Converting a Performer RPM intake to a Spreadbore

[road chicken]

Has anyone ever done this and if so what were the problems encountered or issues you had. I won't go into great detail but I am thinking about doing this to an Eddy Performer RPM so I can mount a T-Quad on it. I don't have room for the adapter plate, ( and really don't like them anyway).
My thinking was to have material added around the secondary area and then have it bored for the TQ valves. Smoothing / blending the secondaries out the to the plenum. The right side should be no problem but the left side might be of some concern. Would this affect the distribution characteristics significantly?

 

[AMX364]

Something very close. Yes it can be done, BUT it can not go back if you do not like it. Did on a FE428 PI intake for Holley 2 barrel Projection system. Little grinding and test fitting needed and use of half round files.

 

[twinscrew698]

road chicken,If you do this can you post pics?
Interesting idea to see if it could be done.

 

[62 Dart Convertible]

Interesting idea.
I have never tried this before, but sounds like something I would be willing to do if a satisfactory gain was there to be had. I'm sure a good job could be done by those competent with a TIG welder, air grinder and a mill, and how well it turns out depends on their skill and care/time taken. It may well change it's flow characteristics, so I would first take the advise of a competent head/manifold flow specialist. I'm not sure the gains would justify the effort though...
Good luck and please let us know how you go with it.

 

[road chicken]

I looked at Eddys other applications and the closest to the RPM for the B block is the SB chevy manifold which has a spread bore pattern, but very similar runner routing. I think what I will do is copy what they did. So building up the material then machining and final blending. All it all it shouldn't be too difficult, ( famous last words just time consuming.Which is why you're always good to a good machinist / job shop!!!
It makes sense for me because the combo I am running, ( 383/rpm heads/484-284-108 cam, rpm intake and 800 thunder avs square bore) can really use the smaller primary s for improved throttle response and pick up a couple mpg out on the highway. That is what I want to improve. The 383 is relatively lazy on the bottom end- but picks up at 2500 like no tomorrow up to 6500. With those fat bores on the avs I knew this was probably going to be a issue and with any square bore carb because the combo really likes the spread bores characteristics. I was getting 20 mpg with a spread bore on a very similar combination with good low end response and a wicked powerband. So this is being done for those purposes and goals.
I will document the process and post the results however, don't look for anything anytime soon. This will be a winter project.

 

[Ron Ward]

Just a curious question here....

If you are going to go to the time and expense of adding material to the Edelbrock intake and then machining it for a spreadbore carb, why not just use an M1 intake that is already set up for a spreadbore?

 

[road chicken]

It's a street car that has to be all around good and I don't want to give up any low end or mileage. It a great combo now,but just needs the spreadbore to clean up a couple of rough edges.

 

[rumblefish360]

So if that is the case you need to find a old Holley Street Dominator. It will handle the TQ, it is a low no rise single plane with small runners. The intake will stand toe to toe with any intake for a street application. It will be one heck of lot cheaper easier and simple to do. You just have to find one.

 

[Ron Ward]

So if that is the case you need to find a old Holley Street Dominator. It will handle the TQ, it is a low no rise single plane with small runners. The intake will stand toe to toe with any intake for a street application. It will be one heck of lot cheaper easier and simple to do. You just have to find one.

Excellent suggestion.

 

[AMX364]

The Performer intake will take either square or TQ carbs but, is not as high rise as RPM intake.

 

[Herr_Poopschitz]

It's just aluminum. You can add material and mill/grind to your hearts desire. Making parts fit your needs/desires is the essence of hot rodding, and unfortunately becoming a lost art.

 

[road chicken]

All valid points.

Compared to the Dominator and Performer, the RPM is still a better manifold...ALL AROUND. Both good choices if your willing to compromise somewhere, I am not willing to do that unless I HAVE too. Yes I'm one of those that wants it all The Single plane is mush below 3500 and the Performer is limited to 5500, which is no good because this engine make great power up to 6500. The RPM matches both of these and has better overall average output than either of them. With the TQ I can eliminate the sluggish off idle response and pick up the MPG to 17-18 out on the highway without losing the ability to make some very expensive euro-trash tuck their tails in from 0-160mph.
Mr. P hits it on the head, ( thank you very much you have to be willing to go beyond bolt on to really make things work well where others are not willing to go.
I did see that the ford RPM does have a spread bore intake pattern, so the distribution question is answered.
I have this on a 71 air grabber car and I wasn't supposed to be able to do that either. Well a fiberglass base plate, a little measuring and trimming, and some vacuum hose and my AG is fully functional with the RPM intake.

Again, I appreciate the input, but the question really wasn't "should I do this", it was more of "has anyone done this before". What you bolt on is just a starting point.

 

[AMX364]

When I ground down that FE police intercepter manifold it had enough material to make the spreadbore pattern fit without issues, does the RPM have enough room. Use gasket is easiest to check. And I had the FE performer intake, but wanted to use the taller high rise.

 

[rumblefish360]

Unless you can heli arc/weld the aluminum it is impossible to do.

 

[road chicken]

The RPM doesn't have enough room as cast. The right side will need to be built up at the gasket surface. The Left side will require material built up the depth of the bore ( left side is the lower of the two. It'll be an hour or two sitting with the TIG welder and adding the material. From there it's another couple on the mill and maybe an hour cleaning up the edges.

 

[satman72]

Well, if you can do it yourself, it'll cost nothing more than time.


given that you're figuring 5-6 hrs worth of work, would'nt it be worthwhile to perhaps just get a manifold that already works with a spreadbore carb?

 

[Longroof]

Why not just get a later model cast iron intake? They really are not all that bad... lots of stock eliminator cars run them and I'd say those cars run pretty strong...

 

[rumblefish360]

Better off with a Performer or a M1 single.
Select the intake that suites the performance of the build and run the TQ.

 

[twinscrew698]

Question for anyone that can answer.
Will a performer with a Thermoquad fit with a N96 Ramcharger setup?

 

[road chicken]

No, there is no quick fix to where I want to go. I could down size the carb, or swap intakes to something easier, but then I lose performance somewhere in the curve. I'll grab the TIG and build up material where it needs it and bore and shape it for the TQ. Then I get as much out of it as possible all the way around. Just the savings in fuel should make the 5-6 hours up in a year or less plus I get to keep the WOT performance and better throttle response I'm looking for.