TriPower and Edelbrock

[PaulProe]

Can anyone tell me if the Ford Tripower manifold (FE) is compatible with the Edelbrock Alum. heads?

Edelbrock tells me their heads are "medium rise" I don't understand "rise" and I don't know what the Tri-power manifold is

Thanks

Paul

[Carnut427]

First, an explanation of "-riser"...first came the Low risers, which allowed plenty of room between the air cleaner and hood. Then came the High risers, which were a race-only setup which needed a bulge in the hood for clearance. Finally came the Medium risers, which fit under most stock hoods and put out almost as much hp as the race-only High risers.
The Ford tri-power manifolds are low risers, which refers to the height of the carburetors in relation to hood clearance, but there are also port size differences between a medium riser head and low riser intake. The intake will bolt up to the Edelbrock heads, but the intake port in the heads is smaller than the corresponding port in the intake. Fortunately, there is plenty of metal in the Edelbrock heads so that you can open them up with a die grinder to match the intake ports. So to answer your question, yes, they'll fit, but need a bit of work for best performance.

Dan

[My427stang]

All the information above is essentially correct, however, to be totally 427 anal LOL the "riser" determination comes from the intake port location, however, the carb location ends up to do the same, so chicken versus egg kind of stuff

However, one bit of advice concerns me above. Most hardcore FE guys wont match the intake port to the low riser intake.

Matter of fact, most of us will do one of two things.

1 - Ignore the mismatch, because we know a low riser intake port angle isnt ideal, but we like the intake and want to run it
2 - Weld (or not quite as good, epoxy) the floor of the intake manifold to match the medium riser port and them port match for width

The reason is the short side radius (SSR) basically the floor of the intake port as it curves around to make the corner of the valve, is an area you want as gradual as you can for air flow

By opening the Edelbrock head to LR size, you essentially ask the intake charge to take more, and possibly a sharper corner by the time it gets its way to the valve bowl. At high RPM, this can even move so fast that the charge cant make the corner, and you lose airflow due to turbulence

By leaving it alone and ignoring the mismatch, you actually get a bubble of turbulent air in the intake, where the mismatch is, that acts like a ramp and really effects the airflow less because its so far away from the valve, and the head has time to bring it to the valve in a gradual corner. Seems illogical, but it is 100% true, that run from intake gasket to valve is infinitely more important than the intake gasket to carb.

The best bet is to fill the bottom of the intake manifold ports, and blend them as deep toward the carbs as you can. However, epoxy can loosen up, and welding 8 holes and porting them all aint cheap if you cant do it yourself

To make you feel better about ignoring the mismatch (even though it seems backwards), even Ford showed a 30 hp gain in the 70's with an SCJ 429 intake on standard heads. This is the worst mismatch you'll ever see (intake bigger too like this, but significantly bigger) , but B/L with the way air behaves, its better than hogging out the intake port floor on the head and affecting a nice clean flow to the valve

[Carnut427]

Originally Posted by My427stang

...the "riser" determination comes from the intake port location, however, the carb location ends up to do the same, so chicken versus egg kind of stuff...

I don't know if that's true or not, first time I've heard it. The book "Ford Performance" by Pat Ganahl says it refers to carb height. I'll let others chime in so we can get the correct answer...if I can learn something, great.
I'm familiar with the article where they put the 429 CJ intake on standard 429 heads, and as I remember the increase was 15 hp and worked well on the dragstrip. IMO the fuel will puddle in the low (mismatch) area and cause distribution fluctuations on the street, such as when stopping, turning, etc. Again, just my opinion, I haven't tried it.
I, like you, prefer medium risers, but here we have a gentleman who evidently wants to run a tripower setup, which is a low riser. 428 Cobra Jets are low risers and run pretty well. If this gentleman wants every hp he can get, he should do as you suggest. If he wants a hard running street engine, low risers are fine.
My 2 cents,

Dan

[My427stang]

If you listed the "old rumors and or myths" from Pat Ganahl's book, you'd have another book LOL However, I will see what I can find for documentation

Problem is with port matching to a low riser is you affect your SSR, any rpm range you do that is bad.

I'd wait for KC to chime in, but the power is in the bowl and transition to the seat, that is far more important than port mismatch.

Matter of fact, if I had a set of stock edelbrocks and a low riser intake, and was money limited (not saying he is, but if he was) I would IGNORE the mismatch, and spend my money on the bowl and seat transition, thats where the power is especially at low lift

Basically, I think we sort of agree on "build it for what he wants"

I am not chasing HP either, if he wants a good running street engine just bolt on the low riser intake but dont port

(or, epoxy/weld the intake if he really wants to make things line up, its not tough to do and you only have to go in an inch or so the way the intake floor is shaped)

Then if he wants to improve later, he still has a good set of med riser heads.

Finally, a 428CJ was a great motor, I have had fun in a couple, but if thats the level of power he wants, I'd advise a 390, with a modern cam and headers, it'll run right with it for MUCH cheaper. With a 428 and some work in the bowl, and all the usual upgrades, even with the port mismatch, its way ahead of a CJ league

[PaulProe]

I really appreciate the help on this.

I am waiting for the heads to arrive so I am unable to visualize the mismatch. I understand the manifold is lower than the port in the head, but approximately how much?

If I chose to match it, or at least get it closer, what type epoxy is recommended?

Thanks

Paul

[My427stang]

Its around 1/4 inch, maybe a little more. I actually have a piece of epoxy I save as a conversation piece from doing it once, I'll take a picture and you can see it

Generally, a company named Devcon makes good stuff, also Moroso A/B putty from Summit and the like works well. One thing you need to make sure is you grind it well and apply the epoxy ASAP, once the alum starts to oxidize again it doesnt like to stick as well

This is all Dremel-level work too if you use epoxy, not tough work

[PaulProe]

I am a boat and airplane (composites) guy so am familiar with epoxies - I know Devcon.

I thought it would have to be a filled material, kind a like JB Weld (which is nothing more than 30 min epoxy with aluminum filler - but a good epoxy)

I understand the surface prep and the problems of adhesion, just looking for as many tips as I can.

I can see going with as long a cure time as possible (typically means better strength and adhesion) and then also filling with aluminum powder so the two items as as close as possible to each other?

A picture of your piece would be helpful. Is it a section that flaked off or just a piece of epoxy. It will help me to understand what I am looking at

Thanks

Paul

[My427stang]

I just got home, I'll try and post a picture.

I used a cheap brand of 2 part putty with an alum filler, I also ground it one day, then put the putty on the next AM

So basically, I had 8 pieces that I lightly tapped with a hammer and they popped off in one piece. Ultimately they would have failed I think, but I changed to a med riser manifold.

The piece is the entire piece as it filled the floor, aside from the edges that didnt come off clean when I popped it off