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Author Topic:   will a 307 crank fit in a 350 block or vise versa
ray14
Dirt Full Roller

Total posts: 67
posted October 03, 2002 09:22 AM
hello i have a few questions i have a great little 307 not sure what the stroke is but i thnik they have a shorter stroke than 350 i was wondering what the results would be bye putting 307 crank in 350 block or 350 crank in a 307 block.i have both and just experimenting.thanks for all info on this

c21
Dirt Freak

Total posts: 346
posted October 03, 2002 10:49 AM
a 307 uses a 3.25" stroke (same as a 327), so a 307 crank in a 350 should give you a 327.

a 307 has a 3.875 bore, using a 3.48 stoke crank (from a 350) would give you something like 329"

c21

ray14
Dirt Full Roller

Total posts: 67
posted October 03, 2002 11:02 PM
has anyone ran those combinations before and how much would it change the performance of them both thanks for the info c21

birdcage
Dirt Full Roller

Total posts: 57
posted October 04, 2002 03:02 AM
I've used several of them. Limited late models used to have a pound per cubic inch rule. A 309 cid worked out be be at minimum weight. A 302 with a 3.00 stroke didn't have the torque to come off the corner so I used a 311 (3.905 bore x 3.25 stroke). Then they made a rule change and have three wieght classes a 0-336 337-362 363-388. So I used a 3.905 bore and a 3.48 stroke I had alot more torque than a 3.25 stroke 331. The engine I had (still have) made 515hp and 445 torque. I really liked the motor real smooth. These work a long as you're limited on cylinder heads if you're not use a bigger bore and shorter stroke.

ray14
Dirt Full Roller

Total posts: 67
posted October 04, 2002 08:56 PM
what engines have a 3.905 bore 350's are 4.00 bore aren't they? im just eperimenting with small block chevy's never have built a stroker or destroked one but really would like to i think it would be better than my little 355.

tilley88
Dirt Freak

Total posts: 353
posted October 04, 2002 09:46 PM
Ran a 307 block bored .125 thou. with a 350 crank, comes out at 350 standard bore, fast and reliable. Only prob is lack of bore-out later.

birdcage
Dirt Full Roller

Total posts: 57
posted October 06, 2002 01:36 AM
A 3.905 bore is a .030 over 307 block. the only problem is I have broke several main caps(2 bolt) you'll need aftermarket caps or use straps across the mains. Ran with 3/4 straps at 8600 rpm no more cap problems ran same engine 3 years and still have motor to this day just don't use it anymore.

ray14
Dirt Full Roller

Total posts: 67
posted October 06, 2002 03:18 PM
wanna sale that motor?

birdcage
Dirt Full Roller

Total posts: 57
posted October 08, 2002 02:56 AM
I actually have two, the 311 (3.905 x 3.250) and a 335 (3.905 x 3.49). yes I'd sell them I don't use them. The 311 has 4 races on a freshening and the 335 is all new with 2 races and some hot laps. I have dyno sheets as well.

CHECK YOU PM'S

[This message has been edited by birdcage (edited October 08, 2002).]

racer 4
Dirt Full Roller

Total posts: 34
posted October 21, 2002 12:52 AM
hey birdcage, i bought a motor from a guy that needed money pretty bad and he was pretty proud of it i'm planning on running it in a mod this spring but i really don't know what to expect it's a 3.905 bore,with a cola 3.75 internaly balanced crank,true carillo 6.0 inch rods,weisco .550 dome pistons the block has splayed caps with steel aftermarket front and rear caps. it had a roller setup in it which i replaced with a crower 00356 solid cam the heads are 2.05 valve darts that i spent $1100.00 getting them ported to flow 305 on the intake and 195 on the exhaust i had a well known machine shop in dallas install and degree the cam and did all of the cylinder head work i have no idea what to expect from this combo low end torque with top end or what? the strange combo was built for a guy to run ascs sprint cars and had to meet a 360 cubic inch limit. what do you think?

birdcage
Dirt Full Roller

Total posts: 57
posted October 22, 2002 03:27 AM
One thing you need to watch is the intake valve hitting the cylinder wall. Mine if if remember right would only take .600 but this was with a head that had a 40/60 split on the valves and the head dowels were shifted .060 to move the valve away from the cly wall. If it's all assembled I'd remove an intake spring and indicate how far the valve can lift before it hits the wall. May be close may not alot depends on the cylinder head. One of mine had a roller in it and i had to chamfer the top of the cylinder wall (like a bbc is). The small bore will severly reduce the flow on the head. An 18 degree flows about 6 percent better on a 4.100 bore that a 4.000 bore so I'd say you'll lose about 18 cfm which means about 36 horsepower.
Sounds like you got a nice piece for little money. It should work fine, unless you race on extremely heavy race tracks. You'll probably need to use alot of gear and turn it around 8000 to 8300. I don't reconize the cam # your using so I'm guessing.
What's the compression ratio you ended up with. I ran all of mine with 14.5 to 15.0 to 1 if you have alot less than this, you can't but a cam in it to makes real good numbers with out it being lazy on the bottom end.

P5Racing
Dirt Full Roller

Total posts: 41
posted October 22, 2002 04:56 AM
IF ray14 doesn't buy them. How much do you want for them.

racer 4
Dirt Full Roller

Total posts: 34
posted October 22, 2002 08:33 PM
birdcage, the compresion ratio was guessed at 13.6 to 14.0 and the cam is only .540/.557 lift the track i will be running is a smooth dry little bull ring with a hoosier ump tire i figured turning it to 7500 you think 8000 is ok with that 3.75 stroke?

birdcage
Dirt Full Roller

Total posts: 57
posted October 23, 2002 02:44 AM
I always turned my 311 (3.25 stroke) 8600 rpm even when it still had stock rods but it has pretty light pistons for a 311. I had to replace the crank at every freshening because it would be cracked. The 335 (3.49 stroke)i turned 8400 the two races I ran it but a friend drove one of my spare cars with it and was turning the **** out of it. Never got the see the tel-tec as he stop on the front straight for trophy. But he was running a 6.32 gear on a fast 1/2 mile. I was running a 6.18 w/ a all alum 18* 360 and I was turning 8700. He was just under powered against these motors so we put a gear in it. I couldn't catch him thought!!
Both mine aren't 3.75 stroke but I don't think I'd be to worried about turning it some. I gear mine so it comes off the corner like I want and let it turn what it will. I figure if it can't take it I didn't want it anyway.

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