piston to valve clearance

[fun kart kid]

Has anyone ever checked piston to valve clearance on the 420a
with high comp pistons and high lift cams. My brother and I just took the head off his engine and we could see damage to the pistons from the valves hitting them. I was just wandering if anybody checked piston to valve clearance with a setup like this.

wiseco 10.5 pistons
crower stage 3 cams
crower valve springs
1mm oversize valves

 

[Boosted_talon98]

Has anyone ever checked piston to valve clearance on the 420a
with high comp pistons and high lift cams. My brother and I just took the head off his engine and we could see damage to the pistons from the valves hitting them. I was just wandering if anybody checked piston to valve clearance with a setup like this.

wiseco 10.5 pistons
crower stage 3 cams
crower valve springs
1mm oversize valves

Take it to a machine shop and have them degree it... you will need adjustable cam gears..

 

[fun kart kid]

I know how to use a degree wheel and know that the next set will need to be fly cut for clearance unless JE pistons have more clearance. The thing I am interested in is if any one else had issues with it.

 

[bullettdsm]

Interesting that you had Wiseco's in there. Any chance you can take a pic of the top of the piston?

As for contact, there could be one of any number of reasons (most being a breakdown or misinstallation of parts). I know that when I did my 12.5 JE's with Crower 3's, I used adjustables just to primary check the relief's and they had room so I never came up with a clay number.

I can't imagine with proper installation, that the set-up would contact (even with the head decked. Keep in mind that my set-up has the head decked .020).

MB

 

[fun kart kid]

thanks I will get a pic up when i get home tomorrow.. thay only hit in the side of the valve reliefs

 

[bullettdsm]

thanks I will get a pic up when i get home tomorrow.. thay only hit in the side of the valve reliefs

I'm more curious because of a conversation that All Motor Mike and I just had about the Wiseco's.

MB

 

[fun kart kid]

It has me thinking because the next engine is going to need more piston to valve lets just say the set up is changing a bit here is the pic

Jonathan Swindell's Photos | Facebook

 

[bullettdsm]

Yeah, that coincides with my curiousity. JE does a better job of allowing for valve relief. Both intakes and exhausts contacted. Did the engine have a timing belt slip? Honestly, by looking at that, I'm wondering if the oversized valves hit the piston, just because they were oversized (due to the way Wiseco made their pistons and valve relief). Now it could be an overrev as well. Hard to tell without claying.

MB

 

[fun kart kid]

I just checked his msq and the rev limit was set at 8500 and that was never hit in the 300 miles it had on it the timing was dead on. I also think that size standard valves would have hit the next engine will have je pistons and it will be clayed this one would have but town is a 45 mile round trip and the clay I had from my go kart days was hard. When I get time i will clay this engine.

on a side note whats your peak timing

 

[bullettdsm]

the next engine will have je pistons

I'll bet my dupa that you'll be fine with the JE's (keep in mind my current set-up that I already listed. As well as the fact that she is running on adjustables that are currently -2 each)

on a side note whats your peak timing

This is the spark map from my 10.9 set-up with Crower 2's;

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MB

 

[fun kart kid]

have u seen the base line from symtechlabs that thing has 64 degrees at peak

 

[bullettdsm]

have u seen the base line from symtechlabs that thing has 64 degrees at peak

I have not seen it but....I'm sure they have their reasons? I'm guessing Paul would be better able to answer that.

MB

 

[fun kart kid]

Well after i got home from high school graduation I clayed it and came up with .070 on the intake and .80 on the exhaust side. But if the piston was like new it would be more like .015 to.020 on the intake and .60on the exhaust. Why didn't check this when i built it

 

[bullettdsm]

Well after i got home from high school graduation I clayed it and came up with .070 on the intake and .80 on the exhaust side. But if the piston was like new it would be more like .015 to.020 on the intake and .60on the exhaust. Why didn't check this when i built it

Huh? Piston tops don't wear. I don't get it.

MB

 

[fun kart kid]

No the valves made there own clearance when that hit the pistons changing the clearance the only thin spots are at the point of impact other than there it was about .150 on both intake and exhaust valves. so all someone would need to do is have the pistons cut a bit. I still think that stranded size valves there would be some contact.

 

[bullettdsm]

No the valves made there own clearance when that hit the pistons changing the clearance the only thin spots are at the point of impact other than there it was about .150 on both intake and exhaust valves. so all someone would need to do is have the pistons cut a bit. I still think that stranded size valves there would be some contact.

Wait a sec;

I know that when I did my 12.5 JE's with Crower 3's, I used adjustables just to primary check the relief's and they had room so I never came up with a clay number.

I can't imagine with proper installation, that the set-up would contact (even with the head decked. Keep in mind that my set-up has the head decked .020).

MB

Heh heh, I love quoting myself And I know of a couple of Neon guys that have run this. As for 10.5 with C3's, there are even more.

I gotta tell you that I'm skeptical that this set-up would contact of its own accord. Unless it was a Wiseco design thing There is no doubt that the JE's have plenty of clearance.

MB

 

[fun kart kid]

Think it could be that Wiseco design the pistons for the neon if the intake and exhaust valves were reversed because the different heads.