V8 Issues under load

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did you re check the compression after putting oil in (wet/dry) and what were the numbers?
Also make sure the cable isnt affecting the idle (not returning enough)
 
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I kinda want to keep it carbed up. Don't know why, probably because its a dying thing I guess, but I'm sticking with it not matter how much pain its going to / is cause me.

It my end up being a Webber carb but that's undecided, and the argument over SU / Webber is not something I'm exploring or wishing to expand on now! Just a smooth running SU will be good.......:)
 
Your compression is way too low. Depending on the year and compression ratio of the engine I would expect expect you need a minimum of 135psi but 150psi would be nearer what I would expect. Later high compression engines (9.35:1 efi) should be making 170 - 180psi

Your ignition timing is not right. If this is an early engine, you need to check the serial number on the distributor. The timing could be anything from 3 - 7 degrees depending on which year and dizzy set up is on there. The later electronic ignition systems are typically set between 5 - 7 degrees and as far as I know, 6 degrees should work on carb motors between 1984 and 1987.

So -

First I think you need to set timing to TDC then advance it up to 6 degrees BTDC and see how that goes.

Next I think I would be checking the carbs - do SU's have diaphragms in them?(I'm not the best carb man I'm afraid) Check the diaphragms haven't perished - this could easily be the issue here if the metering rod is unable to rise fully to allow full fuel flow (fuel starvation as others have suggested)

Do a full wet and dry compression test, don't forget to have the throttle wide open when cranking the engine. Sticky valves, blown head gasket or worn piston rings could be factors but FWIW carb problem would be my guess. Also do you know how the carbs are jetted? and are the jets properly clean?

Good luck.
 
classic kev said:
Your compression is way too low. Depending on the year and compression ratio of the engine I would expect expect you need a minimum of 135psi but 150psi would be nearer what I would expect. Later high compression engines (9.35:1 efi) should be making 170 - 180psi

Your ignition timing is not right. If this is an early engine, you need to check the serial number on the distributor. The timing could be anything from 3 - 7 degrees depending on which year and dizzy set up is on there. The later electronic ignition systems are typically set between 5 - 7 degrees and as far as I know, 6 degrees should work on carb motors between 1984 and 1987.

So -

First I think you need to set timing to TDC then advance it up to 6 degrees BTDC and see how that goes.

Next I think I would be checking the carbs - do SU's have diaphragms in them?(I'm not the best carb man I'm afraid) Check the diaphragms haven't perished - this could easily be the issue here if the metering rod is unable to rise fully to allow full fuel flow (fuel starvation as others have suggested)

Do a full wet and dry compression test, don't forget to have the throttle wide open when cranking the engine. Sticky valves, blown head gasket or worn piston rings could be factors but FWIW carb problem would be my guess. Also do you know how the carbs are jetted? and are the jets properly clean?

Good luck.
Click to expand...

Thanks for the guidance, I know the compression is low, however it ran sweet as a nut prior to sitting up. I just want it to run enough for some use prior to taking the engine out!

Ive had the carbs out and cleaned um up, but they were fine. And no, no diaphragms.

Its running on 7 from TDC currently so I will back it off one more.

I will have a go at the above over the weekend and see how I get on.

I will post up after the weekend see if I have any change.....

Thanks guys!
 
OK, I'm try to tune my carbs and have set set the idle now need to do the mix.

Can't find the mix screw for the life of me. Can some one give me a pointer???
 
Hi all,

So another not so successful day solving my problem, but I did get it to idle nicely! No more stalling at junctions.

But I would like to ask a couple of questions:

When adjusting the mix, is the item circled in red on the attached picture, top right, meant to move? Mine doesn't, guides suggest it does, but I may be reading it incorrectly.

Also on the bottom left, what is that nipple for? Mine as a small pipe with a screw in the end of it, which doesn't look particularly original.

(Hope the pictures attaches!)

yourphotos
 
Not sure about top left but botom right seems to me like a vacuum source for something. Does ther other do the same because it's unlikely that both wont move if its ment to.
 
discomark10 said:
Not sure about top left but botom right seems to me like a vacuum source for something. Does ther other do the same because it's unlikely that both wont move if its ment to.
Click to expand...

Referring to the bottom right picture - the circled nipple on mine has a hose on it with a screw on the end so isn't doing any thing, but I'm wondering what it should do. And the nipple just above that to the left is the air bleed for my rad. I have been trying to find an engine manual to confirm but can't find one!

Referring to the top left, this is the inside of the carb with the pots removed, looking in from the top.
 
Hi All,

So I stripped down the carb as the mix adjustment was stuck, so the carbs are now fully tuned and it has made a vast impoverishment on generally running and idling. And she starts first time, runs sweet as a nut, much better than she ever has in my ownership.

But I still have my original problem! Top end in 3rd, 4th and 5th she starts to splutter, lower in the rev range when going up hill.

I have new plugs, leads and coils on order to rule these out. I also have a new ignition barrel on the way as my one cuts the power momentarily if you pull on the key.

I know the head gaskets and rings go on these engines, but its not showing the normal signs to indicate these: starts first time, idles great, no over heating, not loosing water or oil.

Another thing I thought of while messing around in the engine was that this defender had a single point LPG system fitted a while a go, before I removed it. Does any one know if they would have changed the needles / jets when fitting this?

Any ideas of help would be great!
 
discomark10 said:
Might be worth checking the mechanical advance and vac to see if its actually working
Click to expand...

OK I'll give it a go. I've sucked on the vac and heard it moving, but I will take it apart have have a look.

Where is the mechanical advance?

I've Just got back from taking it out, on the way back went up a hill and had to stop on the hill with the handbrake because it was stalling, I then had to get it to high revs out of gear then drop the clutch in first. Even then it struggled not to stall. Some thing is very wrong! :mad:
 
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