Jun bolt on cams issue

[remcafee]

I recently rebuilt my cylinder head from accidentally downshifting from 2nd to 1st, bent all exhaust valves, so i rebuilt the cylinder head, oem valves, oem valve springs and ordered those jun bolt on cams to have a choppy yaris. i reshimmed all the cam followers to spec. timing chain is lined perfectly and go to start her up and all is good! it sounds beautiful with the cams! only 3 days later... i get multiple random misfires and have done every check possible. spark plugs, coils, rechecked timing chain alignment, and i dont know whats going on. car runs fine and pulls strong with cams, but its throwing misfire codes now when they are supposed to be stock evu compatible. anyone else running jun cams bolt on series with stock ecu?

[Jason@SportsCar]

I recently rebuilt my cylinder head from accidentally downshifting from 2nd to 1st, bent all exhaust valves, so i rebuilt the cylinder head, oem valves, oem valve springs and ordered those jun bolt on cams to have a choppy yaris. i reshimmed all the cam followers to spec. timing chain is lined perfectly and go to start her up and all is good! it sounds beautiful with the cams! only 3 days later... i get multiple random misfires and have done every check possible. spark plugs, coils, rechecked timing chain alignment, and i dont know whats going on. car runs fine and pulls strong with cams, but its throwing misfire codes now when they are supposed to be stock evu compatible. anyone else running jun cams bolt on series with stock ecu?

I have the 9.5mm lift set, but run an AEM EMS-2 ecu. Entirely possible there is just a little to much overlap and the OE computer doesn't like it. Jun can say they work with the stock ECU, because it does work, but that does not mean they actually logged street miles and saw what it does. They also don't mention that you have to mill the head to clear the 9.5mm lobes, but you do.

[SirDigby]

They also don't mention that you have to mill the head to clear the 9.5mm lobes, but you do.

huh? why would deck height matter on cam lift?

[Jason@SportsCar]

huh? why would deck height matter on cam lift?

I didn't say deck the head, I said mill it... Due to the casting some space to clear the taller lobes was needed in a few of places on my head.

Other issues with these cams, cant be used with a complete set of ARP studs... The nut used in the stud kit is very tall and hits the timing wheel and flange on the cam gear end. Have to use OE head bolts in those three places.

Most of this stuff never fits/works as advertised.

[DarkShadowFox]

I didn't say deck the head, I said mill it... Due to the casting some space to clear the taller lobes was needed in a few of places on my head.

Other issues with these cams, cant be used with a complete set of ARP studs... The nut used in the stud kit is very tall and hits the timing wheel and flange on the cam gear end. Have to use OE head bolts in those three places.

Most of this stuff never fits/works as advertised.


grind the nut down.

[Jason@SportsCar]

grind the nut down.

The ARP kit uses the same tool as the OE head bolts, you grid the nut down you lose the ability to use the tool. The ARP stuff is crazy long, and the Jun flanges are massive, its not even close.

Even if you want to use ARP's with stock cams you have an issue with the VVTi solenoid, its passage is blocked by one of the studs. Poorly designed kit.

[DarkShadowFox]

The ARP kit uses the same tool as the OE head bolts, you grid the nut down you lose the ability to use the tool. The ARP stuff is crazy long, and the Jun flanges are massive, its not even close.

Even if you want to use ARP's with stock cams you have an issue with the VVTi solenoid, its passage is blocked by one of the studs. Poorly designed kit.

go custom. this really isnt a race engine i think they expect you to remove things like that when installing kits like this and go full race cams and run at full or 80% all the time like on a race track.

kinda like the TRD 4AGE but the economy version.

[DarkShadowFox]

The ARP kit uses the same tool as the OE head bolts, you grid the nut down you lose the ability to use the tool. The ARP stuff is crazy long, and the Jun flanges are massive, its not even close.

Even if you want to use ARP's with stock cams you have an issue with the VVTi solenoid, its passage is blocked by one of the studs. Poorly designed kit.

cut the bolt down. cut a hole for the passage, have a custom bolt designed for that one by APR, contact APR im sure they can figure it out.

[Jason@SportsCar]

go custom. this really isnt a race engine i think they expect you to remove things like that when installing kits like this and go full race cams and run at full or 80% all the time like on a race track.

kinda like the TRD 4AGE but the economy version.

Now I cant tell if you are serious or just trolling. :iono:

I spoke to ARP as soon as we discovered the issue. They built the kit to fit the stock engine, and they did so because an overseas customer put in an order for 50 kits. They claimed to have never had an issue reported to them. Clearly they never test fitted the kit on a stock engine during R&D, the VVTi interference is a pretty major oversight. If you sell a part to fit a stock engine it should fit. But somehow they almost never do.

When I sent them images they could not deny the fitment issue, and the only response was to use a stock bolt in that location. Duh.

They don't do one-offs, you want a set made you have to order enough to make it worth the machine time. Closest thing you get to one-off is finding parts that can be "made to fit". This is what Garm did many years ago when he built his turbo engine. This required having the block machined to fit a different kit. Not unusual when building a race engine - but again, if they are selling a kit to fit that engine it should actually fit that engine.

I have no need to come up with a "custom solution" at this point, happy to have a partial ARP kit in place, so we only have to waste three OE bolts when we tear down the engine.