[joew]

I am in the final stages of a head gasket job on my 85 Veloce. The head has been rebuilt and machined flat, etc. Looks beautiful!
Cams are turned in slightly inward from their marks as this is supposed to provide a slight increase in performance...looking forward to that.

The Alfa expert that remanufactured the head also suggested I install a "baffle plate" in the exhaust side of the block. The purpose of this block plate is to simulate the older block configurations whereas there were channels within the casting that directed positive flow onto each cyl. sleeve.
With US emissions, etc., the newer blocks elimnated that dedicated flow technique and opened up the casting channels to provide more of an indirect flow to cool the top end of the engine. It is said that this indirect flow allowed for increased operating temperatures and better emmission numbers (lower).
Anyway, this plate simply drops in to the exhast side of the block, settles in just below the bloc-to-head surface so as not to obstruct the head gasket seating, and has a (4) 1/4" holes to "squirt" positive flow water onto teach cylinder.

Has anyone used this baffle plate without success? Just thinking or hoping for some positive/negative feedback BEFORE I reinstall the newly refurbed head.

I have attached some pics of the plate installed. As you can seee, the plate is "dimpled" with pliers towards each head bolt so the plate is "pushed back" against the engine block and forms channels.

Looking for your thoughts and experience on this one!

Thanks in Advance,
Joe

 

[Elio Comello]

You will get much more noticeable performance improvement if you replace that restrictive one piece exhaust manifold, with pre 74 or 90 on two piece manifolds. They bolt right on (you will need to do some downpipe work however). Also a less restrictive CAT (I used a magnaflow 94004) will give noticeable result.
I can't comment on that plate mechanically, but I am concerned about electrolytic corrosion between the plate and the engine alloy. Iron is tolerable because it is not as "active", but a sheet metal plate...galvanised?.....
Are you going to race the S**it out of the engine...if not...why do it? I am not aware of ant cooling deficiencies.
BTW the restrictive one piece manifold would raise the temp.
Just my .02US$...
Elio

 

[Alfastruns]

Why is the #2 Exh looking weird ?


Wouldn't waste the effort on baffle

 

[joew]

Elio,
The plate is a thin piece of aluminum ...compatible wit the block?? Probably.
I understand your concern RE electrolosis, however this should not be a problem with aluminum on aluminum.

As far as racing.........none. This will be used as a neighborhood cruiser.

I can pull it out if I hear anything negative. Just wanted to throw it out there.

Thanks,
Joe

 

[joew]

Alfastruns,
The exhasut manifold seems to be modified by the PO. Real ugly...I agree. Not sure why it was hacked like this. I will use a couple of robust machined washes, trimmed flat on edges to fit the manifold flange when bolted back on.

My goal is to get this baby running, then look at a decent header/exhaust system.

The plate is already installed...so no real hassle there.
thanks,
Joe

 

[traga]

I'm skeptical about the benefit of the baffle. Did you Alfa expert say if there's a problem with cooling of the cylinders without the directed flow. I've not heard this come up as an issue. As to the emissions regulations not all steps to reduce emissions are detrimental to performance. A hotter combustion chamber may just lead to a more efficient burn which should not reduce power, may even be a plus. I'm no combustion engineer though . Furthermore, I personal would not put something new in unless I had a good reference on the specific configuration that had been successful in the past (i.e. proven), otherwise it's a bit of an experiment. Maybe you have this detail and it not an issue. After having said all that, my newest Alfa is a 1974, so I don't have much creditability on the 1985s.
Regards, Al

 

[joew]

Al,
Many Thanks for your input.
I tend to agree with you in terms of "not proven". I can only go by what the Alfa guru has told me.
I am now slightly hesitant to keep this plate in???

Thanks,
Joe

 

[head gasket]

I wouldn't go with the plate, nor would I mess with the timing unless you are building a seriously modified engine. The EFI will try to compensate for whatever timing errors there are and performance will end up suffering.
I agree with Elio about the exhaust manifold, a good set of headers are the biggest bang for the buck.

 

[joew]

Head Gasket,
Thanks for your input. I did not realise that the EFI would try to compensate for the "off spec." cam orientation.
I guess "stock is best" as they say!

Many Thanks,
Joe

 

[Andrew]

I 'spect the header modification resulted from having to cut off some studs/nuts, or use an oversize stud/bolt on that cylinder.
These cast 4/2 manifolds are not bad for the rpm range of a Bosch engine; 62-74 Weber/Spica manifiold might be slightly better, probably measurable only on a dyno.
Andrew

 

[joew]

Thanks Andrew,
I would probably use a fabricated header if I were to change it. The one on the car now, as ugly as it looks, seems to work OK and had no exhaust leaks.

My priority is the head job and I am puzzled why no members of the forum have any experience with this aluminum plate that my Alfa guru suggested I use.

Thanks,
Joe

 

[Skid]

You will get much more noticeable performance improvement if you replace that restrictive one piece exhaust manifold, with pre 74 or 90 on two piece manifolds. They bolt right on (you will need to do some downpipe work however). Also a less restrictive CAT (I used a magnaflow 94004) will give noticeable result.
Elio

Is there an easy way to mod the original down pipe? Can a '90s one be made to fit? I have a couple sets of the early two piece manifolds but haven't found a downpipe for a reasonable price.

 

[Andrew]

They're pretty different. The standard Bosch type has two vertical pipes, right next to each other, mating to a single piece manifold with two cast in pipes, with four attachment bolts. The 62-74 type has two separate manifolds 1/4, 2/3 that dump at an angle near the bellhousing, with six bolts.
Andrew

 

[Elio Comello]

Andrew, my experience is different.
First, the pre 74 anr the after 90 manifolds are similar, but not the same...the after 90 are somewhat beefier and with somewhat different geometry in order to acomodate the power steering.
The manifolds 1/4 and 2/3 bolt directly to the head (exhaust). Each manifold has 2 bolts where it connects to rhe downpipe.

Assuming you are using pre 74 manifolds, the Centerline OE405 ($116) will do nicely, but you will need to add the O2 bung. AND if you are in CAT country the front muffler needs to be replaced by a CAT (Magnaflow has one with an intergral 02 bung.

I was able to use a post 90 two piece manifold and rescued the downpipe from a failed OE CAT arrangement.

In any event the downpipes combine just before the "hanger" at the bellhousing. A good muffler shop with mandrel bending can make you a downpipe from the new 2 piece manifold to the existing "hanger". But it is cheaper use the downpipe of the OE405.
Hope that makes sense.
Elio
I can send you pictures.

 

[papajam]

The purpose of this block plate is to simulate the older block configurations whereas there were channels within the casting that directed positive flow onto each cyl. sleeve.

Not exactly.

While the plate does restore the coolant flow pattern of the earlier blocks, it has nothing to do with sleeve cooling but everything to do with cylinder head cooling. Without the plate, coolant flow to the head is compromised which may result in a cracked head.

 

[Skid]

Thanks Andrew and Elio for your help. I'd only seen IAP's ~$240 pipe which was more than I wanted to pay. The Centerline pipe looks like a much better deal.

 

[joew]

Jim,
Sounds like you recomend that I keep the aftermarket aluminum plate in the block?
You probably know the "inventor" of this plate retrofit??

I bought the plate and I was not sure if I should use it or not.

Thanks for any insight you may have!