Anyone who has any idea, or experience with timing on a BBC 502 with 5lb boost intercooler procharger please let me know. What is the max advance I should run still leaving me good hp and some margin for carb or fuel pressure error. I am willing to loose a few ponies to not burn up my motor. I have a v-6 thunderbolt IV on it with only 14 degrees of advance, and run about 10 degrees base. I do not have much experience with timing, so any info is appreciated. I did not put the v-6 thunderbolt on it, but I asked my local marina why someone would do that and he said that it is done in hp motors to advance the timing faster for better low end. Can I leave this v-6 nit on? The boat seams to run well with it, but who knows if I am robbing myself of a bunch of extra power.
I'm also trying to figure out some timing issues for my new PC install. However I will be using a FAST ECU to set my timing along with manifold pressure so it will be a little more complicated.
ProCharger tech will say 28-29 total advance safely with intercooler and that has some safety margin in it. Bottom line is yes, you are leaving quite a bit in the motor with only 24 degrees.
Call ProCharger and check.
Dave
after looking my timming over again today i found that at 1100 rpm i am at 16 deg. my thunderbolt system is 14 so that should bring me to about 30. i can back it down a bit if need be, but the plugs look good. i am having problems getting enough boost. the 3.25 pully that is supposed to give my 502 5lbs actualy only gives me 1-2lbs boost. the 2.95 pully is supposed to give a 500hp 7lbs (not sure about a 502) but it only gives me 4lbs. i run flat on top 3/4 to full throttle becase my carb and jetting on my sec. are set for 5lbs. when i switch pullies form the one producing only 1 or 2 lbs to the one producing 4 it helped this flat on to problem a lot, but still a little flat. the motor actualy pulls harder at 3/4 then full throttle. so now i need to go to like a 2.75 pully or so. the only big mod in my motor is a crane cam intake lift 109 dur. 234 ex. lift 119 dur. 244. other than that and some fast glass ex. elbows it is pretty stock. why the hell am i only getting 4lbs of boost when procharger said this pully shoud produce 7lbs. should i not worrie about what is supposed to happen and just find a pully that does produce 5lb's? or does it sound like something else is wrong? any info would be great
502PC,
what size is your PC?(M1, M2, M3,M4)I would assume that with a 3.25 pulley that is suppose to give 5 lbs on a 502 its an M1. I'm not that familiar with that setup. I have a M3/12 rib and the 502 5 lb pulley is 4.5 and I'm figuring that I'll have to go to a 4.0 to get 5 lbs on my 540.
The pulleys your mentioning sound very small and would give up some surface area for bite.
Once again, call PC and tell them what's up. It sounds like somethings off to me???
http://free.***boat.net/ubb/frown.gif
Keep us posted!
Dave
i have talked to pc many times. it is a m1 unit. they feel that the size of the cam i am running in this motor is really effecting the m1's abulity to build boost. when i had the 3.25 pully on i know it was only building 1-2 lbs b/c my boost ref. fuel pres reg was only inc my fuel pres. by a few lb's. now that i have the 2.95 pully on which is supposed to build 7lb's on a 500hp it is only building 4lb's on my motor, but the fuel pres. is also increasing by 4-5 lbs. so i know that i am only getting 4lbs. i have ordered a 2.75 pully and that should build 5-6lbs and that is as far as i want to boost this motor. any input?
Nordic,
In your box your probably getting your 7 pounds. Under the carb seems to be 2 pounds less. I'm ordering the 2.75 pulley today myself hoping to get 7psi in the manifold. I now get 5 psi with the 2.95 pulley. Max rpm with the 2.75 is about 6000. woth the 2.55 its 5600rpm. These numbers are based on impeller speed of 51000 rpm. My cam is similar. What carb do you have? Greg
i have a nickerson built holly 750 blow through carb. i am still waiting for my 2.75 pully from pc. what boat is this on? what kind of luck have you had with your pc? how much pitch did you increase your prop. any info is great.
Dave,
I run a 434ci, Small Block, 10:1, Alum. Head's, Big Cam, M3 Blower, F.A.S.T. ECU. 55lbs injectors run at 60 psi, I run the engine cold, ( 100 degrees, no thermostat, small restrictor), The timing set at 32-34 max depending on manifold presure. @ 6300 rpm I have 3.8 lbs of boost, running on 93 octane. If I rev engine higher, build's more boost, I'll add 100 octane for safety. The A/F is set at 12.2.
You can hook a lap top up to your engine and have it tuned from remote location, through the internet. I'm in Connecticut and had Craig at DBS tune it from CA. If you have any questions call me (203)258-5222 George
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