Jump to content

Mayday, I have detonation!


Minister88

Recommended Posts

Good day ladies and gents

Wondering if anyone can help. 

My Ra23 celica passed compliance, and now working on getting it to drive properly. currently setup with 40phh mikuni sidedrafts with 18r-geu engine converted from EFI. 

When the celica was fresh off the boat from Perth, it was running on 3 cylinders and had no spark on cy 1. with fouled plugs. as black as you can get them.

I put in new ignition coil, leads, dizzy cap and rotor, spark plugs. had it running on all 4 cylinders to adjust timing.

I adjusted the timing to slightly advanced as it wasn't running well in neutral. in retarded timing, the engine gagged like it was gonna stall... 

With abit of advance timing, it idled and rev'd fine but under load there were some bangs and pops especially uphills.  Sparks started to foul up again.. only cy 3 plug was burning ok.

Carbs have not been tuned yet which may be one reason why this girl ain;t running properly. If anyone who knows what they are doing with carbs and can lend me a hand, I am happy to pay in beer :)

Any other advice on where I should look/check from here would be great.

 

Thanks

Min

Link to comment
Share on other sites

  • Replies 41
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

How many degrees advance is it set to?

When setting up my sidies, a lot of sources recommend quite a bit of initial advance, at least 15 degrees, you then have to make sure any mechanical or vacuum systems don't push it too high, which can cause detonation.

  • Like 2
Link to comment
Share on other sites

banging and popping out the carbs?

usually this means lean, but black plugs say no. 

it may be an ignition timing thing (too much advance) or your cam timing might be off (inlet cam too retarded and compression is pushing it back out again especially under high load/high advance), so maybe both?

could also be over rich idle (black plugs) and lean  main circuit (popping on load) - could be your fuel pressure/flow as well.

Did you clean & check the carbs before install?

(so yeah could be lots of things)

I would start with getting the basics solid (timing, both ignition and crank/cams) before chasing rainbows in the carbs.

  • Like 1
Link to comment
Share on other sites

2 hours ago, azzurro said:

banging and popping out the carbs?

usually this means lean, but black plugs say no. 

it may be an ignition timing thing (too much advance) or your cam timing might be off (inlet cam too retarded and compression is pushing it back out again especially under high load/high advance), so maybe both?

could also be over rich idle (black plugs) and lean  main circuit (popping on load) - could be your fuel pressure/flow as well.

Did you clean & check the carbs before install?

(so yeah could be lots of things)

I would start with getting the basics solid (timing, both ignition and crank/cams) before chasing rainbows in the carbs.

Thanks Azzuro

Yes banging and popping out of carbs but theres definitely knocking with load too. Yeah, I have re-seal the rocker cover gasket since its pissing out oil from the sides anyway so will have a look. Is there any reading/information for cam timing for dummies? Surely google is my friend but if there are any recommendations please let me know.(never done this before).

Fuel pressure was definitely something I am considering. Since its running an electro fuel pump, I assume that is pushing higher than the recommended 4.5PSI. Does anyone have an recommendations for a bypass fuel pressure reg? 

Carbs are definitely not clean either... 

 

Thanks guys

 

 

Link to comment
Share on other sites

I'm assuming that it's been idled around the shipping yard, customs, vehicle testing etc etc so it will probably be carboned up quite a bit from all the slow speed running. But eliminate items one by one in a methodical process.

Start with setting the timing to a known OK (as Spence says, 10 degrees with the vacuum off and plugged)

Next check things like oil is not overfull and for manifold leaks etc, silly things that should be picked up in regular maintenance.

Then compression test and that includes setting tappets and I would even give it a bit of a hillbilly water injection to clean off any excess carbon crap inside the combustion chamber.

Finally check the carb is set right, but seeing as it has come from Perth I would say the climate is much different to Auckland so will probably need different emulsion tubes and chokes at the least. So for that I would take it to Weber Specialties up your way and get him to dial it in. He would have the full range of jets and emulsion tubes and chokes to get it purring.

When setting up the carbs they will adjust the timing to as much as the carbs will allow and what the motor can handle.

It might cost a few hundred but unless you get someone keen to do a perk who knows their shit and has all the bits then you'll be chasing your tail and probably spend more eventually. (the cost to tune will be substantially less than what you paid to bring it over) Ask @vivaspeed how good Weber Specialties work is.

http://www.weberspecialties.co.nz/

  • Like 4
Link to comment
Share on other sites

3 hours ago, k-trips said:

I'm assuming that it's been idled around the shipping yard, customs, vehicle testing etc etc so it will probably be carboned up quite a bit from all the slow speed running. But eliminate items one by one in a methodical process.

Start with setting the timing to a known OK (as Spence says, 10 degrees with the vacuum off and plugged)

Next check things like oil is not overfull and for manifold leaks etc, silly things that should be picked up in regular maintenance.

Then compression test and that includes setting tappets and I would even give it a bit of a hillbilly water injection to clean off any excess carbon crap inside the combustion chamber.

Finally check the carb is set right, but seeing as it has come from Perth I would say the climate is much different to Auckland so will probably need different emulsion tubes and chokes at the least. So for that I would take it to Weber Specialties up your way and get him to dial it in. He would have the full range of jets and emulsion tubes and chokes to get it purring.

When setting up the carbs they will adjust the timing to as much as the carbs will allow and what the motor can handle.

It might cost a few hundred but unless you get someone keen to do a perk who knows their shit and has all the bits then you'll be chasing your tail and probably spend more eventually. (the cost to tune will be substantially less than what you paid to bring it over) Ask @vivaspeed how good Weber Specialties work is.

http://www.weberspecialties.co.nz/

Thanks K-Trip 

I will certainly take your advice on this. I agree with the carb tuning. Since I have never tuned carbs let alone driven one until yesterday.. I will keep some spare cash on the side for someone who knows what their doing. I just want to make sure that most troubleshooting has been done by me to save as much money going outwards as I can. 

Quick question, to adjust the tappets do I really need a adjustment tool or can it usually be done with a socket set?

Thanks

Min

 

Link to comment
Share on other sites

Unsure of the setup & as per my previous 'advice' which may also prove ultimately unhelpful

setting the Tappets on my Avenger requires a open ended 13mm, a Large Flat-blade screw driver & a feeler gauge, and a little know - how (also what ever you need to get the cover off)

  • Like 1
Link to comment
Share on other sites

25 minutes ago, Minister88 said:

Quick question, to adjust the tappets do I really need a adjustment tool or can it usually be done with a socket set?

I've just done a quick online check and looks like 18RG is a shim type arrangement for setting valve clearances. Sorry I should have checked first.

This is typically a set once and forget deal (when putting the head together) and is considered an advanced level job so if you are not sure then it would best be left to the experts.  It probably doesn't need doing but if it does then Murray at Weber Specialties will tell you.

  • Like 2
Link to comment
Share on other sites

3 hours ago, ajg193 said:

Not sure if it is mentioned in the thread, but as you stated you haven't used a carburetter car before, are you sure you don't just have the choke stuck on?

looks like the 2 chokes are connected to eachother but nothing going back to the firewall. I assume its been disconnected since you'd probably not need it in perth? 

I moved the screw on the chokes and they move okay.

Link to comment
Share on other sites

In addition to everything mentioned above.

Make sure the carbs are in balance with each other, both at idle and WOT. They will pop and cracked if ones trailing the other. 

Best to get a carb balancing tool, however a rough way to balance them is use some hose pipe and listen to the pitch of each throttle when its running. Another rough way is to pull the lead off one cylinder while running and if the motor doesn't stumble that much it means that cylinder isn't doing much work, i.e. give that carb more throttle in the idle speed adjustment. 

But yeah best to get the basic tools like a carb balancer and a glass spark plug. Both these tools are awesome for on going tuning after its been setup right by someone like Weber Specialties.

 

Edit: if the fuel pressure was to high it would be leaving massive puddles of petrol on the floor from fuel pouring out the front of the carbs. I've made that mistake before lol. 

 

  • Like 1
Link to comment
Share on other sites

I like adding stuff to stuff

 

were the 40 mikunis the original ones that came on this engine? I know you have stated it was a 18rgeu But what i mean is are they after market, or the ones that were the factory option carb version for these?

 

I only ask, as I had a 18rg powered van with the factory twin side drafts, it would constantly foul plugs, pop and fart, and throw flames out the exhaust on down shift.

 

i read somewhere about those carbs, and that the main jets like to unscrew them selves, causing epic over fueling. i pulled mine part and found exactly this.

depends on the carbs, this could be the cause of your issue.

  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...