Jeep Strokers

The Chevy inline 6 rod has the widest big end of all the rods scat makes (aside from some of the short sport compact rods) it is only .010 thinner than a 4.0 rod (1.060 wide). The next widest rods are for the big block Chrysler but they would have too much side to side play for me to feel comfortable running. The Scat catalog lists all the center to center lengths, crank pin diameters and big end widths.
http://www.scatcrankshafts.com

~Alex

I've pretty much given up on the belt drive setup. After taking a good look at it, the different setups and talking with the boss its looking like it will be scratched from the build. If I was to do it it would add an estimated 350 to 400 dollars to the build and result in no real benefit within my target RPM range. The money would be better spent elsewhere (rocker arms, pistons, rods, intake manifold and such.
Speaking of the intake manifold. Its going to have to flow some air for this stroker. I have a few ideas for what I'm going to build.
1: Use a stock 98 manifold and modify it till it doesn't even look like the stock piece any more by cutting and welding all over the pig
2: Turn the one stock manifold into two manifolds and run a stock 4 banger throttle body on each one.
3: Build my own from scratch, maybe using 2 inches of the stock ones so don't have to locate injectors on the new one, maybe use a 2 or 4bbl throttle body, it looks just like a carb but its just a throttle body.
4: Side draft webbers

~Alex

However unrealistic it may be I like the weber idea.

Another option is to have a custom manifold made.

SilverXJ wrote:However unrealistic it may be I like the weber idea.

Another option is to have a custom manifold made.

Clifford makes a Webber intake manifold, but it would be simple to turn a 4.0 manifold into one for 3 webbers, a saws all some alum tube and a flange to hold each one down. Webbers are no fun to tune and they have lean spots throughout the rpm range and there is little you can do to fix it. If you look at a dyno sheet of a Webber equipped engine you will see the HP curve will follow A/F curve. Basically going back to carburetors is like striping the 4wd out of a lifted jeep.
Check option 3 above. I've built and done some heavy modification of intake manifolds before, its no fun.

~Alex

Thats what I heard about webers too.. that they are hard to tune.

Alex, check this manifold out! http://www.hescosc.com/content.asp?id=90253
John

The dyno operator where I work is very good at tuning Webber carbs because he has been doing it for such a long time. The reasons that Webbers aren't as good is no matter how good you tune them they will still have lean and rich spots.

I had thought about building a manifold similar to that one, but it will not function as well in the lower RPM ranges. Large manifolds (with a large plenum) are better for high RPM's. I need to finish my cylinder head then select a cam and modify/design a manifold to work with it. I plan on using the Pipemax program to tune the manifold.

~Alex

How about something like that Hesco chunk but using 6 small TB's on individual runners, no common plenum keeps the velocities screaming, and makes tuning the lengths and getting even air distribution trivial. The TB's don't need to be tiny as long as you don't mind tire chirp every time you leave a light would be crappy for fuel economy and low speed throttle control but it would sound crazy and rev like a SOB even with the extra long runners to promote torque...

I think the 99+ intake is a fine piece for most apps, long runners, lots of attention to balancing flow and air speed between each runner.

BTW nice build Alex, could use some pics though Nice to see someone else confirm that the 0331 head flows better (intake) than the older heads... It was the first thing I looked at when I got my bench. I bet a dyno comparison would also find that the smaller better shaped exhausts promote considerable low RPM torque over the terribly shaped "lazy" floored early castings. Its a shame that some of them crack, the better exhaust port shape leaves us with more room to improve the port, with a higher floor and more meat to shape the port.

I was almost considering the six little TB's but that would get really expensive fast, not to mention 6 air filters.... but if i cut the hood and stuck a 3 foot tube on it. BAM, instant snorkel I really can't say what i'm going to do for an intake yet. since I have no real deadline for this i can spend lots o time on it if i choose to. But, I do have a girlfriend and you know how that goes.

~Alex

Alex22 wrote: But, I do have a girlfriend and you know how that goes.

~Alex

"Why arent you done with that thing yet?"
"Youre spending more money on it?"
"You said you would hang out with me today"

Yes I do know how that goes..

seanyb505 wrote:

Alex22 wrote: But, I do have a girlfriend and you know how that goes.

~Alex

"Why arent you done with that thing yet?"
"Youre spending more money on it?"
"You said you would hang out with me today"

Yes I do know how that goes..

Yep. I usually get "oh, so you're spending time with your other girlfriend tonight."

As for the stroker. The crank grinder we use gave me a ballpark quote of $300 for the offset and under size grind. He is waiting for a few people to get back to him whether or not they have a 4.2 around.

Alex22 wrote:I was almost considering the six little TB's but that would get really expensive fast, not to mention 6 air filters.... but if i cut the hood and stuck a 3 foot tube on it. BAM, instant snorkel I really can't say what i'm going to do for an intake yet. since I have no real deadline for this i can spend lots o time on it if i choose to. But, I do have a girlfriend and you know how that goes.

~Alex

Man the more I think about an IR intake the more badass it seems, none of the tuning issues of a carb IR, and all of the long runner inertial ramming, with no plenum or single TB you wont even be restricting the high RPM HP with it... not that we can spin up high enough to need tunnel port sized runners anyway.

So Alex have you checked the Olds Roller rocker for length to tip and pushrod cup from the fulcrum? Is it close to the same geometry? It sure would be nice to find out we have a cheaper option than Yella Terra's Gold plated jobs (or Hesco's gold plated jobs).

I know how that girl friend thing goes, yeah. They become Wives sometimes too, so watch your ass, or you'll be spending more time pushing a grocery cart, then working on projects.

To give a definite answer on which rocker arms will work I would have to put my cam back in, crank and timing set then some test springs on the valves and then try the Olds guide plates and the BBChevy rocker arms as well as the 351C rocker arms or maybe some of the late model 5.0 ford rocker arms with the C-channel alignment piece.

The 0331 head:
As I mentioned before A cylinder head that has a reputation for cracking has no redeeming qualities for a street engine in a daily driver so it is not going to be used on this build. I can't remember who said it because its been a while since I listened to the Speed Talk cd's but someone said that the exhaust flow isn't as important as the shape of the graph. A smooth curve will be the best, anything that backs up or becomes turbulent will lower the HP. I haven't taken the head off the shelf for a month or two, winter is coming up and I have the feeling I'm going to need something to do and will continue on the head.

~Alex

Alex,

What did you decide on your pistons?

In another thread you had mentioned you liked the initial numbers but after looking more closely you decided against them. I was wondering what you didn't like about the numbers? Compression height? Dish volume? Customs would end up being more expensive I'm sure. Dishing 2229's would be the most affordable method to meet the proper quench/CR.

Just curious, you have put a lot of time and thought into this build, just wondering your perspective.

Diamond-x,

Its looking like I'm going to be using custom pistons on this build. There are a few reasons I'm going for those instead of the other pistons that you can get to work in a stroker.
1: I'm going to be using a SCAT Chevy rod that comes with a bushing that is sized for a floating .927 wrist pin. The Chevy pins are very common and lightweight ones are available at a reasonable cost (compared to AMC parts). The KB944's are not machined to accept cir-clips and I would need to have them custom machined by KB to accept them.
If I wasn't using the Chevy rods these would be my other reasons to run a custom piston.
2: Forged pistons, As I mentioned above, the KB's won't work.
3: I'd rather have a piston made for my engine than build an engine around a piston.
4: Custom pistons aren't as expensive as they used to be.
5: Low tension rings. I'm going to have the pistons made to use the metric ring set from a LT-1 (iirc stock bore size is 3.905).
6: I work at an automotive machine shop so i get discounts on all the parts and its all my own labor so there goes 2/3 the cost of the build.
7: I want the pistons to be flush with the deck of the block and run the .043 gasket and I'm not going to spend the few hours opening my chambers up to the necessary volume.

~Alex