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Hello all, new here. ive been buliding this second gen rx7 for about 2 years now, started with a stock 302 from a junk yard. I went threw 2 different 302's from 2 junk yards. They both went out on me so for the last 6 months ive been buliding a 347 stroker. Its got a 4 barrel eldelbrock carburetor, msd 6AL, msd coil and a msd pro billet distributor. KB hypereutectic pistons. Comp Cams hydraulic roller lifters, comp cams 0.544 lift roller camshaft. PRW 1.6 ratio roller rockers. D.S.S. racing main support system and windage tray. Flowmaster mufflers 2 1/2" true dual exhaust, bbk shorty headers. Re-built C-4 transmission, TCI torque converter. The carb is the only thing i didnt buy brand new it came on the stock non h.o 302 I dont know what cfm it is but i know i need a new one.

Finally got it in and got it running pretty good. Had some issues trying to time it. My timing pointer has a circle and a straight edge i wasnt sure which to get my timing from. But i think i got that figured out it runs decent and starts up every time. My problem is when i tap the throttle the carb pops really loud and kills the motor. Havnt tried to drive it yet its on jack stands still but if Im smooth with the throttle it revs just fine. It goes into gear too. Im using the stock fuel pump in the rx-7 but i have a fuel pressure regulator so im running around 5 psi. Is 5 ok? Any advice is very much appreciated i've worked very hard and spent all my money on this car. I really want to get it atleast drive able so i can take it to a dyno and get it tuned right. This is my first build so i could use some help. Thanks in advance!
 

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Five psi is a good starting point, as is the 12* of timing. These may need adjustment before you are finished though.

It sounds like your accelerator pump is not working as it should. When it is running, and you move the throttle at the carb, can you see the accelerator pump squirting? One thing to think about is your 347 moves a lot more air than a stock 302, so you might need to make the accelerator pump squirt more gas than it does now.

BTW, Welcome to the forum! You'll find many answers here. :)
 

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I havnt tried to look down the carb when its running seens how it pops so loud when i tap the throttle. But ill try that later today. Does anyone know about the timing marker/pointer im talking about? How it has a straight edge and like a circle bubble, im supposed to get my timing from the upper straight edge right? It came on the 86 302 block. Is it possible that this carb has to low cfm for the 347? Could that cause it to pop loud only when i tap the throttle? Thanks for the reply!
 

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Discussion Starter #5
one more question... Yesterday i pulled all my plugs and noticed that 4 of them were clean and 4 were really black. These are brand new plugs too put them in less then a week ago. What could cause this?
 

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Was the black dry or wet? If it was wet, did it smell like gas or oil?

I have always timed at the edge of that gauge. Don't know if it is right or wrong. :)
 

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they were wet, i pulled them after it wouldnt start a few times figured i flooded it. i got it to run after that. just thought it was weird half were black and half were clean.
 

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Your popping could be timing related. I had my distributor one tooth off and it started fine and idled fine. When I drove it though, it had no power. So my question is, are you sure you have the distributor in correctly? And not one tooth off?

Was the wetness on the plug oil or gas? If it is gas, you have a problem with that old carb leaking fuel down into the intake. Since the carb is almost certainly too small for your 347, and it is the only used part, I'd suggest a new carb.
 

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Discussion Starter #10
Your popping could be timing related. I had my distributor one tooth off and it started fine and idled fine. When I drove it though, it had no power. So my question is, are you sure you have the distributor in correctly? And not one tooth off?

Was the wetness on the plug oil or gas? If it is gas, you have a problem with that old carb leaking fuel down into the intake. Since the carb is almost certainly too small for your 347, and it is the only used part, I'd suggest a new carb.

Yeah i suppose its possible its one tooth off, i've pulled it 4 times already trying to get it right... everytime i have to pull my radiator out just to turn the motor over. Cant get a breaker bar on the crank bolt since i put the 347 in. I had just enough room with the old 302, new balancer sticks out just a little further i guess. really sucks tho lots of work to just turn the motor over. and i think they were wet with gas but i had just tried to start it a few times so it could of been flooded. I agree i need a new carb im just broke right now but i will be getting one asap.
 

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Does anyone know of a way to turn my motor over without getting a breaker bar on the crank bolt? If so please let me know!! It would save me half a days work, otherwise i have to drain the coolant, radiator, belts, electric fan, shroud everything has to come off just to find TDC. thanks for the help
 
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