Originally Posted by: HK1837 
Originally Posted by: castellan Originally Posted by: HK1837 Originally Posted by: castellan Originally Posted by: HK1837 Originally Posted by: castellan Originally Posted by: HK1837 Originally Posted by: HGV8 I didn't realise there was a difference in power with earlier and later LX L31's.
Ours from memory was bought in late 1978. Can't remember it's build date though.
Maybe it was one of the later ones...
Regarding the HR 186S 4 speed. They were a lot quicker then a HK GTS Monaro 307 auto between sets of lights.
But then again the 307 powerglide were not much of a performance car.
Jim
There is basically 6 x different red 308's from HT through to the end of HZ/VB:
HT-HQ and early LH. 9:1, small camshaft (253's cam).
L34. Same small camshaft as earlier engines but bigger valve heads, higher compression pistons (9.7:1-ish) and modified intake.
HJ, later LH and early LX. Bigger camshaft (same grind cam as HK GTS327 and HT-HG GTS350), higher compression 9.7:1.
HX and most LX other than A9X. Same cam as HJ, still 9.7:1 but loses significant power in its intake manifold.
HZ and most A9X. Same as HX but different intake.
Later HZ and VB. Compression lowered to 9.4:1.
Power loss of the ADR27A is due to the lean jetting and dizzy setup and the intake manifold has got no restriction as to a stock engine at all.
The early 308's HT-G-Q cam is the same as the 253 of the same year but the HJ 253 on has a smaller cam.
The 308 HJ on, cam is an emission cam with a longer exhaust duration so as to create more heat in the exhaust to burn off more un burnt fuel, the static 9.7:1 was only to bring the same compression ratio as before due to loss of real compression when running due to how the cam works.
The bigger the duration of a cam the higher you static compression has to be, due to the loss of actual compression due to a bigger cam.
The 308 ADR27A cam is the came grind as the Aussie chev cams, is that a fact ?
In order:
Nope. Manifold is the problem, I even have flow bench figures for both that shows how bad the pollution inlet is. Will check but I don't think power jets or even dizzy settings change all that much. GMH de-rated the advertised power of all their engines (except 5.0L) for LX release so when the AD27A engines appeared mid-LX they didn't look as bad on paper as they were. 5.0L dropped from 250hp peak to 216hp peak at ADR27A release.
Nope. HJ engine is the same as HT-HQ.
Nope. It is a performance cam, not an emissions cam. 308/304 carbided engine never got a changed cam after HJ, same general performance cam grind as all hydraulic cam SBC's on the late 60's, early 70's other than the 350/350hp Corvette. It was the cam used in the 327/275 and the 350/295-300.
True, but also depends upon the Octane rating of the fuel you intend to use on it.
Yes (as above).
It's not the 308 HX intake manifold at all as she can make 260 real HP and I have proven it does not make one bit of difference in performance of a stock 308 or even a small 20/60 cam and all the grunt is not at a loss at lower rev's is it.
I could do 5300RPM in top gear with a 3.08 ratio diff and the speedo said 213KM/H in my old HX sandman.
The worst thing for good performance is that the intake manifold flows to well, that you loose lower rev performance.
Mind you with a big cam then such as a large intake flowing manifold would be desirable.
It is the intake, guarantee you. It is the only main difference between HJ and HX engines. Go back and read the Street Machine flow bench article where the figures come from. The pollution manifold is limiting the standard heads, whereas the pre-pollution manifold flows up to 313hp and flows more than the stock heads.
Fact is that if the flow rate can make 313 HP or HX is only 260 HP the standard HQ 308 can only make 196 net HP with twin exhaust.
A mate had a 308 HQ back in 1980 and it had a stock 253 intake manifold and stock 2 barrel carby on it and she went well for only that small carby on it, we would cruse at 180 KM/H and it could do 200 KM/H.
I don't know why it had that setup but that's how he bought it and it had 308 cast on the block.
So you see that even small CFM works well, it does not hinder performance at any rev range until it's compromised, because until she is having to need more CFM due to the rev's need more CFM.
So that being a fact that an engine only need more CFM due to what it needs.
So such will have no bearing at all in the response of performance until it's compromised, so a HX 308 we know does not respond at 1000 RPM 2000 or even 3000 RPM like a HQ does now does it.
The HX 308 It's a dead duck all over, is it not.
And we all know that high air speed in the intake manifold is what makes performance better especially down low in the rev range, so such does no harm to performance as such.
The Bedford truck with the 308 engine has only a 253 intake manifold on it and only a small carby.
The lack of performance of the HX 308 has to be in the jetting mainly.
When I bought my HX back in 1984 the dude who owned it was a mechanic and he pointed out to me about the jetting she must be such a ratio in the Rochester and such in the 650CFM Holley he said for best performance and fuel the Rochester is better than the 650 Holley he pointed out to me.
I have the ratio some where and it's richer than standard HQ not to mention the HX and the Holley has to run at a different ratio to the Rochester to perform at it's best.
The manifold creates the problem as it restricts or upsets air flow at high rpm, the carbs have a slightly different tune on the secondaries probably as the engine is unable to breathe as well as the earlier engine. They appear the same on the primaries. Advance is similar except full cent. advance is a bit higher on the HX engine. HX-HZ engines go well with an Edelbrock Performer which flows near the same as a pre-pollution manifold. Put the dog one back one and the engine is a dog again. Those flow figures are into a perfect port, and they say they were extremely generous to the pollution manifold - fact is the manifold limits the engine, it is designed to slow the air down and make it more turbulent that is why its all ribbed in the plenum. Use the SBC's as an example, the cast iron manifolds are capable of flowing more theoretical hp than the 300hp on the L48 engine, but engines above 300hp they change to an alloy inlet. Put that same alloy inlet on the 300hp engine and it'll produce more hp despite the cast iron manifold capable of more.
Bedford truck 308 had a 4BBL manifold with the same design carb as a 307 HK-HT. It was normal for GM to put 2BBL carbs on their low comp truck engines.
So that's what that carby is on the Bedford, thanks.
My HX had a HT engine in it when I got it, just a GEM stock reco she only had extractors and twin exhaust but the intake manifold was the same old original HX it came with, old mate had just epoxied up one of the emission ports and tossed it on the pre EGR HT heads, I went out drag racing every week end just about in that HX 1985 to 1986 and never seen any stock 308 out perform it even ones that were worked over, my mate had a full recon engine with a TQ 20 cam in his 308 HJ sandman with same gearing and M21 box, I had it all over him as well even just with 3rd gear runs so it's nothing in it as to skill.
Hell I was neck and neck with a good mates LH Torana 308 with a big 30/70 cam and he had a 3.00 9 inch and M21 box over the 1/4 mile that we had setup out on our cane road that we dragged on, that LH sure went well when I drove it, I was sure it would blow my HX into the weeds, I was so surprised that it could not.
Even a highway patrol cop drove it once and he said f this thing goes, thinking it was Chev powered 350 under it and all it had was a 20/60 cam with stage 3 heads at that time.
No stock 351 XB-C-D-E ever did hose my old pre ARD 27A stock 308 HT engine HX Sandman off and I had plenty of runs and even a mechanic with a small cam in his XC 4SP was to fearful to give the HX a run, he may of just been able but if he lost he would not be able to handle that.
I just dragged out of interest, if I got hosed off did not mean jack to me.
This is why I truly wonder what you are saying about the HX intake, because in my experience it's not true at all.
I would of believed you about the HX intake manifold for sure but I know it's not true for a fact in my experience, hell I owned that van for 20 years and if I thought that manifold was crap I would of tossed it, I even had it welded due to corrosion and put it back on.
If I went to a 25/65 cam I would of went for a HQ type or a 30/70 a Performer manifold, I had seen what the Torquer type did with a 30/70 cam in a mates 308 VB commodore and it was just hopeless.
The engine I got the car with was a early 308 with a HP cast block from a HT Brougham just a GEM recon engine bored out 0.030 now the cam that they regrind the spec to in 1984 who knows what it I truly is, is the same spec as the HT-G-Q or did they do a HJ type spec at the time or do they do their own spec.
I don't think when any company grind a cam that any company can make the same spec as original unless it's under licence to do so, it would be interesting to find out just what GEM, REPCO did and what spec did they do to the red 6 as there are many types that Holden used from EH to HZ.
