Author Topic: 427 popping through the carburetors during acceleration and no power above 3500  (Read 3559 times)

0 Members and 1 Guest are viewing this topic.

66FAIRLANE

  • Hero Member
  • *****
  • Posts: 558
  • Andy
    • View Profile
Have you verified true TDC on the balancer?

e philpott

  • Hero Member
  • *****
  • Posts: 920
    • View Profile
Cam wiping out ?

My427stang

  • Hero Member
  • *****
  • Posts: 3918
    • View Profile
Here is what I would do

1 - Triple check firing order - even the best of us cross a wire now and then.  Changing timing can make a crossed wire or wires run better-ish
2 - Verify TDC - could be a slipped balancer or mismatched pointer/balancer - Seems likely due to advancing the timing helping. Your 26 could be really zero but indicated wrong.  Piston stop is really the only accurate way, but bringing it to TDC with a dowel, etc, and verifying that both #1 valves are closed can show gross mismatch of marks (although a stop is the way to do it)
3 - Put a light on it and see if timing hops around when it misfires
4 - Take a compression test, look for differences cylinder to cylinder.  Doesn't seem that way to me, but need to eliminate a tight or bad valve.
5 - Check to see if any of the rockers aren't moving much, could intake a wiped cam





---------------------------------
Ross
Bullock's Power Service, LLC
- 70 Fastback Mustang, 489 cid FE, Victor, SEFI, Erson SFT cam, TKO-600 5 speed, 4.11 9 inch.
- 71 F100 shortbed 4x4, 461 cid FE, headers, Victor Pro-flo EFI, Comp Custom HFT cam, 3.50 9 inch

Robin Hood

  • Newbie
  • *
  • Posts: 24
    • View Profile
    • Acme Tackle Company
I will check TDC on Friday when I return to where my cars. Thank you both for suggesting it!
I will go through the firing order as well to make sure it is correct.
I did set the valve lash at .028 when the engine was cold because the local speed shop set them at .020 cold and from what i was reading online at the time it was mentioned that .028 was the best cold setting for the valves,
When I adjusted the valves it seamed as though all the rockers were moving well but I will recheck this weekend, along with the valve lash to make sure I did not make one to tight or to loose.
Is .028 a good cold lash for my valves?


My427stang

  • Hero Member
  • *****
  • Posts: 3918
    • View Profile
I woud consider .028 to be on the loosest side of good I would want, but it is good if done on the base circle correctly as it makes no doubt you don't have a valve too tight.

Valve lash is generally better to be slightly tight over loose to ensure it uses the lash ramp and doesn't slam at the end of it, but .028 with a 1.76 rocker should be fine.  I run many down to even .012-.014 with alum heads, iron block, you just can't have zero
---------------------------------
Ross
Bullock's Power Service, LLC
- 70 Fastback Mustang, 489 cid FE, Victor, SEFI, Erson SFT cam, TKO-600 5 speed, 4.11 9 inch.
- 71 F100 shortbed 4x4, 461 cid FE, headers, Victor Pro-flo EFI, Comp Custom HFT cam, 3.50 9 inch

Robin Hood

  • Newbie
  • *
  • Posts: 24
    • View Profile
    • Acme Tackle Company
I will recheck to be sure what they are at currently. Thanks for your advice, I appreciate it.

machoneman

  • Hero Member
  • *****
  • Posts: 3846
    • View Profile
Also, be sure #7 and #8 plug wires do not run parallel. Route them to cross at say 90 degrees and keep them well apart to prevent spark jump.
Bob Maag

My427stang

  • Hero Member
  • *****
  • Posts: 3918
    • View Profile
I will check TDC on Friday when I return to where my cars. Thank you both for suggesting it!


I don't want you to assume I think you don't know, but have seen some odd techniques, so offering one good, one sort of emergency room trauma that might send you back to the good one

1 - Best way is to use a piston stop, thread it in the plug hole, turn the engine with a wrench until it hits, mark the balancer at the timing mark.  Turn it the opposite direction until it hits again, mark the balancer.  Absolute true TDC will be exactly the middle when measured between those two points

2 - Battlefield check - plug out, bump the starter until you get very light pressure on your finger.  Slowly by hand, with a dowel or some other tool, have a buddy turn the motor by hand, same direction (clockwise from the front) and watch/feel the dowel raise.  When you feel it ever so slightly drop, go back to highest point  NOT exact, but it would show if your balancer ring slipped by a large amount or you had the wrong balancer/pointer combo

If that were the case, then you can get a piston stop.  If the balancer slipped you can get a new one, if the timing pointer doesn't match, you can remark your timing marks

The good thing is when you do this and check the firing order, 2 troubleshooting steps are done and behind you.  Best way to eat that elephant
---------------------------------
Ross
Bullock's Power Service, LLC
- 70 Fastback Mustang, 489 cid FE, Victor, SEFI, Erson SFT cam, TKO-600 5 speed, 4.11 9 inch.
- 71 F100 shortbed 4x4, 461 cid FE, headers, Victor Pro-flo EFI, Comp Custom HFT cam, 3.50 9 inch

SMA390

  • Jr. Member
  • **
  • Posts: 33
    • View Profile
What type of distributor ? Is it points or Msd...  I had the same problem once and turned out the magnetic pick up on the MSD dizzy was bad so I replaced the magnetic pick up. And I  installed it incorrectly, I had it in upside down, the car had the exact symptoms you described, Pulled it and installed it correctly and ran good then.

Falcon67

  • Hero Member
  • *****
  • Posts: 2151
    • View Profile
    • Kelly's Hot Rod Page
Mag pickup wired with wrong polarity will cause all kinds f weird issues, especially when hooked to a good MSD box.  But I don't think OP has that setup.  All the above is good stuff to look into.  When you said your set the timing back to 26 initial and it ran better, that was a big red flag that timing, balance, timing chain, firing order, ignition trigger setup - something could be contributing to the problem. 

Robin Hood

  • Newbie
  • *
  • Posts: 24
    • View Profile
    • Acme Tackle Company
This forum is the best! I am printing all of these suggestions out and will go through them one by one to eliminate any of these possibilities.
I am a new 427 owner but i have owned a lot of small block stuff and newer modular stuff.
I havent worked on engines/cars since my father passed in the mid 90's so my knowledge is limited in actual execution but not from an understanding point. But please assume i'm an idiot as I tend to render things down to its simplest form of understanding:)
I have not heard of the dowel method for finding TDC but i understand the concept.
As for the distributor, when I removed the cap there was only an electronic module inside no points. I was expecting points and I know how to adjust them from years back but i have not worked with this system, thank you for the advise on how to check that out I will for sure Friday.
Thanks to everyone for sharing your knowledge i prefer to fix this on my own if possible as I feel like i have the ability but obviously all of your help is definitley going to give me the best shot. I dont want to have to ship the car to someone or remove the engine and send it to a professional if I can avoid that.
Also, I will report back on each suggestion and what if any impact it had on diagnosing/performance so everyone knows.
thanks again
« Last Edit: August 24, 2022, 12:40:54 PM by Robin Hood »

My427stang

  • Hero Member
  • *****
  • Posts: 3918
    • View Profile
Awesome, looking forward to your response

If you could, take a picture of the ignition module.  I had the same thing happen with a Pertronix 3 on the dyno.  Had us scratching our heads. We slipped a set of points in and made 608 HP instantly...I am not one for parts swapping, but after you check the foundational stuff, we'll all keep going
---------------------------------
Ross
Bullock's Power Service, LLC
- 70 Fastback Mustang, 489 cid FE, Victor, SEFI, Erson SFT cam, TKO-600 5 speed, 4.11 9 inch.
- 71 F100 shortbed 4x4, 461 cid FE, headers, Victor Pro-flo EFI, Comp Custom HFT cam, 3.50 9 inch

sixty9cobra

  • Sr. Member
  • ****
  • Posts: 274
    • View Profile
How old are the valve springs?

oldiron.fe

  • Jr. Member
  • **
  • Posts: 83
    • View Profile
           all of above- if this is a older build make SURE the fuel system is cleaned /flushed very good !!  at that comp. ratio i would use my favorite snoco 112 while getting the tune right --also if spring pressure wasnt released on long storage you need to be sure of spring pressure-good luck john  ---                                      old iron                         
66' Fairlanes 427 (08/26/67- present)
66/67' Fairlanes
70' Mustang Fastback
66' Dually

Falcon67

  • Hero Member
  • *****
  • Posts: 2151
    • View Profile
    • Kelly's Hot Rod Page
>As for the distributor, when I removed the cap there was only an electronic module inside no points.

As above - Identify / post a picture of the module in the distributor.  If the output it connected to a control box, then also a picture or some identification/mfg/model/etc will help us help you some more.