Other Franklin Information

Bad running Franklin

Several of you have helped me search for a solution difficulties in getting my Franklin engine running properly. As a brief recap, I bought the PZL Franklin new about 5 years ago and flew it for about 26 hours. It never ran well which I attributed at least partially due to plug fouling. The rings never seated properly. I finally decided to re-sleeve the cylinders to get a softer grade of steel as liners. I sent the cylinders to Davis Aviation for new sleeves. I fly out of an elevation of 8200 ft and it is difficult to get manifold pressure.

After reassembly of the engine and re-installation, the engine ran worse than ever - back firing and popping and difficulty getting RPMs above 1500. I checked everything - induction leaks, carburetor function, mags, wiring, plugs - you name it - nothing helped. I tried to locate centerline intake valve angle but had difficulty locating these number. Eventually, Phil Davis of Davis Aviation located these numbers and sent them to me.

Saturday, mechanic John Welty and I used these numbers to check the center line angle for the intake valve on #1 cylinder and found the angle to be off 6 degrees. Instead of 104 degrees, the angle was 98 degrees. So, the engine was pulled once again. We took off the mags and accessories at the back of the engine and took off the rear cover. Then, we pulled the starter ring, revealing the cam gear and crank gear.

When rotated, the mark on the crank gear meshed between the two marks on the cam gear (or the other way around) just like the book said it should but the center line angle was wrong. We pulled the crank and cam gears and reset them so that the angle was correct. We had to move the gear one tooth - about 6 degrees.

After reassembly and reinstallation, we started the engine and it now appears to be running well. I have not yet flown it but intend to do so this week. It has been a frustrating - and expensive - several months trying to get this resolved.

I'm not sure why this happened but have a guess. It appears that the cam gear or crank gear was miss-marked. When the engine was test run at the factory, it likely did not run at all well. It appears that they opened the valve lash enough to run. When we reset the valve lash to the proper amount, the engine would not run. Now that the cam timing is correct, it runs with the proper valve lash. Sounds incredible but I can't think of any thing else.

If anyone needs or wants a copy of the valve lift versus angle, please contact me and I will e-mail the table to you. Thanks to each of you for your suggestions and help.

Jerry Teitsma
Granby CO
jerryteits at comcast.net

Valve Lift versus Engine Angle

Here is Jerry's data that I OCR'd and corrected. It is not exactly thesame because I took some liberties of pasting in the closed valverange. The open timings should be correct.

For reference, this is an unknown Franklin 6A-350-C1R. The title has: TITLE = NEWF
CYLINDER # = 1
FILENAME=NEWF16
12-20-12
TEST # 16
ADD -.34 TO CRANK DEG.

2 0.1002
4 0.1080
6 0.1157
8 0.1235
10 0.1314
12 0.1393
14 0.1471
16 0.1549
18 0.1620
20 0.1705
22 0.1782
24 0.1858
26 0.1933
28 0.2007
30 0.2080
32 0.2150
34 0.2220
36 0.2286
38 0.2354
40 0.2418
42 0.2481
44 0.2542
46 0.2600
48 0.2658
50 0.2712
52 0.2765
54 0.2815
56 0.2863
58 0.2909
60 0.2954

62 0.2996

64 0.3035

66 0.3073

68 0.3108

70 0.3141

72 0.3172

74 0.3200

76 0.3226

78 0.3250

80 0.3270

82 0.3289

84 0.3300

86 0.3319

88 0.3330

90 0.3340

92 0.3347

94 0.3352

96 0.3356

98 0.3358

100 0.3359

102 0.3360

104 0.3360

106 0.3360

108 0.3359

110 0.3356

112 0.3352

114 0.3347

116 0.3340

118 0.3331

120 0.3321

122 0.3308

124 0.3293

126 0.3276

128 0.3257

130 0.3235

132 0.3211

134 0.3185

136 0.3156

138 0.3124

140 0.3092

142 0.3056

144 0.3000

146 0.2979

148 0.2935

150 0.2890

152 0.2843

154 0.2794

156 0.2743

158 0.2690

160 0.2635

162 0.2579

164 0.2521

166 0.2460

168 0.2398

170 0.2333

172 0.2267

174 0.2199

176 0.2100

178 0.2056

180 0.1984

182 0.1909

184 0.1834

186 0.1758

188 0.1680

190 0.1602

192 0.1523

194 0.1445

196 0.1366

198 0.1287

200 0.1209

202 0.1133

204 0.1057

206 0.0983

208 0.0900

210 0.0842

212 0.0776

214 0.0713

216 0.0652

218 0.0595

220 0.0541

222 0.0490

224 0.0443

226 0.0399

228 0.0358

230 0.0321

232 0.0287

234 0.0258

236 0.0232

238 0.0209

240 0.0191

242 0.0175

244 0.0163

246 0.0152

248 0.0142

250 0.0133

252 0.0125

254 0.0117

256 0.0109

258 0.0102

260 0.0095

262 0.0088

264 0.0082

266 0.0080

268 0.0070

270 0.0060

272 0.0060

274 0.0050

276 0.0040

278 0.0040

280 0.0030

282 0.0030

284 0.0020

286 0.0020

288 0.0020

290 0.0020

292 0.0020

294 0.0010

296 0.0010

298 0.0010

300 0.0010

302 0.0010

304 0.0010

306 0.0010

308 0.0010

310 0.0010

312 0.0010

314 0.0010

316 0.0010

318 0.0010

320 0.0010

322 0.0010

324 0.0010

326 0.0010

328 0.0010

330 0.0010

332 0.0010

334 0.0010

336 0.0010

338 0.0010

340 0.0010

342 0.0010

344 0.0010

346 0.0010

348 0.0010

350 0.0010

352 0.0010

354 0.0010

356 0.0010

358 0.0010

360 0.0010

362 0.0011

364 0.0010

366 0.0010

368 0.0010

370 0.0010

372 0.0010

374 0.0010

376 0.0010

378 0.0010

380 0.0010

382 0.0010

384 0.0010

386 0.0010

388 0.0010

390 0.0010

392 0.0010

394 0.0010

396 0.0012

398 0.0012

400 0.0010

402 0.0010

404 0.0010

406 0.0010

408 0.0010

410 0.0010

412 0.0010

414 0.0010

416 0.0010

418 0.0010

420 0.0010

422 0.0010

424 0.0010

426 0.0010

428 0.0010

430 0.0010

432 0.0010

434 0.0010

436 0.0010

438 0.0010

440 0.0010

442 0.0010

444 0.0010

446 0.0010

448 0.0010

450 0.0010

452 0.0010

454 0.0020

456 0.0020

458 0.0020

460 0.0020

462 0.0020

464 0.0020

466 0.0020

468 0.0020

470 0.0020

472 0.0020

474 0.0020

476 0.0020

478 0.0020

480 0.0020

482 0.0020

484 0.0020

486 0.0020

488 0.0020

490 0.0020

492 0.0020

494 0.0020

496 0.0020

498 0.0020

500 0.0020

502 0.0020

504 0.0020

506 0.0020

508 0.0020

510 0.0020

512 0.0020

514 0.0020

516 0.0020

518 0.0020

520 0.0020

522 0.0020

524 0.0020

526 0.0020

528 0.0020

530 0.0020

532 0.0020

534 0.0020

536 0.0020

538 0.0020

540 0.0020

542 0.0020

544 0.0030

546 0.0030

548 0.0030

550 0.0030

552 0.0020

554 0.0020

556 0.0020

558 0.0020

560 0.0020

562 0.0030

564 0.0030

566 0.0030

568 0.0030

570 0.0030

572 0.0030

574 0.0030

576 0.0030

578 0.0030

580 0.0030

582 0.0030

584 0.0030

586 0.0030

588 0.0030

590 0.0030

592 0.0020

594 0.0030

596 0.0030

598 0.0030

600 0.0030

602 0.0030

604 0.0030

606 0.0030

608 0.0030

610 0.0030

612 0.0030

614 0.0030

616 0.0030

618 0.0030

620 0.0030

622 0.0030

624 0.0030

626 0.0030

628 0.0030

630 0.0030

632 0.0030

634 0.0030

636 0.0030

638 0.0030

640 0.0030

642 0.0030

644 0.0030

646 0.0030

648 0.0030

650 0.0030

652 0.0030

654 0.0040

656 0.00358

658 0.00362

660 0.00366

662 0.00374

664 0.00382

666 0.00394

668 0.00406

670 0.00429

672 0.00453

674 0.00488

676 0.00531

678 0.00591

680 0.00661

682 0.00748

684 0.00858

686 0.00992

688 0.01154

690 0.01354

692 0.01591

694 0.01862

696 0.02181

698 0.02551

700 0.02961

702 0.03417

704 0.03921

706 0.04465

708 0.05047

710 0.05673

712 0.06339

714 0.07031

716 0.07756

718 0.08496

720 0.09256