Technical Car not speeding up!

[Yellblob]

Hi,
I mean really not speeding up!
I’ve recently put my engine back in with new pistons, barrels and machined valve seats.
It revs quite perkily (although with quite a lot of vibration) but once in 3rd gear it bogs down and won’t go any faster.
When I checked the advance with the strobe , the mark advanced but had a big variation and a friend used to British cars wonders if the timing chain could be worn. Pity I didn’t look at the chain before! As far as I can see the distributor does not have too much play although it is fairly old/original. I couldn’t easily figure out where the timing chain is on a quick look , but I take it the engine would need to come out to. Heck it? I guess fuelling could be another issue. Any advice gratefully received. The brakes aren’t binding to rule that out! Thanks.

 

[Yellblob]

Sorry that should read to check it not heck it !

 

[Duffys Dad]

Chain doesn’t usually wear if engine has oil. If it is worn you can hear a rattle or clonk as it slops about. I would start with checking the head bolts torque and the valve clearances. Set the timing static and make sure HT leads are correct way round. Then put a strobe on and check timing on idle. Then rev to see the advance is working. If advance is not working I would suspect the distributor first. Check the fly weights in the bottom move freely. As a last resort you can probably access the timing chain by supporting the engine and removing the rear crossmember and engine mount. Then also the pully wheel and the timing chain cover is accessible behind the pully

 

[Yellblob]

Thanks. I am not hearing a rattle but it isn’t the quietest of engines ; ).
I have marked out the 18 degree to ?23 degree advance and the cover mark moves forward into the zone. It’s just it really moves around say 3-4 degrees either way and I don’t know if that is normal.
I’m pretty sure I have the leads the right way round according to the valves being shut, it is confusing though when the 1 and 2 on dizzy cover are wrong as far as I can see.

 

[fiat500]

Thanks. I am not hearing a rattle but it isn’t the quietest of engines ; ).
I have marked out the 18 degree to ?23 degree advance and the cover mark moves forward into the zone. It’s just it really moves around say 3-4 degrees either way and I don’t know if that is normal.
I’m pretty sure I have the leads the right way round according to the valves being shut, it is confusing though when the 1 and 2 on dizzy cover are wrong as far as I can see.

It should be advanced by approximately 10 degrees at tickover and gradually move forward an additional 18 making a total of 28 degrees once the engine is in the high rev-range. But if the problem isn't the distributor you might not achieve sufficient RPM to achieve that....catch-22. :bang:

 

[Toshi 975]

Chain doesn’t usually wear if engine has oil. If it is worn you can hear a rattle or clonk as it slops about. Then also the pully wheel and the timing chain cover is accessible behind the pully

Sorry I have to disagree , depending on how an engine has been treated most timing chains will show signs of wear after 50,000 miles or so. If the engine has been previously unmolested in that department the test is to see if the self tensioners on the chain have started to nibble into the inside of the timing chain cover. I also think that a worn chain would not account for the bogging down.

 

[1500500]

Also check carby main jet is not blocked.

 

[the hobbler]

Many, many years ago,in a land far away (London!) I ran a slightly tuned 500F. At the time I was working for Radbourne Racing--got to work OK, but when I tried to start the engine to drive home--nowt. I checked everything and realised that the timing was a fair bit out. The cause turned out to be a timing-chain (crank) sprocket with so much wear on it that I am surprised that (a)I managed to run my girl-friend home the evening before and, (b) that I managed to get to work in the morning----on both occasions there was no undue noise and/or lack of performance.
At the risk of being called a number of unsavoury names, I have ALWAYS advocated the renewal of the timing-chain and sprockets whenever major work is carried out on the engine---the cost of the parts is (relatively) so minimal that it is not worth scrimping on the outlay. The cam/valves control the tune of the engine, and as these parts wear, they will detrimentally affect the performance of the engine. As "Duffy's Dad" mentioned, this job can be done with the engine in situ, but the rear cross-member removed (DON'T FORGET TO PUT A SUPPORT UNDER THE SUMP).
Engine timing is 10deg (14mm) BTDC when the engine is idling. If the plug leads were the wrong way round, the engine would be VERY difficult to start and would run exceedingly roughly (if you could get it started). Check tappets, and plugs--the problem could be as simple as a duff plug (or a plug lead not on correctly)

 

[Duffys Dad]

I bow to the experience of others with respect to timing chain wear, but it sounds like they agree that wear is unlikely to cause your issue.
I think Cylinder 1 is the rear most one and the distributor cap should have a locating lug which fits a the slot above the little bolt where the low tension wire connects to align it correctly.