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Discussion Starter · #1 ·
As some may know, I installed a set of gt-40 heads in my 1988 f150 302. It just seems I should be getting a little more power than what I am getting right meow. I had the timing set at 10º and put in new autolite "platinum" sparkplugs that I gapped at .040. The cap, rotor and wires are fairly new so i'd like to wait in the sixlitre upgrade, but I am wondering if I should be gapping a little more, and advancing a little more? I am finding with the upgrade, gapping is up to .055-.06 which is making me wonder if I can cheat with the stock setup.


Also, when I first start driving it, I get some hesitation, like it bogs down and then all of a sudden I get full power. My mechanic ran his scanner and it gave the EGR code, could this be the culprit?

-Josh
 

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When I put gt40's on my 93 351w I had the same problem. Although mine felt as if it never received full power. I started to dig deeper and tried replacing the tps and fuel filter but it ended up being I was only running on 6 cylinders. And then it started knocking shortly after. Now I'm using the same heads and building a 357w. Almost done now.
 

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If those heads have the same chamber size as stock, and you still have the stock cam, I would bump the timing up a little more. All the SBF I have worked with seem to love advance! Also I never had a small block that liked any other plug then the normal copper Autolites. Seemed like anything else I ran, just ran bad. As for the gap, I would ait till you replace the coil. I would not increase it to much on a stock coil.
 

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:stupid

You can probably open the gap a little bit, as my stock underhood sticker said a gap of .052-.056, and when I put the more powerful coil in, I went up to .062.


Never heard of the platinum plugs but you'd be fine with some autolite coppers.
Are you serious?
 

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Practicing Infidel
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If those heads have the same chamber size as stock, and you still have the stock cam, I would bump the timing up a little more. All the SBF I have worked with seem to love advance!

Also I never had a small block that liked any other plug then the normal copper Autolites. Seemed like anything else I ran, just ran bad. As for the gap, I would ait till you replace the coil. I would not increase it to much on a stock coil.
:stupid

Whole heartedly !

Josh, if you take one thing away from the so called "Sixlitre tune up", take away the fact that for every guy here who "gets away with" using platinums........... I can show you ten who've had endless troubles with em'(kinda like your bog;)).

A bog or misfire or stumbling, on the Sixlitre tune up, is usually either platinums or p!$$ poor plug wires or old cap & rotor.

Like s1120 is saying, spend the 99 cents each and get the low line Autolite Coppers. Can't give you a scientific reason why they work better, they just do.

Millions of 5.0 litre Mustang owners ain't wrong. Many of them can afford anything they want to use and yet they still go with Coppers or lowest line Motorcrafts.

I also concur with my esteemed colleague on his advice for advance and at least a .055 plug gap. Since you're no longer stock you may need more or less than 13.5 degrees (over the stock 10 degrees),

I'd keep advancing, 2 degrees at a time, until you run into ping or the intake manifold vacuum readings stop improving or drop off.

A vacuum gauge doesn't care if your motor is stock or not. It tells you how you're doing at idle in regards to intake manifold vacuum and you can't fool it.

An old and cheap tool that is still very effective IMHO. I also recommend getting one for your A-pillar gauge pod too;) They help incredibly with mileage and diagnosing problems.

Sixlitre
 

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Discussion Starter · #8 ·
Thanks guys.

I bought the platinums because the manager at Auto Value said a lot of guys are running them, and like them, but he must of had chevys on his mind.

I'm on my way to the store to pick up some autolite coppers and possibly just buy a timing light

-Josh
 

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Josh which manager? Jason? Probably not because I had a conversation with him about the coppers being better. Figured if it was him he'd say something.
 

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Discussion Starter · #10 ·
Yeah it was jason. I told him I wanted autolites and he said he had (must have been the coppers) or the platinums, which a lot of people like and are turning to. The ones I bought from him were for a stock heads, not gt-40, so when I return them, i'll ask him about it.
 

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Discussion Starter · #11 ·
I changed to Motocraft Coppers as they did not have the autolite coppers, gapped them to .055 and set the timing at 12.5 until I pick up a vacuum gauge and really tweak it then. This quick fix did help a lot, but I still can't wait to swap in some decent gears

All the platinums looked like they were burning fine, still gapped at .044.

Since I bought the timing light, my dad and I checked his 91 f150 302 and he was at 2 º. :doh0715: Thats right, 2º. Our "ex" mechanic must have set it after he replaced him intake gasket. I would have thought either he or I would have heard or felt something, but it really wasn't noticeable. Maybe now he'll get more than 10 mpg:toothless
 

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When I tuned up my 93 E150 fan a hand full of years ago, I found the same. 3 deg!!!!!!!! I bumped it up to 10deg and it ran AWSOME!!!!!!!! Im hoping to sell the thing, so have not done any more to it, to see how more timing would help.
 

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I changed to Motocraft Coppers as they did not have the autolite coppers, gapped them to .055 and set the timing at 12.5

This quick fix did help a lot

Maybe now he'll get more than 10 mpg:toothless
Josh

Now it's your turn to tell people that platinums don't work as well as plain coppers. Save the rest of us from carpel:beer

Sixlitre
 

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Discussion Starter · #14 ·
I am still having some minor issues. It still does the occasional"bog" or when I am accelerating, I have to press more gas in order for it to "kick in"

Also, I am getting some pinging while at idol at stop lights. Most of the times it comes and goes. Sounds like a machine gun, almost as if its not getting gas. It no longer idols erratically when that happens(did before I replaced fuel components) I was thinking it was the sending unit or something along the line of gas flow, so I put in a new tank, sending unit and pump, along with the filter and it still does it. Doesnt seem as bad though. I have replaced my fuel pressure regulator, but its been 20,000 or so. I also replaced my cap, rotor and wires. Plugs are gapped at .052 and timing at around 13.


fix me!
 

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perhaps your cat converter is starting to fail. my 88 had a weird ping at low rpms and was discovered that the converter was going bad.
 
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