01 GA 3400 Rebuild Again

[john_V63400]

OK, so I blew my far right #4 piston again. I scored the cylinder. I was originally going to just throw a stock used 3400 in and leave out all the performance parts. but then it hit me.

Re bore another .020 to make a total of .040 over on my block.
From what I understand is that I can go .060 over before I start having problems right.

I going to reordered some forged pistons from Arias pistons with a .020 larger bore size.
$780 bucks (piston+Rings) no pins. I already have some.

Still debating weather to leave my RSM S/C out of the mix. But if I put it back on the MAF is definitely going back in.

heres what my ideal engine is so far. I have all this but the .040 bore

01 GA GT S/C RSM setup
Milzy stage 1 boost cam
RSM 62mm TB
Ported & polished upper plenum
Comp Cams valve springs
Milzy performance push Rods
RSM S/C kit 8 pounds
Stock spark plugs (should they be colder??????
Stock Fuel pump
Stock injectors
Stock heads
High volume oil pump
And yes Im putting the MAF back in


So other than than that do you guys see any problem areas I should address for a more performance reliable engine. Thanks a million

[onefastV6]

I say put the supercharger back on, put the MAF back in. I would also consider getting larger injectors as the stockers are pretty much going to be maxed out.

Then get a tuner and put the spark table to that of a GTP Grand Prix and work with the PE. The stock spark tables in the grand am with improper fueling, and you are just asking to blow another engine.

Also if you are not going to put the supercharger back on, I wouldn't waste the money on forged pistons.

[SappySE107]

Check your pushrods lengths. Stock might not be the way to go.

[john_V63400]

What PE in what u were saying. Im pretty much set on keeping my S/C kit on (sorry matt) but should i go colder plugs. And im going to order those 36# injectors from milzy

[mfuller]

What PE in what u were saying. Im pretty much set on keeping my S/C kit on (sorry matt) but should i go colder plugs. And im going to order those 36# injectors from milzy

PE = the power enrichment table. Get yourself a DHP PowerTunr and read the manual along with the DHP forum, scan and scan again, make 1 change, then scan again. Might want to go 1 step colder on the plugs but scan first, pull your plugs and learn how to read them. Easier to get 28# injectors from a 4.2L Trailblazer I-6 (they drop right in with no modifications, and it's a smaller change in flow rate so tuning will be a tad easier).
Lather, rinse, repeat. And no worries about the kit.

[john_V63400]

oh I get

[john_V63400]

what year do i order those injetors for that trailblazer

So Im going to order stock injectors from a 4.2 l tral blazer, and they drop right in, no problems.

What year on that blazer so I can order those

[mfuller]

I don't know what year off the top of my head, but there's only been one generation of the Trailblazer so far, an I pretty sure GM only has 1 domestic 4.2L DOHC inline 6 engine, so go with that.

[john_V63400]

What else should I get with my setup


this is what I got so far

MAF sensor
28# injectors from a trailblazor
DHP power tuner

What else.

[john_V63400]

If i buy some injectors from a 2002 trailblazer 4.2 lit. Engine
Your telling me they fit right in no mods what so ever, they just slide right in,

Point being, I found some on Ebay, so Im going to buy them if thats the case some please confirm thanks

[SappySE107]

If you have the multec 2 injectors, then yes. I think you have an 03 so the answer is yes, they will work. I have a set of connectors here from a newer 3400 and I am using those same injectors.

[mfuller]

His car is an '01, which used multec 2's, so they work without any modification whatsoever (unlike the 36#ers Milzy sells).

[AaronGTR]

Yes, the injectors will work with no modifications. All the injectors from any years 4.2l inline six (trailblazer and envoy), they are all the same (28lb/hr). You might have to switch over the O-rings on the ends from your stock injectors as the 28#'s might have thicker O-rings on them, but thats no big deal.

Those would definitely be a good deal to get from ebay. They have a stock spray pattern for a good idle and will be easy to dial in. They won't have as much head room as 36# or 42# injectors, but you won't have to change the wiring harness and they'll be cheaper.

It's better than nothing. Frankly I'm not surprised at all that your motor blew up using stock injectors and no maf after we all told you to put it back in. Oh well, after this rebuild since your doing it the right way you should have a potent setup when you're done! And yes, I think you shouldn't have any problems boring out the block one more time to clean up the cylinder walls.

[john_V63400]

yeah me either, should I stay at .040 over or should I go bigger

[AaronGTR]

I'd think .040 should be fine as long as it doesn't take more than that to clean up the cylinder wall. Get the block cleaned up before you order the pistons obviously. Oh yeah, I definitely think you should also get spark plugs one range colder, and switch to iridium or copper tips.