The exhaust ports have extremely wide floors which are too wide for most headers... so they are drilled for two different bolt patterns. The "AR" specific bolt pattern has the bolts offset, and was adopted by a lot of head porters who did serious exhaust work on later heads.

They are probably a decent head, but "AR" specific headers aren't that easy to find anymore. There's also been a lot of research and development since then. I don't have any direct experience with them, but sure did lust after them when they first came out.

Good Luck!

If you get the chance to bring it up in conversation, that would be great
but don't go burning a long distance call just for this. I came across a
new-in-the-box pair for $500 and the price was too good to pass up. I'd
like to use them on my "project cheapskate" upgrade of my daily driver 5.0L,
instead of the spare DOOE castings I have. A co-worker wants to buy those
for $100 so I'm only out $400 for the aluminum heads and I don't need to
mill and drill them for studs and guide plates.

>These were the very first aftermarket heads available for the small block
>ford.

Except for the exotic stuff like the Gurney-Weslakes. It's a shame those
never made it into Ford's catalog. A local guy has a complete G-W set up
in a street rod. He runs the single 4 barrel intake manifold that was
developed for putting the G-W's in Mustangs but he also has the Weber/injection
adapters. I've got some pictures and articles that I'm scanning in. Neat
pieces. I think they pre-date the small block tunnel ports.

>They came out around 15 years ago and were sold as "AR" heads by Alan Root.
>They were WAY expensive in their day because they were the only game in town.
>These heads were later sold as the "J302" under the Motorsport name.

Yes. I found an article written when they first came out as the AR's.
They were developed for Root by Ken Duttweiler. The chambers are 58 cc's
and they nominally use 1.94"/1.6" Chevy valves. The assembled SVO J302's
came with 2.02" intakes. There's no provision for exhaust heat or EGR.
170 cc's intake port volume, 60 cc's exhaust. Dual exhaust header bolt
patterns for headers up to 1 3/4". Raised valve cover rail for roller
rocker clearance. Machined for screw-in studs and guide plates. Solid
bronze guides, grooved for oil seal retention.

Looking at my set, the intake port measures 1 1/4" wide by 2 1/16" tall
which I think is a bit larger than a DOOE's ports. It's certainly larger
than my C90X intake port, which only measures 1" wide by 1 13/16" tall.
The exhaust ports are much larger than the DOOE's and look quite nice.
Some of the studs go into the water jacket. Is that common with aluminum
small block heads?

>The exhaust ports have extremely wide floors which are too wide for most
>headers... so they are drilled for two different bolt patterns. The "AR"
>specific bolt pattern has the bolts offset, and was adopted by a lot of
>head porters who did serious exhaust work on later heads.

That is a point of concern for me. I have a set of the Motorsport 1 5/8"
stainless shorty headers on the car that I'd like to keep but I don't know
what the header port dimensions are. The exhaust port measures 1 7/16"
wide by 1 5/16 tall. It looks like a 1 5/8" tube would cover the port but
looking back through my old Motorsport catalogs, I see they had a specific
shorty header for J302's.

>They are probably a decent head, but "AR" specific headers aren't that
>easy to find anymore. There's also been a lot of research and development
>since then. I don't have any direct experience with them, but sure did lust
>after them when they first came out.

Searching the web, there do seem to be a number of J302 compatible headers
still available but they mainly look like 1 3/4" long tubes. Fel Pro carries
a header gasket for the J302's. It's p/n 1486 for J302 & K302 (Dual bolt
pattern, stock Ford and inline spread bolt Dart & TFS) Port Size: 1.40" x 1.40".

They look like a decent head but may not really work out for my daily driver
application. I think I'll see if any of speed shops in town have Motorsport
shorty headers in stock and do a fit check.

They'll work fine for your daily driver. The 170cc intake port, along with the 58cc combustion chamber will be about right. If you can't find a set of "AR" specific headers, you can modify yours by grinding them out to size with a die grinder. If the header flange and tube look too thin for that, building them up with a few weld beads will solve the problem.... just don't get carried away and weld up the bolt holes.

Good Luck!

Mike, your probably right. A bit of weld ought to do the trick.