420A 420A engine rebuild

[DSMTIM@G]

Hey man I'm new to dsm and engine rebuilding in general I want to rebuild the spare 420A engine I have but I'm not sure where I should start for example I know I'm going to need a tune after to rebuild does that mean I need a stand alone or can I used the stock pcm also where should I go to look for parts I'm not trying to go completely stock rebuild but I want to get parts that work together so If anyone has rebuilt a 420A before and have any useful info it would be much appreciated also what is a round estimate for rebuild a 420A

 

[BLACK'98DSM]

That's kind of a broad topic and answers will vary. Whether you need a tune or not will depend on how you rebuild it. Mostly stock wouldn't need one. But turbo or drastically changing airflow characteristics/geometry would need one. The stock ECU is not simply tunable so you'll need a standalone like MS3. And the cost of your rebuild will vary largely based on what kind of parts you use.

So what are your plans/goals for the car?

 

[DSMTIM@G]

well my goals slash plans well not to smartest are somewhat reliable and fun I want to add some power but not to much that I have to get a stand alone I plan to stay on top of maintenance one the engine is rebuilt

I pretty Much am looking for it to
Sound Good
Run decent/well I understand its a DSM and a 420A
have some power for now

 

[BLACK'98DSM]

So just basic bolt ons? You won't have to change much internally for that. And won't NEED it to be tuned, but even tuning a stock 420a there is room for improvement.

Or are you trying to go deeper with things like high compression pistons, cams, etc? JE Pistons & Wiseco are the 2 most popular brands for pistons. Crane, Crower, and Brian Crower all made cams for the 420a at one point but all have been discontinued besides the turbo grinds from Crower. You can still buy used sets that float around on Ebay or find some new old stock and pay out of the ass for them. I personally am using Crower Stage 2 NA cams and I love them, but I got my hands on them right before discontinuation so good luck with that. With cams you'll want some springs too. Which will be especially helpful if you decide to utilize your MS for a higher rev limiter like I did. I'm using a Brian Crower valvetrain kit that included springs and titanium retainers. While you're working with the head get it ported & polished as well as shaved. Oversized valves are nice too. But I won't continue much more from here without asking what your budget is. Because I've already covered thousands in parts alone.

 

[DSMTIM@G]

yes I have been seeing Brian crower parts online especially the camshafts and yes I was thinking about rebuild the whole engine from pistons to camshafts don't really have a budget this is kinda something I'm doing over time so with that being said if I was to get new pistons,cams or crankshaft would it need a tune

 

[BLACK'98DSM]

If you raise the compression ratio and change valve timing then you will definitely want it to be tunable. Take the crankshaft off your parts list though. The stock crank can handle much more power than you'll ever make N/A.

 

[DSMTIM@G]

ok so other than the crank what should I look into getting New pistons ,valve springs, cams cam gears?

 

[DrewmHolland]

the stock valve springs are pretty good, iv'e heard they wont float valves until about 8k rpm's but you should probably look into getting some Pt cruiser rockers because they tend to just be stronger

 

[DrewmHolland]

for cams crower stage 2's are perfect for a street build and I would go with those, plus they just sound amazing. also if you're looking to make power then boost is the way to go, an N/A will never make good low end torque and just be sluggish until you're up into the power band where you could look to make 190-200hp at best

 

[BLACK'98DSM]

the stock valve springs are pretty good, iv'e heard they wont float valves until about 8k rpm's but you should probably look into getting some Pt cruiser rockers because they tend to just be stronger

That's not very accurate. Valve float starting occurring right around 7400 rpms for me. And that was with the stock camshafts. Installing cams with higher lift made them start floating at 6800.

And the rocker arms you're looking for are from most Chrysler 2.4L engines of the era.

 

[DSMTIM@G]

the stock valve springs are pretty good, iv'e heard they wont float valves until about 8k rpm's but you should probably look into getting some Pt cruiser rockers because they tend to just be stronger

alright and what does floating mean again?

 

[DSMTIM@G]

also what are rockers and would anyone know what i could possibly get brain cam or a good place to engine parts for 2Gs in general

 

[BLACK'98DSM]

alright and what does floating mean again?

"Valve float" is used to describe the condition when the valves are not closing fully. Which is due to the springs not being stiff enough to close the valves at a high rpm with such small allotted time.

also what are rockers and would anyone know what i could possibly get brain cam or a good place to engine parts for 2Gs in general

Rocker arms are the parts that the camshaft lobes ride on. They "rock" back and forth to open the valves essentially. The reason we suggest 2.4 rocker arms is because of their better design. They have slightly larger holes in them. Which is a good thing because the lifters squirt oil through these holes, which allows better lubrication for your camshafts.

As I stated previously, the Brian Crower camshafts have been discontinued for the 420a. You can still find some used or new old stock but you have to search the web thoroughly. The part number for their stage 2 N/A grind is BC0167.

Also. Since you have so many questions, are you rebuilding this engine yourself? I'm just curious because at a time in my life when I didn't know what a rocker arm was, I would probably have made mistakes with fully reassembling an engine. Which would be catastrophic for you after putting rare parts and cash into it. Just a thought.

 

[Canadian_CD9A]

The 2.4/PT rocker isn't much of an improvement over the 2.0 rocker, I'd skip those. The Chrysler 2.7L rocker is the best, as it directs oil to the proper location. Find a set of 16 from Chrysler 2.7Ls in a junkyard - take rockers that don't have any scoring on the roller. The 2.4/PT lifter is an upgrade over the stock 2.0 lifter too - it has a larger orifice to improve oil flow. I bought a set of EngineTech L2278s for those.

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I'll eventually be selling my well-ported 420A head and a pair of used BC0167 cams. BC discontinued their whole valvetrain line for the 420A/ECC engine, so they might be hard to find in stock anywhere. My ported head has BC valves and BC springs/retainers, but I might use those in a Neon head. The 420A head would come with a near-new set of 2.0L rockers & lifters. The BC0167s will run on a stock engine but they'll run quite rich at idle since they reduce vacuum; the ECU can't really compensate for that, so you'll need a S-AFC to pull fuel. Upgraded valve springs are mandatory for any upgraded cams, in my opinion (they're only $90 anyway). Stock valves are a known failure point since they're 3-piece units, so don't go doing any heavy racing on them.

A quick and dirty upgrade setup for a 160-170 WHP Neon that revs to 7,600 RPM is the following:
-Deck the head 0.030" to give roughly 10.2:1 compression
-Mild head porting with a grinder
-Cam upgrade to something reasonable (BC S2, Crower S2, Crane 16, etc).
-Adjustable cam gears if you want to get everything out of the setup
-Crower valve springs on stock retainers
-PT Cruiser lifters
-2.7L rockers
-Header upgrade
-Improved muffler
-Cold air intake
-Intake manifold porting with a grinder [not sure what people do for 420A]
-52mm throttle body from an automatic transmission Neon [not sure if this works with 420A]
-Mopar ECU [no equivalent for 420A]
-Underdrive pulley
-Crankshaft oil scraper [not essential but they're cheap and help with oiling and free up some power]
-A'Pexi S-AFC

No need to touch the bottom end if it's in good condition. The stock pistons and rods are fine for mild power levels, but you might want to change the rod bolts out for ARPs.
If you have an automatic transmission car, don't even bother modifying it, they are limited to 6,500 RPM shifts. Since 420As have no ECU option like the Neons have, you'll be limited to the stock rev limiter (around 7,200 RPM) and you'll be leaving some power on the table with low ignition timing. Even a manual transmission version 420A has a low ceiling on power unless you're willing to go standalone, so I wouldn't dump too much money into modifying one on the stock ECU.

 

[BLACK'98DSM]

Unfortunately the Neon throttle bodies are completely different than the 420a and could not be used. Getting a 60mm Jeep throttle body is the best option. They use the same sensors and will bolt up to the intake manifold nicely after you slightly stretch the bolt holes. The throttle shaft from the original TB also needs to be swapped due to different throttle cable design.

The best we can do with our intake manifolds is to bore the plenum to match a larger throttle body and to gasket match the ports on the lower runners (works best if head is also gasket matched). Extrude honing is the other option but so far I don't think anyone has done that. I would like to though.

 

[Canadian_CD9A]

Extrude honing is expensive. Porting a Neon intake manifold is really labor-intensive, but a determined DIYer can do it. AMM (All Motor Mike) does make fabricated pieces, but again, likely a waste of money on a stock ECU.

https://www.angelfire.com/space/neon/porting.html

 

[DSMTIM@G]

To answer the previous question yes I will be rebuilding it myself it will be the first engine I rebuild and I wanted to just get a run around for what I might deal and start to price parts and see what I could do with should I stick with stock crank if its not damaged also would changing the pistons required standalone