A 350 Lunati for a Tiger!
An Article by Tim Ronak
Excel Spreadsheet to Calculate Engine Parameters
Small Block Ford Stroker Heaven Table
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I looked closely at ALL of the stroker kits and frankly it was a tough decision as the sticker price of the Lunati Kit at $1995.00 USD was a bit hard to take as a Canadian faced with a rather anemic dollar ($0.65 = $1.00 USD) when compared to the Coast Performance kit at $1495.00 USD. I do not intend to criticize others for their choice but in my mind the fact that Lunati sent me a complete BALANCED rotating assembly complete with Lunati Lightened Crank, a new dual degreed BHJ Balancer (left or right TDC timing mark), Lunati Forged Pistons and light pins with cir-lock circle pin locks, plasma rings, Lunati 4340 StreetRace Rods with bronze bushings and 185,000 lb. cap screws (The rods are strength rated for 450 HP), King Alecular Race Bearings, and a clearanced and tested high volume oil pump with a hardened drive shaft was enough to sell me.
A NOTE ON LUNATI WARRANTY: I did find a defect in the first crank under inspection as it appeared to have been struck by something on one of the rod journals. I contacted Lunati tech support who were helpful beyond compare. I do need to say that the fellow (Billy Dalton) who helped me really CARED about the product and what was delivered. They arranged for shipping back to them for warranty and I shipped the crank with the balancing card and they prepared a NEW crank for me, rebalanced it and sent it back within 6 Days. Now I was really, really glad I chose to do business with Lunati. As in many cases, for me at least, it seems if we buy on price there are a lot of other things we dont consider. In this case I FIRMLY BELIEVE I received TREMENDOUS VALUE and would highly recommend and use Lunati in the future.
How good was the stuff ??
I did have my Machinist friends Rod Derry and Chuck Waddel at D&W Custom Engine in Calgary check over every dimension and surface of every part and they indicated that they also were extremely impressed by the quality of the workmanship. They measured less than .0002 (2/10ths of 1000) of an inch run out in the main journals over the entire length of the crank and appeared to be impressed by that level of consistency. The crank Mains were at standard bearing size but the Rods throws were at .010 undersize. When I asked about this Billy Dalton at Lunati indicated that for them to machine the generous filet radius they build into every one of their cranks throws they have to turn down that far from the blanks they start with for my Rod / Stroke combination. This was a Good enough explanation for me !! Every rod was exactly sized at spec and they were within 1 gram of each other in weight. Each piston had its weight written on it with marker and I verified the weights. The balancing sheet computations Lunati used for balancing the rotating assembly even made an allowance for the weight of oil in the ring lands.
The Final Combination Choice and Specs
- 1990 Ford 5.0 HO Block assembly
- Lunati EA-31 Flat Top Stroker Kit (w/Twisted Wedge Pistons) Balanced 50-ounce assembly with a bobweight of 1591 Grams
Balance specs in Grams:
Rod Rotating weight 372
Rod Rotating weight 372
Rod reciprocating weight 168
Piston and pin 553
Locks 1 set 4
Rings 1 set 54
Rod bearings 2 sets 62
Bobweight total 1591 Grams
- Edlebrock Performer RPM Manifold (with a plenum transfer slot machined in and port matched to the TFS Heads) Intake selection was limited due to hood clearance.
- Holley 650 Double Pumper
- Trick Flow Twisted Wedge Heads (lightly Ported and port matched to intake)
- Lunati Double Valve Springs (130 lbs seat pressure)
- Competition Cams 7/16 stud Stainless Roller Rockers
- Trick Flow Stage 2 Hydraulic Roller Cam
(Specs Duration at .050 Int - 224 Exh 232 with Intake lift at .542 and exhaust at .563 with a 1.6 rocker)
Advertised duration is I 286 and E 294
- Trick Flow Seamless .080 wall .050 long Pushrods
- Crane Roller Hydraulic Lifters (They were cheaper than Ford)
- Centerforce Dual Friction Clutch, Ceramic Coated Headers (Caps Bright Hot in Fresno did an excellent job Sunbeam Specialties Headers)
349.5 cubic inches at 10.02:1 Compression with a rod/stroke ratio of 1.577
Expected peaks of 425+ HP. at 5700 RPM and 395+ lb.ft at 4500 RPM
The Build UP
Clearance the Block for the Crank
Installing the stroker crank is not a bolt in modification as there is some fitting that is required. First you need to ensure that each counter weight clears the engine block when the crank rotates. Notice in Crank Clearance picture, where the screwdriver is pointing, as that is where many 347 kits contact the block and sometimes this becomes an interference point on oil pans. The Lunati machining process used when lightening and shaping the crank apparently reduces the diameter of the crank on this throw substantially enough that clearance to the oil pan rail was not an issue. The piston skirt to crank clearance must also be checked to insure that at BDC the piston skirts sufficiently clear the crank throws. The Lunati kit has this already done.
Oil Pan Pickup
It is important to note that the same counter weight needs to checked for rotating clearance to the underside of oil pump casting where the pickup bolts on as well. The Lunati EA-31 Kit comes with a specially cast high volume oil pump that already has sufficient clearance for the counter weight machined into the casting. Other kits may not, so you do need to ensure that there is sufficient clearance in this area. If you look closely at the two rear counterweights in the picture Crank Lightening Holes you can even see the knife-edge shape of the rear counterweight on the leading edge followed by the radiusing of the rear edge of the weight, which is visible in the picture Crank Clearance. This shaping helps the crank move through the suspended oil with less drag. As an aside they also machine lightening holes into the crank throws to decrease reciprocating weight. If you look at the crank rod throws visible in the picture Crank Lightening Holes you can clearly see the machined holes in the first 2 rod throws.
Crank Lightening Holes