Grey Power !!!

vmx-mxr · Post by **vmx-mxr** » Fri Oct 23, 2009 9:04 pm

Just curious.

Always had reds so can someone tell me what can be done to a grey to extract a little more power without affecting reliability too much.

We have s decent set of triple SU's sitting around and a Speco cover (yes I know - no power from the cover but looks the biz!

Interested to know your thoughts or perhaps a direction to an old thread?

Dave Mac

Trev · Post by **Trev** » Sat Oct 24, 2009 4:48 am

Dave, 2 things that were done to mine (which I haven't had running yet) was up the compression and get it breathing better, red motor valves and a bit of porting, Trev

.

mrs ratbox · Post by **mrs ratbox** » Sat Oct 24, 2009 6:44 pm

should get it to go ok but it'll never be a red motor

maybe better off getting rid of the su's and go for a set of twin strombergs unless you want to build a more serious motor
pretty much what trev said bit of head work ports valves comp, mid cam, twin strommies, extractors

Mick Jagger · Post by **Mick Jagger** » Sun Oct 25, 2009 4:19 am

you can always paint it red

mrs ratbox · Post by **mrs ratbox** » Sun Oct 25, 2009 8:41 am

won't help

actually i wanted to paint the "red" motor going in my car gray but at the time the guy didn't have it so now it's the red oxideish colour of the early reds

Mick Jagger · Post by **Mick Jagger** » Sun Oct 25, 2009 1:09 pm

It would save a hell of a lot of rego problems,Just paint the red grey and modify a grey rocker cover to fit,hmm theres an idea

mrs ratbox · Post by **mrs ratbox** » Sun Oct 25, 2009 1:51 pm

i'm just using a 138 red so no real hassle anyway

Craig · Post by **Craig** » Sun Oct 25, 2009 2:44 pm

As the others said like all early motors breathing is the priority porting bigger valves extactors ect carbs are always an interesting choice but as Ratbox said the tripple SU are more suited to Hi Po stuff and if you want a mildish motor the twin strombergs would probably be better they are a simple realetivly trouble free carb
cam choice is even more fun resist the urge to go too silly as it can become a dog

I still believe the gearbox on greys (especialy a hot one) let them down a 4 speed withe the right diff to suit the sort of driving you want to do will help keep it in its power band (for want of a better term)

If you want real power for reasonable money a grey is not it but for a bit of fun and that nosalgic look they cant be beat IMHO

mrs ratbox · Post by **mrs ratbox** » Sun Oct 25, 2009 3:23 pm

Craig wrote: I still believe the gearbox on greys (especialy a hot one) let them down a 4 speed withe the right diff to suit the sort of driving you want to do will help keep it in its power band (for want of a better term)

had mild hotty gray with 4 speed 3.36 diff in the chop top that was the end for me swore i'de never have another BUT this was mostly due to highway use

they are kool to look at though

vmx-mxr · Post by **vmx-mxr** » Mon Oct 26, 2009 1:01 am

Thanks guys

Between here and the FC forum I am building up a good idea of where we need to be heading for Jimmy's old girl.

Nothing silly and no need to put in a cam that makes the car a pig! Mild is it but I reckon you can't beat a rack of SU's hanging off a head, lol.

I am interested to know more about the magnesium 'Monaro Motors' twin Strommy manifold.

Dave Mac

FB MAD · Post by **FB MAD** » Mon Oct 26, 2009 10:03 am

Years ago ( early '80's when I was an apprentice ) the Repco engine shop in Newcastle ground a grey cam for me to go in my FC wagon I had at the time.

Still remember its specs, it was a 23/60 sports cam grind.Went well, with a throaty sound and good mid range.Don't ever make the mistake of over camming an engine, bigger isn't better.

If your engine is drag strip only then yep, cam it up, but for street use best to go with a sensible cam grind and modify the engine to suit.A correctly worked out modified engine is lots of fun ( just ask Craig or Thommo

who , from memory, runs a 30/70 cam in his grey ?? )

In comparison, I remember also working out the original specs for a grey motor cam but can't remember the exact specs for it although it was something like 11/45 or similar.

So camming up a grey with mods to suit can really transform a stock engine.The grey motors were basically designed ( in a smaller way and some small design differences ) from the stovebolt 6 Chev which first appeared in 1929 so they are an old design and weren't designed for big power......... more designed for tractor type power.

The head doesn't flow well but can be improved with port work and bigger valves. Standard red motor valves just fit. You may be able to fit bigger valves but would require combustion chamber releif and transfer port enlargement. Red motor valves will be good enough.

Port match the manifold and extractors to the head.Fit a modified curve electronic distributor.Pick your carb combo.Increase the engine compression if you can ( shave the cylinder head and/or special hi comp pistons < expensive mod though )

and DON"T FIT A FIBRE TIMING GEAR !!

Have fun!!

Stygian · Post by **Stygian** » Mon Oct 26, 2009 12:12 pm

Question FBMAD (or anyone else) - What are differences (e.g. engine characteristics, fuel consumption, power, fun), in your opinion, between a 25/65 and a 30/70 cam? Is 35/75 too "big" for a "warm" grey? I know a guy who had a grey with a Bathurst XU1 grind cam. It went OK at speed but down low it wasn't that great and idled roughly.

FB MAD · Post by **FB MAD** » Mon Oct 26, 2009 1:16 pm

Depends on what you want in a car as to how you should build the engine.

Want something that is a pig to drive around town then install an XU1 spec cam.Just remember that the higher the cam specs the higher RPM the engine needs to "come on cam" or "on the power band " .

You can't have it both ways though.

XU1 type cam specs will see high RPM power but nothing down low.Be ready for clutch riding and stalling.

A workmate years ago installed a 202 in his LC GTR Torana that was spec'd to LJ XU1.He pulled the engine out 3 months later as he was fed up with how it went.He reinstalled the 161S GTR engine.

From memory the last LJ XU1 spec cam was around the 45/85 ( may have been more ).
Great on the track but a shopping trolley it did not make!!

Stock cam gives you old farts driving style but starts to run out of puff around the 3000/3500 rpm range.

The engine is only a 4 bearing engine as opposed to the red motor 7 bearing engine and it has weaknesses in that and other factors that will limit it rev ability.Spend up big dollars and you can make a grey fairly good at high RPM's.

Or you can find the middle ground and do a fun sports motor that is more forgiving down low and still gives you some thrills when the pedal is down.

If I was to build up a grey today for fun, I'd probably go at something like Thommo has and follow his engine build specs.He had a video on U tube taken from the inside of his car at the Bendigo Nationals and it went and sounded good.Someone on here may be able to find the link??

Personally a 30/70 cam ( maybe 35/75 ?? ) would be what I'd stick around with head work,multi carbs,distributor recurve/electronic ignition and extractors.And your engine will be your best friend if you give it a balance........ smooths them right out!!

Spend some more $$$ with high compression pistons and main bearing braces if you have the $$$ and can get the parts.

And the grey crash box is probably not going to be fun to use with a sports engine.4 speed ( ideally a 5 speed ) would be better.

And you can't get power AND economy, it's either one or the other.

Some other blokes might have other ideas but that's my thoughts,

Craig · Post by **Craig** » Mon Oct 26, 2009 2:45 pm

Cant go wrong with what Terry said you want more bottom end than top
my cam is a 40/80 ( I didnt build it) and no fun in traffic with the 3 speed it will pull 50mph in second and at 65mph in top is just comming on the cam no good for a daily (and probably wont stay together if I keep driving like that) and is a bit of a dog especialy in traffic that is moving too slow for second and you need to stop to go to first and realisicly only has bragging value (if you are that type )

Stygian · Post by **Stygian** » Mon Oct 26, 2009 4:24 pm

Thanks Terry and Craig

Much appreciated.

I want a well behaved sports motor, not something that is a pig to drive around town. That's not much fun. I felt that a 30/70 cam would be a good "middle ground" compromise, so thanks for confirming my intuitions.

Although I'm a newcomer to this forum, I must say how helpful, interesting and encouraging the posts generally are, from cams to the Ratbox Corporation Patented Car Turneroverer.

Cheers, Andrew