LPG on a 308

Post by **Fieldsy** » Thu Mar 11, 2004 2:38 pm

I have got myself a blue 308 without heads ( got it for the right price) and I am thinking of setting it up for gas right from the start. my question is if I decide to go this way what heads manafold etc would be the best to get?

Post by **ORSM45** » Thu Mar 11, 2004 8:53 pm

any just make sure you have the proper valves and valve guides for gas.

is it dual fuel or straight gas?

manifolds are all the same. because gas is already a gas (oh derr) you dont need to heat the intake manifold (as required to atomize petrol).

just get yourself a good aluminium manifold, like a performer. single plane manifolds like the torker II are supposedly better for gas but i run a dual plane on mine and its fast enough.

MaccA

Post by **Fieldsy** » Thu Mar 11, 2004 9:33 pm

any just make sure you have the proper valves and valve guides for gas.

is it dual fuel or straight gas?

what sort of valves and guides are the right ones? I was kind of hoping that someone would tell me to get xyz heads cause they will work fine when stock. I have been told that all 253/308 heads are interchangeable. Is this true?

I am thinking of running it on straight gas. I don’t do long trips and it would let me get rid of the tank under my seat and make up better seat mounts. ( my feet get stuck all the time) and I don’t need to buy a carb.

Also as mentioned in another post you can find kit’s in the paper for $300 to $400. this sounds very cheep are these kit’s any good or are they generally nothing flash

another thing is do you notice a drop in power from petrol to gas? I have herd that a motor running on stright gas makes the same power if set up right is this true?

thanks

Post by **ORSM45** » Thu Mar 11, 2004 10:22 pm

you can run higher compression with gas. so power will still be there. you can make the same power and sometimes more than with petrol if set up right.

i think they are stainless valves and stainless valve guides. not sure sorry.

Post by **Punchy** » Thu Mar 11, 2004 11:36 pm

Stick with the early heads (siamesed exhaust in the center.
preferably about the HQ era.

you can run a little more compression if you want to but then you may loose the option of dual fuel if you choose to do so later.

The earlier cast heads have a better flow charateristic and lean towards lpg gas and bottom end torque.
The air speed in the ports for the newer hi port heads is a little slower and thus affects your bottom end responce / power output. Injected with petrol they are fine but they really dont come alive till 2600 -3200 rpm. And somtimes thats 1000 rpm to late.

New stelite vales are sufficient. With bronze guides and inserts in for the valve seats. (save your money on the stainless valves and put it on good valve inserts. It's all you need)

If your gonna wheel with it its about bottom end power and torque.

You dont need big pipes either,,,tri y's at the most.

I used this combinatation for santa on his rig and he's alway had enough power without even blipping the throttle for crawling. It's not an rpm rig..(it can do it tho) It was designed to lump over stuff and do it all day long! :armsup:

Hope this helps

Post by **ORSM45** » Fri Mar 12, 2004 11:42 am

they were the valves and valve guides i was thinking of but had a mental blank.

tri-y extractors are supposed to give you better response and low end torque. if you build it for low end these will compliment all the other things.

it will still make alot of torque up top too. just the majority of it will kick in sooner.

MaccA

Post by **Fieldsy** » Fri Mar 12, 2004 1:21 pm

cool this is gold!

So if i get some heads off say a red 308 bung in some stelite vales and bronze guides and inserts. Throw on some tri-y extractors and top it off with a $300 to $400 LPG system from the tradeing post I should have a bloody good off road motor that will run on just about any aingle!

another question is the manafold. I think i can get the one that used to be on the motor but as this is a blue and I'm talking of useing red heads will it fit?

To top it all off my motor is also a 330 I'm told the power diference betwen a 308 and 330 is more torque in the bottom end , so bottom end on this motor should be good. ........... I hope

Post by **Fieldsy** » Fri Mar 12, 2004 1:24 pm

another thing is the exhaust. duel or single? what is the diference? cosmetic or will this afect the power?

sorry bout all the basic questions but I I know stuff all bout V8's haveing never owned one in all my 30 very very long years

Post by **ORSM45** » Fri Mar 12, 2004 7:46 pm

330? how do you work that? longer stroke?

im not sure about holden V8s but if its a cast iron one i wouldnt bother putting it on.

dual with a balance pipe between the 2 is supposed to be better because of the extra flow, if room permits get the dual pipes.

Post by **Fieldsy** » Fri Mar 12, 2004 9:22 pm

330? how do you work that? longer stroke?

im not sure about holden V8s but if its a cast iron one i wouldnt bother putting it on.

It’s a 338 which is a stroked 308 it’s out of a VL commodore. So I spose it is a cast iron block. Why would you not use it? There is no way I could pay for a later year fuel injected one.

Post by **ORSM45** » Fri Mar 12, 2004 10:14 pm

nah i was just wondering how it worked out to be that. wasnt picking on it. yeah it would be a cast iron block.

it will go pretty hard non the less.

mine is a 1976 350 block so age dont really mean crap. new 5.7L SS commodores have trouble passing even at 160km/h.

Post by **DAZZ** » Fri Mar 12, 2004 10:37 pm

I don't think a blue moter intake will fit on red (pre Polution) heads.

Post by **Fieldsy** » Fri Mar 12, 2004 10:42 pm

bugger but red heads will fit on t blue block right

Post by **ORSM45** » Fri Mar 12, 2004 10:48 pm

yeap. but because the intake on the red heads are different you wont be able to use the blue manifold.

just look in the trading post, about 150 bucks will get you a good aluminium edelbrock performer.

some people cut the divider out of the dual plane manifolds when running on gas. i dont remember the reason for it but its supposed to be better aswell.

Post by **jessie928** » Sat Mar 13, 2004 1:58 am

Compression can go up a fair bit, you can run 12.5-1 on straight gas and more.
seats and valves as noted before, dont forget the cam, the single most important object in ANY engine, is a "properly" dialed in cam, this wil govern how your engine behaves, select the cam that will work best with the compression you wanto run and the power range you want.

heads, i would go for late model heads, its a simple fact that later model 308's have more power than earliyer models.

Also, dont overlook your disributor, electronic is a must, and you must get it graphed to suit your cam and LPG,

you will find that with a good setup, you will make more power than a comparable motor running on pump petrol

you can plug your gas bbq into the car, it will be more economical, and run upside down to boot!..

JEs

Post by **Fieldsy** » Sat Mar 13, 2004 6:41 pm

dont overlook your disributor, electronic is a must, and you must get it graphed to suit your cam and LPG

really this is starting to sound bigger than I thought it would :cry:

can anyone tell me why a red 308 makes 161kw / 400nm and a blue makes 117kw and 336nm ?? is it all the pollution gear or the heads?

jessie928 late model heads arn't really an option they just cost way too much. I'd rather spend this mony on suspension.

383FJ45 did you ever drive your cruiser with the old motor? I have never driven a V8 cruiser but I asume the power diference to be pritty awesome or am I setting myself up for a disapointment?

Post by **jessie928** » Sun Mar 14, 2004 12:08 am

the difference between the old 6 banger and the 8 is definatly a BIG difference in power, drivability and fuel economy, you WILL be pleasantly suprised.

btw regraphing your dizzy is not a big deal, nor is it a big cost.
i would recommend you get electronic 200%, but you can live with the inadequecies and under power of a points ignition if you like

initial power difference was due to emission control regulations, the engines had to be "greener"

Jes

Post by **Fieldsy** » Sun Mar 14, 2004 9:31 am

so because my blue won't have any of the green stuff it should make 160+ kw

BTW my whife saw me writeing my post

bugger but red heads will fit on t blue block right

causeing quick fireing questions

cause she is a red head and is convinced all I use the net for is p0rn.

and now I think of it

DAZZ
Posted: Fri Mar 12, 2004 10:37 pm

--------------------------------------------------------------------------------

I don't think a blue moter intake will fit on red (pre Polution) heads

I think your right DAZZ

Post by **Fieldsy** » Sun Mar 14, 2004 9:36 am

you can plug your gas bbq into the car, it will be more economical, and run upside down to boot!..

But could I plug in the BBQ while the truck is upside down? now their is an Importand question

Post by **ORSM45** » Sun Mar 14, 2004 7:49 pm

i drove my 6 for a while. it went pretty well used to chirp 3rd with 35s. but the difference between the chev and the old motor is unbelievable. best thing is, it cruises at what ever speed limit on any size hill and it does it with ease. and i return better economy.

like i said before, commodores dont know what theyre up against. :twisted:

MaccA

Post by **the_smoo** » Sat Mar 20, 2004 6:01 pm

I have a 308 in mine and for information regarding these V8's you cant go past " How to Rebuild and Hotrod Holden V8" by ellerys. I have seen them for sale in kmart! 30 odd bucks.

There is a whole chapter on head options alone for these engines, as well as heads recommended for gas.
Also a section on modifying the ignition setup.. Generally a book of tweaks and tricks for holden V8.

should have you wheelstanding in no time......

Post by **Fieldsy** » Tue Mar 23, 2004 9:15 pm

thanks for that I will have to pick up a copy.

another question is what brand of bell houseing adaptor's are you guys useing for your trucks? I have looked at the marks one but It costs more than I thought it would

Post by **ORSM45** » Tue Mar 23, 2004 9:21 pm

i got mine with a sh1tbox i bought with good running gear.

it has 'seton' stamped on it. so im guessing that

Post by **the_smoo** » Wed Mar 24, 2004 8:09 am

Mine also had it already in...

Mine is from Dellow Automotive in Sydney. I do know that it comes in kit form but not sure about the price..

I have ordered some replacement parts from them in the past and to say that they are extremely helpful would be an understatement.

http://www.dellowauto.com.au/main.html

They will also provide you with instructions and advice....

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