Good read Jack! I missed the solid motor mounts.

If you're still using the solid mounts and having issues, swap them out. Richard always recommended against them.

Thanks for the thoughtful input. Greatly appreciated. Found your forensic work on the EMPI carbs to be very helpful.

On carbs, mine are PMO's from the Richard Parr era. They were a good set of used carbs purchased a decade ago and then lightly gone through by engine builder. I've checked linkages and done some higher level tests on throttle valves to ensure they're all properly seating. If all else fails, I will remove carburetors and do this more thoroughly.

The headers are 1.75" OD and 31" in length. I don't recall the dimension of the secondaries but as you know, it's a little more complex given the routing into the top and bottom of the GT3 exhaust. I've safety wired the active exhaust shut so that I am only using the "quiet" port on the GT3 exhaust (to remove the variable of that opening at ~4000 RPM).

The cams are Elgin cams 306-288-102. Now cams are a black hole for me and I know Elgin has a different way of spec'ing his vs Dougherty and Web. Best I understand these cams, they're similar to a DC43 carburetor cam with slightly more duration and slightly less lift on intake and exhaust.

Lastly, I mispoke ... I am running Wevo semi solid mounts. Curious if these are also potentially problematic or if I can park that for now.

I will send through photos of the valves later today.

i have Wevo mounts... (another item that Mr Parr didn't like but I kept them....).

I would focus on what's going on with your idle circuit. Gotta give the engine what it wants and all, but you are certainly using what would seem to be unusually small idle jets, considering your engine configuration.

My engine is still more rich than I would like at lower rpms (idle ~ 2k, 10.5 ish) , which I think causes some lag off the line. I've accepted this tradeoff to get smooth, strong power without hesitation through idle/main transition. I use the wideband to ID trends vs certain #.(14.7 etc). Someday I will get back at it ...

Keep after it.

Was going to say, as long as the mounts aren't metal to metal, at least some of the engine vibration will be attenuated. Sounds like that's been Gordo's experience.

Nice to be able to potentially rule that out.

Got a bit bogged down in a suspension refresh and missed an alignment / corner balance appointment before weekend. Will be a few days before I can get back at the tuning in earnest.

Thx for all the tips so far and have a nice Labor Day weekend

1986 Carrera MFI is what’s being channeled. Motor just needs to play ball.

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http://forums.pelicanparts.com/uploa...1756559061.jpg

I am not hyjacking your thread, I have had a bad weekend when my 8 month old Webers took a dump.
Here are some more things I found and fought in the last 48 hours..
AFR started to go to 18 on full throttle. F66 tubes, 42mm chokes, 190 main, 190 main air bleed, 60 idle jets, 135 idle air bleeds. I spent 5 hours on each carb cleaning them and going back to base line of the new carbs. 2 cracks under the shafts from over tightening the hold down nuts, filled the cracks with blue Locktite, it worked the best. Good looking carb base gaskets, but they were leaking.
Got it running and found the manifold to head gaskets and spacers were leaking so I replaced those and found cylinder 5 spacer was still leaking so another total tear down. Then one of the 1 month old brass floats from Italy was leaking and was replaced with plastic type. Then a leaking needle valve flooded the 2&3 cylinder so another tear down to change the valve and found another bad brass float so I replaced them all with the plastic type and had to go through the fuel level setting procedure.
Then another leaking inlet valve ..Grrrr. I used ether starting fluid to check for gasket leaks and IMHO this works the best at finding micro leaks.
SO.. now it runs with a very strong idle signal .. 38mm chokes, 950 RPM = 8 LPM air flow. Had to back off on the timing to get it to clam down, I am close.
3.2ss, DLC coated everything,
38mm chokes, ported heads, M1 cam, 123 dizzy, 175 mains, F24 tubes, 165 main air bleed, 60 idle jet, 80 idle air bleed.
I am at 13.8 at WOT so I will drop down to 125 main air bleed a see if it is happy.
The main take away that saved me was the ether spray, brand new gaskets leak, do not say " I just changed that" check and check again. I looked like a John Force drag team tear down specialist as many times as I did a total tear down . Do not give up, carbs are amazing.
I would like to thank Shane, Jack, Ian , William and the rest of you for helping me and giving up good ideas and hard won information on dialing in a 45 year old car.

Thanks for sharing your experience. Wouldn’t a leaking base gasket manifest as lean across RPM range and not just under hard accel?

Recall my symptoms are rich to “perceived evil lean” under accel. “Perceived” bc I’m starting to Q whether it’s actually lean VS incomplete combustion manifesting as lean. “Evil” bc it’s not a gradual progression lean issue. It’s rich to 20+ AFR.

Some gentleman have been helping me on the side. To update, I pulled out needles and idle jet holders again and checked O rings. See below … I get differing opinions on the needles. Neighbor builds custom Harley D bikes and he swears he’s seen needles like mine wreak havoc with carbs. See below.

I’m convincing myself I have an ignition issue … recall, twin CDI+ boxes, Parts Klassik coils, JB Racing Dizzy. I need to systematically test ignition when I’m back with car but electronics does intimidate me.

In meantime, is it conceivable that bad coils would present as sharp stumble and “perceived evil lean” under load? Ie. Incomplete burn exacerbated by engine demands.

I have the coils mounted horizontally on the ledge before the firewall. Could orientation (v. upside down like original Bosch’s) and vibration be part of problem?


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http://forums.pelicanparts.com/uploa...1756917011.jpg

Car has been on stands and so have had time to think and look into ignition a bit more.

The theory being that if ignition is incomplete, then I’ll be reading very rich at idle and part cruise and could read very lean when engine is under load. Exhaust and lack of scavenge could explain that. It could also be poor or scattered spark.

I’m using twin Classic Retrofit CDI+ boxes and a JB Racing distributor. I’m very fond of the team at Classic Retrofit and insisted on using their CDI with the JB Racing dizzy instead of MSD.

JB Racing distributor is unlike Bosch and other distributors in that it fires on the rising edge of the pickup signal. The polarity is reversed relative to what a CDI is used to seeing. For that reason, Classic Retrofit requires that the positive (orange wire) be wired into 31D and the negative (violet wire) be wired into 7 … the opposite of how a Bosch dizzy would be wired in.

I pulled the ignition to CDI harness (a Parts Klassik number) and it looks like it wasn’t altered for the above. It’s wired for a Bosch dizzy.

I’m particularly out of my depth on this subject but as it’s been explained to me, that changes the phasing of the spark relative to the contact in the cap. It means that it has to jump ~10mm within the rotor cap and can cause it to scatter at high RPM.

That’s going to drive incomplete combustion at low RPM. It’s also going to create very weird timing advance /retard when engine is under load which could be driving the “perceived evil lean” stumble.



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http://forums.pelicanparts.com/uploa...1757173919.jpg
http://forums.pelicanparts.com/uploa...1757173919.jpg

I’m surprised it was drivable at all with the distributor like that. I don’t know everything about distributors but when I made my electronic 3.2 distributor I fired it with a MSD and the rotor phasing was nowhere close to where I designed it to be. It would idle ok ish but as soon as it started advancing it was very clear something was not happy. I swapped the wires on the MSD and the rotor phasing was right where I planned and it was completely transformed. My understanding is that the wires need to be swapped depending on distributor rotation direction (counterclockwise vs clockwise)

I drilled a hole in a spare cap to test rotor phase but not sure I would do that and destroy a 12 plug cap !