Bridge-Point CC Method

[MaxRaceSoftware]

Anyone here has used the "Bridge-Point" CC-Method ???

Goodson sells what i call a "deck bridge" a upside down
"U" shape that spans a cylinders bore to check the deck heights of piston's depths in bore at TDC

but you remove the 1.000" inch dial indicator and replace it with a metal rod with a point

you place the bridge on the block's deck ..and untighten
the rod and let the point hit the block..thereby setting
the point exactly to block surface level ...or you
will be using the cylinder head shaved surface to set the point height

you then dead-level the head ...place the bridge across the
chamber to CC....and then fill the chamber to just
the point where the CC-fluid "JUMPS" to the point...you take a CC reading........this eliminates some of the hassle involved with CCing heads by not needing the PlexiGlass plate and sealing grease mess to cleanup...its a little faster method.....but also not as accurate..but its as close as .5 CC accuracy

you have to constantly keep pouring CC-fluid out of burette
at a very steady pace..and at a slower pace...keeping the burette end just an inch or less above the fluid surface to prevent disturbing waves..to increase CC-accuracy reading

if you are looking for a quicker less messy way..but don't mind a lttle loss in accuracy of .5 CC volume
it might be of interest ???

Stay with the Old-Method if you are dealing with Sanctiong Organizations and Rules !!!!!!! Larry Meaux (meauxrace2@aol.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

 

[sbc]

Sorry to disagree, but it seens that with this method
the head or block surface would need to be perfectly
level. I don't mind the grease so much as the water.
I use a shop vac to suck up the water.
Since you already have a burette, a pc of glass will
do & may have less error. We have a cc rule here at a northeast oval, along with a compression rule checked
with a 'whistler'. Therefore I also have to ck piston
cc including deck height etc... closely.

 

[evelrod]

Larry, that method sounds like a lot more work than the tried and true. I think I'll pass that one up and stick to my burette and polycarbonate sheet. I sometimes have used water, but most often not.


Rod

 

[MaxRaceSoftware]

Rod and SBC if you read my post carefully ..
i'm not saying the Bridge-Point CC Method is more accurate

i'm just mentioning an alternative method to CC'ing that some one might be interested in

it can be a little useful..like if you have the
cylinder head already setup in the "head resurfacer machine"
....and you are needing to take a bunch off the
surface to get the chambers to a certain CCs ....

and especially if you are shaving a new-style you haven't
checked out before ....you can mill the head .010" off
then check how many CC's per thousandths
you are taking off with the Bridge-Point method
fairly easy .....this would be very hard or almost impossible to accomplish if you tried to measure the head with a plate ....you would have to have a plate with the hole in the middle and be willing to "chase" the air bubble around....impossible sometimes with heads like BBC or SBC that have valve margins sometimes sticking above decks

Usually the Bridge_point method shows you
for example 60.0 CC ..but in reality its 60.5 CC
..it gives you a +.5 CC cushion ..some engine builders don't push their CC chambers closer than this

i personally push my chamber CC to .25 to .50 cc from NHRA
specs and keep ports 1.00 cc from max NHRA specs

Larry Meaux (meauxrace2@aol.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

 

[evelrod]

It sounds OK, Larry but, I'll stick to my plate with 'the hole in it'. As for valves sticking out above the head surface,a common practice on hemi and semi-hemi heads that I work with, I have a spacer plate or ring, rather, that I know the exact volumn of. Actually, I had the ring glued on a piece of glass but I dropped and cracked the glass. Now I sorta slickem together! Still works OK.

I have posted a question, or a little quest for you in the "Engine and fuel engineering" forum, have a look.


Rod

 

[evelrod]

Oh,yeah, I forgot to say that I sometimes use water, but most often I use 'antifreeze' . It has a color to it, it's the right viscosity and I usually have a few bottles of it around. It also is quite consistent in density due to temperature changes. A little messy, but I 'suck' the stuff up with a 50cc syringe when I'm done.


Rod

 

[MaxRaceSoftware]

Rod... i use Valvoline wheel bearing grease Part # 632
to seal the PlexiGlass plate to the heads..it has pretty good adhesion to keep the plate from moving around .

NHRA tech officials use a tube of grease and squeeze
a tiny line around the chamber's edge when they CC-check heads .....this stuff works really great ...but i don't
know what it is (black in color)

Have any ideas on types of grease ???

i guess i have to call NHRA tech guys and try to find out the exact kind of grease they use ? Larry Meaux (meauxrace2@aol.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

 

[evelrod]

Naw. No idea what they use, I use whatever is handy, usually StaLube Moly grease(black in color). It's in a tube and is easy to manage. Sometimes I use LubriPlate,(white)--- an old can I've had for 40 years and still an excellent general purpose grease.


Rod