Home > Open Discussions > Domestics > 87 built 318 falls on face

87 built 318 falls on face

  1. Ok so i have a project truck that i have been working on for a friend. Its an 87 Dodge W150 w/318cid. So brief history on motor... I took out the original 318 and put in a 318 that he had from a 74 but wanted me to go thru it. So we punched it out 0.060 put in a bigger cam w/ .484 lift and .282 duration took heads down .010 had to shave valve guides to accept the cam lift. Has edelbrock 750 carb (freshly rebuilt) on edelbrock performer intake.....k so my problem...is this dam thing has a "flat spot" on heavy acceleration. So was thinking the distributor i used was for the original motor (87) and we put 74 motor. So bought a new dist. W/ vacuum advance installed retimed and flat spot persists..any ideas???
  2. Define "flat spot" for my french needs more precision.
  3. What is your total timing? Meaning base/idle timing plus advance when vacuum not hooked up. Are you around 10 on your base timing?

    Usually, you never adjust timing with vacuum hooked up. You hook that up AFTER you have set total timing. Most modded engines don't use mechanical advance distributors. I would think you would want 36 total timing @ around 3500 rpm. 10 + 26.

    I would usually recommend a racing dizzy here as the distributor has stiffer springs for the mechanical advance.

    So before I go any further, I want your definition of flat spot in more words and also what you have as timing set at right now. You can't really time this engine as stock any more can you. Tricked out as it is, you will be looking for any thing between 10 and 14 base timing.

    On these older trucks, you had different SCC's. (spark control computer). Which one do you have installed in that truck. Base timing will vary by SCC number. Some want 8, 12, and even 16.

    Best to go with a MSD type coil and distro to go with it.
    What did you buy? If your base timing is set @ 8, try it at 10 or 12. Might make a good difference. Plug that vac advance and see if your flat spot still occurs.
  4. Dodge wants you to check total timing @ 2500rpm. But with a set up like yours, checking @ 3500 is more realistic as that is maybe where yo are getting your famous flat spot.

    Regardless that you have a 74 engine in there, it all goes down to the electronic spark controls this truck has. Usually the best is to circumvent the OEM spark controls when tricking out a ride like this.

    Now this is just me, but I would bypass all that ESC crap and go with a aftermarket NON esc dizzy and ignition module. If your friend went to the extent of punching it out, shaving heads, bigger cam, 750 carb and intake to go with it, I don't see why he would keep the OEM esc stuff. It just hinders what he wants to do with this project.

    Now that I have said all this, I don't even know what you installed as a new distributor. Or even if you guy's even tried to remove the ESC crap dodge installed in most engines from 1972-1991

    I think these older trucks used a 2bbl carter feedback carb. Now that there is a 4bbl 750cfm carb in there, the lean burn set up is probably going wild trying to correct timing or something to that effect. Going to a single pick up with V advance is preferable to the dual pick up these trucks came with.

    Moving away from the distributor vacuum control system and just using a manifold vac port for the advance is probably better for this application
  5. Ok i have set base timing to 10, 12, 14, &16 and the flat spot is at 1300 rpm trans in drive. Revs like a banshee in neutral/park. Just put a cheap spectra dist. To see if vac advance was y...nada. I have dist. hooked up to ported vac off carb. If i put vac source to manifold wont it command advance early and fall off as throttle opens and ported vac increases?
  6. We are limited by emissions on what we can get rid of but most esc crap is gone. Heres a few pics of the truck. [​IMG][​IMG]
  7. Something like this should do the trick. Coupled with an e-core coil, cheap. http://www.ebay.ca/itm/330636973614?rmvSB=true

    But if he wants to go all out,all in, MSD all the way.

    Basically, what I am trying very hard t repeat is, if this truck has lean burn and ESC on board, which most of them did, get rid of it.
  8. Depends, that ported carb port should be same as manifold port, but to confirm, I would need a picture of the set-up.

    Thx BTW for answering questions so fast. I will correct some of the stuff I wrote before. When you say flat spot, what do you mean? Does the engine bog down @ 1300prm? Does the spark get weak/cold? What is timing doing @ 1300rpm? all that nice stuff I need to know.

    No reason this engine will rev like a banshee in neutral, but flat out at 1300rpm in drive unless something is affecting.

    Try keeping all tests with 10deg. It is a good base line between 8 and 12. After that, it is fine tuning. What is fuel pressure @ 1300?
  9. That sucks, cuz up here, we don't have those limitations.
  10. You could try a distributor recurve kit with lighter springs, but it is throwing me off that it revs like a banshee in neutral.
  11. Ok my "flat spot": if i stomp the gas and hold it down in gear it dies, if i feather it past 1300 rpm i can stomp on it all day without it dieing. But neutral/park motor seems legit. I have to go do an intake manifold this morning then when i get home i will get you more answers nickb2 like fuel press. and all that good stuff
  12. Funny thing is engine acts same with vac type dist and with electric dist... Maybe just got a bad dist and vac adv. isnt working?
  13. When you say most of the ESC stuff has been removed, what in the following snapshot has been removed?

    If you are using a distributor with two connectors, one for run, and one for start, that means you still have the SCC/ESC in play. The SCC does monitor engine load and will vary spark accordingly. Screenshot (106).png
  14. Ok, talk later. I am still on vacation till monday. Back to the grind, but I will keep trying to find some answers for you.
  15. Ok i still have the exhaust manifold lol. Truck never had dual dist. Only single w/out vac adv. thanks a ton man my buddy is coming to pick up his truck thursday so im needn it ready to drive to colorado when he gets here. Gotta say im gonna probably cry when the truck leaves
  16. Everything else being good - fuel pressure* - timing, float level etc - I would look at carb power valve
    What is vacuum at idle? esp as the cam is getting long in duration.

    I Am guessing no EGR yes/ no ?

    *this is a carb so not much is needed. We have a FI mindset.
  17. 1 last pic, im pretty proud of this truck. But off 2 work i go. Will get back w/ some better answers later today nickb2 thanks again[​IMG]
  18. So many words (and mud) flying around, I hesitate to jump in and "muddy" the picture any more, but...

    Free-revving won't tell much. It takes so little power to do so that an engine would have to be running horribly to not sound like it is free-revving well.

    It probably does not matter, but is that cam duration "advertised", or the effective duration at .050" valve lift?

    Like Kev, I'm wondering about the EGR. Have you tried just blocking it off?

    The "ESC" is Electronic Spark Control"? It sounds like bastardizing that is the root of your problem. Put it back to pure stock if you can not get away with any "emissions related" mods. But it sounds like that isn't the case, really, since you now have a vac advance can hanging out there?

    I think the emissions-testing concerns are key here. Do they inspect for installed equipment, looking for stock or an authorized substitute for everything? And also do a sniff test? And is that loaded on a dyno or just free-revving/idling? Depending on the answers to those questions, I may have more on the subject...

    Personally, I would not waste time and money on any dizzy-based ignition mods for this "toy"; MSD or otherwise. Leave it stock, if required, or move on to a wasted-spark direct ignition. V-8s simply run out of time for adequate coil dwell with a single-coil (dizzy) when speed gets above 5000 rpm. All those tricks with dual points, "multiple sparks", capacitive-discharge, etc. where rendered obsolete with the advent of DIS. You could install a MegaSquirt ECU on there for about $500 if using it for spark only and have both endless control of the spark curves and real-time display and logging of what the spark advance is. Later, if you finally move past the carb, most of the EFI install would already be done...
  19. I agree on all counts, including mine. But I am thinking about the EGR. It is electronically controlled by the SCC on these trucks.

    So if I read right, there no longer has a SCC here to control EGR.
    I am also having a hard time finding documentation on 1987 318's that did not have vac spark advance controlled by the SCC and that only one connector to the dizzy.

    But this having an edelbrock intake, 4bbl carb 750cfm edelbrock also. Also, now we know it did not have a vac adv dist before, now it does, it is getting hard to advise.

    My initial take on this was to just bare bone it as much as possible with a good MSD kit that can be found on e-bay or used and basically just wire in the few leads needed and just tape back all the rest of the emmision lean burn and ESC stuff. But that seems to be done already if Krazy says it pretty much only has an exhaust manifold left that is stock.

    So I also am thinking, was the EGR reinstalled in this project? If so, how in the heck is it being controlled? Is the emissions sticker still visible in the hood of this truck?

    So this is a disclaimer, because canadian emissions were not like calif equipped. I may throw into the weeds here. Back in those days, canadian models varied greatly from USA models in that regards. Nowdays, pretty much all is similar. Back then, it was a nightmare fixing a USA car/truck for us northern techs.

    I remember when I started in this trade back then, we would get USA models and just rip everything emissions related out. Nobody cared. Going to canadian tire to buy MSD kits were as common as blocking of EGR ports and ripping out as many vacuums as we could that weren't necessary to the function of the engine.
  20. Another mopar gadget we would rip out was the orifice spark advance control which controlled the vacuum going to the dizzy. That thing was only to reduce NOx.

    So again, this having an aftermarket carb, did it have this orifice vac spark control or not. I assume not since the dizzy was non vac.

    So, as Billr says, before I muddy up this whole thing, more info from Krazy will be needed.
  21. In this picture, we can easily see the orifice vac control for the distributor. Screenshot (107).png
  22. Ok sorry guys havent been able to get on here. But had a few mins this morning and found apparently i didnt get rid of all esc crap but tried plugging vac lead to esc diaphragm and plugged vac signal to egr and still "flat" but definitely moving in right direction. So now if i unplug vac to esc shouldnt computer go into a default mode?
  23. what dist are you using?
    I ASSUMED it was conventional just a vac and mech advance not ESC controlled? my bad*
    There is an EGR? - and it is now disabled for testing am I correct?

    BUT "falling on its face" has me thinking carb.

    *reading comprehension again..... likely old age
  24. We have rebuilt carb 2x first time was with build of motor, 2nd time was after a serios mudding trip.... When i first got the truck customer had taken 2 bbl intake/carb off and put 4bbl on and lost alot of parts in process. We had to get an egr valve for it and had to drill it into intake manifold.
  25. Sorry phones acting up. But b4 installing egr we had this same "flat spot" or engine bog as some would call it. The first time rebuilding carb i did it myself as its a pretty straight forward carb. But that got us nowhere so i thought "maybe we just couldnt get the gunk out of carb" so this time i took it to another shop that specializes in carbs. And had it vatted and rebuilt again... Same outcome.
  26. I am not questioning the carb rebuild - I think maybe its the carb setup/adjustment.... that is a big carb.

    What is the idle vacuum?
  27. I kinda thought 750 was big but with the mods we would b ok. I got a cheap "spectra"dist. w/vac adv from oreilly helped a little but just likes resting its teeth on the pavement i guess.lol
  28. Emissions tags and vac diag on truck[​IMG][​IMG]
  29. Why would you even do that??
  30. We installed egr trying to kill engine bog to begin with and good ol emission standards . edelbrock said it would work and only dif is their other opt was pre drilled
  31. that stock decal is great but that is no longer the full picture.
    Lets talk about the dist, do you have wiring dia for it, we will need to understand how integrated it is with ESC lean burn or what it was back then.

    The carb 750cfm seams a good choice - just that is a lot of carb to snap open esp with a cam -
    This is a rebadged 'carter' carb so we have to go way back to the old days and memories are fading (for me).
    > A thought - try richening OR leaning - maybe cover secondary's or open a vac leak, see if either improves flat spot- its doing something to address this.

    I suggest you get engine vacuum at idle, and add info on the dist, how many wires, colors, maybe its just a 87 dodge plug in.
    But why mech and vac systems on a computer controlled dist, seams unnecessary if a 'PCM' will be doing timing.
  32. Vac at idle is 17 in. Thats idle set at 1100 rpm bc when put in gear idle drops to 750rpm just above choking out. Dist. Was just 2 wire red/black. I assumed the same that pcm would take over timing regardless of vac adv. But after talking to carb shop he told me to put vac adv dist. To smooth out flat spot, so ot the ok and gave it a shot. And here i sit teeth on floor wishing i had some salt for this pavement. Lol
  33. I will look for wiring diag for esc-dist and get back to you. Thankyou all again!!! I really love the camaraderie here
  34. 17" at idle - What is base timing deg? That is with vac removed from dist.
    did you play with metering rod springs yet?
    Accelerator pump rod location?
  35. Base timing is 10°btdc, havent messed w/ metering rod springs, accelerator pump is on position closest to carb body giving it most throw possible havent tried least throw yet bc middle was worse than most
  36. No doubt this EGR is purely vacuum operated, but is it a single port or two vacuum ports? I still am a bit suspicious of the EGR, and would block the actual EGR flow, not just try to disable it by disconnecting vacuum lines.
  37. That is a big cam for 318. That cam will not start working until about 3K RPM. Auto ? You may need a looser converter or a lower gear ratio for it to preform
  38. Single port egr. But had same symptoms b4 drilling manifold to accept egr[​IMG][​IMG]
  39. LynnM: yes auto (havent messed w/trans at all) but have redone both diffs
  40. Ok got fuel press. And somehow its reading 1 psi if i kink hose or put it in gear, otherwise its reading 0psi at idle.... Gonna change pump. This system should b at 7-9 psi if i remember correctly (please correct me if im wrong)
  41. 5 psi is what I usually look for with a carb; but it isn't real critical, you just need enough to fill the bowl.
  42. Ok now i am getting about 5 psi. But if computer changes timing thru single connector, wont it still fight the vac adv system i put on it(even w/vac disc @ esc)?
  43. Yes, and that's why I feel I can't really help you. You have a bizarre system now, of unknown config.

    I'll ask again... will your emissions requirements allow you to deviate from stock? If not, put it all back stock; the ignition system should be adequate like that. If you can deviate from stock, then there are aftermarket options to get this beast working fine by eliminating the stock ECU.
  44. This truck leaves for colorado tomorrow not sure what their emissions are but would have to assume its pretty comparable to ours. I cant really go "stock" unfortunately it came with a 2bbl factory but cust. put 4bbl on before bringing it to me. I know this is frustrating but seems like its getting close
  45. It is going to remain in CO? The customer really needs to figure out what emissions requirements are going to be. All this work may be a waste of time and money if the new manifold and carb aren't allowed; no matter how well you can get it to run. Same for the ignition stuff.
  46. Well returned the truck today, and gotta say a few tears built up in my eyes[emoji24]. Was hard to see her go but as the saying goes... Love to watch her leave. Customer was thrilled w/performance of truck upon retrieval. Once again i really appreciate the help.... A mind boggler like this is never fun to figure out alone. Im sure we will have a few hang ups w/ emmissions in Co. but when he gets it there we will just have to cross that bridge. Thankyou all again!!!!