L20b engine. New leads, new spark plugs, new coil and new electronic ignition. Car started sounding like a tractor just driving normally on the way home last night. Considerable loss of power. I'm thinking timing chain?

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My 1977 L20b powered 200b

have you got compression in all cylinders?

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1979 Datsun Stanza Coupe
1982 Datsun Stanza GX - "D4T5UN"
1969 Datsun 1600
2001 Holden VX Commodore
1974 Toyota Landcruiser Stallion (SWB)
EziAutoParts

They all tested perfect a month ago. I am a good hour and a half drive from a mechanic to have them tested again

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My 1977 L20b powered 200b

just take the plugs out and turn the key and feel if air is shooting out

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1979 Datsun Stanza Coupe
1982 Datsun Stanza GX - "D4T5UN"
1969 Datsun 1600
2001 Holden VX Commodore
1974 Toyota Landcruiser Stallion (SWB)
EziAutoParts

I'll check tomorrow morning and let you know. Thank you

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My 1977 L20b powered 200b

The good news is it's very unlikely to be timing chain unless it's so worn out that it's slipped a tooth on the top sprocket (I've never heard of that happening). The other worry would be a burnt valve or blown head gasket but they are usually caused by bad tuning and/or overheating. More likely is a plug lead slipping off so you're running on 3 cylinders, cracked distributor cap or even the distributor moving and retarding the timing if the bolts holding it aren't tightened.

First step is check the plugs and leads for tightness, then the distributor. Check all the vacuum hoses to the manifold to make sure one hasn't fallen off or cracked. I don't know what carburettor you're running but a fault there can cause the sort of problem you describe. If squirting carby cleaner or similar hydrocarbon around the carby base(s) or inlet manifold flanges alters the idle speed you have an air leak (gasket not sealing).

Check the coolant (brownish sludge indicates oil in the coolant from a cracked head) and run the car with the radiator cap off (lots of bubbles in the coolant mean a compression leak into the cooling system- blown head gasket).

If you still haven't found the fault, run the car and carefully, with insulated pliers disconnect one spark plug lead at a time. The idle should drop until it is reconnected. If it doesn't you've found the cylinder with the problem.

Good luck!

Bluebird electronic dizzy ? If so, the "black box" module under the cover on the side can fail, causing misfire / loss of power.

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1970 ex Group A Rally P510
1971 P510
1972 180B SSS
1965 SP310 Fairlady
1966 SP311 Fairlady

Jap dizzy with pertronix kit

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My 1977 L20b powered 200b

It sounds like a bad exhaust leak from inside the car

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My 1977 L20b powered 200b

take off the rocker cover and make sure everything looks normal. Make sure a rocker arm hasn't jumped off due to a sticky valve.

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1979 Datsun Stanza Coupe
1982 Datsun Stanza GX - "D4T5UN"
1969 Datsun 1600
2001 Holden VX Commodore
1974 Toyota Landcruiser Stallion (SWB)
EziAutoParts

Ok update. Number 2 cylinder isn't firing. Removing the lead makes no change to idle. There is spark (ouch) and there is also plenty of compression as I can feel the air shooting out from the neighbors yard.

I'll go take the cover off now

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My 1977 L20b powered 200b

Everything look good under the cover

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My 1977 L20b powered 200b

Well it's got me buggered now. Everything still looks good and new but the second cylinder isn't firing

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My 1977 L20b powered 200b

did you check it for compression by taking out the plug and turning it over and either using a compression tester or feeling if air shoots out?

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1979 Datsun Stanza Coupe
1982 Datsun Stanza GX - "D4T5UN"
1969 Datsun 1600
2001 Holden VX Commodore
1974 Toyota Landcruiser Stallion (SWB)
EziAutoParts

Feeling air shooting out. I am miles away from any decent tools

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My 1977 L20b powered 200b