Hi Beans, yes I checked the spark at the plugs. Only removed a couple but they were sparking ok. Good sign as the ignition system must be working at least Fuel is definitely getting through to the carb too. I'm wondering if I flooded it! Will be on the case this weekend or maybe one evening. I could do with fitting the new fuel rail seals first. Watch this space!
Fitted the new carb seals and gaskets which seems to have sorted the leaking fuel rail. Did have an issue with fuel gushing out of the vent pipes to the primary and secondary bowls but sorted this with a bit of adjustment to the floats. Anyhow, been trying all weekend to get the engine to fire but to no avail I know I've got fuel supply and I know I've got a spark. However, the spark looked a bit week so I checked the voltage at the coil. The supply wire at the +ve terminal is giving over 12v, so assume this is good. However, when the engine is cranking, the +ve terminal reads about 8.5v and the -ve terminal supplying the dizzy is only reading 3.9v. Shouldn't this be 12v as well? The coil is new and is a Lucas DLB198 which is for electronic ignition and 12v. I wonder of the coil is faulty? I seem to have everything I need to start the car except the 12v supply to dizzy! Any thoughts or help welcome.
Oh, another issue might be oil pressure, but this should not stop the engine from firing as the ignition is not linked to the oil pressure switch like some cars are. The warning light is on when ignition switch turned to 2nd position, but when cranking the light stays on. I'm wondering if the oil pump needs priming? I've never removed the pump so not sure it should need re-priming, but engine has not been started for about 16 years! All fuel and ignition parts are brand new though.
"Beans"
posts: 5642 Netherlands joined on Sun 5th Mar 2006
posted Mon 31st Jul 2017reply 184 of 228
Bear in mind that the original TR7 wiring has a resistor wire to the coil. So with the original wiring you need a 6V coil. With the engine running (or ignition ON) there will/should be a 6V power supply to the coil. But during starting, the resistor wire is bypassed to give a stronger spark (12V instead of 6V to the coil).
What fuel pump do you use? Another problem could be overfuelling caused by to much fuel pressure.
1976 TR7 FHC (currently undergoing some TLC ...) 1980 TR7 DHC (a.k.a. Kermette, my first car bought in 1988 ) 1981 TR7 FHC (Sprint engined, a.k.a. 't Kreng) http://tr7beans.blogspot.com/
Bear in mind that the original TR7 wiring has a resistor wire to the coil. So with the original wiring you need a 6V coil. With the engine running (or ignition ON) there will/should be a 6V power supply to the coil. But during starting, the resistor wire is bypassed to give a stronger spark (12V instead of 6V to the coil).
What fuel pump do you use? Another problem could be overfuelling caused by to much fuel pressure.
Thanks Beans. I thought about the resister wire but when the car was converted it used electronic ignition and I think S&S must have used a 12V feed from the ignition. I've retained the same feed in effect and tested the voltage at the coil end which reads 12.5V, so ok. However, when cranking the engine the positive terminal at the coil with the wire attached, reads just over 8V and at the -ve terminal reads just under 4v. I thought the output from the coil to the dizzy should be 12v? I know with points you need to reduce this to 8 or 9v to prevent the points burning out.Not sure why I'm not getting 12v out of the coil to the dizzy when the supply is definitely 12v? Faulty coil? I bought it brand new about a year ago. Lucas DLB198. The fuel pump is from S&S. It's a low pressure electric Baco unit and is definitely sending fuel into the carb.
Well, not got it going yet. I've got fuel to the carb and spark to the plugs and I've tried another coil which is definitely giving a stronger spark. I was thinking that maybe compression is low in a couple of cylinders so I fitted my Gunson gauge in no8 cylinder and the reset button flew out like a bullet! It's an old guage and must have had a broken reset button. Good job it didn't take my eye out lol! Anyhow at least I know no8 cylinder has some compression! New gauge on order so will try again next week. I think the cylinders might be flooded so will leave plugs loose for a few days, try the compression and try again. Could need timimg fine tuning. Also could be the hydraulic lifters not working as oil pressure light not going out when cranking. I will almost certainly need to re-prim the oil pump with Vaseline. In the meantime I've been trying out what the fastback buttresses might look like. I've seen it before on a couple of TR7s but mine will be stick on in lieu of the side vents. I might even use the side vents as a base to fix them to car. Here's some photoshop pics I quite like it. Only a simple mod but has a dramatic affect on the appearance!
Here's a photoshop pic with the rally colours, but I'm still pondering doing a carbon wrap to the sides, but leave the bonnet and boot lid as they are.
I like it, something I've always pondered doing with my TR7 I've seen a few including the Le Mans car which I think looked especially cool! Only a bolt on mod using Perspex painted or wrapped so easy to revert to standard. Need to get the car going before I even start on this though Doesn't look bulky to me!
Hi All, Back from holiday and uncovered the TR for the first time since getting back. I am now in possession of a new compression gauge so put it to the test. I think I have a problem! These are the readings:-
Clearly an issue with cylinder 1 and 6 and number 5 is only just into the green! The rest are behaving and number 8 is just showing off!
Now as the engine has been stood without being started for about 15 years! I'm wondering if I have a sticking valve(s)? This clearly would also stop the car from starting/firing on the defective cylinders. If the valves are closing ok, would a V8 with 3 cylinders giving low compression still fire up? Any advice is welcomed, cheers
Try some injector cleaner, and/or "Upper Cylinder Lubricant" but while you're getting that, try an 'oil test'. Under the same conditions, engine hot, all plugs out, throttles wired wide open, dobthe test again and then repeat, with a squirt of engine oil down the bore. The oil will promote piston ring seal, but do nothing for a valve leak and provides a diagnostic test between the two.
John
Serial Vitesse racer.
Old Blue. 1995-2001 Silverback. 2001-2007 SofS. 2007 - to date.
Try some injector cleaner, and/or "Upper Cylinder Lubricant" but while you're getting that, try an 'oil test'. Under the same conditions, engine hot, all plugs out, throttles wired wide open, dobthe test again and then repeat, with a squirt of engine oil down the bore. The oil will promote piston ring seal, but do nothing for a valve leak and provides a diagnostic test between the two.
John
Thanks John, I forgot about squirting some oil down the plug hole! This will show up defective rings or bores if the compression reads ok. I'll try it. If, the compression is still low, then it must be a sticking, or worn valve/seat? I can't get the engine hot though as it won't start! Been sat for 15 years
I don't think that one or two cylinders down will stop a V8 starting. My Six regularly starts on four, as the injectors drain down while parked. I can hear the laggards start up one by one as the engine note changes back to smooth. I'd pursue other reasons for non-starting as vigourously .
Johnjohn
Serial Vitesse racer.
Old Blue. 1995-2001 Silverback. 2001-2007 SofS. 2007 - to date.
Thanks guys. I just tried the oil test in cylinder 6 but I think I must have squirted too much oil in! The gauge went ballistic! Ooops! It hit the top reading above 200psi ! I think the new guage is now goosed as it sits at 25psi when reset and was full of oil and was squirting out of the reset button! Just hope I haven't caused any damage to the engine All my fault, I didn't guage the amount of oil squirt properly! I suppose this confirms that maybe the bore/rings are a bit worn. The engine has only covered about 40K miles so I wasn't expecting any badly worn rings or bores as it was always well looked after. Anyhow, as you have mentioned, two cylinders down should not stop the other cylinders from firing, so I will persue the reasons. I know I've got fuel to the carb and a spark at the plugs so back to head scratching. Must be a timing issue but nothing has been altered with the timing at all? Thanks again for any ideas
I don't think you will have done any damage as the tester seems to have "taken one for the team"
It will be a bet rod if not...
Hope I've not bent a rod I suppose a dose of very high compression in a combustion chamber could only cause damage to valve seals or piston rings, or even try to lift the head. It was only a few cranks and nothing fired so hopefully no damage. Battery on charge again at the mo, but will probably be next weekend before I'm back on it. Not sure how those offenhauser inlet manifolds deliver the fuel, but the carb just seems to drop it in?
Not about the car, slightly off topic, but was browsing ebay and came across these. A bit expensive, but couldn't resist! Even bought 2! These are actually the cheapest!
Not about the car, slightly off topic, but was browsing ebay and came across these. A bit expensive, but couldn't resist! Even bought 2! These are actually the cheapest!
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"Beans"
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Fuel is definitely getting through to the carb too. I'm wondering if I flooded it! Will be on the case this weekend or maybe one evening. I could do with fitting the new fuel rail seals first. Watch this space! 
I know I've got fuel supply and I know I've got a spark. However, the spark looked a bit week so I checked the voltage at the coil. The supply wire at the +ve terminal is giving over 12v, so assume this is good. However, when the engine is cranking, the +ve terminal reads about 8.5v and the -ve terminal supplying the dizzy is only reading 3.9v. Shouldn't this be 12v as well? The coil is new and is a Lucas DLB198 which is for electronic ignition and 12v. I wonder of the coil is faulty? I seem to have everything I need to start the car except the 12v supply to dizzy! Any thoughts or help welcome.
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