Re: was timing, now Engine Compartment Hot Air Exit

["James J." <m1garand@speakeasy.net>]

James Nazarian wrote:

> I read in a summit racing tech tip that when placing a cowl induction scoop
> you should align the opening roughly 1-2"s from the windscreen in order to
> take full effect of the high pressure area in front of it.  
I think James N. is absolutely right, 1 to 2" is about as far away as 
the opening can get.  Part of the equation is that it not only has to be 
a "high-pressure" area relative to the atmosphere, but it has to be 
"higher" than the area you want it to flow into.  When a cowl induction 
system is ported into a carb, which is at engine vacuum, you'll 
definitely get flow.  Some parts of the engine bay could be at a 
higher-than-atmospheric pressure due to a ram-air effect (probably near 
the front), some could be at atmospheric, if the air isn't moving at all 
(probably towards the firewall) , and others could be 
lower-than-atmospheric if there is some air-flow in the region (around 
the block).

I'm eagerly awaiting a fiberglass MGC hood (should be here 
tonight!!!!!), but I've heard that it still won't clear a rover EFI 
plenum.  I have found a small hood-scoop on the web that is intended to 
have it's opening face forward to allow air in, but it has roughly the 
same shape and low-profile as the overall MGC bulge if it is turned 
around (opening backwards).  I hope that this will not distract from the 
lines of the B (um, C?), will allow clearance for the EFI plenum (or 
carb untill I get the EFI thing worked out) and will aid in hot-air 
extraction w/o making me look like a refugee who has been hiding out in 
the J.C. Whitney warehouse for too long (Ooooo, Look... Fuzzy dice and 
neon tubes for my rocker panels!!!).  I'll post a link for the scoop 
when I'm on my other PC.

There is a fellow on the web who makes a fender-vent for the MGB, that 
goes on the area of the fender between the wheel well and the door (like 
a Corvette).  It has 3 vents and looks kind of like gills on a shark.  
These could easily be used to suck air out of the bay (engine, not 
Chesapeke) .  The only problem is that the guy doesn't seem to want to 
sell them very much.  It's a father & son operation, and the son makes 
them.  The father has called me back, as well as a friend of the family 
who has used them, but the son apparently hasn't decided on a price.  My 
glass fenders from speedline haven't arrived yet, so I'm not in a huge 
rush yet.  They also told me that they could possibly make a 2-vent 
version if it would fit better behind the sebring flares.  We'll see.  
I'll post the link when I'm on my other PC.  Maybe if a few people are 
interested he'll get in gear and come up with a price.

There have been some really informative posts lately!!  I wish I could 
find the smoking gun, though, that allows some MGB V8's below the 
Mason-Dixon line work fine, while some up in Canada are overheating, 
even though many of the same precautions have been taken.  I think the 
RV8 style exhaust makes the largest difference, from what I've heard, 
followed by a shrouded aluminum radiator.  My 2-cents from reading 
posts, having neither installed yet.
James J.

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