Jeep Strokers

G'day folks,

Anthony here from Perth, Western Australia. This is my first stroker build up and a lot of research has gone into it so far (I'm sure you can relate).

I started this project due to a failed temp reading from my Jeep on the way to the airport about to catch a plane to Greece in December last year. The car overheated without any indication inside (I assume because there was no coolant thanks to a cracked radiator) which resulted in a melted front piston and cracked my 0630 cast cylinder head (already replaced the cracked 0331 cast not 18 months before). Thankfully I still made my flight!

I'm still sourcing parts for my stroker but I have some on the way.. what i'm doing is pretty textbook but i've got a few 'niceities' that I've gone out of my way to get a hold of..

-- Existing 2001 4.0L block from my TJ. Will be milled 20 thou to leave a .08" deck height and +.060 overbore
-- Jeep 4.2L 3.895" Stroke Crank from a 1980 : 3214723 Cast number w/12 counterweights, 64mm nose will be shaved to 54mm.
-- Keith-Black Silvolite UEM-IC944 +0.060" bore pistons. Forged, 21cc Dish Top, 3.935 in. Bore. 1.38" pin height
-- Mopar Performance gasket 0.043"
-- .051" quench height. Theoretical compression of 9.61:1 (thanks Stroker Compression Ratio Calculator )
-- COMP Cams SK68-231-4
-- Yella Terra 1.6 Adjustable Roller Rockers (Ordered, currently being made, I expect them in about a week)
-- Ford/Bosch 26lb/hr injectors
-- 4.2L Sump 1980
-- PERFECT Hi-Velocity 68mm Throttle Body by Painless

I really wanted a 1991-95 7120 cast YJ Wrangler Head but my supplier from the US doesn't seem to be coming to the party. It's looking like an 0630 cast instead sourced from here with 2.02"/1.60" intake and exhaust ports. I don't think there's much difference between the two cylinder heads anyway.
Mopar Performance Valve Springs : P5249464 : Valve Spring, Single, 1.418 in. Outside Diameter, 1.640 in. Installed Height, Each
Mopar Performance Valve Spring Retainers : P4452032 : Valve Spring Retainer, Chromemoly, 8 Degree, 1.420 in. Outside Diameter, .650 in. Inside Diameter, Each

All of this will run in my 2001 TJ Jeep which is sitting on 33"x12.5" Mickey Thompson Baja ATZ's with 15"x8" Mickey Thompson Classic Lock 2 Rims.
Besttop front bumper and a rock rear bumper with swing away tyre carrier.
3.5" Rubicon Express Super Flex Short Arm Suspension system with Old Man Emu shockies
Rugged Ridge super short SYE and Omix-Ada rear driveshaft
High-flow magnaflow cat with full cat back exhaust and Omix-Ada exhaust headers

I need a bit of advice on the following from the experts out there...

*Pushrods... Can i use standard length? I've got adjustable roller rockers on the way.. How can I determine what length i need?
*Valve cover spacer to accommodate the roller rockers.. do I need a spacer for the thermostat housing? The hesco site is confusing me!
*Mopar Performance gasket with .043" thickness. Does anyone know the product code for this or an alternative I can use? I was looking at getting this gasket teardown kit http://www.chicagoconnection.us/index.p ... ts_id=1633 (not necessarily from here) but it doesn't specify gasket thickness.

Many thanks Jeep brothers and sisters, speak to you all soon.

Regards,

Anthony



This video is with the 4.0L with high flow cat and exhaust, headers and some port work done on a 0630 cylinder head. Amazing power difference over stock!

Mopud wrote:I need a bit of advice on the following from the experts out there...

*Pushrods... Can i use standard length? I've got adjustable roller rockers on the way.. How can I determine what length i need?
*Valve cover spacer to accommodate the roller rockers.. do I need a spacer for the thermostat housing? The hesco site is confusing me!
*Mopar Performance gasket with .043" thickness. Does anyone know the product code for this or an alternative I can use? I was looking at getting this gasket teardown kit http://www.chicagoconnection.us/index.p ... ts_id=1633 (not necessarily from here) but it doesn't specify gasket thickness.

G'day mate, or should I say yia sou?
Since you're going to shave 0.020" from the block (the IC944 pistons have a compression height of 1.353", not 1.380") and use a 0.008" thinner head gasket than stock, you'll need a set of pushrods that are 0.025" shorter than stock i.e. 9.600". Crower have a set that are exactly that size and the Summit Racing part no. is CRO-69960-16.
If you're using adjustable roller rockers, you'll need both the valve cover spacer AND the thermostat housing spacer.
The Mopar Performance gasket teardown set P4529245 that you refer to does indeed include the 0.043" head gasket that you're looking for.

Haha that's it mate, geia sou

Fantastic, thanks so much for answering all of that, you covered it all.

May I ask, as far as valves are concerned, is there a specific set folk are using in their 0630 cast cylinder head when they're ported out to 2.02" intake and 1.60" exhaust? I was looking at getting the Mopar Performance valve keepers but need a valve to suit (i hear the Dodge Magnum 5.7L valves work fit OK?). Unless you can recommend a different combination.

I would have recommended keeping the stock sized valves but since you're going for 2.02/1.60, I suggest you use the Mopar Performance 5.9 Magnum valves. I know they're more expensive than the Chevy valves but they're the correct 8mm stem diameter so you won't need to have the valve guides machined.

Well, I haven't had the machine work done on the head yet, it's still sitting in my workshop as I'm yet to send it off. I was going to go for the 2.02/1.60 because it seemed to be unanimous with most of the buildup sheets i've looked at for the 4.7L. I'm not afraid to spend a bit more if i will get more from it unless it's a complete waste. Why do you recommend i stick with stock valve sizes? I understand bigger isn't always better and you can lose some velocity, I just thought this was the way to go. You recommend keeping stock valve sizes?

Regards,

Anthony

Unless you plan on revving your engine beyond 5000rpm on a regular basis, it would be a waste of money going for bigger valves. In any event, going much bigger on the exhaust valve can lead to shrouding issues. Even Hesco use stock 1.91/1.50 valves on their aluminium head.

Many thanks for the advice Chero, I appreciate it. It's a daily driver so no it won't see consistent use above 5000rpm, I will keep the stock sizes

How's your project going?

Hey bud,

I only just dropped the main bulk of my components (head, conrods, flex plate, harmonic balancer, crankshaft) at the machine shop at the beginning of this week.

I finally sourced the stroker crankshaft after buying a used 1983 4.2 out of a J10 and stripped it down just last weekend. Unfortunately the engine was water logged with a bent pushrod and the crank had already been machined 20thou so i'm hoping it's still all OK.
There will be some port work done on the head with new valve springs and retainers to go on it but they're still on back order - i'm hopefully receiving those next week.

My biggest hold up is Summit Racing... i've come to the conclusion that their ETA dates are about as accurate as a blind man playing darts. I'm waiting on the keith black pistons and new push rods but the dispatch eta was dropped back to end of august. Still, the machine shop are going to do everything they can until the rest of the parts arrive.

I only just ordered the throttle body last night as well, Painless Perfect 68mm - it cost me a packet but I wanted it. I also won a bid on ebay for a set of 27lb bosch 3 injectors this morning so they're on their way also.

Hopefully i'll be able to start the actual build up some time in mid September

I am in the same boat as you with Summit Racing. Waiting on my KB pistons. First expected arrival date (in their warehouse) was 08/02/2010 but that has been bumped up to 08/12/2010. I tried calling other shops around here and they gave delivery time of September and the price was $100 more than Summit .... So just sticking with Summit and waiting ...

I tired looking for a used 258 crank but couldn't find ANY! So just ordered a brand new SCAT 258 crank from ebay (370 shipped including king main and rod bearings) and it looks good!

Can't do anything until my pistons arrive

for you guys waiting on summit racing call rpm machine. they had my pistons sitting on the shelf and they were like $100 cheaper then summit

http://www.rpmmachine.com/shop/index.ph ... ail&p=5972

huh i guess summit dropped there price. they were almost $500 when i ordered mine

Ahhh others who feel my pain!

I found a number of sites that sold the pistons i was after (inc rpmmachine) but summit were the cheapest. I also needed to order the 9.600" crower pushrods and so i thought i'd get them together from the same place. Finding these sorts of parts here in Aus is a JOKE with most retailers ordering them from summit anyway.

Haha damn you, i'm green with envy!! I was over that scat crankshaft as it's a little heavier than stock and is perfectly machined with the snout length etc to drop straight in but the cost to get it shipped here to Perth, Western Australia = .. the machine shop here has given mine the all clear though.. they've just had to go with the 30 thou oversize bearings (which is the absolute max for these crankshafts btw!).

I know... everything else is good to except for the damn pistons!! What a PITA!!

I just checked my summit order ETA...
CRO-69960-16 ONE PIECE PUSHRODS Expected Arrival on 8/17/2010
UEM-IC944KTM-060 PISTONS AND RINGS Expected Arrival on 8/12/2010

If they stick to these arrival dates it means i should see the rest of the good stuff by the end of the month

Also, we are manufacturing our own spacer plates for the rocker cover and thermostat housing to support the yella terra adjustables. We've already measured it up and have made a dummy out of mdf, when all is well we'll cut them out of bakelite. Full credit to my father for this, he has drawn them up and will be supplying the materials and the cnc machine at his workshop to make it happen!

If you would rather have a taller valve cover instead of the spacers I know someone that makes them. That is if they would ship to Australia and you would want to wait for shipping. Or if you weld you could just get two valve covers and make your own.

However, if you do make one and can repeat it there maybe a market for it.

When you get the Yella Terra adjustables, can you post a pic of them? I had a set of Yella Terra none adjustables and I preferred their design to Harland Sharp's.

I know hesco makes a spacer but they were lousy with their communication. I filled out their online contact form three times and never heard back from them!

If the spacers don't work out (I doubt it, my father is a genius with this stuff) i might give you a shout and ask about those rocker covers.

I've received the roller rockers already, i'll post a few pics shortly