Type 3 small stroker build

Who is the best person to rebuild your engine? You...

Moderator: sparkmaster1

Post Reply
User avatar
Thenoj
Posts: 6
Joined: Tue Nov 17, 2015 8:37 am
Location: Safety Harbor FL

Type 3 small stroker build

Post by Thenoj » Sat Oct 01, 2016 6:15 pm

IMG_4178.JPG
.042 deck with no shims, CR of 11.3. Cam is C20 with 1.4:1 rockers. Heads are 044 castings, no port work and I think 40x35.5 valves with single high rev springs. I figure I'm going to add barrel shims to get the CR down a bit. I'd like to build this thing with the parts I have on hand but if a cam change would make this thing run on US 87 octane I could scrounge up a few bucks.


Sent from my iPhone using Tapatalk
You do not have the required permissions to view the files attached to this post.

User avatar
Thenoj
Posts: 6
Joined: Tue Nov 17, 2015 8:37 am
Location: Safety Harbor FL

Re: Type 3 small stroker build

Post by Thenoj » Sat Oct 01, 2016 6:19 pm

This is a street engine and the carbs are dual 40idf's.



Sent from my iPhone using Tapatalk

66brm
Posts: 123
Joined: Mon Apr 12, 2010 8:55 pm
Location: Perth, Western Australia, The Southern Hemisphere

Re: Type 3 small stroker build

Post by 66brm » Sun Oct 02, 2016 7:02 am

Keep the tight deck and open the chambers up, can that cam run with 1.4s?

User avatar
Thenoj
Posts: 6
Joined: Tue Nov 17, 2015 8:37 am
Location: Safety Harbor FL

Re: Type 3 small stroker build

Post by Thenoj » Sun Oct 02, 2016 1:02 pm

Yeah, the C20 is supposed to work well with 1.4 rockers. If I could add 10cc's to the chambers, that would bring the CR down to about 9.5:1.


Sent from my iPhone using Tapatalk

User avatar
Marc
Moderator
Posts: 23646
Joined: Thu May 23, 2002 2:01 am
Contact:

Re: Type 3 small stroker build

Post by Marc » Sun Oct 02, 2016 1:42 pm

Take the piston deck up some - .042" is scary-tight for a 90.5 bore, and with a little more you'll still have good "quench".
I'd go with .055" and 55cc chambers (or .050" and 56cc), that'd give you 8.4:1 static and a chance of getting away with 87 (R+M)/2 gas.
Even better, mill a shallow flat dish in the piston top and remove less from the head. For example, a 2" dia dish .060" deep would add ~3cc unswept volume and still leave a >3/4" wide quench pad around the perimeter.

User avatar
Thenoj
Posts: 6
Joined: Tue Nov 17, 2015 8:37 am
Location: Safety Harbor FL

Re: Type 3 small stroker build

Post by Thenoj » Tue Oct 04, 2016 3:23 pm

Old configuration of this engine had 5.7 rods and .054 deck for 9.6:1 CR. As you can imagine, it ran hot.


Sent from my iPhone using Tapatalk

User avatar
Thenoj
Posts: 6
Joined: Tue Nov 17, 2015 8:37 am
Location: Safety Harbor FL

Re: Type 3 small stroker build

Post by Thenoj » Mon Nov 07, 2016 7:55 am

I was able to get the chambers up to 50cc and put a .020 shim under the barrel to get down to 8.8:1 static. The cam and long(ish) rods get the dynamic down to 7.9:1. The engine should be running this week.


Sent from my iPhone using Tapatalk

User avatar
Thenoj
Posts: 6
Joined: Tue Nov 17, 2015 8:37 am
Location: Safety Harbor FL

Re: Type 3 small stroker build

Post by Thenoj » Tue Mar 28, 2017 9:43 am

4K miles on this engine and it runs great except needs 89 to not ping. Not a terrible situation but missed my goal. Marc was probable spot on with .050" and 55cc but I wasn't comfortable removing any more material from the heads I had and I thought more deck would kill quench and cause other issues.

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest