Visit The Dirt Forum for More Information

Author Topic:   Ford S/S Motor ideas welcomed
c21
Dirt Freak

Total posts: 346
posted September 30, 2002 10:30 AM



This is for a #3000 Ford Street Stock running on a High banked 1/4 mile usually tacky clay track with 8" Hoosier Dot tires.

Motor rules are:
4412 on a Performer Rpm Man.(untouched)
untouched OEM heads (Larger valves up to 2.02 OK)
360 cubic inch max
10.5 : 1 Max
roller rockers ok, (no roller cams)
Gasoline only

Lookingfor some suggestions on.....
Head choices (best castings),
valve sizes,
header tube sizes,
bore & stroke combos,
rod lengths,
and cam specs
..we have a good supply of 302 blocks, will they hold up with a 3.5" stroke?


any and all help is very much appreciated,
c21

outlawstock17
Dirt Forum Champ
Total posts: 620
posted September 30, 2002 12:26 PM
347 stroker with gt-40p heads would be my first choice. the gt-40p head is available new from ford and they're pretty cheap. 69-70 351w heads would be my second choice. use the 1.94/1.60 chevrolet type valves in the 351w head. the 2.02's are shrouded by the combustion chamber too much and may be awfully close to touching the exhaust valve.

another good head is the 65 289 head without the thermactor bosses in the exhaust port. it has 1.78/1.45 valves and a smaller combustion chamber than the 69-70 351w. if you use the 65 289 head, don't use valves bigger than the 1.84/1.56 351w valves or they will be shrouded by the chamber too.

go get 'em.

d4490
Dirt Maniac

Total posts: 113
posted September 30, 2002 06:38 PM
Can you run OEM aftermatket heads (N351)?

I would get a good 347 crank kit, look in Muscle Mustang & Fast Ford magazines for some quality suppliers. I would call your cam manufacturer of choise with all the info you can give them.

Get the most compression you can get (how do they chech you?).

outlawstock17
Dirt Forum Champ
Total posts: 620
posted September 30, 2002 06:53 PM
d4490 is right on. i gathered from your post that you had to use factory stock heads, but if you can use the "N" head, do it. i use them and i'll go as far to say that they're the best unported cast iron head on the market today....ford or chevrolet. it's a 10 degree design and you can run up to .650 lift with no notches on the pistons. if you wanted to angle mill these bad boys, there's a ton of meat and the valve angle could be close to zero. they're so effiecient that ford recommends 28-30 degrees of timing.

the N351 head is the real deal boys.


c21
Dirt Freak

Total posts: 346
posted October 01, 2002 09:35 AM
Why is the 3.47 stoke reccomended over just running a 351 (with it's 3.5 stroke)? I relize there is a small weight savings (less than 30 lbs?), but what are the other advantages?

Thanks for the heads up on the N351 heads, gonna check that out.

Our compression is tested with a device they refer to as "the wistle". It is a machine that blows air into a sparkplug hole and calculates the chamber volume at TDC. The displacement is keyed into the machine along with a tempature correction factor. A compression ratio is displayed that is sometimes accurate, but more often than not .... low.


c21

d4490
Dirt Maniac

Total posts: 113
posted October 01, 2002 10:09 AM
Putting a 3.50" stroke crank in a short block like a 302, the rod ratio and the wrist pin location in the piston is a bad set-up. The rod ratio would be to short and the pin hole in the piston would be to high (piston rocking). With the 3.40" stroke kit, you can get rod ratios that are respectable.

outlawstock17
Dirt Forum Champ
Total posts: 620
posted October 01, 2002 03:37 PM
c21, i believe that the weight difference between a 302 and a 351w is closer to 75-100lbs. a 347 stroker is a .030 over 302 block, a 3.40 stroke crank with a 5.40 rod length. i use the keith black piston. if you build one, pay special attention to the ring installation instructions with the pistons. the oil ring has to be modified a little and you MUST balance the reciprocating assembly. i've got one in my street '88 mustang GT and it'll burn rubber forever.

Back to the Archives