302 Chevrolet Engine Build

[Greg Reimer 7376]

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.

[Hacksaw]

Originally Posted by Greg Reimer 7376

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.

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.

[Greg Reimer 7376]

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.

[Hacksaw]

Originally Posted by Greg Reimer 7376

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.

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.

[Greg Reimer 7376]

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?

[Greg Reimer 7376]

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.

[killintime6968]

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.

[Greg Reimer 7376]

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.

[Hacksaw]

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

[Mark Yacavone]

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.