302 Chevrolet Engine Build
 

I've always been fascinated by first generation Z/28s, which brings me to my first engine rebuild, a 1966 October 657 casting block with matching 462 casting heads. I will post pictures as I go along. The first pictures show the core cleaned along with the block prepped for machine work which I will start this coming week.

Re: 302 Chevrolet Engine Build
 

Is this a restoration type project?

Re: 302 Chevrolet Engine Build
 

No it will be dyno tested then put on a cradle until I get a car. The machine work starts today.

Re: 302 Chevrolet Engine Build
 

Very cool build.

Re: 302 Chevrolet Engine Build
 

I have a fresh lg journal 302 crank for sale if you need it. Just balance and go. PM me if interested

Re: 302 Chevrolet Engine Build
 

If you are building a race motor, you probably should consider different rods.

Re: 302 Chevrolet Engine Build
 

I would take Dwight advice, they make some nice aftermarket rods and N.H.R.A. approved list.it all depends how much H.P ,lot of variables

Re: 302 Chevrolet Engine Build
 

Why are you starting with a 2 bolt main block, 302 came with 4 bolt? The original blocks where 618 castings in '69. I'm not questioning your build, just pointing out different items, but in 1966 maybe they used 2 bolt blocks.
Also, if you are using an older block be sure to test the walls for pin holes. I personally got burned by the pin holes twice.
Casey Miles
69 Z/28

Re: 302 Chevrolet Engine Build
 

Thanks, but I have a crank. I will have it ground and indexed, and the stroke will be set at 3".

Re: 302 Chevrolet Engine Build
 

This is my first over haul, I hope to race, but I will keep the RPM around 7000 RPM, I will be running a light piston with a low drag ring pack. There was a guy that came around my Dads shop that bought a new 1967 Z/28, he said he buried the tach every day-anyone else ever heard this story?

Re: 302 Chevrolet Engine Build
 

My build is a 1967 302, which did use a 657 2 bolt block as I have, my heads are also 462s the only difference between my block and an original 302 block is the code on the deck. I did sonic ck my block after cleaning, I think it will be ok, hoping for 400 HP on the dyno.

Re: 302 Chevrolet Engine Build
 

Pictures of rods. I will balance them next.

Re: 302 Chevrolet Engine Build
 

Thanks!

Re: 302 Chevrolet Engine Build
 

Setting up for the line hone.

Re: 302 Chevrolet Engine Build
 

Nice progress.

Re: 302 Chevrolet Engine Build
 

Are you building for street or strip ? Higher quality rods would be a good idea. I have spun my Original 69 Z28/RS to 7200rpm on many occasions, but that is playing with fire. On one of my 302 engines in my Super Stock car I have spun it too well over 9000.

Re: 302 Chevrolet Engine Build
 

Today I finished my line hone, set housing bore to 2.4914. Next I will clean the block and set up for decking, assembly height:


Stroke 3.00
Rod length 5.698
Comp height. 1.800
Total height. 8.998

I need to decide which head gasket thickness I will use, then I will cut the block.

Re: 302 Chevrolet Engine Build
 

Mike Jones you are doing a fine job, keep the Build updates coming. It's great to see a young fellow developing an ability. Your combination of parts should workout just fine, keep it light and low drag. The preparation of all the components are important, but you appear to have that handled. Keep up the "GOOD WORK"… Maurice.

Re: 302 Chevrolet Engine Build
 

Thanks! A member on here donated this 1967 small journal Z/28 windage tray, which was very appreciated, very hard to find piece. I will clean it and punch the holes out.

Re: 302 Chevrolet Engine Build
 

Very cool! Lots of great members here that's for sure.

Re: 302 Chevrolet Engine Build
 

Great looking engine build, but don't use OEM small journal rods. They break where the big end and the beam connect at the flare. Get the Manley rod or something else. The 67 engine DID use a 2 bolt main 327 4" bore block and a steel small journal 283 crank, so the assembly was very light for an OEM configuration. Also, do your early 462 heads have 2.02 intakes and 1.600 exhausts? I have a pair of those on my core shelf, and the rocker studs are cross drilled through the stud bosses with little roll pins through them and the studs. Only motor I ever saw like that were 62-65 hi po 409's. I wonder now if that is what these heads I have originally came on, if not a 68 325 horse 327. Very interesting engine build you have here.

Re: 302 Chevrolet Engine Build
 

The 302 had a special 3" stroke crank, not a 283 piece. You can check the date code on your 462 heads, some had 1.94 intakes. The small roll pins were an early common fix to prevent the press in rocker studs from pulling out.

Re: 302 Chevrolet Engine Build
 

Got motivated today, rolled my wagon out a bit to access the cylinder head rack, pulled out both those 462 heads, one has a date cast of H 6 6, the other one looked like H 12 6. Rather early castings for 462's, but they definitely have 2.02 intakes and 1.60 exhausts. I haven't taken them apart to inspect anything, but they were kind of interesting.

Re: 302 Chevrolet Engine Build
 

Greg: If there is no provision on the side of the head for the water temp sensor, then these could pass for 67 Z heads. Aug 6th and 12th 66 castings.

Re: 302 Chevrolet Engine Build
 

Interesting. I will check this weekend for the water temperature boss and the threaded hole. Winder if these came on a 327 350 horse or even a '68 325 horse 327. When did the screw in studs and push rod guide plates come along?

Re: 302 Chevrolet Engine Build
 

Well, curiosity being what it is, I got back out there and checked. No coolant temperature switch hole,no provision for one. I checked the other two pair of cores I have, none there either. I then went into the trailer, opened the hood on my race car, no temperature switch holes or boss for one on them either. Now, heads made in 1968 had them, as the 3917290 and the 3917293 castings, which are '68 only, do have a plug or a water temperature switch opening. Seems that '68 was the year stuff like that started changing.

Re: 302 Chevrolet Engine Build
 

My 69 Z28 was built in late May 69 and has screw in studs and guide plates. Not sure on the date codes on the heads though.

Re: 302 Chevrolet Engine Build
 

Well, according to the NHRA Tech Bulletin pages, 462 heads are only legal on the 67 Z/28. There's several other accepted heads, which carry over into 68 and 69, but the 68 and 69 cars don't show a 462 head as being legal. The 69 cars had the later casting with the bolt holes for accessory mounting brackets, because 69 was the first year for the long water pump and brackets mounted to the heads and block instead of the exhaust manifolds. All Z/28 engines had the 2.02 intake/1.60 exhaust valves, but the OEM 67-68 heads had no boltholes. 67 Z's were so rare anyway, it's very unlikely anybody is going to find a set,originally.
In the summer of 1980, I wrapped up my days of working in dealers and one of the last jobs I did there was to put a rear main seal in a very nice low mileage 67 Camaro SS 350. Camaro was the only Chevy in the lineup that got the 350, and when the pan was off, I noticed it was a 2 bolt main block but it had a steel crank. I've wondered, since it was a one-off combination if that engine that year only was a small journal 350.That would have been before the changeover to the large journal engine division wide the next year.

Re: 302 Chevrolet Engine Build
 

A 67 z had 462 or 291 heads and the 68 z had 291 castings. Of course your results may differ. LOL

Re: 302 Chevrolet Engine Build
 

Are you guys thinking that guys like Tony Pizzi and Ben Wenzel, Durbin and Sartwell, Wheatley Bros. etc, were breaking rods back in the 70's?
How about all the 283's that would leave the line on the mat back then, with an even smaller rod? I realize the Z pistons were heavier, with the dome, but Mike said they would be lightening them.
This is a street and strip, but mostly street build.
I'm sure the Chevy rods will be fine.

Re: 302 Chevrolet Engine Build
 

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.

Re: 302 Chevrolet Engine Build
 

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.

Re: 302 Chevrolet Engine Build
 

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

Re: 302 Chevrolet Engine Build
 

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...

Re: 302 Chevrolet Engine Build
 

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

Re: 302 Chevrolet Engine Build
 

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.

Re: 302 Chevrolet Engine Build
 

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?

Re: 302 Chevrolet Engine Build
 

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

Re: 302 Chevrolet Engine Build
 

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.

Re: 302 Chevrolet Engine Build
 

Looking good son, keep it up.