Building a Performance IH 345 - Part 1

On July 5th, 1999, I overheated and killed (took out a few bearings among other things) the '77 304V8 in my race Scout II ("Little Devil"). I put my spare 304 in, and towed the Little Devil to the Rocky Mountain IH Rendezvous in Denver, Colorado, behind my '77 Scout II "Tigger." On August 5th, arriving in Denver (900 miles from home), the motor began to lose power. It was replaced with a borrowed 345 while in Denver so I could return home. I later found out I had overheated the 304 in Tigger and had collapsed the rings. Strike two.

And thus, I began in earnest the rebuild of my very first engine, a 1977 International Harvester 345V8.

The engine was purchased in March of '99 for $80. It had been disassembled and was believed to be in sufficiently good condition that a simple re-ring operation was all that was necessary.

When it came time to start the rebuild, however, slight rust pitting was found in the cylinder walls which required going to an overbore. Note that at this point, I should have opted to buy a 392 short-block core from the junkyard - building a 392 is som ething on the order of $20 more than building a 345. Like I said, had I been thinking..

I began by taking the bare block, crank, timing cover, water pump housing, valley/tappet cover, etc to the machinist. These parts were all hot tanked. The crank was magnafluxed and checked for wear - it was within standard sized bearing tolerance. The cylinder bores were first checked for original piston reuse and found unsatisfactory.

The miscellaneous pieces were retrieved from the machinist. Northern Auto Parts was contacted and the engine rebuild components were ordered. I ordered a standard .030 over re-ring kit, upgraded to single moly rings, added Federal Mogul Sterling H997CP hypereutectic pistons with teflon coated skirts (.030), an oil-pump rebuild kit, and timing gear set. Gryphin Racing provided the Iskendarian 262 duration camshaft, lifters, and valve springs. I ordered a Deluxe Head Porting kit from Summit Racing to begin porting my own heads.

When the engine kit arrived, it contained a composite head gasket. The stock gasket is a steel shim. There is an important distinction between the two - the stock gasket is .018" thick compressed, while the composite gaskets hover around .040 thick comp ressed. This would result in lower compression!

The 345 started out at 8.28:1 according to the factory. It was determined that I would have the block machined ("decked") .040. This would remove the same amount of material as the new composite head gaset, leaving .018" extra removed (by not using the stock steel shim) which would reduce the combustion chamber volume and raise the compression ratio.

Some math was involved that resulted in a new compression ratio of 8.6:1 without milling the heads. Since I didn't want to buy Premium fuel, 8.7:1 is right about where I wanted to be.

3 7/8" bore, 3 21/32" stroke. 3 7/8 * pi * 3 21/32 = 44.487 cubic inch displacement in one cylinder bore. My 345 is .030 over, so it's actually 3.905 * pi * 3.65625 stroke = 44.832 cid.

44.832cid / 8.28:1 stock ratio yields a combustion chamber of 5.41447cid. Now remove .018 * pi * the bore (3.905) to achieve the new combustion volume of 5.41447 - .2207106 = 5.1937594 cid. Taking the original displacement figure and dividing it by the new combustion volume yields 8.632:1.

Since the heads are not perfectly round, but rather tapered and slightly "dished" shaped, removing a similar amount of material from the heads would not have quite the same effect on compression ratio.

To have the block decked, I had to take it to a second machinist since my 345 block was too big for the first guy's machine! I then took the pistons in to have them fitted to the block, along with the new timing gears and camshaft. The machinist acquire d and installed the new camshaft bearings.

Tomorrow I retrieve the engine parts from the machinist to bring home. I'll then take the connecting rods, pistons, rings, crank, harmonic balancer, and flywheel to a different machine shop to have the entire assembly balanced.

And thus, Part 1's costs to-date. Note that additional costs include some tool purchases not listed here - Valve spring compressor for $25, dial-indicator kit for $25, piston ring install for $4, piston install for $10 or so, dial calipers for $20.

MachinistCylinder Bore$88 ($11/slug)
MachinistBlock Decked .040$100
MachinistPurchase and Install Camshaft Bearings$50
MachinistPress Camshaft and Crank gears$25
Northern Auto PartsRe-ring kit$130
Northern Auto PartsUpgrade - Moly Rings$15
Northern Auto PartsH997CP Pistons$160 ($20per)
Northern Auto PartsTiming Gear Set$50
Northern Auto PartsOil Pump Rebuild Kit$30
Gryphin RacingIskendarian 262 duration camshaft & Lifters$225
Gryphin RacingValve Springs, keepers, etc$125
Summit RacingStandard Abrasives Deluxe Head Porting Kit$40

The next installment - porting the heads myself, painting the new engine, fitting the various pieces together, and machining the intake for my new induction system..

I expect to spend another $200 for the balance, $160+ for a valve job, paint.. I already spent the $375 for the used Holley 670cfm fuel injection system. Plus there'll be "incidentals" - maybe a new waterpump, new alternator, new fan & clutch (I've never had a clutch fan), etc. I figure it'll come in just under $2,000 - but that includes the fuel injection system which anyone is free to skip.

Jumping to the end of this, I ran Desktop Dyno 2000 against my new motor which displayed the very flat torque curve.. and an impressive 346lbs-ft of torque at 3500rpm, over 300 at 2,000rpm. Peak of 286hp at 5000rpm throu gh the stock headers and mufflers.

When I pony up the bucks for a pair of headers, it becomes a jaw dropping 385lbs-ft at 3500rpm (368 at 2000) and 340hp at 5000rpm. While a stock 345 experiences valve float approaching 5,000rpm (factory redline of 3800rp m), the Big Block Chevy valve springs will allow safe operation up to 6500rpm (though sustained 6500rpm operation is certainly not recommended).

-Tom Mandera, Helena MT
Copyright 2000.