Holden HQ One tonne ute

[longracing]

Make: Holden
Model: 1973 HQ utility
Engine: 350ci Chev
Transmission: T350
Ignition: LS1 coil, Modified Chev distributor, Hall-effect sensor.
Injection: Holley Pro-jection TBI
Bosch fuel pump, Carter lift pump, aluminium surge tank
ECU: MegaSquirt 2 v3
Mods: Mild cam, flat-top pistons, ported heads, Edelbrock manifold,
Genie extractors, 2 1/2" dual exhaust.

I decided to do the conversion on my ute mainly to learn about EFI.

I rewired the engine bay, converted the distributor and had the MegaSquirt running the ignition only to begin with. Then after getting that reliably sorted I moved to adding the fuel side. The 3/8" aluminium supply line was installed and the original 5/16" line was used as a return. The carter lift pumps supplies fuel to the surge tank that is mounted in front of the fuel tank behind the cabin.

I've had it running fuel & ignition now for a couple of weeks and with a bit of tuning it is getting a lot better to drive. There seems to be more power. One side effect is that it is also louder. It has pretty bad "tip-in" at the moment, tuning is helping but I think it also because the throttle body is on the large side for this engine combination as well as being throttle-body injection. Still a pretty good combination. I have had two ideas on how to reduce the tip-in, the first was to remove the link rod and just use two injectors & two throttle bores the other idea was to install a roots-type supercharger ( the 4-barrel throttle body will bolt straight on top of)... with the current exchange rate I am leaning towards getting a super-charger kit from the states, maybe. I really should save my money.

I can't upload any pics at the moment but if you have a log in you can check it out on the MSruns site under General Motors, Holden HQ one tonne ute

[Fred]

If the TB is large AND the plenum volume small, that will make it worse. If you increase the volume it could help, though I'm not certain about that for TBI setups.

Looking forward to those pics when you get your photo account setup :-)

Fred.

[longracing]

Here are a few pics.

As it first started out several years ago.

Has a few changes now and the paints is quite faded.


Modified Chev distibutor. Hall effect sensor installed, slotted disc machined up on mill & lathe. The top bush was seized so I machined it for a ball bearing instead. The mechanical advance was locked out by the two screws on the top.




After the engine bay was rewired and modified distributor installed. MS2 running ignition only.


The modified distributor installed and LS1 coil mounted on the firewall.


The relays and fuse block mounted near the battery.


Surge tank & pump. The surge tank has a craddle on top for mounting the pump. Big thanks to Port-Hacking Automotive for their help installing the aluminium fuel line & surge tank. It was hard enough for me routing all the hoses and wiring (it's a bit hard to get under there with the lowered suspension).


The old Rochester Quadrajet next to the TBI unit. The Quadrajet is a great carb. but hard to get the right needles and jets to tune it on a modified engine.


The installed unit. I had to use a carb spacer so the built in fuel regulator on the TBI would clear a vacuum fitting on the manifold, as well as make a new throttle cable bracket.


This is the little plastic (on the right) sector gear that caused me grief. On the left is the one a made out of aluminium, it won't be breaking any time soon.


The sector gear installed.

[Fred]

Sweet, I LOVE utes :-)

[longracing]

After a bit of tuning I have improved the tip-in and it shows serious performance potential.

I have had a bit of trouble tuning the idle & starting. It would have been better if I could get hold of 45lb/hr injectors but for the moment I have disconnected the secondaries and two injectors.

The biggest headache at the moment is the intermittent fault causing the engine to die. Looking at data-logs and on the lap-top it appears to be losing the RPM signal for several seconds. It didn't have any trouble before running as ignition only but I am going to try the MSnS E mod on the Hall input to see if that fixes the problem.

I might try disconnecting the Idle-air motor to see if that is causing a fault. If it is the low-impedance injectors I might modify the manifold to port injection. Hopefully I won't have to go that far, if I do then I it will give me the chance to try the MS2-Extra code.

[Fred]

The biggest headache at the moment is the intermittent fault causing the engine to die. Looking at data-logs and on the lap-top it appears to be losing the RPM signal for several seconds.

Sounds like noise/grounding :-)

I might try disconnecting the Idle-air motor to see if that is causing a fault.

Could easily be that if the wiring isn't perfect and you haven't modded the board? The idle transistor puts grounds through the CPU signal ground stock.... not good...

If it is the low-impedance injectors I might modify the manifold to port injection.

It could be this too. In either case you need immaculate overkill wiring to make it clean because of the shared and mixed ground signals.

Check this out : http://www.diyefi.org/forum/viewtopic.php?f=6&t=224

if I do then I it will give me the chance to try the MS2-Extra code.

Do you have one of each CPU? I'm sure you know, but you can only run each variant on it's own CPU. Sounds like you are using MS1 at the moment.

Good luck!

Fred.

[longracing]

Update: I've made the MSnS_E mod to the Hall-input and that has improved the tach signal. I also lifted the ground for the fast-idle (which I am using for the thermo-fan) and ran it direct to a connector ground. The car is running and goes OK but the starting and idle is still quite unreliable. The car still has the tendancie to lose the rpm signal for several seconds, I'm trying to figure out if this is a reset or resync. Before the injectors and idle-air were connected it performed reliably. I used a completly new wiring harness and have also tried re-routing the alternator wiring, power-filters, etc..

I've decided I am not happy with the TBI set-up's performance (mainly the idle, economy & starting) and now I need to spend more money to convert it to port-injection. One of the reasons I did choose the Holley Pro-Jection unit was because it would make a good throttle-body with TPS and idle-air built in. I've purchased a Weiand Team-G manifold (second-hand cheap!ish). It is a single-plenum design which isn't as good for torque but a lot easier to mount injectors in, it's also supposed to make power from 2000rpm up, which should be fine with the stall-converter I'm using. I've got a set of injectors from an LS1 (LS1's use the common Bosch connector, LS2's have a different style connector) and had trouble getting fuel-rail extrusion but found some at http://www.VPW.com.au. It even arrived the very next day (I placed my order after 4pm).

[Fred]

Ya know, several seconds sounds very suss to me. It's not something like a regulator overheating and shutting down for that time is it? The length makes it sound thermal, that's all :-/

Good move on the port injection :-)

[shameem]

Where do the injectors get their +12v? Have you tried running a separate wire from the battery (relayed of course) for that purpose - i am asking because this solution helped someone eliminate a lot of noise and related resets in ms forums.....

[Fred]

Where do the injectors get their +12v?

How else would you do it?