One320B

I've been tweaking my '85 project a little more and I will admit I am not a carb guy. I've built numerous FCs, but my experience with FBs are limited (thus the reason I wanted one - to learn)



I'm running a holley 650 on stock ports, which I know is massive, but I also know it should run ok enough to drive.



Here's what I'm experiencing though.



Drove it about 1 mile down the road today, the whole time while going up to about 3-4K RPM it was very irratic, sputtering, etc. It SOUNDS like ignition, but then I went into 3rd gear it somewhat just bogged, then stalled. I have my fuel pump on a switch, turned it off and cranked. It would start up for a few seconds with the pump on, which led me to believe it was running really rich and probably just flooded it out. I towed it back to my parents house (where I've been working on it) but it won't restart.



I was fearful that it may have popped the engine as it just wouldnt start at all, but a poor-man's compression test confirmed 3 "puffs" while hot on each rotor. I will do an actual compression test next weekend to confirm.



Even a few weeks ago, while revving in neutral, it would break apart around 3-4500 and not rev much past 5K. Would this be that the carb is just too large or ignition. I want to do the DLDFIS system, but I'm also one who likes stock parts to be where they should before doing any upgrades, etc.



I also have not confirmed timing as the car has an irratic idle, (again...i know the carb is big, but i've had rotary pros tell me that the 650 will work)



Would it be the coils? maybe a bad pickup in the distributor? Too much fuel, i've dropped the jets down to the smallest I have (53). All the emissions are disconnected/removed as well.



Any thoughts would be appreciated. I did this setup to be able to drive the car enough to know if anything else was busted as I bought the car w/ a blown engine. So far everything works great and I should have my bridgeport engine done around february (thus the holley stuff).....

j9fd3s

sounds like ignition? in my experience carbs dont go bad

One320B

I didnt think the carb would "go bad" either. It was brand new, sat for a while, rebuilt then installed.



However, when I pulled the bowl off to swap the jets out - there was a LOT of white residue in the bowl. It was clean before. I'm not sure where that came from.



J9 - whats your opinion on the 650 cfm size for stock ports. When I mentioned "rotary pros" I referred to Mike (?) at Racing Beat from a few years ago saying they used to run 650 on stock ports but it wasn't the best route.



I'm just pissed because the thing wont even start now and my battery is getting weak from trying

j9fd3s

white residue = what? see the carb wont work right if you're not feeding in a liquid...



650 is prolly big on a stock port, but it should run....

trochoid

Pull your plugs, clean and dry them, then charge your battery and try again. 650 is really too big for even a streetport.

RX-7Doctor

I'm with trochoid on this one. 650 CFM is way too much for a stockport engine. That's all you are doing is dumping fuel and fouling out the plugs.



Your best to dump that carb setup.



If you are going to try and run it right now. The best you could hope for is to turn the fuel pressure down, install the 2nd gen leading coil and run a step hotter plug for the leading side.

One320B

I know the 650 is "too large" for the stock ports, however I did get some more detail on why it's ok to run it.



Since it is vac secondaries, for most of the time, the carb isn't running 650cfm.. closer to 325-350, which is almost stock carb rates..



If the secondaries do open its only under circumstances when the engine pulls enough vac and warrants the additional intake.







As for my problem - I found it mostly - and you all were/are right.



My POS Holley FPR was not working. My carb friends told me not to use, but its all I had... when I tried turning it down to 5psi from 7psi it just "broke" and lets the pump go straight through (which a holley blue will push about 20psi of fuel unregulated)... needless to say I made a custom "plate" with a drilled hold to manually regulate the fuel, jetted the carb down to 53s in the primary and put new plugs in.... it ran a TON better.



I've got a video doing some sliding around afterwards. It bogs a little between gears, but thats just some minor tuning. I'll have to play with it, but its running a lot better. The only side affect is the higher idle (1700RPM) for now - which I should be able to adjust. My FPR actually died again and held 0psi so the car just died, but thats where I left it. I'm assuming the plate I made filled shut and wouldnt let any fuel in.



No big deal - I now know the trans works, rear is ok and steering (minus a leak) seem to be fine which was my biggest priority before swapping in the bridgeport (which is why i have the 650 to start with).



The 650 does give the stock 12A a decent pump in torque though....