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-   1st Generation Specific (1979-1985) (https://www.rx7club.com/1st-generation-specific-1979-1985-18/)
-   -   13b downdraft manifold? (https://www.rx7club.com/1st-generation-specific-1979-1985-18/13b-downdraft-manifold-611756/)

josh...just josh 01-06-07 11:31 PM

13b downdraft manifold?
 
I'm going down after class :fawk: (happy to be back in school...) monday to see what can be done, but I'm sensing a rebuild. I bought the car expected that but I was optimistic.. anyway hopefully it's somewhat rebuildable (I have 2/3 compressions on the rear, someone told me that my rear iron is probably toast fpr the side seal :mad: ) Anyway since this will not be an everyday car I'm considering a street port and a carb swap for simplicity sake. My question is that I saw a carb upper manifold (meaning I assume that you use the stock efi lower intake and can bolt a carb on top after plugging the ingecters) I dont remember where and I think it was sidedraft. does anyone know where I can find a manifold like that but for a more common (i.e. holly) downdraft?

josh...just josh 01-06-07 11:38 PM

I found some downdraft manifolds (the whole one). I might have made that up about the upper, dont even know if the manifolds are split. anyway, would a normal 650cfm holly work for this?

Rx-7Doctor 01-06-07 11:55 PM

The recommendation for a street port 13b is a 600CFM.

85rotarypower 01-07-07 02:31 AM

The recommendation is a 600cfm, but a 650 will work just fine. Either go with the RB holley, or use an Edelbrock 600CFM like I am. I've got a stockport NA S4 engine running quite nicely on the 600 edelbrock performer series. Seems to really like a lot of fuel though.

broke7 01-07-07 08:12 AM

run a side draft with the rb beat upper manifold very easy setup to tune

josh...just josh 01-07-07 08:39 AM

the rb upper is for a Dell'orto carburetor, I couldn't find those anywhere. Everything that I read said that they dont make them anymore

Rx-7Doctor 01-07-07 09:39 AM


Originally Posted by josh...just josh
the rb upper is for a Dell'orto carburetor, I couldn't find those anywhere. Everything that I read said that they dont make them anymore

That manifold also fits Weber/Mikuni and OER carbs which there are plenty out there. IMHO the side draft carbs are a better choice.

Naegleria_Fowleri 01-07-07 09:58 AM

I have a Holley, and before the engine went bye bye on me, the flat spots around corners would kill you. The carb was a good line - so long as you kept going straight. Go with a Weber, Mikuni, or OER Carb. Simplicity makes them much easier to tune and they don't get flat spots half as bad as the Holley does.

spoolin 01-07-07 12:43 PM

i wonder if the racing beat prepped holley does this or if it is magically cured with the wave of mederer's magic wand? i am buiilding a bridge at some point when i have the time (and chassis-i have all the engine parts) and am debating on using the 650 douple pumper i have or buying the racing beat version. ive heard many good things from owners who have the RB prepped ones about just bolting up and goin' with no tedious tuning or troubleshooting

1badFB 01-07-07 03:21 PM

An old trick I have seen done on old nikki or maybe hitachi carbs was the installment of 4 springs in the barrels of the carb below the venturi.
While your driving around normally, the fuel will flow past the dangling springs with little or no noticable effect, leaving a bit of fuel condensed on the springs surface.

But...when the car is turned hard and subsequently starved of fuel for a fraction of a
second where you would have felt a lean bog, the fuel on the springs will atomize in the oxygen rich air and add the little bit of fuel needed that the carb just couldnt give you.

This may sound crude but it has shaved seconds off lap times on a short track for people I know. An old racers trick, but I dont see why it wouldnt be an option for those who experience starvation when cornering (ie: you holley guys). Just make sure that those dangling springs are gonna stay in the carb! haha

Siraniko 01-07-07 08:28 PM

what is this crap
 
http://img.photobucket.com/albums/v3...r/DSC07310.jpg

nick812 01-07-07 08:44 PM

Wacky I have seen that pic so many time but dont know if i ever seen the rest of the car.

josh...just josh 01-07-07 08:49 PM

man I like the way that looks...normally I'm against all things carb'd, but it just cleans up the engine bay so much. I know that a lot of things can be taken out of the SE's engine bay, but nothing simplifies it like a carb.

josh...just josh 01-07-07 08:57 PM

How is the car to live with with an aftermarket carb? Does car have problems with engine flooding like with the efi? does the car stumble or hunt when you drive it. the fact that all of these sidedrafts don't have a choke makes me wonder...Iowa can be cold in may

broke7 01-07-07 09:42 PM

got a dellorto setup i will swll you and it does have a choke

Siraniko 01-07-07 09:54 PM


Originally Posted by nick812
Wacky I have seen that pic so many time but dont know if i ever seen the rest of the car.


here ya go.
http://img.photobucket.com/albums/v3...r/DSC07327.jpg
http://img.photobucket.com/albums/v3...r/DSC06996.jpg
http://img.photobucket.com/albums/v3...r/DSC06988.jpg
http://img.photobucket.com/albums/v3...r/DSC07316.jpg

Rx-7Doctor 01-07-07 10:32 PM

48 IDa weber/2nd gen alt/2nd gen fuse block/Msd blaster coil/2nd gen leading coil/MSD 6AL/relocated battery/inline FPR with top mount guage/adapter block for mechanical guages/2nd water pump housing/fiero/taurus fan/modified camber plate/fram oil filter(WTF)/lots of nyties and a pair of red cutters. Did I leave anything out?:)

josh...just josh 01-07-07 10:57 PM

I thought the 48 IDA was sidedraft not down? gorgeous engine bay...love the simple. it seems to me that an EFI rotary takes a lot more to make work than an EFI piston engine. I have no idea what half the sensors under my SE's hood are!

nick812 01-07-07 11:06 PM

LOL Thanks wacky i have seen pics of the outside before just didnt relize it. I am getting ready to swap to all mechanical gauges. I am doing the 2nd gen coil and 2nd gen fuse box. LOL seems like I am going the right way with this.


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