Volkszone Forum banner
1 - 20 of 72 Posts

·
Registered
Joined
·
3,403 Posts
Discussion Starter · #1 · (Edited)
Hi all I need some help. I’ve just rebuilt a new 1600 twin port engine for my bug.
the specs are
stock case
stock crank
engle 110 cam
twin dell 40s
new cooler
stock pistons and barrels
timing set to 7° BTDC @ 900 rpm and 30° BTDC @ 3000rpm
all tin wear is in place
The flaps in the fan shroud are in and working

now I did the bedding in run and dropped the oil. Refilled with 15w30 oil. Balanced the carbs. A week later ( today) I went for a drive she started up first time went for a drive and straight away I noted that they was no power at all, the rpm would slowly get to 3000 rpm in first and second gear put once in third there was now power at all and 37 mph was go it could do. Anyway I stopped at the petrol garage filled up went to start it and the engine would hardly turn over. Anyway I had a jump start and decided to get the bug home which is 3 miles away, now in them three miles the oil temperature went through the roof and hit 120°C on the gauge and the save my bug was also reading a high oil temperature.
now when starting the car on the drive and in neutral the engine will rev up just fine and is very response to the throttle.

please help I have no idea on where to start.
 

·
Registered
Joined
·
3,403 Posts
Discussion Starter · #3 ·
I was told to set the timing between 28⁰ and 32⁰ BTDC max so I have mine set to 30⁰BTDC which gives me a idle timing of 7⁰ BTDC

What shoult I set it to?
 

·
Registered
Joined
·
3,403 Posts
Discussion Starter · #4 ·
Right I just went back out to the car. The engine has been off for a round an hour. Any way I went to touch the coil and you can only hold your hand on it for a few seconds before the heat gets to much, is this normal?

I've also just sulked on tbe hose for the vacuum advance and the advance moved just fine but it is only connected to one barrel on one carb
 

·
Registered
Joined
·
1,394 Posts
Change the coil, the wrong type of coil will cause problems too. Test again. Eyes on the gauge. Vac to 1 carb is OK, so long as the vac pipe is fitted above the butterfly. Put a finger tip in the exhaust tail pipe. Don't burn ya sen. No soot is a weak mixture, thus cause heat as well.
 

·
Registered
Joined
·
3,403 Posts
Discussion Starter · #6 ·
OK some more information for you.
Just put the timing gun on all four leads and something strange is happening. On lead one and four the timing light is flashing fast as is making the timing look a little messy as in SCATTERED BUT on two and three the light seems to be firing at half the speed but the timing looks solid no flutting at all. All the leads are reading the same at idle and at full advance.

When I say scattered timing I mean that the reading is between 5⁰ and 9⁰ BTDC, where as on leads 2 and 3 the timing a solid 7⁰BTDC but the light is flashing at half the speed.
 

·
Registered
Joined
·
3,403 Posts
Discussion Starter · #8 ·
Yes mate same engine, I was running 15w50 oil but that cause way to much pressure and the engine got hot fast. When I dropped down to a 15w30 oil the engine ran for ever in neutral but even at running at idle it still hit 100⁰C.
 

·
Registered
Joined
·
3,403 Posts
Discussion Starter · #10 ·
In the photo you can see that the oil temp was high it was actually reading 120⁰c on my dipstick calibrated meter, also the engine was turned off that's why there is no oil pressure, when the engine was at 900 rpm idle the oil pressure was still reading 10 psi at 120⁰C.
Also the distributor is in a strange position because I messed up the distributor drive shaft position when I was building the engine, it's out counter clock wise by 90⁰.
 

·
Registered
Joined
·
3,403 Posts
Discussion Starter · #13 ·
Just to let you all know just went back to the bug, it started up the second I turned the key. The engine is very responsive to the throttle with no coughing or banging or stumbling. The engine can rev right up to 4000 plus rpm when in neutral BUT as soon as it’s in gear there is no power, the more you push down on the accelerator the deeper the exhaust noise gets and the induction noise gets. I have no idea what’s going on?
 

·
Registered
Joined
·
2,617 Posts
Big Cam and Carbs for a stock crank :) What heads with what valve sizes and springs do you have fitted? What distributor? Is the vacuum T’d to both carbs or just one? Have you sucked on the vacuum can and confirmed that it’s moving the advance plate in the distributor. Where’s you’re oil temperature sender fitted, could be heat soak and non temp related. What fuel pressure have you got? Could be fuel, could be ignition, could be lack of compression, I guess ignition 🤔
 

·
Registered
Joined
·
1,394 Posts
It's all a process of elimination. Change coil n test. Tick off the list
Change dizzy. Tick off the list.
Move coil.
If it's the same think carbs.
Are they getting plenty of fuel to them.
If you press the throttle and it just bogs down and does nothing, that's like loads of air going in (open throttle). But no fuel going in to increase the power out put.
A struggling engine will get hot cause its trying to push the car forward
 

·
Registered
Joined
·
3,403 Posts
Discussion Starter · #19 ·
Right I hope I'm about to answer all your questions.
The heads are empi ones that have 40x35.5mm valves and single HD springs. They have been machine to rise the compression ratio up to 8.5:1

I got the plugs from vwheritage and I'mnot sure what heat range they are. I've not pulled the plugs and checked the colour of them either.

It has a SVDA distributor, the vacuum advance plate is moving when I suck on the hose. The vacuum hose is plumed onto the only vacuum port on these two carbs which is on the number 4 barrel.

The oil temperature sender is in the rear oil pressure relief valve position next to the crank pulley, my save my bug dipstick was all so reading high oil temperature.

The fuel pressure is at 3psi and I'm running the stock points in the distributor.

The engine doesn't bog down when you floor the throttle when in neutral only when you are in gear.
 
1 - 20 of 72 Posts
Top