Whats the problem??? Please email suggestions

**matta** · 24th December 2008, 02:31 PM

Hi everyone.... I am seeking some suggestions on how to eliminate a small but annoying problem on my 77 that has me all but buggered on how to fix it..

Let me explain..

I have owned my rangie for 8 years and I know it pretty well... It was running a stroked P76 with the original manifold and twin carb set up with electronic ignition..(The elec ignition was done by a auto elec.. It runs an MSD Blaster to coil with Bosch fuel module.) It ran great but needed better carburation to maximise its performance so the time came 1 year and a 1/2 ago to upgrade the manifold to custom Willpower Manifold and upgrade the carbs to Holley Projection...

Now I will state the holley projection came off a donour car that had a worked 4ltr rover in it and ran like a cut snake... Amazing..
So one weekend we installed the manifold and projection and got it all running... New fuel lines etc etc... On instalation we noticed we had a high rpm miss.. Ran great at start up and id throttle but when we gased it it developed a very bad miss.... Let the games begin.. So far I have done the following to try and get rid of it..
Step 1.... (basic electrical)
All new plugs and gap checked to correct gap 28 thow
Timing set at 6 degree BTDC
Leads and coil leads all new 8mm
New dizzy cap...

At this point I took it to Carb N Ject in Brisbane to help eliminate the problem. The car sat in their shed for 2 weeks and when I went to pick it up the guys said to me to just rip out the pos Holley Proejction and replace with a carb... He said that he had changed the plugs.. (They were new) charged me $50 for doing sweet FA and wasting my time and said come back in the new year as he was shutting for Christmas...
* Didn't go back and told all my race car mates not to go back either! Arrogant pigs..

So teh problem was back to me... Next stop..

Step 2... (Possible fuel issues, over or under fueling..)
New inline fuel filters
New Fuel pump
New EFI hoses
New return hose to larger diam return pipe in tank
New custom swirl pot and primer pump

Step 3... (Possible fuel pressure regulator isues..)
Fuel presure regulator check.. all good set book spec to 15 -18psi
Lamda sensor up its bum to check styrometric pressue. All good. Perfect even..
N.B. We did manage to improve but not eliminate the miss by upping the regulator pressure to 25psi but the system is not designed for such high psi.. Problem still existed..

Step 4... (Losing spark maybe???)
Coil wiring changed to run constant 12v. Was previosuly 12v on start up then 9v which is the pre elec ignition arrangement... Now constant 12v. Also gave the projection a constant 12v spark from the battery rather than any piggybacks.. Check ohms to the TPS and all set to book spec.

Step 5...(Holley Projection is the problem??)
Much research was done regarding the holley projection as seeing as though all else was proving fruitless I figured it must be the projection.. It starts first go, gets me 16ltr to the 100k and is as crisp as but at full open noise no go.. so I bought myself a BRAND NEW Holley Truck Avanger 670cfm carb..... Pulled out the HP, fuel lines, pump etc and did the conversion to the carb... All new lines etc etc..new linkages..new throttle cable bla bla bal.. Started her up first go..adjusted choke, idle and bowl settings and mixtures... Took the old girl for a blat around the block.... SAME PROBLEM EXISTS....... (*&^(*&^RK!!!!! Thats a day and $800 down the drain..

Step 6.. ( HPgoesback on)
As the truck avenger didn't solve my problem I removed it (Ran in the car for 15mins) Anyone chasing a brand new carb cheap? and re-installed the projection.. New hoses back except this time I didn't bother with re-installing the swirl pot etc as it just doesn't need that much fuel. With al the new adjustments and changes it runs sooo sweeet but open throttle is still a joke...

Step 7....
I have bought a brand new coil and ignition module but as yet have not installed it... The previous coil and module wouldn't be 5000kms old but I thought maybe having the coil only getting 9v after start up may have upset either item so I will install new module first and then if still no luck I will do the coil...

Step 8...
The only thing I have left is the dizzy.. It has no slop in the shaft and on elec igntion there is bugger all in them to go wrong.. I have cleaned the unit and checked the vac advance is working all ok.. It is.. I have also checked for vacuum leaks using some aerostart etc but without any leaks found. As the missing issue is only under load and not idle I believe it is a spark isue rather than a fueling issue...

The questions.. What next..
Could the MSD coil have too much spark???
Is the dizy stuffed...???
Could the ignition module be wrongly matched to the coil...??
As these were fitted to the vehicle by a auto leckie I am guessing no...

Any help would be of huge assistance.. A match and some fuel has already been suggested! I am prepared to listen to all suggestions but please note the Holley Projection was replaced with a brand new carby and teh problem remained so it isnlt the projection unit.. They do seem to have a bad name butits not it...

Merry Christmas..
Matta

**bblaze** · 24th December 2008, 09:09 PM

mabe not related
Years ago had a guy ask me to look at his 351 engine, had a high speed miss. He went on to tell me he had all ready taken it to about 75% of the mechanics in town, he went on to run them all into the ground as the problem hadnt been fixed and many thousand later he was getting really ****ed. I refused to look at it because I didnt want my name put with the rest of the mechanics. Speaking to him again about 6 months later and asked if the problem had been fixed. Yes it had, it was a slightly bent CONROD. So dont discount this possibility either. I know you say it runs fine with carbs but not after mods, I have no answer ther exept it may be the different fueling systems causing the problem to show its self. The 351 run perfectly apart from this slight miss/flutter in the high rev range. Do a compression check and see what you find
cheers
blaze

**justinc** · 24th December 2008, 10:24 PM

firstly, check that the ignition module and distributor are earthed well. No, attached to the engine is NOT good enough. I have had to run a small earth lead in the past from a distributor mudule to the actual battey neg to gain a good constant spark in a RRC 3.5.

Secondly, ar you using Champion plugs? I have nothing but problems with these, and only use NGK or Bosch now.

Good luck, sounds very frustrating

JC

mike 90 RR · 24th December 2008, 10:35 PM

The more horse power you get out of a motor ... the more it brings up the parts that it can't tolerate

A simple explanation to the above is ...

A old motor running original electrics runs great .. except it has worn rings and it is time to recon it
So you recon the motor as a long block (heads & block) and stick all the original electrics back on it ... as it ran perfect before
So you start this motor up and it runs like a bucket of snot ... You end up changing all electrics to brand new to resolve the problem

In short .. You have upped the horse power ... and now it doesn't tolerate old and worn parts

So possibilities are
Manifold gasket's are wrong
Stretched Cam chain
sloppy or bent Dizzy shaft
Wrong advance weights

So try the following
....Try a standard coil
....Disconnect the capacitor from the coil or points
....Try another Dizzy

Hope it helps

Mike

**matta** · 25th December 2008, 06:36 AM

Hmmmm, some of those remedies sound bloody expensive... but thank you all for the suggestions...

first stops include coil, dizzy and module swaps... Will keep you posted!

matt

**NOFUSS** · 26th December 2008, 09:59 AM

Have you put it on a asilascope( spell check) find one normally tucked away these days in back of mechanics sheds you can see from the coil throught to the spark plug while engine is running . any sort of short or resistance in eletrical system in this spot should show it self at any rpm ht leeds that are grouped together can cause a miss at high rpm ,one other thing iv come a cross was a perished vac hose ok on low rpm but when rpm high one pot ran lean causing a miss type symtom. more for you to think about

**Pedro_The_Swift** · 26th December 2008, 10:04 AM

while most engine shops can measure leads "on the machine"
its very easy to do yourself with a cheapo meter.

**NOFUSS** · 26th December 2008, 10:11 AM

Originally Posted by Pedro_The_Swift

while most engine shops can measure leads "on the machine"
its very easy to do yourself with a cheapo meter.

Its one thing to check the resistance of a lead but thats all you do it dose not check magnetic field break down or spark jump/cross while engine is running and you can see what all pots are doing at the same time thats the bonas

**Chucaro** · 26th December 2008, 10:12 AM

asilascope

Oscilloscope in my Spanglish is the correct spelling

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Whats the problem??? Please email suggestions

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