Found some reworked aluminum heads and an offy 4bbl manifold for a 300, but I was under the impression that the alum. parts don't fit the 65? Is this true? Have a good running 300 I hate to change out, just needs more power. Yes, I know a 350 bolts right in. Thanks.
300 heads and intake should bolt on. You may want to find out exactly what “reworked” has been done. From what I understand, the aluminum heads have smaller ports and valves then iron heads . So gains may be minimal. If your starting with a 2 barrel engine, your compression ratio is lower also, probably why your looking for more power. Did you do try power timing yet? And a 350 trans with alittle more converter may show improvement. Or better yet, a 3.73 rear gear and a 2004r trans. Since both have a 2.5 or better first gear
Thanks, Andy. My motivation is that these heads are half the price of a rebuild on the iron, with other parts included. What is power timing?
http://www.v8buick.com/index.php?threads/power-timing-your-buick-v8.63475/ Check out Larry’s post on timing. I assume you mean they have been rebuilt. Find out if the valve springs have been replaced as they are weak at 50 years old, also combustion chamber size can be modified for increase compression by shaving down heads.
Yes, I meant rebuilt. They have been shaved .010. Is the carb hard to find, it does not come with one.
You can get something universal, but You will need to correctly jet and meter carb for your engine . An air fuel meter can help with that. .010 probably won’t gain much in compression. You would need to find out cc of iron heads and the aluminum heads.
"Performance improvement" and needing more power might be misleading. The new heads with smaller ports and power timing added to your tuning will probably make the engine snappy and more responsive off idle and midrange. The smaller ports usually choke out the engine sooner, so there would be less hp at the top of the range...unless the heads are ported. The replacement top end being cheaper, will probably meet your needs. Be careful that the added cylinder pressure doesn't go right past your rings. Well used and good running engines don't always show the power improvements. A good thing to do is a compression test before and after the swap.
> Found some reworked aluminum heads and an offy 4bbl manifold for a 300 Be aware that Offenhauser never made an intake manifold for the Buick 300 but they did make several of them for the Buick 215. Offenhauser made several 215 intakes including the Equa Flow 360 (very short runner split plenum single plane), JWR/Dual Port 360 (runners split into upper and lower halves) and a 2 x 2 barrel. None of these would be particularly well suited to a performance build Buick 300. A Buick 215 intake is designed for a shorter deck height so is narrower. A quick way to tell a 215 intake from a 300 intake is the 300 intake is cast with a valley cover while the Buick is open (valley is sealed by the "turkey pan" intake gasket). You'd need an adapter to use a 215 intake on a Buick 300. I've not done it before but I'd guess that a 1964 Buick 215 2 barrel aluminum intake could be milled out to make an intake adapter. If the head ports are the same size and the Offenhauser intake, they are also Buick 215 (or Rover). Buick 215 ports are considerably smaller than aluminum Buick 300 which are somewhat smaller than cast iron Buick 300. The combustion chambers are also much smaller in Buick 215 heads (37cc versus 54cc so compression ratio will be increased a bunch). With Stage 1 Buick V6 valves (1.775" intake and 1.5" exhaust), my ported Buick 300 heads flow 200 CFM intake and 150 CFM exhaust with very good low lift flow. I've not measured one myself but I'm told a stock iron Buick 300 head flows around 170 CFM intake and 105 CFM exhaust. By means of comparison, a Ford 5.0L HO cylinder (E7TE casting) and an unported Buick 300 aluminum head are both in the mid 150s for intake flow. My ported Buick 300 aluminum head flows on par with an entry level aftermarket Ford 5.0L head (Ford Racing GT40X, Edelbrock Performer, etc.). No one made an aftermarket 4 barrel intake for the Buick 300. If contemplating a 215 intake (and adapter), the Huffaker single plane has ports that match the intake ports of the aluminum 300 heads perfectly. All the other commonly available Buick 215/Rover intakes have smaller ports. > Is the carb hard to find, it does not come with one. They used a Rochester 4GC (not a Quadrajet or AFB). Buick 215s also used a similar carb. I should have a spare one around here if you need it. I've also got a stash of jets for tuning somewhere. Dan Jones
Thanks all. I've decided to pass on the parts lot, too many variables. Guess I'll keep looking for that decent older 350/350.
Probably better off getting a good core and building it yourself depending on needs. The only hi compression engines are 68-70 4 barrel engine. And those are a truly only 9.2-9.4 compression . Which isn’t bad, depending on your needs/goals. Otherwise 68-74 2 barrel is about 8.2. And you will want to change front cam bearing and update oiling modifications
