Originally Posted by: HK1837 
Originally Posted by: castellan Originally Posted by: HK1837 All
I just noticed an anomaly with red 308's.
HT-HG are essentially the same engine with same basic components and 9.0:1 compression, although later HQ got the leaner idle 704 Quadrajet. Early LH are the same.
At HJ release a far superior 9.7:1 308 was released and also went into later LH and early LX.
HX-HZ seem to be quoted still at 9.7:1, however VB Commodore seems to be 9.4:1. It is that way in the VB Service manual, Scientific Publications and even Dr Terry has it at 9.4:1.
HX-HZ at 9.7:1 is in parts catalogues, Scientific Publications and also Features manuals.
The V8 engines did change to the new "blue" type block at VB release so maybe the 308 did drop in compression at that time but it was never documented in HZ anywhere that I can find. I have the service letters for the whole year where the block changed and there is no mention of a change in HZ's 308 specs.
Are there 2 x different 308's from VB release until 1980 or is the VB info simply wrong?
Unfortunately the late LX parts catalogues still have both 4.2 and 5.0 as 9.0:1.
Far superior HJ 308 come off it, it has a cam for pollution and a intake that is squared off.
And the HJ 253 has a smaller cam for pollution then the early ones did.
Sadly power was rated at nonsense figures.
I believe all blue engines all got improved strength pistons and this may of started before the blue engines came out.
What's different with the V8 blocks in the blue ?
I have seen original red block with 3.3L casting on the block of a late HZ ute and it had the blue motor exhaust valve rotators and the head was a little different casting near the in and ex manifolds to early HZ-X.
The HZ 6 CYL gets the better rods and bolts when the great starfire 4 comes out.
The Starfire 4 gets UN cast on the block and the VC on they get a 1.9 casting.
Funny they get the UN casting at the start of the starfire 4, just like the early 179 gets HP and the early 308 gets HP, and I have seen a NP cast on a 202 block.
HJ 308 is superior in performance to a HQ 308, 100% fact. They jump from 9:1 to 9.7:1 with no other changes. That is a huge jump in compression, similar US engines see up around 25hp gain from similar compression hikes, however in the HQ-HJ case the heads didn't change so you'd expect something around 12-15hp gain. There was no cam changes. Power was definitely not nonsense figures, in fact gross hp figures are the only sensible figures as they are all conducted in the same fashion, same temperature, same humidity on an undressed engine so are easily comparable between engines. GMH didn't adjust their hp figures for the HJ engine unfortunately but the cars were significantly quicker, the best evidence if you can find it is in LH figures for the early cars with the HQ engine and the later cars (or early LX's) with the HJ engine.
V8 blocks from VB release have the longer valley head bolt bosses.
The HJ 308 cam is PN 2825882 it has one ring cast into the cam, this cam is the same cam up to the VL Commodore the spec may sound bigger than the HT to HQ V8 cam PN 7438871 but it does not perform as well because it's an emission cam just like the HJ to VH 253 cam PN 92000944 with 2 rings cast on it, the reason why they made a 253 and a 308 cam was due to emission standards even before ADR27A.
HT to HQ 253 and 308 had the same cam.
Holden spec on the cam is old backward rubbish spec done at 0.002 or so that makes it very hard to read in reality when 0.006 is a much better way or the modern day at 0.050 reading a cam spec not to mention all the other things one can look into with a cam.
I don't swallow that the 308 HJ went any better than a HQ, as for the car test back in the day they were mainly hopeless idiots that could not drive for jack and the idiots did not have well prepared tuned cars let alone inform use of the diff ratio of the car tested, so that all makes it bloody hard to work it all out in reality.
I remember a mate of my dads talking at the pub maybe in 1979 he had a yellow HJ 308 GTS auto and he said it did not go better than a GTS HQ 308 auto.
The old SAE gross HP ratings is a sad joke, it's just rubbish, The USA got rid of such out dated rubbish in 1972 and went to more of a reality figures, just look at the wild claims we had in the 70's a XY GT-HO is rated as the same HP as the GT ? and anyone knows that is not true at all, now don't they.
I will put it to you that a XB 250 falcon had 155 HP but in Net HP figures that's around 111 HP.
Look at the B/S we had put forward with the XB Falcon V8 302 stating 240HP and the 351 with 260HP now both have a 2BBL carby, now in reality the XB 302 is 159HP and the 351 is 183HP and the 351 4BBL rated at 290HP truly was only 214HP.
Now that's the facts.
