Rebuilding a 4.0

sidewaysstarion

Coffee Drinker
NAXJA Member
Chapter BOD
About a year or so ago, I acquired a malfunction stroker, I figured I might as well take you along for the ride on this adventure and provide a guide for those that are new to engine rebuilding and these engines. I'll also try to provide links to any special tools that were used so hopefully you can follow along at home.

Part 1: Assessing the patient

Back in 2017, I was offered a Golen stroker that I was told had issues with pinging. I figured why not roll the dice and see if I could fix it.



First order of business was to pull the head off and see what I bought.



Golen appears to really love allen headed bolts.



Fancy, we have dual valve springs.



I see the previous owner tried some octane booster in an attempt to fix the issue.



We also have some nice sealed power pistons that are .030 oversized and the bores don't look too bad.

In the next part we'll dive deeper into the motor combo and see if I can figure out why it's pinging.
 

RCP Phx

New member
Those are some things that I always wondered about something like a Golen motor.
First aren't they a short rod motor?
Second would be where did they get "rated" allen head bolts?

Those are single springs with a damper spring.

I know you'll make a good build out of it!
 

sidewaysstarion

Coffee Drinker
NAXJA Member
Chapter BOD
Those are some things that I always wondered about something like a Golen motor.
First aren't they a short rod motor?
Second would be where did they get "rated" allen head bolts?

Those are single springs with a damper spring.

I know you'll make a good build out of it!
Yup, It's a short rod motor, but I'll get into that in the next part. :cheers:
As for the headbolts, they looked like they were just an off the shelf machine screw and not really for use as a headbolt.
 

sidewaysstarion

Coffee Drinker
NAXJA Member
Chapter BOD
Continuing from my previous post, Chris and I dug into the Golen's stroker in hopes of figuring out why the previous owner was having pinging issues.

Part 2: Deeper diagnosis

First thing we did was check cam timing, as cam timing can cause cylinder pressure issues which can lead to pinging.



One thing we noticed when we were finding true TDC was the piston sits pretty far in the hole.



After taking note of the cam events we decided to pull the cam and see what it had in it, as the numbers weren't stock.



Looks like we have a comp cams 68-235-4, and pulling up the cam card, it appears the cam was installed right. Damn, Ok let's dig deeper.



Let's CC the combustion chamber, maybe we have too much compression.
CC kit used: http://a.co/d/1hWqM9r with rubbing alcohol and food coloring



So after CCing the head and the chamber and calculating the volume of the head-gasket, we came up with 8.8:1 compression. Not really enough to cause a pinging issue. But the poor quench height could be our cause as the pistons were .030 in the hole.

One thing I did notice, the crankshaft seemed to have an excessive amount of end play...:smsoap:
https://photos.app.goo.gl/F5B8yHezFzx9t4GN8
 

old_man

NAXJA Member
NAXJA Member
I have over 200k on my stroker with H802cp pistons. I am running the stock 4.2L crank and rods. I decked the block around .020 IIRC to bring the quench height down to around .050" which helps with ping. I run pump gas with no ping.

My thoughts are that somehow the timing must have been off, the injectors were not flowing enough (MAP adjuster/O2?), or there was a vacuum leak.
 

sidewaysstarion

Coffee Drinker
NAXJA Member
Chapter BOD
I have over 200k on my stroker with H802cp pistons. I am running the stock 4.2L crank and rods. I decked the block around .020 IIRC to bring the quench height down to around .050" which helps with ping. I run pump gas with no ping.

My thoughts are that somehow the timing must have been off, the injectors were not flowing enough (MAP adjuster/O2?), or there was a vacuum leak.
I lost my notes with the exact measurements, but we were around 0.85 quench height :gee:
 

old_man

NAXJA Member
NAXJA Member
I lost my notes with the exact measurements, but we were around 0.85 quench height :gee:
You mean .085" right?

Adjusting the quench height REALLY makes a difference. I also run the thin metal Mopar performance head gasket. IIRC it was around .038"

I run the absolutely cheapest gas I can find with no issues. Heck, I even run E85 every once in a while, but I can dial the mixture. With a stroker where you are playing with all the variables, I highly recommend an AFR gauge. I built a custom MAP adjuster and routinely dial the mixture when I am towing on the highway or pulling long mountain passes to optimize power without overheating.
 

sidewaysstarion

Coffee Drinker
NAXJA Member
Chapter BOD
Great, so I guess we're pulling it all the way down and going from there.

Part 4: Figuring out the plan

Now that it was all torn down, what we ended up with was a stroker motor with a bad crank, pistons that are sitting too deep in the hole and a great low end torque cam. Which is a great combo for pinging on premium and having lack luster performance. So I figured let's take the stroker road that is not often traveled, let's build a performance-ish motor on a somewhat budget and see what happens.



After getting it all torn down, the block was really clean on the inside, the bores looked good. so we can save some money by not having to pay for machine work on the block. Ok, let's build this motor around a cam, I cracked open the Lunati catalog and picked one of the more aggressive cams. Here's the cam card of what I picked.

 

sidewaysstarion

Coffee Drinker
NAXJA Member
Chapter BOD
You mean .085" right?

Adjusting the quench height REALLY makes a difference. I also run the thin metal Mopar performance head gasket. IIRC it was around .038"

I run the absolutely cheapest gas I can find with no issues. Heck, I even run E85 every once in a while, but I can dial the mixture. With a stroker where you are playing with all the variables, I highly recommend an AFR gauge. I built a custom MAP adjuster and routinely dial the mixture when I am towing on the highway or pulling long mountain passes to optimize power without overheating.
Yup, typo on my part, if it was .85 in the hole I dont think it would run lol.
 

RCP Phx

New member
The H802CP piston comes up about .035" short of the deck by my math, but with that low of CR I can't image that causing any "pinging".
 

sidewaysstarion

Coffee Drinker
NAXJA Member
Chapter BOD
Part 5: Starting with a clean slate/Ordering parts

After pulling the motor down, on further inspection the one of the cam bearings was trashed, but surprisingly the cam journal where that bearing is was not harmed at all, which makes me think when this motor was built they reused the cam bearings. Anyways, off to the machine shop the block went for new cam bearings. Thankfully I had them swap out the cam bearings as they found two were in the wrong places and the reason the one was damaged was because it was improperly installed partially blocking the oil hole.

Now that I had the block back from the machine shop, I decided we should get some pistons and rods on the way, which means I need to measure the bore and the deck height.



Tool used: http://a.co/d/a05f3AA

The way you measure for bore is to use a caliper and measure the bore. In my case it was 3.905 bore (.030 oversized).

The way you measure deck height is to measure from the top of the bearing saddle to the top of the deck, then you measure the side of the bearing with the cap installed, divide that number in half and add it to the first measurement you got. In my case I got 8.101 from the top of the bearing to the deck, the bearings are 2.692, so 8.101 plus 1.346 = 9.447 or pretty much a stock deck height.

In the meantime I had found a Scat stroker crank on ebay at an unbeatable deal from Clegg engines that had been cut 10 under on the mains. I emailed back and fourth and ordered all of the parts and gaskets to rebuild the engine minus the rods, pistons and rings. I also ordered a Felpro 26211pt MLS head gasket. The kit I got from Clegg has a melling high volume oil pump, clevite bearings and a felpro gasket set.

The only thing left on the list was to give Russ Pottenger a call and get a set of pistons and rods from him. I ended up picking his 10.5:1 compression forged pistons and rods, and with the deck height I had it nets me a 0.015 protrusion of the piston from the deck to help with quench.
 
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