ok i have a 79 rx7 i just got car has an 850 cfm carb stock im with an adaptor rb header and exhaust and its bridge ported the car runs fine starts every time idles fine but when i rev it it only goes to 7k rpm and cuts out im not super familiar whit rotory motors so any help would be appriceated just trying to narrow down my problem could it be not enough spark ?

 

You need to upgrade the ignition

 

Carb is way to big. As much as I dislike Holleys on a rotary, a 650 cfm is more than suffcient for even for the most radical porting. Look into a DLIDFIS using a 2nd coil or an MSD set up.

 

thanks guys

 

ok so what in the hell is a DLIDFIS idk much about rotarys or there ignition at that i was a honda owner lol is there anyone in upstate ny who car tune this thing or atleast knows what they are doing

 

Tuning a carbed engine is a trial and error thing. Go down a size on one jet, drive it, note the feel. If it improves, try going down again, if that's worse, go back. If going down a size makes it worse, go up a size and try again. Do this with everything. When you get it running right, start playing with your timing, then rejet as necessary. The ignition is simple, and not really exclusive to the rotary. Search DLIDFIS using the search bar up top. That should yield the results you need. Basically it's a direct fire system, which runs the spark directly from a coil to the plug instead of through the distributor.

Oh and Troichoid is definitly right, your carb is ridiculously big. Sell it and get something smaller.

 

thanks guys im working on getting a 650cfm carb and possibly a rb manifold ill look into that dldfis or is there any alternitives. trying to keep prices as low as possible unemployment does not pay much

 

would a holley 500cfm 2brl work there pretty cheap like 250 bucks or i could take off the linkage on my 850 to make only 2brls work

 

A 650 dual feed/double pumper, 4150-4160 Holley is what RB recommends for bridgeports. If your's is a 1/2 bp with sp primaries, find an old Rotary Engineering dual DCD Weber carb set up. That's what I have on my 1/2sp-1/2bp and couldn't be happier with it after trying a 600 Holley and a Mikuni 44 PHH. I have yet to find anyone who can get their 1/2bp to idle as low as 800 rpm. I keep the idle at 1400 though for better throttle response.

 

Wow. Ok first of all, you'll never find much searching for the wrong thing. Everyone keeps forgetting the first I in DLIDFIS. Why is it so awkward to remember? I don't understand it. It's only seven letters. If you read the acronym as "dlid-fis" it's quite easy to remember all the letters as each one has a sound. Then you can search for and find all voluminous posts on the subject.

You can't have DLIDFIS and an MSD at the same time.
You can't have DLIDFIS and 2GCDFIS with the transistor trick at the same time.
You can't have DLIDFIS and 2GCDFIS with a GM HEI ignitor at the same time.
DLIDFIS can not be used with any other leading ignition upgrade. You have to pick one. DLIDFIS is to be used on leading only. Trailing can remain stock except you can move the trailing plug wires to the leading part of the cap, as can be done with any direct fire leading ignition upgrade.

I have not upgraded the igniton of a 1st gen RX-7 so I am not a good person to ask. I've only done older points ignition upgrades to DLIDFIS in old schools like REPUs and some rotary conversions.

 

Id try a 500 cfm 4 barrel if you can find one unless your spinning 10k+ with a turbo, I see (from my own trial and error)no need for anything bigger than a 500 unless your spinning it that high .Dont forget your ballistic blanket wrap around the tran for when it goes at that high a rpm I had a 650 edelbrock with a turbo streetport it would pull heavily from 2.8k till 10k I had problems with losing traction in 3rd gear ,I would have to back out of the throttle a little just to keep it straight

As far as the direct fire setup im flirting the idea myself I just dont know anyone personaly that has done it where I live, Id love to see it first hand before I try it

heres another quick extra horsepower trick take your stock fan off and can it put on an electric fan with a decent airflow, youll like the results

 

i've only done the 2gdfis (using a 2nd gen coil, no Transistor trick) and that itself gives me a bit better gas mileage and seems like it pulls better and more even through out, but this is in a stock port engine.

 

thanks guys