A typical rebuilder will inspect the core block, make sure it is free of cracks and warpage. The stock 4.00" bores are cut .020" over (if you want more, ask for it, as most rebuilders will overbore the least amount neccesary in order to ensure the block can be used again down the line.) The bores are then honed, the block is hot tanked, and then cleaned. New freeze plugs and oil plugs are installed, all the main and head bolt holes are chased with a tap. New cam bearings are installed. The crank is cut and polished, and the rods may or may not get resized depending on their condition. Finally the short block is assembled to factory specification for clearances and torque.

All this is fine for your neighbors Crown Vic, but we feel that there are a few more steps that you should ask for to gain a performance edge and increase reliability. For example, it is not standard rebuild practice to surface the deck, or align hone the main bearing bores. These machining options are only done if the block requires it or if you, the customer, specify it and pay extra.

Our shop conviced us that align honing was not neccesary, since the core did not have a spun bearing or crank damage. We agreed.

We did opt to pay $100 extra to get the deck milled about 0.015". We did this to not only ensure a dead flat surface for the head gaskets to seal properly with the aluminum heads we would be using, but also to increase compression ratio by ensuring the piston is not below deck.

Furthermore, before you lay down any cash, ask what new parts will be used, and get part numbers. For example, will the shop install new rod bolts? (May rebuilders do not.) What pistons will be used? We ran into some trouble here - our rebuilder stocks one piston for all 289-302 rebuilds. The piston (Silvolite 1177) is actually 0.020" shorter in compression height (height of the piston above the top ring) than a true 5.0L replacement piston. This sort of cost savings by the shop, will cost you power in the end.

Eventhough we had paid $100 extra to have our block machined for zero-deck (piston top is dead level with the top of the bore) the fact that the shop used the wrong piston, meant our piston was actually 0.018" below deck. This seemingly minor difference would make the compression ratio 9.0:1 rather than the 9.5:1 we desired. More on pistons below.

Make sure you ask the rebuilder for all the part numbers for the parts they'll use in your engine. Then look up those parts in the manufacturers catalog or website, and make sure they will yeild the results you want. If you want to make changes, such as different pistons or bearings, let them know up front, and settle on an additional cost or credit depending on who will supply the upgraded component.

Piston Problem
The following chart shows the problem we encountered with the KB Silvolite replacement piston number 1177. Our engine rebuilder carried this piston as a OEM replacement for all 289 and 302 engines. However the 0.025" shorter compression height results in an effective compression ratio loss of one-half point. The 9.0:1 ratio would significantly hurt power with our aluminum heads. We identified the correct piston to be part number H3101, and had the shop re-assemble the engine. (We did have to pay an extra $50 for rebalancing.) Note that some rebuilders stock a Silvolite 1195 piston, which has the correct 1.605" compression height, but has a 4cc dish! In other words, it's a compression killer, do not opt for this piston unless you need to lower your compression.

We were fortunate that our rebuilder uses Silvolte pistons for the fact that these pistons are true flat-tops with stock size valve reliefs, thus the head volume (volume of the piston top) is only 3cc. We found the TRW and Sterling flat-top pistons to have head volumes of 6 to 7cc due to the larger than stock valve reliefs they use.

Unless you are planning to use 2.020" or greater intake valve in conjunction with a "large" cam (224 or greater duration, .500" or more lift) there is no need for the huge valve reliefs. As the numbers show, all they do is hurt compression ratio. With the Silvolite piston we can easily achieve 9.55:1 with a 60cc combustion chamber, without any need to mill the heads. With the TRW piston you'd need to mill 4cc from the heads (roughly 0.030") to achieve the same compression. Continue

Part No.	Cyl. Engine Bore	Compression Ratio with 0.003" deck and 60cc head.	NOTES:	Rings	Head Shape
H3101	V8 302 5.0 L 4.000(IN) 101.6(MM) FORD ENGINE	9.55:1	Hypereutectic, not destroked. Flat top with four valve reliefs. Not intended for race application. APPROXIMATE HEAD VOLUME=3cc Comp. Ht. 1.605 Pin Dia..9122 Offset	2-5/64 1-3/16
1177	V8 302 5.0 L 4.000(IN) 101.6(MM) FORD ENGINE	9.09:1	Flat top with four valve reliefs. Comp. Ratios with cyl. heads: 51cc=9.7; 54cc=8.8; 64cc=8.3; 69cc=7.8. APPROXIMATE HEAD VOLUME=3cc Comp. Ht. 1.585 Pin Dia..9122 Offset	2-5/64 1-3/16