Thread: 383 for towing a travel trailer

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Yep, got 'er right here.

KB135 hyper D-cup pistons, 18cc dish, hung on 5.7 rods. Pay close attention to KB recommendations for top ring end gap.
L31 Vortec heads, 1.94/1.50 valves. Stock except Comp springs and retainers. See spring requirements on cam card.......
http://www.compcams.com/Cam_Specs/Ca...x?csid=85&sb=0
Talk with Comp about using springs that have these specs, but are the same diameter as the spring seats in the stock heads to prevent having to spend money cutting new spring seats. There are some super-keen Beehives available for this application.
1.750" long-tube, equal-length headers with "X" pipe right after the collectors and 2 1/2" pipe to the rear through mufflers of your choice.
Edelbrock Performer RPM dual-plane, high-rise intake manifold mounting a 600 cfm carb of your choice. Cam advanced 2 degrees. 9.700:1 static compression ratio, 8.384:1 dynamic compression ratio. Set squish between 0.035" and 0.040". Stack will measure 9.008". If you need a little thinner gasket than normal to set your squish, a Victor Reinz #5746 compresses to 0.025". This combination makes a nice torque motor......
RPM HP TQ
1000 62 328
1500 113 397
2000 164 430
2500 206 432
3000 256 448
3500 308 461
4000 348 457
4500 379 443
5000 392 412
5500 365 349

Now, I just happen to like the L31 heads, but you could certainly do it close to these results with the GM 882 heads. You would have to use different pistons though, because the 882 heads are 76cc's. Use KB134 flat-tops to achieve the same 9.700:1 static compression ratio we had with the L31 heads.
RPM HP TQ
1000 62 325
1500 112 393
2000 163 427
2500 205 431
3000 256 448
3500 308 462
4000 348 457
4500 377 440
5000 387 407
5500 344 329

Changed to 750 carb and CompCams 12-262-4 because the OP already has this cam. This cam is for a computer controlled engine, but will work with a carbed unit like we are using here. The timing opening and closing points are a little different, but it's basically the same cam used on the other two sims.
http://www.compcams.com/Cam_Specs/Ca...x?csid=92&sb=0
Cam installed straight up on the marks.
RPM HP TQ
1000 63 330
1500 111 389
2000 160 420
2500 201 422
3000 253 444
3500 309 463
4000 354 465
4500 386 451
5000 400 420
5500 359 343

Dropping down to 1 5/8" on the header tube size drops 5 hp and 3 ft/lbs of torque, so if it's easier to fit the smaller tubes, I'd do it. DO NOT GO ANY SMALLER THAN 1 5/8". Using those cheezy "shortie" headers however, will drop 36 hp and 32 ft/lbs of torque, so I wouldn't do that. Stock cast iron manifolds drop 54 hp and 50 ft/lbs of torque down low where you need it.

The key to making this whole mess work on pump gas with a 9.7:1 static compression ratio and iron heads is the squish. In order to have a good, strong squish of fuel/air mixture jetted across the chamber, you need to have a nice, flat area on the piston crown to mate up with the underside of the cylinder head. This type of piston crown WILL NOT WORK.....
http://store.summitracing.com/largei...=stl-423np.jpg

This type of piston crown WILL WORK....
http://store.summitracing.com/largei...l2256f60_w.jpg

And if you need a dish piston to reach your target static compression ratio, use a D-cup piston such as this. Notice the nice flat crown area on the right side of the photo. This is the part of the piston that will mate up with the underside of the head to create squish.....
http://kb-silvolite.com/performance....etails&P_id=92