CAM CHOICE for GM fastburns on 355

[rewguy]

The engine is a 355, for stock car on 3/8 mile track. MAX RPM of 7000. Operating range of 4000-7000. The heads are big, I know....AND they are ported.....pretty well. Runner is very big on 355, and we know it. They flow 290@.650 with a 2.0" valve, 272@.500. Probably finish at 217ccs. The engine will be 10.4-1 compression, solid flat tappet, max rpm of 7000.
How can I cam this to produce the MOST MID RANGE POSSIBLE (due to the large runner)? Tighter lobe center? Single pattern? Was thinking 243/243 @.050 on a 104, with .550 ish lift? Pick some quicker lobes? Thanks for any suggestions.

[rewguy]

for example.....maybe they run roller cams, BUT years ago a circle track near me had alot of the 9-1 aluminum headed late model cars. They also ran large heads, like the Brodix -10, etc.... But they sounded like they had alot more compression I'm sure in part due to the cam timing. Some were conservative and turned 7500 or so. This will be a tamed down version of that with a solid flat tappet if possible.

[Walter R. Malik]

Some other engine builders I know, (we DO talk with one another all the time), use a larger head on a some oval track applications on purpose. This way, the driver does not need to have a super educated right foot to keep from spinning tires as the bigger ports have a "soggy" bottom out of the corner and they end up going faster.

The type track which it has to run will usually determine the camshaft particulars. 1/2 mile flat asphalt or 1/3 mile banked dirt will certainly benefit from different camshaft grinds.

Can you use a roller or is a flat tappet required ...?

EDIT: Is a larger diameter Flat tappet possible ...?

[Walter R. Malik]

sorry ... double post

[hoffman900]

for example.....maybe they run roller cams, BUT years ago a circle track near me had alot of the 9-1 aluminum headed late model cars. They also ran large heads, like the Brodix -10, etc.... But they sounded like they had alot more compression I'm sure in part due to the cam timing. Some were conservative and turned 7500 or so. This will be a tamed down version of that with a solid flat tappet if possible.

Probably a lot like this Bush Grand North engine.

https://www.youtube.com/watch?v=Ne6nsVVykWw

Fresh rebuild and dyno tested NASCAR Ford 358. 600 HP at 6900 RPM and 500 ft-lbs of torque. Dyno sheets available upon request. Shipping weight is approximately 650 pounds. Engine was "pickled" for storage. Engine was assembled using the following components:

Yates C3 Heads
9:1 Compression
3.480 Stroke
4.030 Bore
6.2 Steel Rods
Del West Titanium Valves
2.18" Inlet
1.6" Exhaust
Manley Nextec Springs 1.550" Diameter
260 lbs. Seat Pressure
JE Pistons
CV Pushrods
Jessel Rockers (1.6 Ratio)
Cloyes Chain
2.1" Chevy Rod Journal
Cam Motion Camshaft
Weaver Oil Pump
Moroso Valve Covers with Oilers
MSD Dual Pickup Distributor
Edelbrock Victor 351 Manifold

https://www.savannahraceengineering.com/nascar-ford-358

[F-BIRD'88]

Use Summit Racing solid cam # SUM ct-108 It will be very torky. EG: coming off the corners
You can dial in the torque by cam installed position (advance) and by the valve lash setting. I believe these are made by Howards Cams. If you are going to jack up the rocker ratio to get more valve lift get good dual coil valve springs.
Add a K to the summit part number for a cam+lifters set.

If you find this cam too "torky" and want more top end use Isky cam cam #201547
Still a LOT of torque and punch. More top end. Also needs good valve springs.

Don't worry about the heads.

[CamKing]

The engine is a 355, for stock car on 3/8 mile track. MAX RPM of 7000. Operating range of 4000-7000. The heads are big, I know....AND they are ported.....pretty well. Runner is very big on 355, and we know it. They flow 290@.650 with a 2.0" valve, 272@.500. Probably finish at 217ccs. The engine will be 10.4-1 compression, solid flat tappet, max rpm of 7000.
How can I cam this to produce the MOST MID RANGE POSSIBLE (due to the large runner)? Tighter lobe center? Single pattern? Was thinking 243/243 @.050 on a 104, with .550 ish lift? Pick some quicker lobes? Thanks for any suggestions.

M73359-74359-105
248/252 @.050"
.359"/.359" Lobe Lift
.590"/.555" Net Valve Lift w/1.7-1.6 rockers
105 LSA
101 ICL

[blykins]

What's the exhaust side flow?

[Keith Morganstein]

The engine is a 355, for stock car on 3/8 mile track. MAX RPM of 7000. Operating range of 4000-7000. The heads are big, I know....AND they are ported.....pretty well. Runner is very big on 355, and we know it. They flow 290@.650 with a 2.0" valve, 272@.500. Probably finish at 217ccs. The engine will be 10.4-1 compression, solid flat tappet, max rpm of 7000.
How can I cam this to produce the MOST MID RANGE POSSIBLE (due to the large runner)? Tighter lobe center? Single pattern? Was thinking 243/243 @.050 on a 104, with .550 ish lift? Pick some quicker lobes? Thanks for any suggestions.

M73359-74359-105
248/252 @.050"
.359"/.359" Lobe Lift
.590"/.555" Net Valve Lift w/1.7-1.6 rockers
105 LSA
101 ICL

Looks good!
Mike has a whole lot of experience with cams for these heads and the application. I'd use his cam, not just the spec.

[rewguy]

Sounds great......byw the exhaust port flows 207 at. 550 with no pipe

[blykins]

Sounds great......byw the exhaust port flows 207 at. 550 with no pipe

The intake port volume isn't as huge as what you're thinking. I'm used to dealing with 4V Cleveland heads on 302/351 sized engines, or FE Tunnel Port heads on 427's. Typically, we tighten the LSA up to help the exhaust scavenge the intake. Keep in mind that a 4V Cleveland head is around a 240cc port volume on a 351 cube engine and we will end up with anywhere from a 108 LSA to a 105 LSA depending on the application.

With that being said, with a 217cc port volume, I don't think I'd deviate too far from the "typical" game plan.

What intake and carburetor are you running?

[rewguy]

I was thinking about a dual plane at first.....but after reading the new post about the Engine Masters winning engine that Randy331 helped with......and knowing there are a few direct similarities between these two engines...... (granted.....not enough for this engine to TOUCH their kind of power), but cubes, lower compression, cyl head flow is pretty close, etc).... he said that the single plane Motown stomped the dual plane from 4000 up. This car will never see less than 4000 in its operating range, and the Motown may be a tick big still...not sure......but I'd likely give the Holley strip dominator a try.......or maybe even a simple vic jr. This engine will have no vac. pump, no light rings, no high ratio rockers, no real frills.......so Id be happy if it made 475+ at peak....near 6500, and 375 or so at 4300 or so. This will have 10.4-1 compression, fat ugly ring pack, maybe .550 gross lift, No trick oil pans or windage help, but anything over 450 would please him for certain....as long as good mid-range power is feasable.

[CamKing]

I'd go with the Vic Jr.

[CGT]

What was done to the Vic Jr to make it fit those heads properly? Because they don't without trying.

[blykins]

I was thinking about a dual plane at first.....but after reading the new post about the Engine Masters winning engine that Randy331 helped with......and knowing there are a few direct similarities between these two engines...... (granted.....not enough for this engine to TOUCH their kind of power), but cubes, lower compression, cyl head flow is pretty close, etc).... he said that the single plane Motown stomped the dual plane from 4000 up. This car will never see less than 4000 in its operating range, and the Motown may be a tick big still...not sure......but I'd likely give the Holley strip dominator a try.......or maybe even a simple vic jr. This engine will have no vac. pump, no light rings, no high ratio rockers, no real frills.......so Id be happy if it made 475+ at peak....near 6500, and 375 or so at 4300 or so. This will have 10.4-1 compression, fat ugly ring pack, maybe .550 gross lift, No trick oil pans or windage help, but anything over 450 would please him for certain....as long as good mid-range power is feasable.

So what rocker ratios will you use?