First Build. 4.6L '98 TJ

[jsn_hog]

Hi All. I wanted to thank you for the information each of you have added to this site. I've undergone a HUGE learning curve over the last month. I was wanting opinions on my current proposed build. Want it to be more of a daily driver than a torque monster with trying to keep reliability good. I have a coworker that has built 5 different strokers now and loves the RVOB. Hesco cam should be more torque low to mid range and double timing chain should allow me to advance the timing to get the HP up for the top end (freeway speeds). Let me know what you think. Block and head are at the machine shop now.

ROVB_Calculationsa.JPG

ROVB_Calculationsb.JPG

Planned:
505 Performance Racetec Pistons 4.6 comp 9.1.1 - 20cc Dish
258 Crank
HESCO RVOB Cam kit
HESCO Double Roller Timing Set
4.0L Rods
+'99 "Horseshoe" Manifold
0.043 Head Gasket
Head work to get 61cc

Still researching other parts.

Thank you for the Help!!

[FlyinRyan]

Whatever you do, DONT BUY FROM 505, and DEFINITELY don't use 505's specs for Racetec's pistons. Had a 4.7 that had to be rebuilt due to Zak's specs being double what Racetec recommends.

[jsn_hog]

I think you might be right. Since I posted this this morning, I got a shipment from them. I ordered the pistons from them with the rods, crank, and bearings and its all supposed to be balanced.

They shipped me an entire turbo kit instead!

I made out better in the deal I think. But I was not going the turbo route at all!
At any rate... we shall see how it gets handled. I was hoping on getting these to the shop tomorrow.

[jeepman]

Yup I am not too thrilled with 505 myself right now...

Ordered parts:
- ARP head bolts ( I already have studs but can't use them in my MJ)
- 20thou shorter pushrods
- rocker shim kit
- Stainless steel Valve set with retainers and locks
- Valve spring kit (just Comp Springs but better price then Comp)

They never sent the ARP Head Bolts
20thou shorter Push rods are more like stock length even a smidge longer then stock so that's $50 for nothing

I am now afraid that the springs and valves I bought are not going to work out for me but I don't have time now till I get back from vacation in the US and gone for 2 weeks...

[SilverXJ]

I Haven't purchsed anything from 505. Based on others experiences as well as their pre-sales helpfulness (or lack there of) I wouldn't touch them with a 10 foot stick.

However, Racetech pistons are very good pistons. Perhaps purchase them form someone else.

Personally I wasn't that thrilled with the RVOB cam. Its not bad, but I feel there are better grinds out there. I felt that it compromised too much low end torque for not enough upper end power. I'm personally in favor of custom cams as you get a cam that is custom tailored to your engine, gears, tires, transmission, vehicle, etc.

[jsn_hog]

I was thinking of going the custom cam route, but my drive train is still stock with a DANA 35. In fact, I was prepping to change it out with an 8.8 until I had a rod knocking. Priorities changed a little bit after that. Maybe after I have all that done, I can change it up.

As far as 505, They are sending my parts tomorrow and sent a new label to ship back the turbo kit. I wonder what the other guy thought when he ordered a turbo and got a crank instead.

My main concern at the moment is what you all thought of my final numbers with SCR @ 9.2, DCR @ 7.5, and a quench @ 0.048. Also, the HESCO valves are the older style for length and are single groove valves. Should I get an angle job on these? Will this help increase the head volume to get the chamber up to 61 cc'S?

[SilverXJ]

Are the Hesco vales stock sized stems? IIRC they are larger. You will need a valve job with new valves and you should most definitely get a 3 angle at least. Consider back cutting the intake valves as well. I wouldn't go with much larger than stock though as the combustion chamber and cylinder wall can shroud the valves.

[jsn_hog]

So... I need a little help/advice from a few more experienced builders.

The machine shop I have my head at is not too familiar with increasing the combustion chamber on a 4.0 head. Based on my build sheet from the calculator, I would like to get 60 to 61 cc's out of it. First question I have is in regards to the stroker calculator on this site. The combustion chamber listed in the calculator I assume is head chamber and not the whole chamber. Correct? Just looking for verification on this in that I am not doing anything stupid. Also, the calculator states the 58cc is most common. I am assuming this is after polishing the head chamber, correct?

My question right now is how far will I be able to deviate from the 0.04 to 0.06 quench value with a SCR in the 9.3 range? I live in Phoenix, so I'm worried about the altitude and heat. If I leave the head and block stock (based on the calculator) then I get SCR @ 9.3, DCR @ 7.5 and Quench @ 0.0645. The reason I ask is for 2 reasons: 1) The machine shop cannot deck the block without full assembly. I did not know this. Has anyone else had this issue or is this common knowledge that I have missed? 2) As stated above, machinist is not too familiar with increasing the head volume and is uncomfortable with it unless I can give him a good write up on it. Anyone have a good link to such a thing? I find information on porting/polishing and milling, but not too much increasing chamber size. If I increase the chamber size, the numbers get a lot better. I have a 0630 head.

To answer XJSilver's Q... The Hesco valves are older 4.0 jeep valves that are longer to be able to work with their recommended springs for the RVOB cam. Head work needs to be done for the springs to seat correctly, but HESCO sent great information on the spring setup.

Thank you all for the great information and help on this site!!

[SilverXJ]

The combustion chamber listed in the calculator I assume is head chamber and not the whole chamber. Correct?

Yes, the combustion chamber is just the head part.

Also, the calculator states the 58cc is most common. I am assuming this is after polishing the head chamber, correct?

IIRC that is a stock chamber.

My question right now is how far will I be able to deviate from the 0.04 to 0.06 quench value with a SCR in the 9.3 range?

What do you mean by deviate?

1) The machine shop cannot deck the block without full assembly.

It is not really full assembly. Its throw the crank withs ome bearings in, and put a couple pistons in then measure. Far from full. That is the only way they can get a number on the deck clearance.

2) As stated above, machinist is not too familiar with increasing the head volume and is uncomfortable with it unless I can give him a good write up on it.

That right there makes me feel uneasy about this guy.

To answer XJSilver's Q... The Hesco valves are older 4.0 jeep valves that are longer to be able to work with their recommended springs for the RVOB cam.

Huh? I don't think older 4.0l valves are longer.

[jsn_hog]

The machinist is uneasy because he hasn't done that kind of work on a 4.0 head. So he doesn't know where to take the material off without any kind of specs.

From HESCO site:

The retainers and keepers are for single groove valves. 1997 -up 4.0L engines will also have to replace the stock triple groove valves with the earlier single groove valves for the valve stem tips to protrude up far enough for the rockers to contact them.

Maybe I am reading it wrong? They are the same length but the retainers are set at a different position?

As far as decking the block, wouldn't he have had to put it together that far in order to check/make clearance on the the side of the block for the longer crank throw and 4.0 rods? He's done lots of engine work and comes highly recommended by several of the 4x4 shops in town but mostly V8's from what I gather.

[jsn_hog]

As far as what I mean by deviate, I guess my question is how high can I make my quench with a 9.2 CR and still be able to run on pump gas? The stock quench is up to 0.0725 but RC is at 8.5 at 1100 ft. With the CR being raised that much, how important is it to get my quench down to 0.045? If the optimal window is 0.04 - 0.06 and I can get it to 0.0645 with stock decking and head chamber, is the quench too high for a 9.2 CR?

[johnj92131]

Think you want to set your quench first, then if you need more volume in the combustion chamber to hit your target - Make the piston dish larger and/or adjust your head volume to hit the compression ratio you want. That way you get both the quench you want and the compression you want.

[SilverXJ]

The retainers and keepers are for single groove valves. 1997 -up 4.0L engines will also have to replace the stock triple groove valves with the earlier single groove valves for the valve stem tips to protrude up far enough for the rockers to contact them.

Ah.. ok. The valves are the same lengths. The locks require the single groove.

As far as decking the block, wouldn't he have had to put it together that far in order to check/make clearance on the the side of the block for the longer crank throw and 4.0 rods?

It depends if he has done a stroker before. That is also part of assembly and not necessarily included.