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Discussion Starter #1
Put my FE Galaxie on the dyno:
stock rebuild, 8.5 to 1, with headers, dual exhaust, MSD 6, Performer 390 manifold

Holley 600 carb, straight out of the box.
the car runs like a Timex.

the dyno results were...surprising. super, super-duper lean, all the way through the run.
my question: what would you re-jet to?

165783
 

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Better exhaust system, especially headers, always lean out a system. Try jetting, 2 numbers at a time and if Vac Sec, check your spring color strip and try a weaker one. Your sec my not be opening. unless you're seen them open while doing the dyno run. If I read it right, your air/fuel ratio was 12.5 during the run. That's pretty good right there. What do your plugs look like. Try also 2 degs more timing and see what happens.
 

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Discussion Starter #3
i may be reading it wrong. i've interpreted it as off-the-scale (more than 17:1) until just past 2500rpm, where it finally drops down onto the chart.
it dips smoothly until maybe the power valve runs dry, then at 2700 rpm it jumps up to nearly 15:1, and wobbles horribly until finally getting alllllmost to 12.5:1, way up at 4k rpm.
 

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Where did they take the A/F reading from?
Sniffer in the tail pipe, or do you have and O2 sensor somewhere?

At any rate, an exhaust leak, even a tiny one that you can't hear, will seriously mess with the A/F readings.

You could always get one of those A/F gauges and monitor while driving.

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You siad a holley 600. What type of Holley 600? Vac or mech sec? Have you checked the jet number and PV number? I always tear them apart when I get them. Just to make sure every thing is clean inside and tight. What's your timing set at and the plugs look like?
 

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Discussion Starter #6
the A/F reading came from a sniffer in the tailpipe.
vacuum secondary Holley 600. i didn't tear it apart when i got it, was assuming that the insides would be as advertised (dumb).
timing - Duraspark distributor, 12 initial and 36 total, curve slightly better than stock.

A/F gauge...that would be interesting. when i got the exhaust done, i did get a bung put in just after the collector.
time to use it-

it'll take me a bit to get to the plugs, but i'll try to get a photo before too long.
 

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If you're not there to see if the Sec are opening, use a piece of clay down by the Vac lever to see if it makes an empression in it. You'd be surprised how many aren't opening.
 

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Put my FE Galaxie on the dyno:
stock rebuild, 8.5 to 1, with headers, dual exhaust, MSD 6, Performer 390 manifold

Holley 600 carb, straight out of the box.
the car runs like a Timex.

the dyno results were...surprising. super, super-duper lean, all the way through the run.
my question: what would you re-jet to?

View attachment 165783
A 390 with a 600 you got that motor on a diet 600 vac 2nds is way to small for a 390 I would suggest a edle 700 avs you could fatten up the Holley below 3000 rpm but after that it would still be lean on top just my 2 cents
 

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Discussion Starter #11
unfortunately, i'm sure about the 8.5:1.
one of my buddies built it for a pickup truck, but the project fell apart and it ended up in my car instead.

i'd wondered about the size of the carb, but all the CFM calculators say that a 390 running 4500rpm only needs 500 cfm.
(this wouldn't be the first time i've caused myself problems by following the numbers too closely.)
 

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caculations can be done by displacement but I've also seen that they must B adjusted by the actual design - ie some can get closer the that CFM optimal, some less. Mine for instance is very low (70% efficiency) due to the 'log' intake of 4 of the 6 "falcon" ThriftPower or ford i6 motors. X-Flow motors may have the highest #s? Not sure. Been a long time since I saw that all.

2nd - the caculations I'm familure w/give static compression results and must B converted to dynamic for our puroses (C my above ?static v dynamic?) post justa garage rat so don't have my hands on all the material, but am cognizant of the concepts (sorry just a hack, nota expert)...HTH anyway
 

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Personally, until you get that comp up to around 9.5, not much is going to help. Unless you put a blower on it. 8.5 is perfect for that type of setup. It might be worth it just to pull it apart and change the pistons. Get ones that are direct replacement for what you have and move the rings onto the new pistons. Keep them in order of piston and cylinder and they won't know they difference. Not to bad mouth the builder, but you don't know what they did unless you were there to see it. They may have retarded the cam, use old 352 heads or cam. You just don't know. It may not even be a 390 but a 352.
 

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Locate the casting number. The casting number on all Ford FE big-blocks (390) is found on the passenger side of the block near cylinder two, which is the third cylinder from the rear. C7AE-6051-A, for example.

 

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Discussion Starter #15
don't worry about the top part of the dyno chart...that is what it is.
i just want to get the AFR right, so the motor can "be all it can be".

@rickyracer1983 - yeah man, blower/nitrous has always nibbled at the back of my mind...i keep trying to ignore it :)
 
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