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4.6L Stroker, Help me build it please!

XJoshua

NAXJA Forum User
Location
Pueblo, CO; USA
Well for a year Ive wanted to do this, but never had enough income and now I do. So Ive decided 4.6L is the way to go. Ive spend countless hours studying Dino's page, and other links. Now Ive finally come up with something, and I just need some suggestions and someone to double check what Ive come up with.

Now for the math, and towards the bottom Ill put all the nifty gadgets and plans.

Bore: 3.905
Stroker: 3.895
Deck Height: 9.418
Head Gasket: 0.045
Combustion Chamber Volume: 56.4
Piston Dish Volume: 22.0
Rod Length: 5.875
Piston Pin Height: 1.585
-----------------------
Compression Ratio: 9.56:1
Quench: 0.0555 +0.018over
Deck Clearance: 0.0105
Rotating Length: 9.408
Rod/Stroke Length: 1.508
Rod Angle @ 90*: 18.647
Rod Centerline to Piston Top: 7.460
Cylinder Displacement: 279.9ci
CALCULATIONS PROVIDED BY: AndreasStrokerCalc

Now the CR is very close to what I want being 9.5:1 so I should still be able to run premium fuel without any additives, since this is a daily driver. I will be using Ford 24# injectors with adjustable MAP and FPR. Quench height is TDC to head right? The calculator I used showed in the green so that means I wont get valve lash right? I dont unsderstand what combustion chamber volume is so if someone can clear that up for me that would be great.

As far as parts go:
1988 4.0L Long Block
1991 4.0L HO Head
2001 Intake Manifold
Ford 65MM Throttle Body
4.2L Rods
4.2L Crank(12 Counterweight)
3.905 Federal Mongul Cast Pistons
260/272 Crane Camshaft
DIY Gasket Match Port/Polish
Bore & Hone (Kind of a Duhh)
Valves Laped(Is that the correct term?)
Mopar Performance Valve Springs
Harland Sharp Rocker Arm 1.6

I think thats most of it, probally missed something, just jump in and tell me. Thanks much.

-Joshua
 
Harland Sharp roller rockers will only fit under the valve cover if you cut the valve cover CCV baffles and shorten the rocker bolt bosses by 0.4". Coupled to the fact that they're stud mounted and will need pushrod guideplates and chrome moly hardened pushrods to keep the valvetrain stable, they aren't the best choice.
Go for the Yella Terra 6627A 1.6 ratio roller rockers. They're shaft-mounted and fit under the stock valve cover. I've ordered a set for my stroker directly from Yella Terra in Australia at a cost of $364 plus $59 shipping.
 
Dr. Dyno said:
Harland Sharp roller rockers will only fit under the valve cover if you cut the valve cover CCV baffles and shorten the rocker bolt bosses by 0.4". Coupled to the fact that they're stud mounted and will need pushrod guideplates and chrome moly hardened pushrods to keep the valvetrain stable, they aren't the best choice.
Go for the Yella Terra 6627A 1.6 ratio roller rockers. They're shaft-mounted and fit under the stock valve cover. I've ordered a set for my stroker directly from Yella Terra in Australia at a cost of $364 plus $59 shipping.

Only 1.6 ratio? I thought you wanted higher lift from 1.7s.
 
What about the Hesco Hardened Rockers? Im thinking this would be a cheaper more pratical part. Would these accomodate the larger lift, or am I going to have to much lift for the stroker to run properly on 93octane?
 
I've been playing around with the same Excel spreadsheet doing calculations for my stroker. The combustion chamber volume is the area below the valves down to the bottom of the head. If you turned your head upside down, you could fit 56.4 cc's of water in each of your 6 combustion chambers. The stock head has a volume of 57 cc's. Are you planning on shaving .004" from the head to get that 56.4 cc's? You are correct on what quench is.
 
Last edited:
What Excel Spreadsheet Are you guys talking about?
 
XJoshua said:
AndreasStrokerCalc

Search it, I found it on this forum, but have lost the link. Its really small and useful.

I just went with the 56.4 because thats what it had in first stroker idea colum. Maybe adding that back will give me the 9.5:1 on the dot I need.

How do I figure when my pistons will slap the valve when opened? Kinda something I dont want to happen.
 
Weird I cant find the edit button. Well I put in the 57cc combustion chamber volume and that gave me 9.50:1 compression on the dot. But the calculator says 58cc is stock, and comments on this?
 
Is there much difference between a 4.6 and a 4.7? Other then that .1 of a litre. I dont think it would cost anymore, but is there even a butt dyno notice? The only gain I see is it would look like a cooler badge on the hatch.
 
XJoshua said:
But the calculator says 58cc is stock, and comments on this?
I don't have it near me at the moment, but I was looking at the engine chapter of my FSM yesterday and I'm fairly sure that it said that stock combustion chamber volume for a 4.0 (a 1990 RENIX) is about 64cc.
 
That figure of 64cc is for the 4.2 head. The 4.0 Renix head comes in at ~58cc while the HO head comes in at ~57cc. I've cc'd two 7120 heads and they came in at 56.5 and 57.0cc respectively.
Mambeu, the combustion chamber volume does NOT include the head gasket volume.
j99xj, I was advised not to go for the 1.7 ratio roller rockers 'cause I'm already getting 0.456"/0.484" lift from the Crane 753905 cam with 1.6 ratio rockers. The extra lift (0.484"/0.514" with 1.7 RR's) would have raised the open valve spring pressures to a degree that would accelerate cam lobe wear especially on the exhaust lobes.
 
Well since I have a HO going onto the Renix block sounds like my calculations are done. Just time to get the engine down here, and start buying parts, and hope for the best in febuarury when I get it in.
 
Engine arrives next saturday(the fourth). Ordering the camshaft tonight. Question is Im getting a 260/272 and the stock camshaft is what? Im trying to see if my valves are going to get slapped by the pistons with my quench being 0.0555(+0.018).

Also whats a good kind of bolt to use for securing the block to the engine stand(length, and type, also the type of nut to use)?
 
It looks like your stroker will be nearly identical to mine. The stock camshaft is a straight 270 degree for the 91-95 4.0, and a split 256/260 degree for the 96-02 4.0. I've turned my engine over by hand, and I did not have any clearance problems in the valvetrain. You're looking at your chart wrong for the quench...you will actualy have .018" MORE quench than a 4.0, meaning you'll actuay have .0905" of quench, more than enough. Your chart must look like column '"E" below:
strokerchart.jpg


I don't remember what kind of bolts I used on the engine stand. I found some that threaded into the top and used some that would fit through on the bottom and secured with a nut.
stroker017.jpg
 
Here's what Ive come up with using the calculator.
Jeep4.jpg


Im trying to figure out the bolt size to mount the engine because when the engine arrives the only cherry picker will be the one on his truck so I have to get it mounted right then and there until Im ready to put it in. Im hoping I can just go out there and screw some nuts on to the current engine and one will slip over and then go bolt match it at the hardware store.

For the camshaft on the '88 Block I show 253/253. So would the 260/272 let the stroker breath? Cant remeber what ti said on Dinos page, but he has a couple setups and all differ when mines the cheapo setup with the higher end stuff in it.

Also to clear things up Im using a '88 Renix Block and a '91 HO Head.
 
AMC V8 roller rockers are not wide enough to work on the Jeep I6. Indeed, none of the V8 roller rockers will work.
I just received my Yella Terra 1.6 roller rockers (YT6627) and my Crower chromemoly hardened pushrods (70158-12) yesterday in the post. Total cost was exactly $400. I plan to install them tomorrow and do a write-up, so watch this space. :D
 
So let's say I build one of these with a higher compression, say the 9.75:1 on the end, pull the computer & fuel system, install a 4.2L distributor, advance the hell outta the timing, and run on propane.

Any thoughts on how this would work? There are kits available for the 4.0L intake, and I'm considering this now before I go drop a bunch o money on a regular fuel cell, high-pressure pump, larger injectors, better ignition, premium fuel, etc...
 
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