302 Chevrolet Engine Build

[Dwight Southerland]

Yac-
Leaving “on the mat” back then is not the same level of strain as the sustained 8000+ rpm runs of today’s cars. Secondly, we broke a bunch of rods back then, too! And if you break a rod in an engine today, it’s way too expensive to consider taking a chance.
There were only three small journal rods - early 265, ‘57-‘62 265 & 283, and the ‘63-‘67 283 & 327. There ware no special high performance forgings. The solid lifter ‘65-‘67 engines sometimes got “green” rods which meant they were magnafluxed before they were machined. All these rods are 50+ years old today. Do you want to trust them for a $10K engine?
Head casting numbers changed due to engineering changes that had nothing to do with port design. 462 changed the combustion chambers, 291 made allowance for closed crankshaft ventilation with open slots between the push rods, and 186 had the provisions for bolt holes in the end.
Just a bit of history.

[MAURICE BLENDHEIM]

Early 1967 Z/28 cylinder heads were "462", Late '67 castings were "291" with no temp sender provision. Early 1968 Z/28 heads were "291" with introduction of temp sender and late 1968 castings were "186". Screw in studs and guide plates ONLY came on Performance Optioned small block engines with factory installed 2.02 & 1.6 valves. All the above mentioned heads were also available with 1.94 &1.5 valves and came with NO factory installed screw in studs and guide plates, "291's" may have an un-drilled lug for temp sender. The 1967 Z/28 connecting rods (3864881) were a regular production rod, that utilized a press pin. The floating pin was a late 1968 Z/28 introduction. Hope this helps... MB.

[Dwight Southerland]

Screw in studs and guide plates came late ‘69 production year on 186 castings used in high performance engine applications.

[Rich Biebel]

Originally Posted by Dwight Southerland

Yac-
Leaving “on the mat” back then is not the same level of strain as the sustained 8000+ rpm runs of today’s cars. Secondly, we broke a bunch of rods back then, too! And if you break a rod in an engine today, it’s way too expensive to consider taking a chance.
There were only three small journal rods - early 265, ‘57-‘62 265 & 283, and the ‘63-‘67 283 & 327. There ware no special high performance forgings. The solid lifter ‘65-‘67 engines sometimes got “green” rods which meant they were magnafluxed before they were machined. All these rods are 50+ years old today. Do you want to trust them for a $10K engine?
Head casting numbers changed due to engineering changes that had nothing to do with port design. 462 changed the combustion chambers, 291 made allowance for closed crankshaft ventilation with open slots between the push rods, and 186 had the provisions for bolt holes in the end.
Just a bit of history.

I could not agree more with Dwight......Seen way to many stock rods break and you will destroy the engine if one fails....No maybe about it...

You just don't see stockers blowing up much anymore and its not because they really prepped their stock rods....Its because they aren't using them.....along with all the other parts that routinely broke...

[killintime6968]

I would think fatigue would be a factor in the rods in this day and age

[Greg Reimer 7376]

What does it cost to properly rebuild a set of OEM good used rods these days? Mag, resize, equalize the center to center distance, rebush, size for pins,also, how many cores do you go through until you find eight nearly perfect ones?Also, these rods are 50+ years old, how many duty cycles have they accumulated?In short, where are they along the length of a normal lifetime?Now, I bought Manley legal replacement rods that are Stock Eliminator legal. You have to check all dimensions,(who doesn't?),but most of the time they are very close to optimal. These rods are around $100 each, but subtracting the price of used rebuilt parts from the cost of new rods certainly makes them cost effective in light of what another block, pistons, crank, cam, and all the busted stuff you take out of a motor that died of rod failure costs. A local racer that I know has a real aversion to buying used parts. He says that"you build a car out of a pile of used stuff, all you have is a pile of used stuff".Some places, used parts are OK, but not rods from an unknown source.

[Mark Yacavone]

Again, this is a mostly street engine.
The cost to re-work a stock rod is not a factor here .
This is an exercise for Mike to learn how to recondition a stock factory rod, among other things. What would he learn by taking a Manley rod out of a box and checking the balance?

[Hacksaw]

More than anything it's the 11/32" rod bolts that would scare me.

[MIKE JONES 302]

Last week I decked the block. My goal was to use the factory steel shim head gasket, this didn't work out, the block measured 9.013 on one side and 9.027 on the other, bad factory machine work, so I went 9.00 and set it up for a Fel Pro head gasket .038. I will bore the block next.

[Nmbr1GMfan]

Looking good son, keep it up.