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  1. #26
    FEP Super Member JTurbo's Avatar
    Join Date
    Jan 2006
    Western MA


    You've made great progress on this Pace Car.

    On another bright side, the timing belt is much easier than the turbo.....
    1979 Indy Pace Car Mustang 302 / 5spd
    1982 Mustang GT T-Top 302 / 4spd
    1986 SVO Mustang - 1C

  2. #27


    I finally got everything put back together very late yesterday. It's been a tough road for sure that's not over. I got it to start with all timing marks on their "static" setting. It burned a lot of oil out of the tailpipe once it started. No oil leaking out from over by the turbo though like last time. I was worried when I saw all that oil burning again but it got less and less as the engine idled, and now has stopped completely. I'm thinking it was just oil that had leaked out thru the turbo seals last time when I had the bad turbo oil drain back.

    I've got exhaust leaks for sure in what sounds like the cross-under pipe. Sound seems to be coming from by the turbo and also near the exhaust manifold. Sounds kinda like a tractor. For now it doesn't quite want to idle very well. I can't seem to find the "sweet spot" yet. But seems to like 10-12 degrees btc. I'll hunt up m81mclaren's info on how he set up initial timing today. Seems like between rotating the distributor, idle mixture setting ( yes, mine can adjust), and little screw on throttle linkage they all kinda interact a bit. Will not idle at all below 10 btc. Interesting because the factory idle setting should be 2 degrees btc book says, and I think that's what smog check is looking for on idle setting. I'll verify static timing marks again to make sure it hasn't jumped a tooth. I think I remember that the dist. vac line should be plugged and maybe a connector disconnected on the Duraspark module? I'll do a search on the forum but can someone validate which connector if any needs disconnecting? I'm going to concentrate on getting it to idle properly, and then tackle the exhaust leaks. Thanks everybody for all their help.

  3. #28


    Here is the Weber carb choke, idle, and mixture setup procedure that seems to be the best description I could find on how to set things up to run best as the 5200 is a Weber design copy. I used this along with other factory timing procedures to get my initial setups and smog certs done (it had no power anywhere @ factory timing but passed with flying colors) then immediately gave it much more timing to it's liking but still have some mixture fine tuning to do to make mine run best at partial/mid throttle.

    What’s best for your setup and car, year, & calibration code may be different! Hope this helps.

    Choke Settings
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    1980 2.3 Turbo Mitchell Ignition Timing procedure

    Redline Weber carb SET UP ADJUSTMENTS
    Start set up by confirming carb base line settings. Do not depend on the factory delivered settings. Check them before the carb is installed.
    All settings are done with choke disengaged or warmed up so that the choke is fully opened and disengaged. This is done on automatic choke carburetors by first opening the choke butterfly by hand and inserting a wood block or wedge of some kind to hold open while the linkage is cycled (linkage operated through its full movement ) to clear the choke cam. (You will hear a metallic click as the cam is released. You can check the fast idle screw under the choke assembly to confirm that it is not in contact with the choke fast idle cam.)
    Set the Idle stop screw (speed screw see fig 1) by backing out the idle speed screw until it is not in contact with the throttle stop lever. Cycle the linkage again to be sure that the linkage comes to close without any assistance. (Checking for linkage bind) Now bring screw back into contact with the lever and continue to open or screwing in 1 turn no more than 11/2 turns.
    Set the mixture screw (see Fig 1) by first screwing in until the screw stops, bottoms out. DO NOT FORCE OR BIND AS THIS WILL CAUSE DAMAGE TO THE SCREW AND ITS SEAT IN THE BODY OF CARB. Back out the screw 2 full turns.
    Start the engine, the engine will run very slowly more like a tractor. As long as the engine stays running idle speed is not important at this point.
    The first thing to do is not set up the idle speed, but to set the idle mixture screw to lean best idle setting. First, turn in the mixture screw until the engine dies or runs worse, then back out the screw (recommend turning ¼ to ½ turn at a time). The engine should pick up speed and begin to smooth out. Back out ½ turn more, or until the screw does nothing or runs worse then turn back to the point where it ran its best.
    Use your ear, not a scope or tuning instruments at this point. You want to tune the engine by sound. Adjust to best, fastest and smoothest running point.
    Now that the mixture screw is at its best running location, you can adjust the idle speed the screw. The screw will be sensitive and should only take ¼ to ½ turns to achieve the idle speed you like.
    Check and set idle to your driving preference. Put the car in gear and apply slight load, (AC on) and set the Idle as you like it. Don’t set it too high, as this will cause causes excessive clutch and brake wear. The Idle only needs to be 7 to 900 RPM with light load or AC on.
    Recheck timing and vacuum hook ups. Recheck mixture screw to lean best idle again. If all is still best and smoothest idle then confirm and note the final settings.
    To confirm settings with the engine running. Start by screwing in the mixture screw and count the number of turns it takes to bottom out and note if the engine dies. If Idle Mixture screws are within ½ turns of base line setting then all is well and have fun. Also check the speed screw and note how many total turns from initial contact. You may have opened (turned in) the speed screw. Your final setting should be under 2 full turns. Reset the screws (back in) to the best final settings (Per your notes) and go on a test drive and have fun. If the settings are other than described then you may want to recalibrate the idle circuit (low speed circuit) to your engine’s needs. This is done by following the rule of thumb BELOW.

    Simple Rules for low speed calibration
    If the mixture screw is more than 2 1/2 turns out turns then the idle jet is too lean (too small). When the mixture screw is less than 11/2 then the Idle jet is too rich (too large). These assumptions are based on the fact that the speed screw setting is not opened more than 11/2 turns. If the speed screw has to be opened 2 or more turns then this is also an indication of a lean condition usually requiring greater change. At times it may appear to be showing signs of richness or flooding it is really a lean condition. See pictures and notes in the tech 2 article supplied in the kit instructions, view and please understand the need to keep throttle plate as near to closed as possible so as not to prematurely expose the transition holes. This is what causes the visible rich condition, and confirms the need to increase the jet size. JET KITS are available if needed.
    EXAMPLE With the speed screw set at no more than (1 1/2) turns in after contact with the stop lever; and the best idle occurring with the mixture screw set at 3 turns from bottom, indicates the need for a larger idle jet. Achieving the best idle at under 2 turns indicates the need for a smaller idle jet.
    The secret to understanding the critical nature of the carburetor set up and the advantages of a WEBER over other carburetors is the idle circuit. Referred to as the low speed circuit by Weber, this circuit is responsible for 80% of the driving operation. This is the reason that the Weber should give a fuel economy improvement over most factory carbs along with significant performance gains. In the worst case you should not see a significant fuel economy loss over stock, while improving HP & Drivability.
    The Weber Carburetor is a sequentially timed device to the motor like the distributor. Time taken in the setup will provide more fun later.
    Last edited by m81mclaren; 08-12-2019 at 09:38 AM.
    Current FEP:
    1980 M81 McLaren Carb Turbo 2.3T #003P ... IT'S ALIVE after a 22 year slumber thread!

    Past FEP:
    1986 Capri GS 5.0- very missed but in goods hands
    1985 LTD SSP- quick little fox 5.0

  4. #29
    FEP Super Member gr79's Avatar
    Join Date
    Jun 2009
    SE Michigan

    Default tune notes

    Great tune up guide. Looks same as factory wrote but much easier to refer to.
    Each 2.3 engine is different but basically use the same general initial settings for baseline tuning.
    Mods complicate things. We are on our own to find the new tuning window and fine tune within it.

    Have done much experimenting. Stock 5200 turbo carbs, n/a 5200s with turbo parts, now the Holley 2305.
    Carb tuning for driveability did not involve ign timing on mine once sweet spot was found.
    Changed couple vac line routings plus carb calib only. Most of the emissions spaghetti items are long gone.
    Made things easier. No egr, pvs connections, air cleaner items, air pump, choke. Durability, reliability fine.
    Interestingly, engine now runs the same or better as in 1980 when all was connected.
    Last check ave 26 mpg city/hwy combined. Power, starting, drive ability same or better.
    Rarely drive it hard, rev over 4k but will scoot when the bell rings.

    When i wanted to final set timing once engine was broke in, did it on the road.
    Took the dis wrench and vac gauge with me. No timing light.
    Engine always liked much more timing than 6. Barely runs no matter what at 6.
    Dis. is connected to manifold vac. Connecting it to carb seems to move the overall idle window down a bit.
    My notes say on 3rd engine run, bumped timing up to 16, higher like the 2.3 automatics use.
    Then drove for hours taking different roads. Flat, hills, freeway, side streets. Goal was max power, max driveability.
    Set max total timing (above 2000 rpm) then -2 or so degrees to be safe with no knocking, pecking, on 87 RON.
    Did not disconnect anything to set timing. Wanted to set timing for real condition driving, not shop spec or emissions.
    That is when the 12+ base timing was discovered. Is where engine ran at idle when total timing on the road was set.
    Idle, mid, boost ok. Carb, vac lines, adjusted to comply. Used vac gauge to tune to 18"-20" idle when warmed up.
    A couple vac lines were changed to smooth out things. During rebuild, actually lost track of what went where.
    Is not far off from stock config. Most of the tuning was needed for idle and transition smoothness due to mods.

    Can change back to 5200 turbo carb in an hour without any changes except for power valve and carb vent hoses.
    I changed the larger 350 cfm carb internal parts to closely match the turbo 5200 as a base tune to drive it.
    Engine seems to like that fine. Prob will eventually experiment to see where the tuning window limits are now.
    What this has told me is the engine's tuning window, one found, did not change much after certain mods.
    It needed the air horn vac bleed to idle nice with the 5200, but not needed now. Stuff like that.
    Wondering how upcoming cool weather will affect new setup. Am ready. May take a year to get settings nominal.

    For example, 95% tuned out the off idle flat spot and idle speed setting with idle mix, pri and secondary screw adjs.
    The n/a 5200 carb totally needed vac line rerouting even with turbo parts in it.
    Had bad flat spot accell to and cruise 20-40 mph. A good cleaning did help too.
    When close, even tiny adj can make a diff, as does weather conditions.
    Found tweak to seasonal temperature changes 4x year is good enough.
    In car vac/boost gauge sure is a great thing to have for monitoring. A/F gauge would and will be just as handy.
    Last edited by gr79; 08-12-2019 at 12:10 PM.

  5. #30


    Thanks to gr79 and m81mclaren once again. I've been pouring over m81mclaren's old post and have decided I need to verify all the vacuum connections and parts similar to what he did. Right now when it idles (poorly) it only has 12 inches of vacuum. Should be more than that I believe. This engine was removed for some work twice so I don't really have confidence everything was put back together properly when they originally did the engine repairs/replace 18 years ago. And I know I replaced all the noodles in the right place. It was good to find out that with the two port VCV that it doesnt matter which which associated vac line goes into the ports. It's simply a vac. switch that opens or closes.

    I do have a BoPort Stage 2.1 cam so I don't know how that would affect the vacuum. But just looking at the vacuum diagram for the 49-state Mustang-Capri 2.3L Turbo Calibration 9-2E-R93 there are so many inconsistencies that I don't believe everything is connected as it should be. That's even though it was running fairly well before the Boport Stage 3 head upgrade work. Even before the head work it was only pulling 14 inches of vacuum.

    I'm using the vac. diagram below to verify all vacuum connections.

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    I'll also pull some of the vac. line parts and verify if they are working properly. I think I was rushing trying to just get it running again. I think I will slow down and verify functionality of parts, etc,

  6. #31
    FEP Super Member gr79's Avatar
    Join Date
    Jun 2009
    SE Michigan


    Happy to help. I post long ones attempting to contain something of value. Throw out incorrect info.
    Not a rock star in efficient compositions or use of wording, nor know how much detail others already know.
    Recalling reasoning timelines thinking this stuff out, having totaled 350K on the carb 2.3T so far. Still learning.
    More and more people stop to ask "What year is it, 85?, "Still got the turbo on it?".
    Gas stations, parking lots, red lights. Some know exactly what it is, others never seen one.
    Some ask if they can see the engine turbo. A rare sight. That is why i try to help/share thoughts with you guys with same engine.

    Stock RON calib and related parts are ok for factory config, but after mods, good only for base tune if that.
    Mystery as to what to keep, what does not work anymore, what needs to be added or changed.

    Cannot really help on performance tuning. Mine is a dd.
    Like to keep it well mannered stock like, quick starting, retain bit more than stock performance, reliability, low op costs.

    Trying to describe again of what readings are with stock head, tc, SVO/TBird 'big cam', .030 over. 3.45/T5.
    Have changed carb from 5200 series to 2300 series. Found engine, carb, tuning, operation, very similar.
    Engine will pull 20-22 inch of vac on long deaccell in gear like exiting a freeway.
    -Assuming my autometer gauge is correct or my Sears handheld vac gauge (which reads 2-3" lower). Split the diff.
    Cold, vac usually 17", well warmed up idle usually 20 or, depending on load, weather, steady 18 or 19.
    Likes to idle 900 full electrical load or at 1000-1100 no load.
    Torque to run 10 mph in 2nd, 15 in 3 gear, car cruise stop and go manners. Can cruise level road 4th at 30 mph, 1300 rpm.
    Cold startup lately will run at 600 rpm by itself, say 15" vac then warms up. Will allow rev and hold at 1500-1800 to speed warmup.
    Recent micro adjustments to carb allows clutching off a stop, moving out slowly at 1200-1300. Another tuning checkpoint.

    So given that, 12 or 14" is not right. Unless combo of mods wont allow more.
    Engine should run fine with only dist vac line and turbo related vac lines as the only connected vac hoses.
    Found that once cam, spark, advance timings are optimized, carb tuning, etc made the bigger differences afterward.
    The back and forth adjustments to find and stay in the best tuning window.
    It helped knowing the stock 5200 carb was already set correctly internally.

    One major type of tuning i focus on. Low-mid rpm torque. If car can do this, everything else usually is close enough.

    Found tuning to keep it running seems to be close to as when it was 'full up' with everything connected.
    Possibly temp pinch off sections, disconnect and or plug all the emissions. Isolate possible problem(s).
    Low vac can be timing or vac leak but is able to run that way. Would bother me too.
    The engine sound is different when not set right, whatever that sound is for a particular engine.

    Also 79 has a different vac routing to the carb air horn from the intake manifold.
    Diagram ids: VCK-V, tee. Connections to: runner 4, carb V, F.
    Air horn connection on the side (V) necessary for the engine to idle correctly. Strange correction but works.
    A hose routes a tiny bit of air from the carb horn direct to intake manifold, bypassing carb.
    A controlled vac 'leak', with a ck valve to stop boost pressure from entering secondary venturi i guess.
    Same hose sections supply vac signal to pv from the tee before the check valve.
    When i changed to a non-5200 carb, engine does not like that 'leak'.

    PV tube (front air horn barb F) is for a boost referenced signal to add extra fuel. PVs need to stay closed when not needed.
    N/a engine vac drops under carb when accelerating, opens valve if vac reading drops below pv rating.
    Vacuum signal under carb, on boosted engines, is always vac, pv never opens.
    -The reason a separate vac line, from manifold downstream of the tc/sc to activate the pv directly, is needed.
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    Pro carb internal calib prob ok- especially with todays fuel blends compared to 1980 gasohol or pure gasoline.
    Head mods prob ok. Even being ported smooth, it is said turbos atomize carb fuel pretty well.
    Cam profile prob ok straight up "The 2.1 is a stout cam and very good for low end drive ability."
    Timing- try around 12° base and go from there as to what engine wants.
    Last edited by gr79; 08-14-2019 at 12:22 PM.

  7. #32


    I replaced quite a few of the 40-yr old vacuum lines by the left fender vac sw/sens array. I found a large leak by where the #1 runner hard line transitions to the rubber line. So then I decided to replace all the lines on that fender array. I can get the car to idle quite comfortably at 1200 rpm/12° BTC. It really won't idle well below that though. So I think I have a few more leaks to find. I'm chasing the leaks with carb cleaner, but still hard to find in all that tangle of vac. hoses. At this point, I will end up replacing all the old line even if they appear ok visually. The rubber on the old line is so hard, and cracks are hard to see.

    The book setting for this year '79 2.3L turbo is 2° BTC at 900rpm. I don't know how I will get there at this point, but one problem at a time. I also still have a leak at the exhaust manifold ball housing connection to the exhaust pipe. The pipe doesn't quite seem to mate up properly with the ball joint. And that is some hard steel. I did get the turbo side leak stopped but that darn exhaust side..... Might end up taking it to a muffler shop to make a new cross under. Trying to position both sides is a nightmare. I also put in a new distributor. I ended up ordering two. One from O'Reilly's had the right side screw hole threads stripped and the cap wouldn't tighten on it. It was also a dual-vac type distributor w/ top hole plugged. I ended up using one from Summit Racing, same Cardone part number but it arrived and was a single vac. line dizzy which is really what I wanted. The old distributor was really in bad shape with no hard plastic socket left to plug into the harness. Just orange, purple, and black wires hanging out separately. I was plugging the line into the socket one at time with the old distributor. Glad to be rid of that. I might try rebuilding it myself later. New distributor runs great.

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    Vacuum Array

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    Old Distributor

    Next up, replacing ALL the old vacuum lines. I'm getting really really fast on disassembling everything on this car. I've pulled the alternator, belts, radiator, vacuum lines, distributor, turbo multiple times and that's helped me to know how to do it quite rapidly. The only thing I really dread is pulling the turbo, and the cross-under pipe.
    Last edited by radartek; 08-18-2019 at 06:29 PM.

  8. #33


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    Old Distributor

    Next up, replacing ALL the old vacuum lines. I'm getting really really fast on disassembling everything on this car. I've pulled the alternator, belts, radiator, vacuum lines, distributor, turbo multiple times and that's helped me to know how to do it quite rapidly. The only thing I really dread is pulling the turbo, and the cross-under pipe.

    I've got an extra new rebuilt single port distributor if you need one...
    Current FEP:
    1980 M81 McLaren Carb Turbo 2.3T #003P ... IT'S ALIVE after a 22 year slumber thread!

    Past FEP:
    1986 Capri GS 5.0- very missed but in goods hands
    1985 LTD SSP- quick little fox 5.0

  9. #34


    Thanks for the offer m81mclaren. The Summit distributor is single vac. and working great for me right now. I did end up taking the car to a muffler shop and had an all new cross-under pipe made. Had a bung put in for an O2 sensor so I can install the Wideband AFR Autometer gauge I have. Found switched (ignition +12v) and instrument cluster dash lighting power for nightime gauge visibility.

    I still have an exhaust leak from a cracked exhaust manifold to deal with now. I found one for '79 ( can you believe it?) on eBay, and it should arrive on Monday. In the meantime I fixed some wires on the vac. array that broke (turbo light was not coming on with boost).

    Also found out for sure that I can't really go by the Factory timing specs. any more with the BoPort Stage 2.1 cam. I'll have to find my own timing specs by setting up total timing, and then seeing where the initial ends up at. I won't want the total timing to be more than about 27-28°@3000-3500rpm, with a non-intercooled turbo. I'll have to play with the distributor internals a little bit. I can practice on the old distributor that I have. I might could push that a bit with the methanol injection kit I plan to install but for now I'm going to shoot for 27-28° total timing.

    Taking it slow, and deliberate but still determined.
    Last edited by radartek; 08-23-2019 at 12:23 AM.

  10. #35


    The intake manifold came in, and it's a '79 (can you believe it?) and not cracked anywhere at all. I cleaned it up as it had all kinds of gunk on it. Still have to install it though. Maybe tomorrow. I did install the wideband AFR gauge, and it's giving some pretty interesting readings. Haven't taken the car for a spin yet, but good AFR everwhere except for idle RPM. Shows lean, lean, lean. Maybe that 's why I have trouble getting it to idle below 1100-1200 rpm. Thinking of getting some beefier idle jets for it to see if I can get the AFR up in idle.

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    Junkyard eBay 79 manifold
    Last edited by radartek; 09-06-2019 at 06:33 PM.

  11. #36

    Default It's done

    This will be my last post on this particular thread. I have more things to do on my Pace Car rebuild but the title is not accurate any longer. But I'll update on the latest here and then I'll start new threads that address each particular upgrade or project. I'm basically done with the engine rebuild/mod and everything is running great. The sweet spot is 12° BTDC @ 1100-1200 rpm. I installed the exhaust manifold and it's working great with no issues. I put in some hood insulation for the carb turbo engine. I think it needs better paint but I'll put in a pic of it here. It fit perfect. I've taken the car for some cruises and have got complements on every drive I take it out for.

    For the future I have a SVO T-5 transmission, aluminum driveshaft, stage 3 clutch, new pressure plate with all the hardware needed to install. I guess I should get a new throwout bearing and replacement that at the same time. Beyond that I've also got the AJE A-arms with spring perches, AJE K-Member with the 2.3L engine mounts. Coming in last I also have on hand the Maximum Motorsports panhard bar.

    Not sure which one I'll tackle first but as I said I'll post up the new challenges as they are selected. I want to throw some acknowledge out once again to all the folks who provided advice and encouragement throughout getting the Pace Car running. Especially m81McLaren and gr79.

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  12. #37


    Looking great and sounds as though you have the power down! Where'd you install the bung for the wideband? I only get good AFR reading under some throttle pressure. I think the location of the sensor in front of the secondary CAT and the need to get the exhaust pressure up enough to get a reading is why I see a delay. Just my theory which is why I am asking in case there's a better solution!
    Current FEP:
    1980 M81 McLaren Carb Turbo 2.3T #003P ... IT'S ALIVE after a 22 year slumber thread!

    Past FEP:
    1986 Capri GS 5.0- very missed but in goods hands
    1985 LTD SSP- quick little fox 5.0

  13. #38
    FEP Super Member gr79's Avatar
    Join Date
    Jun 2009
    SE Michigan


    Yes i agree great stuff to hear (read).
    Mine likes to idle higher like that. And even with the different carb.
    Is fine around here in winter. Running high elec loads tends to drop idle rpm too low when set at 900.
    Most always temp drops lower when the throttle is kicked when idling with every carb i have had on there.
    Changes with the weather or just day to day.
    Never figured it out to date. As long as it idles steady and runs good, am happy with the extra 200 or so rpm.
    I think its in part due to the same higher timing settings we use. More initial advance, higher idle.

    Am curious about the lean idle AFR. Getting more interested in getting a AFR meter. But not spending 200.00.

    My car had silver foil backed insulation glued under the scoop from the factory. Took it out when i got old.

    Check the carb fast idle cam make sure it is kicked off when engine warmed up.
    You are lucky to have a carb man. Maybe ask him what he thinks about the high idle.
    Last edited by gr79; 10-02-2019 at 08:56 PM.

  14. #39


    Quote Originally Posted by m81mclaren View Post
    Looking great and sounds as though you have the power down! Where'd you install the bung for the wideband? I only get good AFR reading under some throttle pressure. I think the location of the sensor in front of the secondary CAT and the need to get the exhaust pressure up enough to get a reading is why I see a delay. Just my theory which is why I am asking in case there's a better solution!
    I put the O2 sensor on the turbo downpipe right after it bends beforegoing to the cat input. It works well there and reads all the time.

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    Last edited by radartek; 10-18-2019 at 08:04 PM.

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