Recommendation for am 390 cyl kit
- Thread starter kcr357
- Start date
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I’ve not had a problem with the el cheapo kits. Yet.
Read the feedback.
Iffin it looks shabby, raise hell. Evilbay has the customer covered. [emoji106]
Read the feedback.
Iffin it looks shabby, raise hell. Evilbay has the customer covered. [emoji106]
Jedthro
Double Naught Spy
I did this one.
https://www.ebay.com/itm/THE-DUKE-S...-a8ab-441c-b0b4-7d5eb44a023e&redirect=mobile#
I was also a little concerned with the super cheap kits, so I read up on nikosil, learned that porche used the process back in the seventies so I figured it was good enough for me. Hlsupply had the 49mm cross popup pistons on sale for 9.99, so I got one of them. The intake was a little rough, but it only took a minute with a dremmel and 1/4" sanding drum. I also broke the edges on both intake and exhaust ports. They were a bit too sharp for my liking.
I planned on new bearings and seals anyway, then I realized all I would need are the crank, engine pan and bolts for a complete short block replacement. I now have the original complete engine in a box that will likely never see the light of day again. My saw had the HD-5 carb, so I didn't have to replace the main jet. I decided against the decompression valve and plugged it. I'm running .325 stihl rs chain on a 20" bar. I'm liking this upgrade a lot. Very noticeable increase in power. I have about 5 or 6 tanks through it. Starts on the first pull when warm. Takes maybe 2 pulls prime and then 1 or 2 pulls fast idle when cold.
A couple issues I encountered. The pan bolt holes are not threaded. I bought hyway pan bolts and promptly snapped one off. I posted a thread on it and tried some suggestions such as working them in VERY slowly and back and forth to cut threads and snapped off the second bolt. I ended up tapping m6 threads, bought some grade 10.9 flanged hex headbolts and installed with blue loctite. The bolts haven't loosend up yet, but I'm keeping an eye on it. It appears the oem bolts are harder than after market.
Second issue was in removing the bar stud. Using 2 bar nuts tightened against each other and unscrewing with the bottom nut just wouldn't hold enough to remove the stud. I tried heating the stud with a hot air gun but it just would not come out. Finally used a 6" pipe wrench and cheater pipe to get it loose, destroying the stud in the process.
Pourous castings and bad chrome plating on a lot of them, make sure you can return it if you order a cheap one and have a problem.
On a 290 project now myself. Ready for reassembly. But I used this style of stud remover for the long stud. Same as the $50 Sthil single socket. I believe you also can use it to install them with much damage. May have to run a die over the threads to clean them up a bit.
https://www.ebay.com/itm/3120202609...583c:g:7s8AAOSw7ihdl-gh&LH_ItemCondition=1000
https://www.ebay.com/itm/3120202609...583c:g:7s8AAOSw7ihdl-gh&LH_ItemCondition=1000
