71 valves to make throttle response a little less soggy. The rods were beefed up Hipo 289 rods and pistons were short Clevelands. Pushrods were unique, but are still readily available. The intake was unique as well. Ford had several versions, and there have been some aftermarket versions available over the years. All in all, there is still a good selection of intakes out there. Pistons are available off the shelf, and tubular makes swap headers for B302 apps... So doing a Boss 302 is not hard, or even expensive. However you lose gobs of bottom end power, lose some engine compartment space, and gain a little weight by doing the swap. It is not worth it IMO. You would get more from an aluminum headed 331, or a lot more from a 408/427 stroker. Edit: The highest gear ratio you could get in a Boss 302 was 3.91! 4.30 was an option. The only tranny was the wide ratio TL with the 2.78 first gear! Your average 302 car had a 7:1 final drive in first... The Boss 302 had up to 12:1 ratio in first! (and they still had no throttle response!)
The gear is a 3.55, what is a 408/427 stoker? A 351 block stroked? I have only heard of 331, 342, 347 stroker kits for 302's.
Also the Boss 302 blocks had 4-Bolt mains on the center 3 crank journals as well as threaded core plugs in the block.
3.55 is a decent gear. You could go steeper, but your economy would suffer greatly. The car would feel better, depends on your priorities. The 351w strokes to: 393... Aftermarket crank, stock rods, 302 pistons. Cheap stroker. 408... Aftermarket crank or 400m crank, wide choice of rods, unique pistons. Popular for middle of the road pricing, easy building, and durability. 418... A little more money/work than 408, a little less durable. 427... A maximum effort 351w stroker. Low rod ratio, lots of block mods, short piston with less stability. A really bada$$ engine, especially with good heads. I have seen one in a 65 Stang with Cleveland heads that was just insane strong. Have you 'supertuned' your current combo? You might have gobs of power hiding in there.
