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4G63 DOHC rebuild for free runners

zzrblacklady

Active member
Joined
Jan 14, 2012
Messages
25
Location
78736-Harthausen, Germany
Hi all,
wanted to know if anyone has ever converted a 4G63 DOHC for free runner? /ubbthreads/images/graemlins/worthy.gif

The 4G63 SOHC is one, I know from experience. /ubbthreads/images/graemlins/banghead.gif
Belt has been broken, and 2h work later he runs again without problems. /ubbthreads/images/graemlins/wink.gif
I just do not know if it was by the piston valve pockets or by the distance of the pistons and valves.

Now my question: Is it for the 4G63 DOHC pistons with valve pockets, so this gets a freewheel?

I am grateful for feedback,
regards ZZR-Blacklady
 

belize1334

Well-known member
Joined
Nov 18, 2003
Messages
3,316
Location
Bozeman, MT
Are you referring to interference vs. non-interference engines? I don't believe it's possible to build a non-interference 4g63. If you break your timing belt, valves and pistons WILL collide.
 

fuel

Well-known member
Joined
Feb 23, 2009
Messages
2,165
Location
Toronto, ON, Canada
A short answer is NO.

With the compact pent-roof combustion chamber, larger total valve area and lift of the valves there just isn't enough room for the open valves to occupy a space when the piston is at TDC.

The best thing to do is just make sure your timing belt is changed at its intended intervals - usually it's 100,000kms (62,000mi) or every 5-10 years.

Of all the interference engines I have owned, I have never had a timing belt snap on me purely because I carry out the maintenance when it is required.
 

iceman69510

Turn Right Racing
Staff member
Joined
Mar 5, 2001
Messages
10,964
Location
Michigan
Sure you can do it. Get really, really low compression pistons and some short rods. That'll clear the valves.
 

zzrblacklady

Active member
Joined
Jan 14, 2012
Messages
25
Location
78736-Harthausen, Germany
Hi guys,
Thanks for the replies, I do not have "4G63DOHC engine / cylinder head" disassembled, so my question.
So thank you again for the replies, I will regularly check and change the timing belt,
regards Holger
 
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