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Something wrong with the old trusty 202


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#1 evl666

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Posted 16 September 2019 - 07:05 PM

Long story but bare with me....
202 running a stage 3 yt head and some decent cam with a 350 Holley.
I got this engine with the car so it was a bit of unknown. It drove off the trailer, idled fine, blew no smoke etc so i took a punt on it. Fast forward 6 years later after the car has been put back together, it’s drives fine.....not setting any land speed records but it went ok, no pinging etc just a bit sluggish. Right of to the mechanic for a tune. Now this guy has been around for a long time and has been in the preformance game before I was born so I trust his judgment. But I’m confused with what happens next. Gives me a call and tells me that it appears the top dead center mark was out as well as it was advanced heaps so set it where he thinks it should be. Remember this engine drove ok and no pinging etc. 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. Maybe it’s the valves??? Did a leak down test and the valves appear to be fine. Maybe it’s the cam timing? Looks like that’s ok so it’s got to be the rings? Then why isn’t there any signs of blow by? Can some one give any ideas on what’s missing here? Like I said I didn’t expect this to happen today as it was all good but now it won’t even hardly drive without a heap of throttle etc. I’m going to go through the basics myself to see if it’s all correct but I’ll take any ideas on what you guys think?

#2 yel327

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Posted 16 September 2019 - 07:39 PM

Sounds to me like the harmonic balancer needs replacement, basically the TDC mark has moved with the outer ring. Easy fix, fit a new seal while it’s out. You can check how far out it is by using a stick of some kind down the plus hole on #1 cylinder to give you a rough idea of where TDC is.

#3 evl666

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Posted 16 September 2019 - 08:05 PM

I have taken the plug out of no 1 cylinder and watched the piston stroke and it appears to be set correctly to top dead center mark on the balancer

#4 RallyRed

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Posted 16 September 2019 - 08:49 PM

Bloody hell, just typed this, and it got lost somehow.

Had a similar problem with 1/2 race LJ at a Hillclimb, a factory dizzy with a worn top bearing resulted in a foam filter fire ( tripple Webers) as it fired with inlets open.
Got talked into a Chinese Bosch copy electronic dizzy. At Challenge Bathurst, same thing, foam filter fire...this time it was found tbe little key in the shaft of the elecronic dizzy reluctor wheel had sheared off, changing the timing.
Moral - dizzy issue?
Moral for me - dont buy crap.

Hope that helps mate

p.s. Aussie "Scorcher," electronic dizzy fiited an no more dramas

Edited by RallyRed, 16 September 2019 - 08:54 PM.


#5 evl666

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Posted 16 September 2019 - 08:59 PM

I’ll throw a timing light back in it first to check it’s correct but I can pull the distributor from my other car and see if it helps/changes anything. Surely if it was the rings I’d see some blow by and smoke

#6 rodomo

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Posted 16 September 2019 - 09:36 PM

Worn cam lobes/lifters or head gasket blown between cylinders?

#7 UCSLE

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Posted 16 September 2019 - 11:31 PM

think it's obvious the mechanic is a goose . Put more advance back in it

 

If i remember right to check the balancer the keyway on the crank should be at 12 0'clock when the timing mark is at TDC ( to give a ruff idea )



#8 evl666

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Posted 17 September 2019 - 06:39 AM

Ok so I have set up the timing marks on the pulley and the distributor like in the pic from old johnos information so tell me how much advance should I be running? The distributor marks line up to number one and on the mark on the distributor body.

Attached Files



#9 S pack

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Posted 17 September 2019 - 07:58 AM

I would start with 6 deg advance and go from there.



#10 evl666

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Posted 17 September 2019 - 08:05 AM

It’s set at that at the moment and it’s running like a pig. Struggles to move and poping/carrying on through the carb

#11 yel327

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Posted 17 September 2019 - 08:21 AM

Is the vacuum advance mech free to move and the mechanical advance mechanism all free?

With the plug on #1 out use a rod that the piston will hit down the hole and rotate the engine (by hand) both ways so the piston hits the stick as it comes to TDC. Mark the balancer against the 0deg mark at both points where it hits. The balancer mark should be exactly in between the two marks. I still think the balancer ring may have moved.

As UCSLE says though just feed it some more advance and see if the problem goes away. Make sure the dizzy is free though and that the balancer ring isn’t going to come off on you.

#12 evl666

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Posted 17 September 2019 - 09:35 AM

Thanks guys. The balancer mark is definitely correct it’s all set like old johns pic above. I’ll have a crack on the weekend and see what happens. I know it likes advance cause it ran way better before the mechanic brought the advance back down to where it should be

#13 Rockoz

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Posted 17 September 2019 - 11:46 AM

Was the dizzy ever re set and regraphed for the new cam?

Think thats the words anyway. Damned painkillers fog the brain.

Have you dropped a bit of oil onto the felt for the bob weights under the rotor button?

Other good suggestions have been made above.

 

Cheers

 

Rob



#14 evl666

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Posted 17 September 2019 - 11:57 AM

Rob I have no idea if it’s been regraphed. Like I said it ran ok but when you start setting the top dead center and timing where it should be it just turns to shit

#15 S pack

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Posted 17 September 2019 - 01:00 PM

Just to clarify 6 deg initial advance, if you have the mark on the balancer aligned with the 6 deg advanced mark on the timing cover, then the scribe mark on the rotor button is aligned with the mark on the edge of the distributor housing?



#16 evl666

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Posted 17 September 2019 - 01:48 PM

Correct s pack. This is how it is set up at the moment and it runs like shit

#17 N/A-PWR

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Posted 17 September 2019 - 02:30 PM

Hi Evl666,

Check plugs are clean,

leads have same resistance reading, dizzy cap underside are clean (no white corrosion buildup),

and put in a set of new points with a matchbox cardboard thickness gap.


Also do a tappet adjustment (hydraulic cam and lifters only),

while engine idles (oil will run over motor a little, unless you cut the top out of an old cover),

with tappet cover off, turn anti-clockwise each of 12 tappet nuts,

one at a time, and hear loud tapping,

then clockwise turn nut until tapping stops and turn 1/8 of turn more and stop.

All 12 tappets are now set properly.


Now loosen dizzy retaining bolt a little,

and by hand rotate dizzy either way while motor running till it runs nice,

then tell us what the strobe light reading is.

Regards Dave I


P.s. Hydraulic Tappet adjustments works for any cam, head, or carbs used,

except for solid cam and lifters, you use feeler gauge tappet adjustments while engine off.

#18 evl666

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Posted 17 September 2019 - 05:46 PM

The plugs are clean and have only done about 50 klms driving. Leads are new also but I’ll check the resistance. The distributor is a Bosch electric one so no points there! I have an old cover I’ll chop the top out of and go through your suggestions. If I knew how it was set up when I took it to the mechanic I would go back to those settings cause like I said it drove alright. It’s just got me stumped how something that drove alright now is shit when you go to how it should be set up. If it was the rings or head I would of thought it would be running shit all the time

#19 N/A-PWR

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Posted 17 September 2019 - 06:07 PM

Here is an example tappet cover I did:-

 

Attached File  292 Tappet Cover.jpg   149.17K   4 downloads



#20 N/A-PWR

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Posted 17 September 2019 - 06:18 PM

by the way,

 

 you will also notice the sound changes when doing the tappet check,

 

 and know if the cylinder is working or not.

 

 

p.s. you never know what the mechanic did, so back to basics for us.



#21 S pack

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Posted 17 September 2019 - 07:30 PM

Bosch HEI ignition you say. What gap have the spark plugs been set to? Do you have 12v at the coil with ignition in the ON position? Do you have the correct coil to suit the HEI?

With the initial timing set at around 6 deg advanced and backfiring in the inlet manifold could be a sign the cam is out a tooth or could be a very lean idle fuel mixture.


Edited by S pack, 17 September 2019 - 07:31 PM.


#22 evl666

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Posted 17 September 2019 - 08:34 PM

S pack it has 12 volts, correct coil and plugs are correct gap. I run an identical set up on my other car. If the cam timing was out can you compensate by running more advance than what is deemed ‘normal’? I’m going to run through the suggestions then if that doesn’t work I’m going to pull the timing cover off and check the cam timing. I’ll do the timing light check on the weekend and post a video of it running for you guys to have a listen to.

#23 S pack

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Posted 17 September 2019 - 09:13 PM

You should be able to get a good indication of the camshaft phasing just by checking when the crankshaft is at TDC.

Remove the plugs and the rocker cover. Turn the engine over by hand until the exhaust and inlet valves are on the rock on #1 cyl (dissy will be firing #6).

When the timing mark is at TDC the exhaust valve should be closing and the inlet valve starting to open.

 

Try richening up the idle mixtures. Lean mixtures burn slower. Perhaps that is why the engine needs lots of initial advance, so a lean mixture has time to burn completely before the inlet valve starts to open again.



#24 yel327

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Posted 17 September 2019 - 10:07 PM

It did drive OK though before it went to the mechanic other than just needing a little tune up? Just advance the timing and see where it runs best.

Might seem like silly questions but:

Auto or manual?
Where is the vacuum advance connected on the carb?
Are you using ported or full vacuum for the dizzy advance?
If you are using full vacuum are you disconnecting the vacuum advance to do the initial timing check?

Note that most carbied Holden engines use ported vacuum for manual and full vacuum for an auto for vacuum advance. This is why pre-canister cars (pre 1/75) have different carbs for manual and auto, but after 12/74 they are the same as all cars need ported vacuum for the canister purge.

#25 evl666

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Posted 18 September 2019 - 05:42 AM

Ran no problems at all. Little sluggish when you put your foot down but all good through out the rev range. Started first turn of the key and idled nicely when warm. This is why I went for a tune up just to check it was all good. Manual car and has vacuum advance connected on correct port on the 350 Holley. I’ll do the timing check on the weekend. Spack the mechanic did take the rocker cover off to check the cam timing like how you suggested and seemed to think it was ok. I’m going to do timing check and see if I can get it happy again by giving it some advance, if that fails I’m going to start swapping the distributor and carb from one car to another cause I know the other engine is good.




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