What cam for original poor man stroker. RENIX?

[Supakas]

Greetings from Europe !

Im building 89 Wrangler YJ. (sit 7 years under the tree) It has 4.2 AMC 258. Its running now, but its very tired. So im gona stroke it !

So i have complete 4.2 AMC 258 and 88 4.0 from XJ.

Idea:
4.2 3.895" Crank. - problably needs machining.
4.2 Rods. - have them cheked
sealed power 677 pistons .030 over
New rings,bearings etc.
New injectors.
Stock head (DIY port it? ) , intake , exhaust. Bore TB.

Im aware of the big quench problem but for me to order custom pistons and use 4.0 rods is out of the game because of the cost.(shiping etc.)
I dont see detonation problem an issue because we have high octane fuel.

Machining is cheap- i can deck it down .040 ? shorter pushrods?

So my question is, what cam i should buy for this combination ?
Closest dealer is selling Melling MC809 - so this would be the cheapest option. But im willing to go the right way.

And i know. HO engine would be nicer, but in europe we dont have junkyards full of 4.0HO-s so it is what it is. ( Had do buy full XJ to get this engine)
Im not looking 300HP monster. Just a little HP boost with stuff i already have.

Sorry for my bad english , and thank you for this community !

Few pictures if someone cares:

[Cheromaniac]

The Melling MC809 is the same spec as the stock cam but if you want a mild performance increase, Russ can supply you with a lower lift version of the CompCams 68-232-4 that allows you to retain the stock valve springs.

[Supakas]

Thank you Cheromaniac.

'What can you suggest from the shop?
Maybe something i can find in europe from parts dealers ?

In overall.
Should i deck the block down ?

[Supakas]

Some math:

Stroke: 3.895
Rod: 5.875
677P piston height: 1.585
Jeep 4.0 Deck height: 9.450

Deck clearence : 0.043

Compression calc :

Bore: 3.905 inches
Stroke: 3.895 inches
Combustion Chamber: 60cc dremel it to 60 ?
Deck Clearance: .043 inches
Gasket Thickness: .039 inches
Dome/Dish/Valve Relief: 15 cc

Static Compression Ratio 9.36 : 1
Dynamic Compression Ratio 6.92 : 1


In case of stock chamber size
Static Compression Ratio 9.74

Quench: 0.08199999999999999 ?


Am i correct ? Considering high octane fuel in europe. 98 equivalent to 93 in US. Seems okey and safe ?

[Cheromaniac]

The original poor man's stroker in my Jeep was almost exactly that spec except for a 3.895" bore (square engine), 677P pistons with dish increased to 17.7cc, and a 58cc combustion chamber. The static CR was 9.25:1 with a deck clearance of 0.045" and a quench of 0.088" (0.043" head gasket).
I had absolutely no problem running it on 95 RON octane fuel (91 US) and that was using the stock Champion RC12LYC spark plugs (not colder plugs).

[Supakas]

Great. Ordered the pistons.
I also managed to find 1720 head.- can i still use stock intake and fuel rail or it will choke the good flowing head ?
If im looking to delete EGR system- should i change timing on cam ?
Problably going with the Melling MC809.

[Cheromaniac]

The HO head will require an HO intake manifold and throttle body for best results. As for the cam, install it straight up.

[Supakas]

What should the bore clearence be?
On the package it says min 0.0001 inch.

[Cheromaniac]

It'll be whatever the piston manufacturer specifies 'cause the type of material used makes quite a difference. Hypereutectic pistons require the smallest clearance from the bore since they have the lowest expansion rate.

[Supakas]

Hei guys.

Head, block and crankshaft are at machining.

Meanwhile getting other things ready.
Im considering keeping all the 4.2 acc And V-belt.
Just to keep it simple. Because im building a wrangler i will not going to use AC anyway.
And because the 4.0 is from cherokee the fan sits on the other pulley. ( on wrangler its on waterpump) and it will line up with original rad placement.

Any cons goint that way ?

[amcinstaller]

Just make sure you use the right water pump. 4.0 ones spin opposite direction from 4.2s. The AMC guys have been using 4.2 accessories on 4.0 for a while here

[Supakas]

AMC 258 crank machined.
7120 resurfaced and new valves.

[Supakas]

[Hellfrekke80]

Greetings from Europe !

Im building 89 Wrangler YJ. (sit 7 years under the tree) It has 4.2 AMC 258. Its running now, but its very tired. So im gona stroke it !

So i have complete 4.2 AMC 258 and 88 4.0 from XJ.

Idea:
4.2 3.895" Crank. - problably needs machining.
4.2 Rods. - have them cheked
sealed power 677 pistons .030 over
New rings,bearings etc.
New injectors.
Stock head (DIY port it? ) , intake , exhaust. Bore TB.

Im aware of the big quench problem but for me to order custom pistons and use 4.0 rods is out of the game because of the cost.(shiping etc.)
I dont see detonation problem an issue because we have high octane fuel.

Machining is cheap- i can deck it down .040 ? shorter pushrods?

So my question is, what cam i should buy for this combination ?
Closest dealer is selling Melling MC809 - so this would be the cheapest option. But im willing to go the right way.

And i know. HO engine would be nicer, but in europe we dont have junkyards full of 4.0HO-s so it is what it is. ( Had do buy full XJ to get this engine)
Im not looking 300HP monster. Just a little HP boost with stuff i already have.

Sorry for my bad english , and thank you for this community !

Few pictures if someone cares:

The Melling MC809 offers the same specifications as the stock cam. However, if you're seeking a slight performance boost, Russ can provide you with a lower lift version of the CompCams 68-232-4. This option allows you to keep the stock valve springs while still enhancing performance.

[Supakas]

Things are slowly moving.






Managed to find 99 year intake.
Am i right that i need 91-95 TB Because of the MAP sensor. (i have renix)
And also 91-95 Fuel rail.
Can someone suggest Injectors for this setup:
88 block .30+
258 cranck and rods.
7120 head
99+ Intake.