Jeep Strokers

Honestly there is too much info out there and you guys know too much, so that to someone who doesn't already "get it", it can be overwhelming and I don't know what to research and where to read. That being said, please forgive my questions that are likely already answered here somewhere.

I have a '80 CJ7 with a transplanted '83 CJ7 4..2L. It has HEI and a MC2100 carb. I have been preparing to convert to a junkyard TBI setup from Chevy 4.3L, whick will be on my 4.2L intake.

I am also considering the 4.0L head swap, as I think everyone suggests will give me better throttle response and 20+ hp gain. I have read the how-to on those.

However, if I am going to do this, why not transplant in a whole 4.0L, but build a "poor man's stroker" with my 4.2L intake and header, and TBI mod (don't want to deal with MPFI transplanting and my transmission, etc.)

Soooo... can I simply drop in my crank and rods to the 4.0L (assuming no need to bore, etc) and use all "junkyard parts"? What is the bare minimum machine work to run pump gas? What needs to be machined how much? Will a 4.3L TBI setup starve this engine, estimated at ~4.5L? Is there a drop in injector to compensate?

I know there is plenty one can do to continually improve, but I'm cheap and need to get the most for my budget. Thanks for any input on a barebones cheaper than poor stroker.

I suggest you do the following:

Traditional 4.6L poor man's stroker with +0.020" overbore and 677CP pistons
'99+ 4.0L intake manifold
Bolt your Chevy 4.3L TBI onto aforementioned manifold (may need to fab adapter spacer)
4.0L header

The Chevy TBI was set up for a 200hp engine so you'll need a bigger injector (surely Chevy will have one) to fuel the 240+hp you'd potentially get from the stroker.

Thanks for the reply. What about needing to mill the head or block to bring compression ratio up some?

tdkask wrote: What is the bare minimum machine work to run pump gas? What needs to be machined how much?

tdkask wrote:Thanks for the reply. What about needing to mill the head or block to bring compression ratio up some?

So do you want to run pump gas or racing fuel? , to run pump gas you may want to open up the combustion chambers a little and/or have the pistons dished some more, milling the head more than to make it flat is counter productive unless you want to run race gas!, milling the block to get the quench down is a good thing, but the less required to get it down the better.

Can you, in simple terms, explain what quench is?

tdkask wrote:Can you, in simple terms, explain what quench is?

How about http://www.crankshaftcoalition.com/wiki ... ker#Quench

You could always keep it carbed and save a few steps and money.
Yes, you can just drop in your crank and rods. If your crank is good and doesn't need polishing or turning, that's good. Otherwise that'll cost some money. Pretty much any junkyard/cheap/free 4.0 will need some basic machine work - an overbore and plane the head at minimum. Dished pistons is probabaly the cheapest and easiest way to lower compression ratio and if it needs an overbore (likely) you'll need to buy new pistons anyway. I'm pretty cheap myself and I still spent about $1200 and I got my motor for free. I had it bored, head planed, basic valve job, basic 4.0 rebuild kit, and also I paid to have him install the pistons and crank and the crank needed polishing. (Shoulda been turned, but polishing got it close and I was cheap. I regret that one now.....) I didn't do anything to get the CR down since I run a carb and use 93 octane. It doesn't take long to add up to a grand, and that's cutting corners and not sweating the small details. Or even some of the bigger ones. Plan on the basic machine work - I don't think it's worth putting the money into a used motor without it.
For a budget build you can't worry too much about quench and stuff. The quench on a stock 4.0 isn't all that great to begin with. Any time you want the most for your money, it usually costs you more money. Get the comp. ratio down to an acceptable level for pump gas and call it good. You'll be leaving some HP and performance on the table, but you'll keep benjamin's in your pocket. Can't have 'em both (damn it!!! ) Besides, it'll be miles better that your 83 4.2!

stroked'73 How your setup run with mid-grade or regular? Pinging?

Also, What is your quench?

I've never tried it - I knew going in that it was gonna be a high CR so I just always put in high test. I played with the timing a bit to get it not to ping with that - I'm running around 10* initial advance, can't remember the exact number but it's close. Carb is hooked to manifold vacuum so I'm pulling around 15* or so on top of that.

My quench in pretty crappy - the head has been planed 10 or 20 to get it flat, I think 10, and I've got a .043" HG. I think that puts me in the .080 range?? I'll have to fire up the strroker calculator to be sure.

0.0645 apparently! woohoo!!