Lots of snow so starting porting some heads - ZR-1 Net Registry Forums

LGAFF · 12-08-2013

Started porting a spare head I have not as big as some, but valve guide bosses taken all the way down and 35mm goes most of the way down

LGAFF · 12-08-2013

LGAFF · 12-08-2013

Blue Flame Restorations · 12-09-2013

A new way of taking out UPS frustrations??????

Sorry, couldn't resist, Lee. Looks really great!!!

Paul Workman · 12-09-2013

Quote:

Originally Posted by LGAFF

Started porting a spare head I have not as big as some, but valve guide bosses taken all the way down and 35mm goes most of the way down

Must be tapered some... They're bigger at the top than 35mm; that's plain to see. I did my heads in stages, and the first stage was similar to what you've done there as part of my top end P&P. It gave me the biggest single "seat of the pants" boost of anything else I've done since.

XfireZ51 · 12-09-2013

My heads were done by GVD and they start out at 36-37mm tapering down to
~ 34mm at the bottom. The guides are not done as far down as shown here.
Lee,

Will you be unshrouding the intake valves? Bowl port?

LGAFF · 12-09-2013

Yes, will do some research and unshroud the valves on these...

efnfast · 12-09-2013

Alright, I'll fess up to not knowing something. What is "unshrouding the intake valves?"

Paul Workman · 12-09-2013

Quote:

Originally Posted by efnfast

Alright, I'll fess up to not knowing something. What is "unshrouding the intake valves?"

The shape of the stock combustion chamber presents tangential ridges to one side of both intake valves. This effectively impedes flow along that edge of the intake valves.

By cutting a radius into that tangential portion, next to the intake valves, there is better flow and is part of the "500" package.

One of my heads getting the relief treatment.

P.

LGAFF · 12-09-2013

Quote:

Originally Posted by efnfast

Alright, I'll fess up to not knowing something. What is "unshrouding the intake valves?"

Basically the the edges of the combustion chamber(clover leaf) sit too close to the valve edges, this impedes flow, removing material from the edges allows more flow, although it also reduces compression somewhat.

The question is, is the clover leaf design the most efficient or is a hemi design better. Not sure if the clover leaf was more about meeting CAFE and running 87 octane or performance

12-08-2013	#1
LGAFF Join Date: Mar 2007 Location: Crystal Lake, IL Posts: 7,180	Lots of snow so started porting some heads Started porting a spare head I have not as big as some, but valve guide bosses taken all the way down and 35mm goes most of the way down __________________ LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359 Last edited by LGAFF; 12-09-2013 at 12:11 AM.

12-08-2013	#2
LGAFF Join Date: Mar 2007 Location: Crystal Lake, IL Posts: 7,180	Re: Lots of snow so started porting some heads __________________ LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359 Last edited by LGAFF; 12-09-2013 at 12:09 AM.

12-08-2013	#3
LGAFF Join Date: Mar 2007 Location: Crystal Lake, IL Posts: 7,180	Re: Lots of snow so starting porting some heads __________________ LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359

12-09-2013	#4
Blue Flame Restorations Join Date: Feb 2010 Location: Pendleton, IN Posts: 3,899	Re: Lots of snow so starting porting some heads A new way of taking out UPS frustrations?????? Sorry, couldn't resist, Lee. Looks really great!!! __________________ 1988 KOH Prototype EX5023 sold 1990 ZR-1 #444 Convertible 1990 ZR-1 Black #966 1991 ZR-1 Quazar Blue #296 1957 Duntov SS Project

12-09-2013	#6
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,683	Re: Lots of snow so starting porting some heads My heads were done by GVD and they start out at 36-37mm tapering down to ~ 34mm at the bottom. The guides are not done as far down as shown here. Lee, Will you be unshrouding the intake valves? Bowl port?

12-09-2013	#8
efnfast Join Date: Nov 2011 Location: Dunbarton NH Posts: 7,554	Re: Lots of snow so starting porting some heads Alright, I'll fess up to not knowing something. What is "unshrouding the intake valves?"