41 replies to this topic

[Indy Orange]

Yeah ok.

[nanbar]

Can I test a theory with the brains trust here, let me start by saying I am an electrical retard but here goes.

 

If I have had a loose battery terminal, which culminated in it loosening right off yesterday, is it possible I have been getting poor or sub optimum voltage resulting in a lack of fuel burn and poor fuel economy?

 

Just a thought, probably way off the mark.

[RallyRed]

A poor battery connection would normally be most evident during cranking when large cranking currents would result in a big voltage drop at the poor connection, thus meaning reduced voltage at the starter motor and coil etc etc.....and thus, problematic starting.

 

Not sure how your car is wired, but my recollection is that once started, you can remove the battery and it will just run off the alternator....until you stop it, then it's all over.  Thus, I'd be thining a poor battery connection would not cause your issues...unless of course the alternator also has some issue.

 

Is the car fitted with a factory fuel pump? aftermarket? fuel pressure?

[nanbar]

A poor battery connection would normally be most evident during cranking when large cranking currents would result in a big voltage drop at the poor connection, thus meaning reduced voltage at the starter motor and coil etc etc.....and thus, problematic starting.

 

Not sure how your car is wired, but my recollection is that once started, you can remove the battery and it will just run off the alternator....until you stop it, then it's all over.  Thus, I'd be thining a poor battery connection would not cause your issues...unless of course the alternator also has some issue.

 

Is the car fitted with a factory fuel pump? aftermarket? fuel pressure?

Fuel pump is factory Holden V8 as far as I can tell, not sure what the fuel pressure is, have been thinking about putting in an in line gauge.

It has been lazy to start when hot or when its been running for a fair while. I have one of those wind up/down manual terminal isolators fitted, I could do a test whereby I start it and let it run for a bit then isolate the battery and see what happens.

Edited by nanbar, 05 November 2023 - 07:46 AM.

[Cook]

Hi Nando. I'm no expert by any means but wondering if you have a carby spacer fitted.  I know with my WB it would be hard to start when hot and run erratically fromm time to time and did seem a bit smelly in the cab. I fitted the spacer to clear the "fuel vapourising issue" not sure what it's actually called and issue disappeared. Others will have the correct terminology/explanation. Still a bit smelly in the cab but not as much. Cheers Ron

[nanbar]

Hi Nando. I'm no expert by any means but wondering if you have a carby spacer fitted.  I know with my WB it would be hard to start when hot and run erratically fromm time to time and did seem a bit smelly in the cab. I fitted the spacer to clear the "fuel vapourising issue" not sure what it's actually called and issue disappeared. Others will have the correct terminology/explanation. Still a bit smelly in the cab but not as much. Cheers Ron

Hi Mate, thanks for the reply and help. I mentioned a while back to guy who rebuilt my Rochy (didn't fit and tune it) that it was hard to start hot sometimes. He said a spacer will fix that but mine already has it. See photo. He said at some stage I need to bring it to him to tune.

My efforts to date have been to try and fix something obvious to others that I may be able to apply, hence all the questions here.

Cheers

Nando

Attached Files

•  spacer.jpg   312.34K   6 downloads

[claysummers]

That isn’t really a spacer. Something more like 1/2”, with longer studs.


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[S pack]

That isn’t really a spacer. Something more like 1/2”, with longer studs.

Agree, looks more like an insulator or thick gasket.

[nanbar]

Changed the plugs today.

Was looking at the top of the carry with the air cleaner running. The air horns or air valves (I think that's what they are called) above the secondaries rarely open no matter how hard you rev it. Would this mean it's not getting enough air for the fuel going in? I disconnected the choke vacuum break diaphragm valve hose, blocked the port on he carby and the air valves opened more freely letting more air in. Any clues on how they work on a quadrajet?

I think I need to bring it to carby man.

[yel327]

Quadrajet secondary air flaps/valves don't open unless the engine needs the air. These are one of the reasons Quadrajets make their distinctive sound. If they aren't opening properly though it will starve of air but really only at full throttle. Quadrajets aren't a simple carby and really need to be setup by an expert (preferably on a dyno) after being built properly, although if it's built right, you should be able to get it to work pretty well yourself with final tune on a dyno.

[nanbar]

Quadrajet secondary air flaps/valves don't open unless the engine needs the air. These are one of the reasons Quadrajets make their distinctive sound. If they aren't opening properly though it will starve of air but really only at full throttle. Quadrajets aren't a simple carby and really need to be setup by an expert (preferably on a dyno) after being built properly, although if it's built right, you should be able to get it to work pretty well yourself with final tune on a dyno.

Thanks yel, read this late last night which is in line with your comments.

 

https://www.gtoforum...aphragm.137427/

Edited by nanbar, 06 November 2023 - 06:21 AM.

[yel327]

Just reading that you can see that Quadrajets can be a tricky thing. GM and GMH never really set them up properly as part of the production process either - the carbs came from Rochester and were put on the engines at engine dress in the assembly plants. The first time the engines were run with the Quadrajet and fuel was on the rollers at the end of the assembly line, where idle was set and then they were away. Sometimes little tweaks were applied to stop the secondaries from opening properly especially on Press Fleet manual cars, and this is why there is no good data for most of these cars in magazines of the day. A tune on a dyno making the secondaries open fully and the air valves at the right time dropped 0.5 to 1.0 seconds off the quarter mile times of cars like HT-HQ GTS350 and pre ADR27A 308/5.0L manual cars. 

 

I doubt any of that in the link is your problem but the carb itself might be. I've had Nigel at Xtreme fuel rebuild Quadrajets for me and also had Hume Performance do another one (the carby for my HJ Premier), and they work flawlessly once done. If you are after performance and not just cruising they do need a proper setup on a dyno though. Less than $400 for a full rebuild (plus major parts if required) and they run them on a test engine as well.

[nanbar]

As mentioned, my thing is a bit lazy starting when hot, reckon I might have found why. Auto Elec up the road told me to check the wiring on the starter motor first. If the wiring was ok, he reckons starter might be on the way out. An absolute bitch to get out but see below photo of the starter solenoid!

 

In removing the exhaust headers to get the starter motor out, I had coolant dripping out from second last bolt hole (cylinder 8). Ill hazard a guess and say that rust spot on the solenoid is just below that bolt hole. Another problem to address.

 

Re the starter, I have enquired about the Rod Shop one which is purpose made for V8 LCs and is alot smaller that the Bosch 9 000 063 062 unit.

 

Anyone here had any experience with the Rod Shop starters?

 

 

 

Attached Files

•  starter solenoid.jpg   143.65K   3 downloads

[rexy]

Just get your original reconditioned.

I had this done a couple of months ago for my LJ (holden 383). Best $150 I have spent recently.

 

None of the aftermarket starters for holden V8 have a good reputation.

[nanbar]

Just get your original reconditioned.

I had this done a couple of months ago for my LJ (holden 383). Best $150 I have spent recently.

 

None of the aftermarket starters for holden V8 have a good reputation.

Thanks for the info, I was attracted to the rod shop one because of its smaller physical size but take your point. Depends on how much the rebuild will cost me I guess. $150 sounds cheap, which state and who did it?

Edited by nanbar, 07 November 2023 - 09:33 PM.

[rexy]

In Burwood Melbourne by some crusty old auto elecs I use every now and again.

 

Where are you located?

[nanbar]

In Burwood Melbourne by some crusty old auto elecs I use every now and again.

 

Where are you located?

Northern suburbs, got an auto elec up the road, Ill go and see him and see what he says.