Porting intake

[opeldean]

if this works...we could cast up a bunch..like fishing weights

[kbishop]

You may want to consider casting this with JB Weld. I ported my intake using Bob's guidelines, breaking through in 8 places, and filled everything in with JB Weld 3 years ago. It is temp and gas resistant, easy to use, flows well enough to cast with, is machineable and inexpensive.

[opeldean]

jb weld sounds great....that may be the most practical

i found this too...instead of lead ignots couldnt we make lead diverters?

[tekenaar]

I understand the reasoning for running the wedge peak to divide the front two cylinders from the rear two for a progressive carb (32/36DGxV, Solex), but has anyone looked at doing it the other way (divide outer and inner cylinder intakes for a synchronous carb (38DGxV, 40DFxV)? Advantages, disadvantages, problems?

Bob?

[Paul]

RallyBob,

Have you ever tried or consisered trying POR-15 Epoxy Pudy for the "divider" inside the Intake Manifold? Reading the product info on the POR-15 web site, it would appear that POR-15 could handle the constant exposure with gasoline. The POR Expoy appears like it should be durable and tuff enough, but what about heat? The product information sheet says that it can be used to repair engine blocks, intake manifolds and cast iron.


What do you think, Bob?

TIA
Paul

[West Coast GT]

What about drilling through the bottom of the manifold, and into the bottom of the wedge, then tapping threads in the wedge?

Is there enough room between manifolds to allow this?

I just ran down to the garage to take a look, but really couldn't tell if there is room. And since its been years since I last removed manifolds, I don't want to trust it to memory.

[RallyBob]

Originally posted by tekenaar I understand the reasoning for running the wedge peak to divide the front two cylinders from the rear two for a progressive carb (32/36DGxV, Solex), but has anyone looked at doing it the other way (divide outer and inner cylinder intakes for a synchronous carb (38DGxV, 40DFxV)? Advantages, disadvantages, problems? Bob?

Personally, my reasoning for using the peaked divider was two-fold. First of all, I had always noticed fuel puddling at the bottom of the plenum, so I wanted to remedy this. Secondly, when porting the manifold to extremes, the plenum volume increases substantially. So by putting the peaked divider in place, I can actually reduce the plenum volume while increasing the flow from the porting.

Regarding running the divider the other way. I think it would partially block the entrance to the runners, and might impede the ability for both barrels of a synchronized-opening carb to feed one runner at a time (since only one runner at a time has a full 'signal' at a given moment).

I never took the time to go much further with manifold development. I figured the next logical step was to scrap the stock intake completely, and build one from scratch, develop that and then have them cast in quantity. Of course, then I retired from the Opel parts business, so I never got much further than a few sketches.

[houserc]

Question for all the mechanical and chemical engineers out there.

If the diverter was made of lead, wouldn't the fuel/air flow slowly eat away at it. Kind of like a scarificial anode?

Also, if it did eat away at it, would that take the place of lead additive to the fuel for the knocking?

I've got JB Weld on an RC engine that works fine.

[billiard13]

My cousin, a machinist, is forming up a 'tent' such as ftl made only he's using sheet aluminum... then making two end pieces (he hopes to contour them to fit the inside of the manifold better) he plans on welding onto the ends of the main 'tent'. Then he plans on cutting the bottom out and then welding the new 'hollow' diverter into the bottom of the manifold.

These are the initial plans, formed with the basis that cutting out the block of aluminum such as ftl did is much more time consuming than forming a diverter with sheet aluminum, making the latter not only quicker but more cost effective hopefully and possibly easier to produce in larger quantities as well.

I'll keep you posted on how it turns out, will be awhile as he's 3 states away and the manifold will have to make a round trip to him to be finished.

[RallyBob]

The manifold shown earlier that I ported had exactly this.....a piece of .063" thick aluminum sheet bent into shape and welded into the plenum.

However, the big issue is there are many types of intakes. I've counted at least 7 variations, and all of them have different plenum shapes. Add to that the discrepancies that may occur between each person porting the intake, and you'll find that no two pieces of sheetmetal will be alike.

When I ported that 'final' intake (the one pictured above) for the Carlisle giveaway a few years ago, I also ported one intake for our own opelgt.com site owner Gary. I did them 'assembly-line' style for consistancy, and made them from the same year/type manifold, but the plenum tents still had to be hand-fitted individually.

[oldopelguy]

With my own dubious skills welding aluminum, I think I'd probably introduce a lot of warpage to the manifold if I wee putting in a large piece. I think I would make a pair of inverted "V" incisions in the manifold, one on the inside edge closest to the head and the other opposite it on the outside edge. These could be made with any small cut off wheel, and ideally you'ld drill a hole clean through from one side to the other to locate the three points.

Once you had the 2 cuts made, a folded piece (or 2 flat pieces) of fairly thick sheet aluminum could be slid into the one side and through the plenum to come out the other, giving you your pent floor inside the plenum. Then you could weld in the piece in place to seal it on the outside of the manifold, where it would be fairly easy, and with the floor intact the warpage should be minimal. Also, if there were pilot holes drilled at the corners, the porting around and under the piece would be unnecessary, as it would slide through no matter what was underneath.

For you guys without aluminum welding facilities, depending on how close you kept the tolerances you might even be able to epoxy the piece in place. It's not being a structural element, after all, all you're doing is sealing the edges.

My $.02, and yes I'll try to photoshop a picture to explain it better as soon as I get my new camera working if anyone is interested.

[jimsky]

I ported a manifold using RallyBob's pictures and article as a guideline, but did not install a "tent". I just opened up everything as best I could. I broke through the stove mounting holes and plugged them solid with JB Weld. The JB Weld in the manner I used it, has been holding up just fine.

I was down right amazed at the performance improvement obtained. Not bad for a $5 eBay manifold, about $50 worth of materials and a few hours of work. Best and simplest bang for the buck mod I've done.

Seems like adding the "tent" as suggested in the "Torquer" modification really adds time and complexity. Just curious, is there any way to quantify the benefit obtained doing this mod?

I mean if a well ported manifold gets you, say...85% of the benefit you're going to get, is the last percentage really worth all the effort it's going to take? Or are the above numbers really wrong, and adding the "tent" is most definitely an untapped resource of performance that's worth the effort? Inquiring minds want to know.

[RallyBob]

The 'tent' adds a lot of torque and throttle response. It also tends to improve idle quality via increased idle vacuum. Simply because of the reduced plenum volume. To me anyway, it's worth it.

[opeldean]

I gave up on lead..JB weld has been tried and true..here is mine

3 steps follow;

[opeldean]

the shell forms the top or lid...i "dry fit' it first..then will cure to place with a second mix of jb weld

[opeldean]

i drilled tru the plenum floor in 2 spots with a 1/4 drill..this will become my "epoxy bolts"...even w/o epoxy glue..my dry fit is snug..

[opeldean]

lots of holes

[jimsky]

Bucky,
I'd just like to clarify that the JB Weld I used was to plug a very, very small hole made in one of the four stove bolt holes while porting. The hole was literally the size of the head of a pin, with a metal flake still covering it most of it. I plugged that bolt hole full and all the others on the manifold. I mechanically cleaned, chemically cleaned the inside of the holes, then filled them with JB Weld. You couldn't even find the repair inside of the manifold after it was made. And that hole is under a LOT of epoxy, so I wasn't too concerned. It has held up over time.

Bucky what you are doing with JB Weld, making a physical structure and gluing it inside the manifold is a far shot from the pin hole repair I did. I do hope the JB Weld works for you. RallyBob's porting article did initially detail how to use other epoxy; but he stated at a later date, that through experience he now felt that welding was the only sure fire method that he would recommend.

I always wondered what would happen if something like what you're building inside the intake manifold "let loose"....I mean where is it going to go? I shutter when I even think about it.

Like I said I do hope this works for you, but I don't want to feel I suggested JB Weld would be applicable for this kind of work.

[opeldean]

think about this:

in the design i have the jb weld entangled...it is epoxy riveted...it mushrooms internal and external.

even w/o adhesion..it cant go anywhere..unless it melts..it not a a stressed area as i understand it...

before i bolt the intake in ...i will have a pro mechanic inspect it..it was thru my discussions with him on saturday that i abandoned the lead idea...He was saying that jb weld is how he plugged holes in his manifolds..


i think there is alot of "prior art" using jb weld in an intake....not a
lot of prior art using lead...

my goal..was to have a way to "mass produce" a diverter...

well here you go..take my pre made shell and reline it to fit the uniqeness of your intake..so what if your plenum bottom is different....the "second mix of jb will allow a custom fit"



rally bob will you give jb your blessing or advise me to throw it in the scrap heap?..i really won't be offended...

opels rule.

[RallyBob]

Originally posted by bucky rally bob will you give jb your blessing or advise me to throw it in the scrap heap?..i really won't be offended... opels rule.

We'll just have to see. The time to check is on the first hot day,after a highway run and then a long idle time which will give a good heat-soak from the exhaust manifold directly below the intake. If that doesn't melt/break down the JB weld, it's gonna be fine.

Keep us informed!