Box Stock

Building a clone?

J

jacobsdad

Member
I am in need of new engines for each of our karts. My daughters will be sent to her builder for a rebuild, so that one is handled. Our other kart is one that I run sometimes for fun and because my daughter likes to beat me around the track. My son also drives it when he is not racing his sprint. So the engine for that kart will be run occasionally and will be used as a backup for my girls kart.
It will be run NKA rules in adult clone, weight 375. The tracks will vary from our regular big high momentum 1./8 mile track to the smaller circles. We race several different tracks depending on my days off.
Due to a lack of funds right now I am considering assembling an engine myself instead of spending the money to have one built. I have a good stock clone block but I think I will buy a bare block. I am thinking of ordering from ARC Racing the CL4 cam DJ1117, a crank and rod DJ1275 the pre clearanced crank and rod kit. I already have an ARC flywheel and a couple of good carbs. The things I am lacking are the piston rings, cylinder head, valves and springs.
I have the mechanical ability to put an engine together, I have been a mechanic for a lot of years but I have limited experience with these engines. I do not have any special tools for these engines. So, is this a worth while idea or will I be regretting my decision? I would just order one built or order one of the performance kits out there but like I said funds are limited. If I can find a builders kit that I can assemble cheap enough I am very willing to go that route too.
 
Hi, I'm an engine builder but I don't do the kind of volume a kart shop does (Does that make me better or worse I don't know). I have a fully blueprinted Blue clone that I built for myself just as clone racing died out around here. I raced it once against two Preditors and won. It has ARC flywheel, rod, dyno cam and other ARC parts I have no use for it now so if you want to buy it make me an offer. I don't know what you need on it but it is ready to bolt on and go with all accessories but I could remove all that if you just want the basic engine. Let me know, Thanks Sundog.
 
Building one yourself is not expensive . Look on here for suggestions and how to's . I would suggest getting a head from Dover or any of the other's that do heads to NKA specs . I buy new complete engines as a starting point , tear them down , check everything to see that they are as they should be as far as spec , then work from there as to what I want done , ie , longer rod , longer crank stroke ect ect . Its a good way to get the kids in the shop , and learning more about what makes their engine tic , besides gas , lol Good luck with whatever you decide , and never hesitate to ask questions on here .
 
I built one a while back. It’s not that hard, but setting cam timing and ignition timing can be tedious. If you call Jody at ARC or Randy at Dynocams they can get you in the ballpark on parts.
 
The assembly is easy for me, my faults have always been in getting the clearances and timing right. ARC has some great videos that I refer to often for assembly. Both of my kids have built and raced their own engines, my son started when he was 9 and my daughter when she was 12 or 13. So far we have just done minor rebuilds, freshened the engines up off the basic BSP. This time I want to get something with more power and that will last a few races. My daughter is now off to college during the week, studying to be a teacher. She still likes working in the shop and racing but school keeps her busy. My son has the knowledge and enjoys racing but he doesn’t care for the mechanics side of racing. He can and will do it but doesn’t have the passion for it. We built his first engine together when he was 9. My failure is getting the clearances right and the fine details. The last 2 I put together punched the rod through the block.
 
The rod going through the block may have had nothing to do with anything you did . Could have been bad parts . Torq parts with a torq wrench and don't guess that your close is the biggest thing some people fail to do . Over tightening parts will cause stress as well; as not tightening them enough . Having a good tach also will keep you from turning the engine to much as well , clones don't last long at 8,000 rpms , lol
 
I torqued the rod bolts to 120 inch pounds, but both engines were pieced together from leftovers from other engines. So used rod and used bolts, also I didn’t plastigauge to check clearances so a lot of potential for failure.
 
I'm curious about having a good stock block and, in spite of being on limited budget, want to buy a new one. Trust me, I know about limited funds and I would spent mine elsewhere. Good luck!
 
I have a block that has had a few races on it. I don’t remember how many nights. I honed it and it looks good, but I don’t have the tools to do any precision measurements to check it out. I am debating on spending the money for a block or not.
 
I've been curious about this too. Is it better to have the super accurate micrometers (mine are not accurate enough) or can plastigage be used? It would be a neat parent child project as long as the whole rod punching through the block thing can be avoided.
 
All measurement tools are simply a comparison tool.

Accuracy is always about using the tool the same, whether measuring the part, or measuring the comparison standard.

Accurate measurement becomes a matter of the tool user. So, it becomes about confidence. Confidence comes from repetition.
If you can get repeatable results from the tool in the tolerance range desired, the tool is accurate enough.
 
jacobsdad said:
I have a block that has had a few races on it. I don’t remember how many nights. I honed it and it looks good, but I don’t have the tools to do any precision measurements to check it out. I am debating on spending the money for a block or not.
Click to expand...
Take you block to your local engine shop or a machine shop and have them mic it for the bore size . NAPA store usually has a shop , and they may even be willing to help with your build for sponsorship . If the block was never over bored , chances are you can just reassemble it with a stock piston and file fit the rings . I always file fit my own rings , but your local speed shop or as I said NAPA store , may do it as well . Your local small engine shop or kart shop may offer a deal for sponsorship as well .
 
The closest machine shop is over an hour away, but it might be worth checking out. The block I have is a stock bore. The cylinder was not showing any deep grooves or scratches. My concern is if the bore is not straight or is worn oval shaped. Reading here I think I should be able to measure the bore and measure the ring gap. After reading here maybe i need to go back to basics. Now I am thinking of just getting a new crank and rod, new rings and a good cylinder head. I have a BSP 4 cam that only has a few nights on it. The place u can see I will fall short is what to do to get a head ready to race, and I always struggle with timing.
 
Cold and snowy tonight so Im looking up parts, and came up with a question hopefully someone can answer. Is the ARC DJ-1116x 14cc high comp cylinder head legal for NKA? I read through the 2019 NKA rules and cant figure it out. My new plan is if my block is good use it and order a crankshaft, rod assembly, new head valves and valve springs. Use the BSP 4 cam I have and go with it.

​

 
Not likely . 1cc for the gasket 2-3 cc for the dish . In the hole say 2 cc .
That's 19 cc . Roughly .
Requirements are 26.5 cc and must be a JT- head
 
Rule 40.4.19..4. 2020 nka rules can be found on nka site.
States minimum combustion chamber volume must be 26.5 cc.

Dang, flattop beat me to it. Lol
 
OK, makes sense. I saw the rules the 26.5 cc, and that head reads 14. I wasnt sure what that would do to the chamber with gasket and piston clearance.
 
If your budget allows the Dover kit with the cc's set is a great value.

Just needs clearances set and assembled with your cam and flywheel.
 
Last edited:
You must log in or register to reply here.
Back
Top