I just swapped out a AMC 258 CID with an AMC 360 CID engine. I am using a GM TBI off an 88 Caddy with a 4.5L v8. The Injectors are 45LBs I think. How do I positivly identify them?
Now I am trying to get the 360 started and I have the reqired fuel at 25.5, 4 injections per cycle, simultaneous injections. I have had to set the VE table entrys at about 180 just to get the thing to cough.
I am wondering if I need to get bigger injectors? If so how do I figure out what size. The engine is freshly rebuilt 1981 AMC 360 out of a Jeep Wagoneer 30 over with a mild low end torque camshaft and an edlebrock performer intake manifold.
Injector size ???
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Read the manual to see if your question is answered there before posting. If you have questions about MS1/Extra or MS2/Extra or other non-B&G code configuration or tuning, please post them at http://www.msextra.com The full forum rules are here: Forum Rules, be sure to read them all regularly.
Read the manual to see if your question is answered there before posting. If you have questions about MS1/Extra or MS2/Extra or other non-B&G code configuration or tuning, please post them at http://www.msextra.com The full forum rules are here: Forum Rules, be sure to read them all regularly.
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RNash
- MegaSquirt Newbie
- Posts: 16
- Joined: Fri Nov 05, 2004 1:52 pm
- Location: (B'ham) Alabama, USA
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This link should help you check what size your injectors are.
http://thegebharts.com/msindex.html
I think you will find that if they are 45lbs they will be too small for that 360 at higher RPMs and load, but you should not have any problem at idle. Sounds like you have some other problem.
http://thegebharts.com/msindex.html
I think you will find that if they are 45lbs they will be too small for that 360 at higher RPMs and load, but you should not have any problem at idle. Sounds like you have some other problem.
Roger
1969 Mustang 351W
MS1 MSnS Holley TBI w/2 85 lb injectors
Ford PWM fast idle valve
Fuel only (for now)
1969 Mustang 351W
MS1 MSnS Holley TBI w/2 85 lb injectors
Ford PWM fast idle valve
Fuel only (for now)
Hi BooBoo -
MS only lets you set up to 25.5ms of fuel and to feed a 360 it calculates you need more but won't let you have it for good reasons. Since you likely need a Req_Fuel of 40 or more, the idle won't happen because it's limited to RF of 25.5. Although you might get it to idle with 45# injectors and concocted numbers, with the addtional fuel for ASE and WUE, if you tried to drive it would likely stumble or die from a lean condition when it tried to apply AE. If they really are 45# then they won't cut it on top-end either. I would suggest you use the injector sizing calculator in the MegaManual to determine the size you'll need and get a set of those: http://www.megamanual.com/v22manual/minj.htm#size
I am tuning a stock GM TBI 350 with 65# injectors and they are none too big as they hit nearly 100% DC as it is! I will be switching to late'80s 90# ones for now and then upping the fuel pressure for mild turbocharging later. The early 350TBI's are torquey but weak on HP (205) so if you think yours might do more - take that into consideration.
Hope that helps,
David
MS only lets you set up to 25.5ms of fuel and to feed a 360 it calculates you need more but won't let you have it for good reasons. Since you likely need a Req_Fuel of 40 or more, the idle won't happen because it's limited to RF of 25.5. Although you might get it to idle with 45# injectors and concocted numbers, with the addtional fuel for ASE and WUE, if you tried to drive it would likely stumble or die from a lean condition when it tried to apply AE. If they really are 45# then they won't cut it on top-end either. I would suggest you use the injector sizing calculator in the MegaManual to determine the size you'll need and get a set of those: http://www.megamanual.com/v22manual/minj.htm#size
I am tuning a stock GM TBI 350 with 65# injectors and they are none too big as they hit nearly 100% DC as it is! I will be switching to late'80s 90# ones for now and then upping the fuel pressure for mild turbocharging later. The early 350TBI's are torquey but weak on HP (205) so if you think yours might do more - take that into consideration.
Hope that helps,
David
I am a little confused. Shouldn't fuel pressure be calculated in as well? Wouldn't my 45LB injectors flow more at say 50 PSI than the 12 PSI of my TBI? The calculator tells me at 200 HP and 2 injectors I need 59LB injectors. Is this calculator assuming a specific fuel pressure? And if it tells me I need 60 LB injectors and all I have access to is 55 or 65, which should I choose?
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Bernard Fife
- Super Squirter
- Posts: 1009
- Joined: Mon Feb 16, 2004 3:15 pm
BooBoo,
The calculator doesn't assume anything about the flow rate, you input the flow rate at your installed fuel pressure. So your selection and implementation of specific injectors does affect the flow rate, but not the calculated requirement.
For example, if injectors are rated at 43.5 psi, then that's what the calculator assumes. If you increase the fuel presasure to 60 psi, then the new flow rate is sqrt(60/43.5) = 1.17 or a 17% increase. In either case, the flow rate needs to be equal to, or slightly greater than, that determined using the calculator.
This is explained in detail here: http://www.megamanual.com/v22manual/minj.htm#size
Lance.
The calculator doesn't assume anything about the flow rate, you input the flow rate at your installed fuel pressure. So your selection and implementation of specific injectors does affect the flow rate, but not the calculated requirement.
For example, if injectors are rated at 43.5 psi, then that's what the calculator assumes. If you increase the fuel presasure to 60 psi, then the new flow rate is sqrt(60/43.5) = 1.17 or a 17% increase. In either case, the flow rate needs to be equal to, or slightly greater than, that determined using the calculator.
This is explained in detail here: http://www.megamanual.com/v22manual/minj.htm#size
Lance.