User Login    
 + Register
  • Main navigation
Login
Username:

Password:


Lost Password?

Register now!
Fast Search
Slow Search
Google Ad



Browsing this Thread:   1 Anonymous Users



(1) 2 »


will i need to notch my bores?
Home away from home
Joined:
2013/8/27 3:21
Group:
Registered Users
Posts: 205
Offline
ok i have a A15 with the standard offset dished pistons. GX .6mm head gasket, valves are 37/33 and running a wade 140 cam. with this setup do you think i will need to notch the bores? does anyone have the same or similar setup?

i ask because my bottom end is all done and assembled but the head work isn't done yet so i couldn't check before the bottom end was rebuilt.

fingers crossed i wont have too. also what is enough clearance for valve to bore?

Posted on: 2016/8/11 0:18
Transfer the post to other applications Transfer


Re: will i need to notch my bores?
Moderator
Joined:
2001/5/3 7:04
From 48 North
Group:
Registered Users
Contentmaster
Usermaster
Posts: 31575
Offline
37 is the factory size, while 33 exhaust is larger than factory size of 30 (late A15 intake was only 35mm intake, while 80HP A15 came with 37mm intake valves)

As little as .005 inch is enough clearance, but more power will be made with .075 inch clearance as it lets air flow around the valve head

Posted on: 2016/8/11 1:52
Transfer the post to other applications Transfer


Re: will i need to notch my bores?
No life (a.k.a. DattoMaster)
Joined:
2002/6/14 7:24
From Sydney
Group:
Registered Users
Posts: 2598
Offline
Its primarily the exhaust valve that needs the clearance in the cylinder wall, as the inlet is located move centrally in the bore. The exhaust sits off to the side.. Especially when you increase the valve head diameter and/or increase the exhaust valve lift. Dummy assembly of the long motor is the go.

Posted on: 2016/8/11 2:01
_________________

-----------------------------------------
1971 B110 Sedan GX Spec
1970 KB110 Coupe Track Car
1970 KB10 Coupe
-----------------------------------------
S13 caliper b...
Transfer the post to other applications Transfer


Re: will i need to notch my bores?
Home away from home
Joined:
2013/8/27 3:21
Group:
Registered Users
Posts: 205
Offline
i guess i'll have to wait and see. i'll keep my fingers crossed.

is the best way to check by looking up the bore from the bottom?

thanks again guys

Posted on: 2016/8/11 2:30
Transfer the post to other applications Transfer


Re: will i need to notch my bores?
Moderator
Joined:
2001/5/3 7:04
From 48 North
Group:
Registered Users
Contentmaster
Usermaster
Posts: 31575
Offline
Use a bit of modeling clay or play-doh, turn the crank two full turns to ensure full a cam cycle and see how far the clay has been squished

Posted on: 2016/8/11 3:53
Transfer the post to other applications Transfer


Re: will i need to notch my bores?
Home away from home
Joined:
2013/8/27 3:21
Group:
Registered Users
Posts: 205
Offline
isnt that what you do for valve to piston clearance? or is it the same process for valve to bore clearance?

Posted on: 2016/8/11 4:21
Transfer the post to other applications Transfer


Re: will i need to notch my bores?
Moderator
Joined:
2001/5/3 7:04
From 48 North
Group:
Registered Users
Contentmaster
Usermaster
Posts: 31575
Offline
Good question, yes, same process, except for checking valve-to-bore do it with pistons removed

You can do variation with it, for example, instead of rotating engine, push the valve down manually (with light testing valve spring). That way you can check even larger valve lifts (larger than the cam you have). Or you can skip the clay and use flexible feeler gauges to measure the clearance

Posted on: 2016/8/11 4:45
Transfer the post to other applications Transfer


Re: will i need to notch my bores?
Home away from home
Joined:
2013/8/27 3:21
Group:
Registered Users
Posts: 205
Offline
do you think its necessary to check piston to valve clearance even with dished pistons?

Posted on: 2016/8/11 5:08
Transfer the post to other applications Transfer


Re: will i need to notch my bores?
No life (a.k.a. DattoMaster)
Joined:
2002/11/26 0:38
From Las Vegas USA
Group:
Registered Users
Posts: 2032
Offline
Go to this link, it gives you the block spec for various cams & valves. It's very handy

http://www.datsuncherry.ch/PDF/Rennteile75.pdf

with dished pistons I wouldn't expect clearance issues but you should check it to be sure.

Tom

Posted on: 2016/8/11 5:21
Transfer the post to other applications Transfer


Re: will i need to notch my bores?
No life (a.k.a. DattoMaster)
Joined:
2002/8/11 8:22
From Perth
Group:
Registered Users
Posts: 2689
Offline
38 inlet
33 exhaust
77mm bore

Not sure if I notched or not... but think I may have

Open in new window



Open in new window

Posted on: 2016/8/11 12:01
Transfer the post to other applications Transfer



(1) 2 »



You can view topic.
You cannot start a new topic.
You cannot reply to posts.
You cannot edit your posts.
You cannot delete your posts.
You cannot add new polls.
You cannot vote in polls.
You cannot attach files to posts.
You cannot post without approval.

[Advanced Search]