44 replies to this topic

[I'm a Red Motor fiend]

Put the timing back in. In your first post you wrote your running some decent cam. If the dizzy curve has been changed to suit and your setting up with only 6 degrees initial your total could be way off.
Measure out degree marks on the balancer outer edge and then set total timing to say 32 degrees.
Without knowing what's been done to the dizzy, playing with initial timing is just guesswork. Set the total.

[yel327]

Did you disconnect the vacuum advance when doing the initial timing check though?

[evl666]

I haven’t done the timing check yet but I will pull the vacuum advance when I do. I’ve only had time since I got the car back home to check that it’s at top dead centre, that balancer is marked correctly and distributor is all timed and in correct position

[yel327]

It just went through my head that if you are using full vacuum and it is a manual the mechanic may not have disconnected the vacuum advance for the timing check. Manual Holdens use ported vacuum so there is no need to, so he may not have. This would show lots of advance at idle if it is the case.

[evl666]

Ok guys going to ask some basic questions before I check the timing....
When I remove the vacuum advance do I block it off at the distributor or at the carb?
When I’m setting the timing at what rpm do I set it at and also set the total timing?

[yel327]

Pull it off at the dizzy at idle, if it’s sucking just stick something in it. If it is ported vacuum it won’t be doing anything at idle. You’ll know it if it is full vacuum and it is idling low as it’ll probably stall.
Try around 600-700rpm or thereabouts. Shouldn’t make a big difference unless it has s massive cam.

[rodomo]

After he sets the timing etc it starts ‘exhausting’ out the inlet manifold. So looks like compression test is in order. Down on 3 cylinders.

What are they down to?

[Potta]

Have you checked that all of your spark plug leads are in the right place?

 

I had similar issues with mine and when we checked we found that the leads on the dizzy were in the correct order but number 1 was where number 2 should have been.

 

May not be it but something else to check anyway.

Edited by Potta, 19 September 2019 - 02:04 AM.

[evl666]

There is no way it will idle at 700-800 rpm....1000 is more realistic. Lowest was 86, 100, 110 then rest were 130 and above

[evl666]

I have a compression tester here so I’m going to double check those results

[S pack]

There is no way it will idle at 700-800 rpm....1000 is more realistic. Lowest was 86, 100, 110 then rest were 130 and above

Must have a thumping big cam in it if it won't idle below 1000rpm or that could just be a symptom of the poor compression?

If those compression readings are accurate then stop wasting your time trying to tune it. Rip it out and have the bottom end freshened up.

You want the highest and lowest readings to be within 20 psi of each other.

Edited by S pack, 19 September 2019 - 06:45 AM.

[N/A-PWR]

For info purposes:-

 

 The lowest idle achieved using two different Carbies I tried on the same motor idled differently.

 

 Using a worked head and a 41/78 Hyd Cam,

 

the 500 2bbl Holley idled at 750 rpm, and the 465 4bbl idled at 1100rpm

[rodomo]

Less than 110 is a missfire

[Rockoz]

If it has a cam it will need more advance.

If you set it at stock, you will have dramas.

There is no getting past that bit.

 

Just for fun, go and start it up at night, maybe take it for a run to get it nice and warm.

Pull over. Open the bonnet, and turn all light sources off.

Have a look for a light show. Often new leads arent very good.

Pull the boots back off the plugs too.

Have known some new plugs in the past that broke down.

You could see some spark moving down the sides.

 

If you have leads that have a spiral core, you may also have induction misfiring between cylinders.

You wont actually be able to see it, but it has the same effect as the leads breaking down and crossfiring.

 

 

Cheers

 

Rob

[evl666]

Hi guys....thought I better up date you on the out come.....so it appears it’s a combination of weak valve springs, wrong cam timing and worn cam lobes. Leak down test showed only 5% loss when rocker gear was removed so bottom end all good. So it’s getting a birthday. New cam with associated parts. The head, which is a stage 3 yt, will get a full reco with screw in roller rockers. I’ll take suggestion on cams if you guys have some ideas. It’s a 202, 40 thou over. 350 Holley, gtr headers, 2 inch exhaust, Celica 5 speed with 3.36 rear end.

[RallyRed]

good info...thanks for closing the loop

Edited by RallyRed, 09 November 2019 - 07:41 PM.

[S pack]

Hi guys....thought I better up date you on the out come.....so it appears it’s a combination of weak valve springs, wrong cam timing and worn cam lobes. Leak down test showed only 5% loss when rocker gear was removed so bottom end all good. So it’s getting a birthday. New cam with associated parts. The head, which is a stage 3 yt, will get a full reco with screw in roller rockers. I’ll take suggestion on cams if you guys have some ideas. It’s a 202, 40 thou over. 350 Holley, gtr headers, 2 inch exhaust, Celica 5 speed with 3.36 rear end.

Some discussion here about suitable cam grinds for the trusty old red 6. http://www.gmh-toran...en-6-camshafts/

[Rockoz]

Back in the day the 30/70 grind was great for a nice sound, a heap of extra grunt, but also very driveable in traffic.

I have no idea what the modern numbers equivalent would be though.

 

For a bit more mumbo, but a bit of a mongrel in traffic, the 35/75 was the goods.

 

There was a 40/80 that was considered "full race cam". It was a real pig to drive in traffic.

 

Then if you knew the right bloke, and could convince him it was track only, you could get a 50/90.

You needed solid lifters with that one.

Waggot told me in the day that this was the grind that was used by HDT in the XU-1s.

Whether that is true or not is a matter of differing opinions.

 

These were all Waggot cams from back in the day, and were regrinds.

I believe there may be billet grinds these days which produce a whole heap better cam.

 

Cheers

 

Rob

[grumpy xu1]

All you need to do for your basic street car, is jump on the likes of camtechs website & pick a suitable grind & associated parts. It's all listed. & i would be at least putting in new rings & bearings & measuring up, whilst you're giving it half a birthday. & clean the oiling & cooling systems. Gary.