15 replies to this topic

[TopCatCustom]

Just tried turning the engine over slowly to get TDC to set up the dizzy etc and it stopped just before, then back the other way stopped just before- the valves aren't hitting but am worried that the pistons may be hitting the head as they come up bloody high- like flush with the face of the block- now need major help!!!!!!!

by the way Its the one I am building from bits so no it has never run as yet!! Gulp

Edited by C4NN0N, 28 August 2007 - 06:12 PM.

[miniboo]

if the valves aren't hitting then it should be fine surely?

[TopCatCustom]

Its a dead stop, are the pistons supposed to come dead flush with the block or down a few mil? Thats all I can think of, uppose the only way to check is take off the head- and buy more gaskets!

[dklawson]

Generally the pistons come up flush (within a few thousandths) of the top of the block. With the cam timing properly set there isn't interference with the valves as when the pistons are at the top, the valves are more or less closed. Remember that the head gasket typically is about 1mm thick so it will contribute extra clearance to the head.

[Ethel]

If the crank will turn nearly 360 degrees then it's unlikely to be valve timing as 2 & 3 cylinders will have been to TDC.

Couldn't be something obstructing the clutch could it? If it's a stuck valve you'd see it with the rocker cover off.

[TopCatCustom]

Jus taken the clutch off and no difference, the only difference from the dry run is that the gearbox wasnt on- ok no clutch so doesnt make any difference in one respect but looked at the original gearbox from that engine and saw this ground down bit on one of the moulding spree mark things or whatever it is- as the prob is when 1 and 4 are down it might make sense if the crank by no.1 is hitting this in the new gearbox??? Means I'l have to lift it up again get the bloody clutch housing off, box off and get new gaskets for the lot? And I locktited all the bloody fittings GRRRRR

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[Sprocket]

That is on all gearbox cases.

Only time it might be of a poblem is if you are using a long stroke crank.

Is it possible you have timed the cam incorrectly?? if you have fitted the dowel type vernier pullies. This can allow the crank to foul the cam.

Edited by Mini Sprocket, 28 August 2007 - 08:02 PM.

[TopCatCustom]

? Just duplex timing chain, and i did a dry run with a good 1mm of stuff on the top of the pistons and no marks atall from the valves

[TopCatCustom]

Anyone?

[Ethel]

So you're saying it would turn fully with the the valve gear built up..cam, rockers, timing chain?

How far can you turn the crank - from just before TDC almost through a full revolution?

[TopCatCustom]

Yea all the timing was done valve clearances etc and bolted the head on just not too tight so not to squash the gasket and with some putty on the pistons I turned it over 3 or 4 times then unbolted the head, checked it and as all good i put the box and clutch housing on, properly, and head on then turning it to get TDC today jus wouldnt go! I rekon it goes approx 340 degrees? If i unbolt the speedo drive end of the box i may be able to look in there tomorrow to get an idea... Cant be the drop gears because no clutch and i can turn them freely

[Sprocket]

One thing to try is remove the dizzy drive gear and see if the problem dissapears, other things to consider are engine mounting bolts that are too long catching the clutch

Infact it has been known for some center oil pick up pipes to catch the crank as well

Edited by Mini Sprocket, 28 August 2007 - 10:28 PM.

[TopCatCustom]

I couldnt get the dizzy drive shaft right out- stopped after about an inch 4 some reason but will check out the others, Cheers

[Sprocket]

Use a 5/16 bolt, the one from the rad side engine mounts work nicely, screw it into the dizzy drive. If it catching on some thing its probibly the crank, turn the crank to 90 degrees so the pistons are half way down the bore.
If it still doesnt come out, this may be your problem.

[Jimmyarm]

My Vote would be for one of the clutch housing bolts hitting the flywheel.

Take the housing off and see if it turns over.