Printable Version | Subscribe | Add to Favourites
New Topic New Poll New Reply
Author: Subject: Crossflow woes/help
Mike Bentley

posted on 20/11/17 at 11:58 AM Reply With Quote
Crossflow woes/help

Hi guys and Girls

Here goes.
I bought this engine a 1600 681F with unknown history it had been standing for 2 years and started straight away without a single Knock or rattle
I opened it up and found it to be bored out to +090 with no bore ridge and still nice honing marks, plus the shells are almost like new.
At first I thought happy days but +090 on a 681!! on further inspection it has a chambered head but "711m" pistons. (Low Compression??)

I was hoping to fit a very big valve and ported head I bought at a good price years back ( After measuring and comparing chamber sizes) along with a BCF2 cam and twin 40s.
But I think the comp ratio will be to LOW.
I have a 1300 engine in the shed (Which should have a flat head on it) so could just fit that.

QUESTIONS
1. IS IT WORTH FITTING THE BCF2 CAM WITH THE STANDARD 1300 HEAD.

2. OR WILL THE FACT THAT A LOT OF GASES WILL BE GOING IN AND OUT OF THE RACE HEAD WITH CAM AND CARBS THAT THE LOWER COMPRESION WONT MATTER MUCH.

I KNOWN I AM PROBABLY DREAMING

Please photos in my Achive

View User's Profile View All Posts By User U2U Member
Brian R

posted on 20/11/17 at 12:32 PM Reply With Quote
Check the bowl size on the pistons. You may have pistons from a smaller capacity engine. It's the easiest way to raise the compression on a crossflow. I've done it myself.


https://www.google.co.uk/search?source=hp&ei=V8kSWvWQOYf1aOrfhtgG&sjs=3&q=ford+crossflow+piston+bowl+size&oq=&gs_l=mobile-gws-hp.1 .1.41l3.0.0.0.273662.1.0.0.1.1.0.0.0..0.0....0...1..64.mobile-gws-hp..0.1.42.3...0.7w53seMZCLA#imgrc=B69aaqot3NoqMM:

The 1600 is on the left.

View User's Profile E-Mail User View All Posts By User U2U Member
gremlin1234

posted on 20/11/17 at 02:33 PM Reply With Quote
if the compression ratio is low, is it worth considering a turbo?
View User's Profile View All Posts By User U2U Member
Mike Bentley

posted on 20/11/17 at 04:28 PM Reply With Quote
Thanks Brian and gremlin
The piston on the left is a 1300 which you put in a 1600 to raise compression
My are deffo 1600 ones.
As for a turbo that should be great but I think the old thin block of the 681 would self distuct
Plus I am on a tight budget so will probably fit the 1300 head and just one 40 on an lynx manifold I have.
And sell the race head etc

View User's Profile View All Posts By User U2U Member
Brian R

posted on 20/11/17 at 07:27 PM Reply With Quote
Sorry. The image I tried to copy was the pic in post no. #11 in this forum thread.

http://www.turbosport.co.uk/showthread.php?t=313551

View User's Profile E-Mail User View All Posts By User U2U Member
Mike Bentley

posted on 21/11/17 at 07:41 AM Reply With Quote
thanks brian
the list is helpfull

View User's Profile View All Posts By User U2U Member
alfas

posted on 22/11/17 at 09:37 PM Reply With Quote
first of all:

the 681 block isnt THAT bad

and THE 711 block isnt THE miracle.

a well balanced 681 might restain more revs or abuse than a badly (or standard ford) balanced 711

in theory the 711 are supposed to have thicker walls, but we're talking about 30-40 year old castings that might have seen 100000+ miles, that were never that accurate in the first place... for a road car your unlikely to stress it more than it can cope , even with a max overbore and some other tuning items fitted.

original 1600 pistons for that engine are rare. the pistons are differtn due to those engine-models having a chambered head
later 1300 pistons will give you around 10/1 ratio

this said...it also depends on the chamber....heads from that age exist with small and bigger chamber.

View User's Profile View All Posts By User U2U Member
Mike Bentley

posted on 3/12/17 at 04:21 PM Reply With Quote
SORTED
Bought a big vale ported flat top from ebay with unknown garage clearance history, just pope it has not hidden cracks.

paid £93.00 so its a gamble.

photo in my Archive

View User's Profile View All Posts By User U2U Member

New Topic New Poll New Reply


go to top






Website design and SEO by Studio Montage

All content © 2001-16 LocostBuilders. Reproduction prohibited
Opinions expressed in public posts are those of the author and do not necessarily represent
the views of other users or any member of the LocostBuilders team.
Running XMB 1.8 Partagium [© 2002 XMB Group] on Apache under CentOS Linux
Founded, built and operated by ChrisW.