JPrubo's try at a stroker

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JPrubo
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Stroker Displacement: 4.6

JPrubo's try at a stroker

Post by JPrubo »

Wow where to start. I am sure you guys have all been through this before and now I'm going to give a try. This is my second stroker project, not sure if you guys would count the first since it was stroking a 2.3 liter mustang out to 2.5. Got a lot more involved on this one though and hope to have some good results.

Enough of that now on to the plans. The basics: a stroker crank from 505 performance, stock 4.0 connecting rods, KB944 pistons and rings (.40 over). After some debate and research I have decided on the comp cams 68-231-4 cam as I understand it should work with my factory computer. I still have to order the cam and the correct time set. After getting the 926 springs from comp cams and releasing there was no way they would work I went back and found their 981 springs. Also ordered new valves as my guides and valves where worn, ordered trick flow LS1 valves, exhaust is .314" stem, 4.9" length, 1.575" diameter (will open up valve seat and throat for new valve, also unshroud valve), intake is 3.14" stem, 4.9" length, 2.04" diameter (getting valve cut down to 1.92"). Of course a port and polish on the head, and removing .005" to clean and straighten the mating surface. Planing on a .043" thick MLS head gasket. Was going to go with .010" off the block but after some research on here was thinking .020" might make for a little better quench number. If I figured correctly .020" decking off the block should give me about .010" piston to deck clearance, sound about right?

Looking forward to hearing any input and sharing this learning and building experience with other like minded individuals.
JPrubo
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Stroker Displacement: 4.6

Re: JPrubo's try at a stroker

Post by JPrubo »

Talked to my machine shop guy. He is finishing cleaning and checking my head. I will be picking it up to do the post and polish work on it myself. While I have the head I will give him the valves so he can turn down my new intake valves from 2.04 to 1.92. Also might check on back cutting the valves (especially the exhaust). I am little worried there will be too much shrouding on the larger exhaust valves and think back cutting them might help. Never had valves back cut before and I'm not if it's worth it or not. Anyone have any experience with it?
JPrubo
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Joined: May 10th, 2013, 6:20 am
Stroker Displacement: 4.6

Re: JPrubo's try at a stroker

Post by JPrubo »

I have been reading everything I can about porting this heads and the different cast numbers and such. Here are the pics of mine after tanking and bead blasting. I plan to start working on it on Sunday. Any advice or tips (like how big can you open them up, and special shapes or areas to pay attention to, place to watch out for water jackets or bolt holes) would be greatly appreciated.

Well here's the pics of my 04 head. Had a 120,000 miles when I pulled it. No cracks but did have a leaky exhaust valve and the intake valves and guides where worn. Also slight warpage <.005".

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SilverXJ
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Stroker Displacement: 4.6L
Vehicle Year: 2000
Vehicle Make: Jeep
Vehicle Model: Cherokee
Location: Radford, Va

Re: JPrubo's try at a stroker

Post by SilverXJ »

Don't try to change the port shape too much unless you have a flow bench to test the modifications. Smooth out the casting grain, leave the intake slightly rough, polish the combustion chamber and exhaust ports. Check valve shrouding with a head gasket, scribe the headgasket bores on the head and do not go past the bores.
JPrubo
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Joined: May 10th, 2013, 6:20 am
Stroker Displacement: 4.6

Re: JPrubo's try at a stroker

Post by JPrubo »

Thanks for the tips. This is my first time porting a head myself. Hopefully I don't screw this up cause this build is pricey enough I don't want to have to buy a new head.
JPrubo
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Joined: May 10th, 2013, 6:20 am
Stroker Displacement: 4.6

Re: JPrubo's try at a stroker

Post by JPrubo »

Well I have start porting the head. I have three exhaust runners opened up and ready for the final polishing path. This is where I ran into a issue. I have gone over it with the 80 grit drums and got it as smooth as I could with those. The next step is to use the cross buff pads but the ones in the kit I bought are to large for the runners. I guess I"ll just have to look around for some smaller ones. Other then that I think it's turning out OK. I'll try and get some pictures up later this week.

Next question, I read that some people polish the top of the head to allow the oil to return to the pan quicker. Is this something I should think about doing while I have the tools out? Just wondering if this was a standard practice for this kinda motor.
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SilverXJ
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Vehicle Model: Cherokee
Location: Radford, Va

Re: JPrubo's try at a stroker

Post by SilverXJ »

What kit did you buy? For them not to fit in the exhaust port they must be pretty large.

Definitely smooth out the casting under the valve cover for drain back if you have time. Can't hurt.
JPrubo
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Re: JPrubo's try at a stroker

Post by JPrubo »

I got a Standard Abrasives deluxe porting Kit from Summit. They seem to be a 1.5" diameter. Haha maybe I didn't open the ports enough. Anyway I can push them but my air die grinder won't spin them then. I might try a cordless drill turned on to the low speed setting and see if that works. Anyone see a problem with this?

I have am in no rush on this engine. I prefer to take my time and make it right. I will definitely clean up the top of the head a little then. How about the casting marks on the head? Leave them on or go ahead and take them and smooth it out? I don't see a reason for them since I already know what I have.

Thanks again this site and you guys have been very helpful and full of knowledge.
JPrubo
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Re: JPrubo's try at a stroker

Post by JPrubo »

Well after hours of grinding I finished up most of it last night. still have to polish the combustion chambers and oil returns. I didn't open it up to much but this is what I got out of it.

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JPrubo
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what length Valves are people running.

Post by JPrubo »

Well I ran into a little problem today. My machinist called me up because he put one of the new valves I bought I in to mock up and see how much he had to remove for the spring height. I used the factory service manual for sizes since I didn't have the motor tore down yet when I ordered. The manual said the overall valve length was 4.822"-4.837" and had a 1.64" installed spring height. I ordered a set of 4.9 length valves to get me closer to the 1.7" install height needed for my springs and cam. When he checked it the height was 1.5"? How did it get smaller :huh: ......well it turns out my factory valves actually measure in at 4.950" in length. Now I have try and return the valves I bought and get new longer ones. I have found some 5.06 which is a difference of .11" and should give an install height of 1.75". Anyone know the overall length of the valves they are running? I was wondering if just my manual is wrong or if there was different lengths for the different heads. Mine is a 0331 Tupy casting.
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SilverXJ
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Stroker Displacement: 4.6L
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Vehicle Model: Cherokee
Location: Radford, Va

Re: JPrubo's try at a stroker

Post by SilverXJ »

I would avoid changing valve length to change spring loads. Not all valves place the retainer in the same place, if going with a valve that uses a different retainer that also throws a kink in to the equation, and you are also messing with the rocker arm to valve tip geometry. Instead I would recommend machining the head to obtain the desired spring load. How much are you trying to change the seat load? Just because a spring recommends a x.x install height doesn't mean you need to go to that install height.
JPrubo
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Re: JPrubo's try at a stroker

Post by JPrubo »

I am looking to increase my spring height from 1.64 to 1.7, this will give me a seat pressure of 105 and give me the clearance for the cam I am running (install height-minus lift and .o6 for clearance). As for the rockers I have no issue adjusting them to get geometry right after the valves are in. I'm not looking to get it all from the valves them selves but since I am ordering valves (and not having much luck finding the same height as stock) I was wondering what ones everyone was running. I have read about people using small block chevy valves but they have different heights available and I was wondering which ones people where going with and how well they worked.
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SilverXJ
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Location: Radford, Va

Re: JPrubo's try at a stroker

Post by SilverXJ »

Look at Chevy LS valves
JPrubo
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Re: JPrubo's try at a stroker

Post by JPrubo »

That is what I thought I had the first time...may have been LT valves. Either way the ones I am finding listed for the Chevy motors aren't 4.950" so I was wondering if anyone else had bothered to check their overall length and what did they have to do correct geometry. I have found parts numbers listed but when looking at the different valves out there most places let you look them up by the dimensions you need and that is what I was trying to figure out with having to look for a valve for this or that specif motor.
JPrubo
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Stroker Displacement: 4.6

Re: JPrubo's try at a stroker

Post by JPrubo »

What kinda of harmonic balancer are all of you guys running. Is a stock 4.0 enough or should I get something else.
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