The Floyd Brothers 68 Barracuda Fastback

Kev · Post by **Kev** » Wed Apr 22, 09 12:21 am

Yep, heat transfer passage. If the manifold doesn't have a corresponding hole, all's good. If it does then cut some shim steel and sandwich it between the gasket and the head to block it off (hold it in place with the trusty silicone. The last thing you need is heat under the plenum, hence air gap manifolds. When putting the manifold on totally clean the block and head surfaces then evo stick the front and rear cork gaskets to the block and wait 'til they are totally dry. Then copious, but not over the top, sealant round all the inlet ports and water ports using the included plastic bits to line the gskets up on the block. Then more silicon on the gaskets (including the cork ones) and oodles of it on the edges of the cork bits (the "forked" ends on the head gaskets can be cut off) where they meet the heads. In the past I have been in a rush and left the plastic location pieces in when bolting down the inlet and had no problems, in fact it was way easier! Don't forget when putting the exhaust manifolds on to liberally silicon the outside studs/bolts as these go into the water jacket. You will have to guess on the torque of the inner inlet manifold bolts, but in general it is FT!

Kev · Post by **Kev** » Wed Apr 22, 09 12:26 am

Nothing worse that first run at the Nats and getting pushed back for leaking water to find that when you rev it a drip of water is exiting from behind the block where the inlet meets the head in the corner.........

Gareth · Post by **Gareth** » Wed Apr 22, 09 12:46 am

Thanks for the info Kev

We had the rear exhaust stud leaking on the old /6 as it also goes into the waterjacket so we're wise to that one.
The heat transfer passages are new to us as they ain't on the six, so thanks for clearing that up.

Philth · Post by **Philth** » Wed Apr 22, 09 8:19 pm

Just for reference, the gap you see around that middle passage on each side of the heads (that looks like a water jacket) is just part of the head casting and doesn't have to be filled with anything.

It's the hole that the manifold is covering up that gets blocked off.

Anyway, good work fellas!

Gareth · Post by **Gareth** » Wed Apr 22, 09 8:34 pm

Cheers Philth

Stay tuned for more dozy questions as we stumble on with it at the weekend

Stu · Post by **Stu** » Thu Apr 23, 09 8:17 am

Kev wrote:You will have to guess on the torque of the inner inlet manifold bolts, but in general it is FT!

Edelbrock site reckons 25 ft./lbs.

Does that seem right?

Was going to ask about the form for installing the intake manifold, as I'd heard it was a right old game!

Any advice on the gaskets to use? (Other than the cork front and rear?)

Have 3 sets, two types. Metal or otherwise? What does who recommend? What's the pro's and con's?

Guy · Post by **Guy** » Thu Apr 23, 09 9:40 am

I would not use the pressed steel unless you are using the stock anchor, if you are using an aftermarket intake I would use the ones at the bottom of the picture. I always found that they give a better seal against a aluminum intake.

Kev · Post by **Kev** » Thu Apr 23, 09 3:42 pm

Guy's right, use the composite ones and use the little yellow things you didn't know had a use in the gasket set......

Stu · Post by **Stu** » Thu Apr 23, 09 4:05 pm

Kev wrote:use the little yellow things you didn't know had a use

You're absolutely right, had no idea what they were!

Cheers Chaps

Stu · Post by **Stu** » Fri Apr 24, 09 1:56 pm

Was looking at a picture from MM Magazine and then reading back through the advice. Want to get this clear in my own mind now.

There are two holes / ports in the centre of each head on the inlet manifold side. One rectangular one and one like an upturned "U" above it. The U I understand is the heat transfer port. Do I take it that the rectangular one underneath it is the same port? Are you saying to block off the rectangular one and leave the U shaped one open?

There is a corresponding rectangular hole in the inlet manifold on each side.

Being a dunce, no doubt, but have to ask to get it right.

Blue · Post by **Blue** » Fri Apr 24, 09 6:09 pm

Yes it's the inner port, it goes directly into an exhaust port. You could block off the whole lot if you want. I used to use thin stainless shim that some cars used to have on the back of disc brake pads.

Stu · Post by **Stu** » Fri Apr 24, 09 7:57 pm

Cheers Blue.

Out of interest, why the hell are the ports if it's better to block them up? Will it really make any difference if they're not blocked?

Won't it just serve to add a thickness and make the seal bad on the gasket if anything is sandwiched in there, too?

Wierd one, this.

Post by **TyreFryer** » Fri Apr 24, 09 8:16 pm

As I understand it, the reason for heat transfer through the intake manifold is to get the fuel dropping into a hot plenum causing the fuel to mist and disperse better and therefore burn more efficiently when sucked into the combustion chamber. The stock iron intake has matching holes for the ones in the heads Stu.

What intake are you using? The Air Gap I fitted just blocks them off anyway, no need to add shims?

Stu · Post by **Stu** » Fri Apr 24, 09 8:29 pm

Jim did explain that to me yesterday, in fairness, but I think it's just dropping straight out the other ear.

Eddi performer, Martin. Has matching hole for the rectangular port, the inverted U pokes over the top.

The matching port is the one that makes me ask if it's necessary to block it off? Still unsure as to the added thickness that will give in that spot and the effect on the seal also.

Not doubting the advice, just trying to understand.

Post by **TyreFryer** » Fri Apr 24, 09 8:51 pm

"If the carb being used has inadequate fuel atomization, the cooler runners can actually detract from output, so be sure to use a carb that does a good job on mixture preparation."

http://www.popularhotrodding.com/tech/0 ... index.html

I'm not sure what the pros and cons for cooler fuel delivery are Stu. It seems to make sense that hotter, vaporised fuel will burn more efficiently. But then why do Edelbrock make the Air Gap to keep the fuel cooler? I guess it may be other changes that demand cooler fuel delivery?

I'm sure someone will be along in a minute.