Tell him BS. They go HEAPS better with a Quadrajet. A 307 as we got in HK is exactly the same engine as the GTS327 engine. Except for two things: 1/8" larger bore on the 327 and the 327 got a Quadrajet. 210hp vs 250hp, although in the USA the same 307 got 200hp but that was with less dizzy advance as it was designed to run on regular fuel, whereas our HK and HT 307 got the 327's distributor and designed for Super fuel.

That same 250hp 327 we got here - in Camaro that engine was used but fitted with the 2 barrel and intake the same as the HK-HT 307. It was rated at 210hp. Only 10hp more than the 307.

I can tell you with certainty, take a bog standard HK 307 and fit the GTS327's intake and carby, you'd think you'd changed engines. It makes that much difference.

Same applies to a 253. People raved about the XT5 4.2. The reason it went better was the 4BBL intake and Quadrajet. If you took a stock red 253/4.2, threw the intake and carby in the bin and fit a 4BBL intake, plus a blue 4.2 Quadrajet (or a red 308 one setup and tuned right) it will go heaps better. Give it a mild cam and good exhaust and it will really surprise you. 283 SBC are like that too, if they are bored a little and given some compression (a pair of 64cc fuelies will do it, hence why you need a bit more bore to deshroud the 1.94 intake valves), very mild cam, 4BBL intake and Quadrajet, they are a little weapon. Forget a 308, those things really go well for a sub 5.0L engine. In something like a Torana they are perfect.

It was all to do with how they wanted to evolve the Holden V8 like they did with the red 6, where it went from 149 over time to 202. It was supposed to not get to 308 until about 1979. They would have evolved it from 2BBL to bigger engine to 4BBL over time. Ford releasing the 302 in XT killed all that so they went straight to 308ci. Norm writes about it in his HK-HG book.

Back in HQ, even dual exhaust and 3.36 rear axle woke them up. A HQ XV2 (SS) with both was basically as quick as a stock manual 308 (single exhaust). If GMH had made them a fraction more special with the 308’s intake and carb it may have changed people’s opinion about 253’s forever. There would have been no point making LH SLR5000 other than the L34 variant.

Edited by user Wednesday, 2 August 2023 7:21:44 PM(UTC)  | Reason: Not specified

I think with the 308,in stock trim, Holden made it a low down torque monster. It wasn't a drag strip machine but designed to tow the boat/van.

Fortunately they are easy to wake up and the ones I have built with simple mods, still everyday streetabe, would make the 350 obsolete!!

Probably comes back to the old saying, "there is no substitute for cubic inches"

That’s sort of true for the original 308. From HT through to HQ it was only 9:1 and used a retarded by 5deg 253 cam. Regardless of the BS 240hp advertised power figure quoted, it was 227hp SAE Gross. Compounding this was every 308 powered HT-HQ cane standard with a single exhaust. In LH SLR5000 the dual exhaust were tiny, the combined cross section barely bigger than the Holden’s 2” single.
The HJ engine was 250hp SAE Gross. Courtesy of compression increased to 9.7:1 and a significantly better cam. This engine was a real weapon, just ask anyone who bought a HJ optioned with dual exhaust or, later LH or early LX 5.0L and replaced the tailpipes. This was the highest power rated 5.0L until the HDT engines. The L34 engine was given more rated hp than the stock HT to HQ 308 (240hp to 227hp) but it was still fitted with the retarded 253 cam, ran the same carby etc. Sure it had larger valves and better headers but without the cam to support it and still having the tiny tailpipes it would have struggled to use that power. On a dyno you’d most likely get it to rev more produce more peak power than the HJ engine, but GMH conservatively rated it. Remember they were trying to hide any involvement in racing!

Edited by user Thursday, 3 August 2023 9:56:00 PM(UTC)  | Reason: Not specified

I hav a Holley 600 for it but if u do pass on the part number for the quadrajet I will hunt one down if they’re a lot better thanks HK1837.
I will hav to hav a look at the manifold to see what it is…
Any other info on how to make these 307s go better is appreciated, heads valve sizes and cams etc…
Cheers,
Rock.

The ultimate way to make them go better is to bore them to 4" and fit a 3.48" stroke crank or 3.75" stroke cranke. Those two options will give you 350ci and 377ci. At 4" bore and 3.25" stroke (the crank you have now) you'll have a 327ci engine.

But the above is better kept to an original 4" bore block.

A 307 shares the same bore as a 283, so to go to better heads with 1.94" intake valves you need to be around +60 thou, where you'll be at 292ci. All you really need to do is buy a pair of old fuellies, or a pair of the mid 80's Corvette alloys. The 64cc fuellies will give you about 9.5:1 compression. The 58cc alloy 'vette heads about 10-10.5 but that is fine with alloys. Just use the right cam. Stick with 416, 291, 040, 186 or 041 fuelies, and makes sure they haven't been converted to 2.02/1.6 valves (or original that way).

You are best off figuring out what you want for it engine, transmission, converter and diff ratio wise and then get a cam made to suit.

7028212 DH is the 1968 327 250hp powerglide carby, it would work on a 307. Its auto choke would work with a 1968 4BBL cast iron intake. If you went with an aftermarket alloy intake you'd possibly be better off with a 308/5.0L carby. As Smitty says, you can get an electric choke conversion for these, and the operator is on the body of the carby. The blue 5.0L version of this is 17059595 CXK, in these auto and manual is the same (they have both vacuum sources on them). You might have to get an aftermarket Powerglide kickdown setup though and that carby won't have the right throttle attachment for a rod type throttle so you'd have to fabricate something. The HX and HZ red motor Quadrajets would work too as they have an integral choke operator.

There is on sedan, not certain about Brougham. I think they might be the same.

A lot of the rest of the HG Brougham will help you. But be careful as there is a fair bit different in some areas. Like leaf springs, gearbox crossmember, gearbox itself and subframe being some of the big things. There are a lot of other idiosyncrasies too that you'll spot when you put them side by side.