First Stroker Build

[jeepxj3]

Something else I just checked, please correct me if Im wrong.

My deck height is close to 9.5",
232 crank comes to 1.75" stroke,
add 6.125" rod length,
1.585" compression distance pistons

I get 9.46" minus the deck 9.5" you get -0.040" This would be quench right? Isn't this a good number?

-0.040" + head gasket thickness = Quench
0.040" + 0.045" = 0.085" quench

[Jeeper89]

So having more lift doesnt do me any good? Should I be looking for a mild cam with reasonable lift? Something closer to .400"?

[akadeutsch]

I would talk to a pro tuner and see what they are able to tune in for you. Im not saying more lift won't help, just that it helps most at high RPMs.

[Jeeper89]

Ok, so I will call some of the cam companies and see what they recommend after I make my decision on the crank or not.

I know im still missing something though with my measurements. I have checked and rechecked my deck height, 9.5" is what I keep coming up with. Am I off on this? Is the stock unmilled height 9.5"? My stock 4.0 pistons have a 1.585" compression distance. I keep coming up with wacky numbers.

232 Crank 3.5" / 2 = 1.75"
4.0 Rods 6.125"
4.0 Pistons 1.585"

This comes to 9.46" Subtract DH of 9.5" and I end up with .040". Add in my head gasket (dont have it yet, but common numbers ive seen) .045" and I have a .085" quench.

Now I think about my stock crank is only 3.41" / 2 = 1.705" That adds .045 to the stock quench of .085" and now I have .130" quench. Am I doing this right? lol!

(Im not trying to argue with anyone, just want to be sure Im on the same page) The last thing I want to do is spend all this money and have the motor go "boom"

[SilverXJ]

I havent made a decision on pistons yet. Im at the point where my block is painted w/new cam bearings. Essentially ready to assemble.

What? How is your block ready to assemble if the bores haven't even been bored or honed for pistons?

[Cheromaniac]

Something else I just checked, please correct me if Im wrong.

My deck height is close to 9.5",
232 crank comes to 1.75" stroke,
add 6.125" rod length,
1.585" compression distance pistons

I get 9.46" minus the deck 9.5" you get -0.040" This would be quench right? Isn't this a good number?

Deck height = 9.453" +/- 0.003"
Rod length = 6.125" +/- 0.002"
232 crank stroke/2 = 1.750"
677CP piston compression height = 1.585"

Deck clearance = Deck height - rod length - stroke/2 - piston compression height

The deck clearance will be -0.007" +/-0.005" and the quench height with a 0.043" head gasket will be 0.036" +/-0.005".
SCR comes in at 9.54 with a displacement of 4100cc (4.1L) on a 0.020" cylinder overbore (assuming 57cc chambers and 15.2cc piston dish).
You can keep the stock cam if you like to save on costs. The problem with most aftermarket cams is that they have narrower lobes than stock (1/2" v 2/3") with a potential for premature lifter/lobe wear especially with today's low ZDDP oils. You also need to upgrade the valve springs in most cases (adding to the cost) so with the added spring pressure, the valvetrain becomes noisier and adds more potential for premature lobe/lifter wear. It's up to you to decide if all that expense is worth it for a 10-15rwhp gain given the high failure rate of aftermarket flat tappet cams. I've been down that road before so I know how it feels.

[Jeeper89]

I havent made a decision on pistons yet. Im at the point where my block is painted w/new cam bearings. Essentially ready to assemble.

What? How is your block ready to assemble if the bores haven't even been bored or honed for pistons?

Sorry, I guess I should have explained more. My block was hot tanked, bored, honed, had cam bearings installed, freeze plugs installed, and all oil / water plugs put back in. Its currently sitting on my engine stand in my garage, with nothing bolted to it. Bare bones! lol!

[Jeeper89]

It's up to you to decide if all that expense is worth it for a 10-15rwhp gain given the high failure rate of aftermarket flat tappet cams. I've been down that road before so I know how it feels.

When I rebuilt my head I bought the mopar high performance valve springs, in anticipation of buying an aftermarket cam. (Old cam, like the rest of my engine had 284k miles. All internals were tired) So the aftermarket cam is in the future. While my engine was apart ive been trying to do anything I can to improve, that is what had lead me to this forum and talking about strokers. I port matched my cylinder head to my intake runners, opened up the flutes a tad, mild polish. Im just looking to make this old Renix run top notch. This is more then likely the only time I will have the whole engine apart, so I just wanted to explore any possible upgrade options.

But since being here, and talking you guys. Im seeing that there is more cost to all this then expected to gain. When I first ventured down this road, it was on the presumption all I have to do was swap the crank / pistons, and boom more HP. (This was recommended to me from another user on jeepforum.com)

Needless to say, I think Im going to jump back to my original plan. Stock crank, 96 pistons, aftermarket cam, smaller head gasket. See if I can get the compression to bump to 9:1. Do a mild cam to try and take advantage of the better breathing ports. Thanks guys for all the help! Your awesome!

[Cheromaniac]

But since being here, and talking you guys. Im seeing that there is more cost to all this then expected to gain. When I first ventured down this road, it was on the presumption all I have to do was swap the crank / pistons, and boom more HP. (This was recommended to me from another user on jeepforum.com)

If only it was that simple. You wouldn't gain much if all you did was to increase the displacement from 3960cc to 4100cc. It's the higher CR plus cylinder head porting, intake/exhaust system upgrades, and performance cam together with the displacement increase as a package that make the difference.

[Jeeper89]

But since being here, and talking you guys. Im seeing that there is more cost to all this then expected to gain. When I first ventured down this road, it was on the presumption all I have to do was swap the crank / pistons, and boom more HP. (This was recommended to me from another user on jeepforum.com)

If only it was that simple. You wouldn't gain much if all you did was to increase the displacement from 3960cc to 4100cc. It's the higher CR plus cylinder head porting, intake/exhaust system upgrades, and performance cam together with the displacement increase as a package that make the difference.

I totally agree with how you worded it. Thats why Ive been doing lots of little tweeks to improve how my jeep will run. For the long run I think doing any stroker project is a little more then I can work on for now. I really do appreciate all the advise you, and others here have given me. Next time I build a project, I feel like Im defiantly more prepared.

Like I said. I think going with a better cam, planning to use '96 pistons, performance head gasket, with my port matched head and intake. I should see a noticeable difference in how my jeep runs. And I wont have to mess with my MAP, O2 sensors, or deal with new injectors, timing, etc.

Thanks again!

[SilverXJ]

Sorry, I guess I should have explained more. My block was hot tanked, bored, honed, had cam bearings installed, freeze plugs installed, and all oil / water plugs put back in. Its currently sitting on my engine stand in my garage, with nothing bolted to it. Bare bones! lol!

I still don't understand. Did the machine shop bore and hone the block without the pistons on hand?

[Jeeper89]

Sorry, I guess I should have explained more. My block was hot tanked, bored, honed, had cam bearings installed, freeze plugs installed, and all oil / water plugs put back in. Its currently sitting on my engine stand in my garage, with nothing bolted to it. Bare bones! lol!

I still don't understand. Did the machine shop bore and hone the block without the pistons on hand?

Yes... now I dont think I understand... If your thinking they didnt bore and hone correctly, Ive checked my bores with my mic, all are 3.895" Thats .020" over correct?

[SilverXJ]

Not all pistons measure exactly to a .020" over bore (any overbore for that matter).. in fact they rarely do and vary as well.. then you have to take into account the different piston to cylinder wall clearance for different pistons. I don't know of any good machine shop that would bore and hone without the pistons in hand so they could measure the piston and figure clearance.

[Jeeper89]

Not all pistons measure exactly to a .020" over bore (any overbore for that matter).. in fact they rarely do and vary as well.. then you have to take into account the different piston to cylinder wall clearance for different pistons. I don't know of any good machine shop that would bore and hone without the pistons in hand so they could measure the piston and figure clearance.

Thats interesting, because they never even questioned that I did not have the pistons when I had the work done. About the only thing he got on my case about was that "You know the pistons have to be pressed into the rods? Thats another cost that most people forget about. Let me know when you get the pistons and I can have that done for you."

I guess if I get my pistons and they dont fit, I will be headed back his was very upset...