4.2 Is Alive. Tuning Time!

Kevin Keenan

Registered User
Hi everyone,

Well the 4.2L is in and running. It runs really smooth and sounds great. Now it's up to tuning to do the rest. I'm getting lots of detonation right now, which seems to be a product of the difference in compression ratios between the 3.8L and 4.2L. We're going to try and tune out the ping by adjusting the timing tables using my EEC tuner and will let you know how it goes.

The timing pickup bracket we made is holding and working fine.
 

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Polishing

Oh and for you polished fans, here's a pic of the engine in the bay.
 

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4.2L?

Is it a different engine or just a stroked version of the 3.8L??? I never thought that the 3.8L could run smoothly, so I'm pretty suprised that it worked out well for you.
 
RE: Stroked Engine

It's not a stroker kit for a 3.8L. It's a 4.2L bottom end from a 97 F150 with all the SC stuff on it.
 
RE: Crank

It's a cast steel crank, not forged. As I don't have the money needed to do my desired 3.8L rebuild, this 4.2 bottom end fell into my lap for free. Bent rod from a blown head gasket. Had the block cleaned and prepped. Got it back and put a new rod and piston in it, new rings, seals, main and rod bearings, and seals.

I know that the crank is a weak link, and this is why I wanted to try this experiment. Lots of people have stroked their 3.8L's but I've heard very little if any about using 4.2 bottom end with SC components. There was some talk on the Ford Truck Performance site (specifically F-150) of this but I wasn't able to find any info about anyone that had tried it already.

My basic goal is to test the longevity of a 4.2 bottom end stroker SC. Using a 4.2 bottom end might be an alternative to Using a stroker kit. I thought (this is strictly opinion; and NOT fact) maybe the that if you machine the 4.2 crank to fit the 3.8 block, that might make it structurally weaker? If the crank is acting as it was intended in the bottom end that it was designed for, could it maybe be stronger? I could be right, I could be just very well wrong, but if no-one tries it, no-one will ever know. :)

Kev
 

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That's cool! Sorry... had to share ;-)

I'll have to think about doing that if my block ends up being cracked...

Paul
 
Cracked block? How would one do that short of throwing a rod through it. Or blocks are solid, must have just as much metal in it as a small block because that damn thing is heavy.
 
RE: Cracked Block

I'll say this,

Aaron is right, the SC block is tough. When I initially rebuilt the motor at 168K the cylinder walls looked hardly scored at all.
 
What...

Question, does the 4.2L have the balance shaft? Is that why it is running smoother?

I know later N/A 3.8's had the balance shaft, but the SC eliminated it in favor of a thicker (and stronger) block casting.

Do you think that the 4.2's block can stand up to the stress?

What is the stock output of the 4.2? I dunno. What SC' goodies are you going to try to run and what is the CR of the 4.2 block?

I've always thought that a 3.8 with 9:1 CR would work good with around 10 psi of well intercooled boost. It would be very powerful but also more efficient at part throttle, non-boosted conditions.
 
bro, you did a beutiful job with the polishing! did you do it all yourself? it really looks awesome. i'm impressed. very nice job.
i lost my engine to detonation this past weekend. i'm looking at the stroker 4.2 kit from morana. it should be done next month or sooner.
joe
 
that is sweet wish i had one hope you get it fine tuned ok it will rip i know my 3.8 does
 
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Link..........!

Just a link to this string, I'm curious about this project, why not lower the boost pressure until it runs in, then add a little at a time, until w.o.t., I did this when I ran my Triumph RS up to 170. Will do the same with my SC. easy does it. cheers and best of luck, Frank H. aka White Lightning.
 
I wonder...

I wonder whatever happened to this project since it was posted over 2 years ago...

Did the S/C ever break the 4.2L cast crankshaft? I guess we'll never know...
 
I have posted on a few threads of guys that were running the 4.2 and never got any feedback either. I was wondering about the strength of the thing too.

Chris
 
Aacccckkkkkkkk............!

This is driving me nuts, as I can get a very low mileage 4.2 CHEAP!!!! I have a nephew, that was a FORD tech, during that engines time, I will call him and see what he thinks of a project like this, whether he thinks the crank is strong enough for a S/C or not. We need to know what that crank is made of. and how well all the ancillary parts bolt up to it. I'll ring him a get back to the forum on it. The last thing we need to do is what these guys with the Stang 6's are doing, I saw one the other day that tried it and the whole bottom end of that v6, looked like that engine the Dodge boys tried putting the NOS inside of, heheheeh! remember that one???? Cheers, and don't forget what day it is, I was up in Canada on this day, and those people were crying for us, and p*ssed off at the same time! safe journeys, Frank H.
 
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