New 4.2L mini-stroker recipes

Newbies, and basic Stroker Recipes... Get started with your first stroker here!!
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Re: New 4.2L mini-stroker recipes

Post by Cheromaniac »

Russ Pottenger wrote: June 2nd, 2019, 1:26 pmI believe that is what Josh is running and it’ll up his static compression ratio calculations more in line what he’s looking for
Yup. I make it 9.50:1.
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Re: New 4.2L mini-stroker recipes

Post by jpradcliffe »

Not Silvolite. 677AP +.030. 15cc dish. Hadn't know those had a larger dish when I ordered them. Oh well. I'm thinking that the low 9 compression is ok considering could always play with a small amount of boost, provided I don't float a valve lol.
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Re: New 4.2L mini-stroker recipes

Post by jpradcliffe »

:deadhorse:
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Re: New 4.2L mini-stroker recipes

Post by Cheromaniac »

jpradcliffe wrote: June 3rd, 2019, 8:32 pm Not Silvolite. 677AP +.030. 15cc dish. Hadn't know those had a larger dish when I ordered them. Oh well. I'm thinking that the low 9 compression is ok considering could always play with a small amount of boost, provided I don't float a valve lol.
It'll be fine.
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Re: New 4.2L mini-stroker recipes

Post by jpradcliffe »

Ok so. Big thanks to Russ for the roller rockers!

Now: Lifters, gasket, head, pushrods & rockers installed.

Oil pump primed.

I go to hand crank the motor to check rockers and pushrod lengths andddddd....... Da dah. Motor will not make a full turn.

I Drain the oil. Pull the pan. And....Guess what?

Ye ol' machine shop had "neglected" to shim/washer the main girdle.

Rods would have hit the girdle and the Motor would have been destroyed on first crank.

I am sure there is wisdom on this subject and would greatly appreciate any advice.

This video https://youtu.be/wH3MkRHSyw0 says to add washers on rod stud and under main....I am not sure that is wise. Please advise.
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Re: New 4.2L mini-stroker recipes

Post by jpradcliffe »

Ok so. Big thanks to Russ for the roller rockers!

Now: Lifters, gasket, head, pushrods & rockers installed.

Oil pump primed.

I go to hand crank the motor to check rockers and pushrod lengths andddddd....... Da dah. Motor will not make a full turn.

I Drain the oil. Pull the pan. And....Guess what?

Ye ol' machine shop had "neglected" to shim/washer the main girdle.

Rods would have hit the girdle and the Motor would have been destroyed on first crank.

I am sure there is wisdom on this subject and I would greatly appreciate any advice.

This video https://youtu.be/wH3MkRHSyw0 says to add washers on rod stud and under main....I am not sure that is wise. Please advise.
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Re: New 4.2L mini-stroker recipes

Post by Cheromaniac »

Here's your answer:

Image
The rod caps wouldn't clear the main bearing stud girdle, so two 5/16" hardened steel washers had to be inserted on each stud to raise the girdle and provide the necessary clearance.
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Re: New 4.2L mini-stroker recipes

Post by jpradcliffe »

Ah. Why thank you.

So I just decided to clearance the girdle at the contact point. Fits and rotates perfectly and the pan fits without the need for further modification.

So that's good.

Anywho. I have another query.

So being that my
Dynamic compression is 8.54 and my
Static compression is 9.15,

Were I to run a small turbo and intercooler setup at say 6 to 8 #'s of boost, what injector would I need? (I've read that folks are running 36#) but at what psi?

I'm currently at 39# ....provided I size the injectors properly, can I get away with running this setup with just a boost referencing fuel pressure regulator and check valve on map until I can understand/afford a mega squirt?

Please advise and thanks in advance.
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Re: New 4.2L mini-stroker recipes

Post by 4.2stroker »

I have a 4.2 stroker engine
2000 xj block
Bored .60 over
New silvolite UEM-2229 pistons installed on the 4.0 rods
AMC 232 crank ground and polished .10/.10 and the snout shortened to use the serpentine crank pulley
0630 head resurfaced
New valves springs retainers and keepers
Mild cam from comp cams
New oil pump and pick up tube

What fuel injectors would you recommend for my 2000 xj?

What other parts would you recommend that I change?

The xj that the motor is going in is completely stock
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Re: New 4.2L mini-stroker recipes

Post by Cheromaniac »

The Bosch 0280155703 injectors should do the job. To help your 4.2 stroker breathe, I suggest you add a 62mm TB, header, and 2.5" exhaust.
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Re: New 4.2L mini-stroker recipes

Post by 4.2stroker »

Cheromaniac wrote: November 11th, 2020, 10:04 pm The Bosch 0280155703 injectors should do the job. To help your 4.2 stroker breathe, I suggest you add a 62mm TB, header, and 2.5" exhaust.
Thank you I appreciate your help
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Re: New 4.2L mini-stroker recipes

Post by Jed »

So I think I had a mini stroker I got out of trade. I had to replace valve cover and oil pan. Someone dropped it off a fork lift. It also sat on it side for 3 + months after being jumped through a barn. It ran great for A few years. Then I thinking it broke from camshaft thrust and would eat the gears off my distributor.

I say it’s a mini because of the Size of the lobes on the cam. I was trying to figure out what can I should buy to replace the one I had. I saw the lobe size was smaller than a stock 4.0. So I ask about it on the forum and someone pointed out that my cam was from a 4.2 due to the size.

So I replace it with a cam from cleggS stage one cam and did throttle body lifters and rods. It runs hot now but sounds good but did I make the right choice in cams? Is the cam the reason it runs hot now or what’s the deal can you help me thanks
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Re: New 4.2L mini-stroker recipes

Post by Russ Pottenger »

Jed,
To help advise you in selecting a Camshaft is your block a 1999 and later block utilizing thrust plate style cam and are you planning on retaining your stock valve springs?
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