help setting up carb....???

[kimcrwbr1]

http://www.ponycarburetors.com/default.asp?page=calculatingcfm read the section on timing.

 

[originalnitro]

What is the reason for 3000 rpm and 33 degrees I thought u set timing at idle?

2 reasons 1-. MDS fires 3 times per powerstroke and can make it hard to get an accurate timing reading. 2- setting it at 3000 with all the advance in you know it want be to much. This is the main reason racers use this method to set timing.

 

[baddad457]

37 to 40 degrees is dangerous on an engine with less than 12:1 compression the higher compression motors require more timing to burn all the fuel off.

UMMMM. NO...................... I've run 40 or there about(timing set at up to 20*BTDC initial) with a stock E6 and E7 headed 302's. and had no adverse effects. As long as they're not pinging, they're fine.

 

[originalnitro]

UMMMM. NO...................... I've run 40 or there about(timing set at up to 20*BTDC initial) with a stock E6 and E7 headed 302's. and had no adverse effects. As long as they're not pinging, they're fine.

there about sounds like someone cant remember. Pinging is not caused by to much timing that is detenation. Pinging is when the fuel ignites due to compression (either bad or wrong octane) before the spark. Detenation is to much timing igniting the a/f mixture to soon tries to push the piston back down as it is coming up. Big time engine killer.

 

[ford1386]

Well I don't have any pinging just a hesitation on throttle opening but I have a #35 discharge nozzle at home so I'll put it on tonight and see what happens, carb currently has a #31 in it now. Is changing the discharge nozzle to a bigger one gonna affect starting its not gonna put too much fuel in and flood easily?

 

[baddad457]

there about sounds like someone cant remember. Pinging is not caused by to much timing that is detenation. Pinging is when the fuel ignites due to compression (either bad or wrong octane) before the spark. Detenation is to much timing igniting the a/f mixture to soon tries to push the piston back down as it is coming up. Big time engine killer.

Sounds like someone hasn't had too much experience experimenting with timing........................................................

 

[originalnitro]

Well I don't have any pinging just a hesitation on throttle opening but I have a #35 discharge nozzle at home so I'll put it on tonight and see what happens, carb currently has a #31 in it now. Is changing the discharge nozzle to a bigger one gonna affect starting its not gonna put too much fuel in and flood easily?

Should'nt, its not that much bigger.

 

[originalnitro]

Sounds like someone hasn't had too much experience experimenting with timing........................................................

Dont need to experiment when you get it right the first time.

 

[kimcrwbr1]

Even seasoned mechanics don`t get it right the first time unlss you get real lucky every engine is a little different especially with aftermarket parts. If dicking with the carb dont work play with the timing. Advance it a little at a time if your worried but if it is running good you need not did you read the link I gave you from pony carbs send them an email I am sure they have alot more experience with the 302 than nitro. once you get the timing and air fuel right it will bring that engine to life. Too much fuel will ruin a engine also as it washes the cylinders down and can destroy the rings. Smell your dipstick if it smells like fuel change it and jet it down. Calculate the cfm on your engine and jet it accordingly in most cases bigger is not better. Where do you have the timing set at if it is at factory set it 10 degrees before to count for no vacuum advance and see how far it jumps at 3000 rpm. anywhere around 35 is more than safe.

 

[originalnitro]

kimcrwbr1, out of 43 sbf's (302/351w) i've built out of the small shop out back with hp ranging from 350hp to over 550 only 3 have came back only 1 of those had to do with timing and it his fault for dicking with it trying to run nos. I always use custom cams and set it up per cams designers spec sheet.

 

[baddad457]

kimcrwbr1, out of 43 sbf's (302/351w) i've built out of the small shop out back with hp ranging from 350hp to over 550 only 3 have came back only 1 of those had to do with timing and it his fault for dicking with it trying to run nos. I always use custom cams and set it up per cams designers spec sheet.

OOOOOOOOO !!!!! We got an "expert" here........................................................

 

[ford1386]

calm down guys.......... but anyway the #35 discharge didnt help it still has a hesitation almost seems worse but definetely not better????

 

[kimcrwbr1]

Sometimes the damper gets worn and the rubber in it stretches giving you a false timing mark can you do me a favor and advance it 5 degrees and see if it improves or have you tried it already.

 

[ford1386]

I'll try it tonight when I get home, I had already advanced it ahead from 14 to 17 and it didn't make a difference. Do I need to drive it after every little change to see if the hesitation is still there, if when I crack the throttle from an idle in the driveway it falls on its face?

 

[kimcrwbr1]

Yes driving it at medium speed floor it you want it to set you back in your seat and keep you there. You will lose power drastically on the upper end when you advance it too far. Just a little at a time until you find the sweet spot then you can mess with the jets and squirters. I hear nothing but good about the duraspark ignition and works great on my 2.8 and a cheap option, with all you have done to the carb it has to be timing. Have you checked the timing chain for slop turn the crank back and fourth a little with a socket and watch the rotor.