Fresh 383 but no power!
#1
Fresh 383 but no power!
I had a machine shop put together my 383. I've got all forged internals, 850 hardcore series carb with 80/80 jets and a 4.5 power valve, patriot freedom heads 64cc, .555 lift comp cam, super victor intake, roller rockers, Holley mechanical fuel pump 110gph, headers, And 3 inch exhaust. Car is built for the strip but I'd be embarrassed to take it there currently. I have a full msd ignition and my initial timing is set at 20 and I'm all in at 36. The car lacks power. I had the same set up before besides my new heads and a bigger cam. Can't figure out what the problem is. Fuel ratio is 14:1 at idle 12.5:1 at light accelerating and 11.8:1 when I punch it. I know I might have a small header gasket leak but don't think that can account for all the power I'm missing. I think my Silverado would come close to beating this car currently. Any ideas out there? Thanks guys!
#2
Member
Re: Fresh 383 but no power!
Make sure no vaccum leaks at all first. Is transmission good or questionable?Auto or manual? Does engine die or is it just not getting power to wheels?
#3
Re: Fresh 383 but no power!
transmission is a th350 that was rebuilt about 2 years ago to withstand 600hp. I was looking for vacuum leaks but am wondering where is thebmost coming place to check? I have obviously checked the carb ports and one goes to my tranny and I plugged the brake booster port. Is there any easy way to check for vacuum leaks besides a smoke machine?
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#8
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Re: Fresh 383 but no power!
My method to check for vaccum leaks: spray bottle with water..I spray on intake gasket areas and listen for engine to stutter slightly...where ever I squirt water and I get engine response is the leak..or u can see positive pressure leak if water bubbles(head to block area)
#9
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Car: 1989-92 FORMULA350 305 92 Hawkclone
Engine: 4++,350 & 305 CIs
Transmission: 700R4 4800 vig 18th700R4 t56 ZF6 T5
Axle/Gears: 3.70 9"ford alum chunk,dana44,9bolt
Re: Fresh 383 but no power!
cam timing ok?
#10
#11
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Re: Fresh 383 but no power!
Thats a good size solid flat tappet deal. Its gonna want to spin some rpm. Will need a fairly good stiff spring in those heads. Would be nice to know the springs that came in those heads to be sure.
Whats the plug gap?
Whats the compression?
Whats the plug gap?
Whats the compression?
#12
Re: Fresh 383 but no power!
Plug gapped at .35 I'm using ngk heat range 8. I will check on the springs tomorrow to see what they have for sure. I really appreciate the help guys!
#15
Re: Fresh 383 but no power!
You may want to fire the engine up at night with no lights on and pop the hood. Issues like this are often caused by bad plug wires. If you see a light show than you know may want to replace the wires.
#16
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Car: 84 TA orig. 305 LG4 "H" E4ME
Engine: 334 SBC - stroked 305 M4ME Q-Jet
Transmission: upgraded 700R4 3200 stall
Axle/Gears: 10bolt 4.10 Posi w Lakewood TA Bars
Re: Fresh 383 but no power!
Was the camshaft actually degreed in?
Is there any easy way to check for vacuum leaks besides a smoke machine?
Spray carb cleaner, but it eats paint. Even better propane torch (not lit).
When you find the leak, the engine will smooth out.
A flat tappet camshaft can have the lobes wiped out in 20 minutes without proper break procedures and oil additives.
It should have been broken in with weak break-in springs, or reduced ratio rockers.
Without actually looking it up, that cam will begin to pull at about 4000 rpm.
With a combination like that, your rear gears need to be in the 4s, possibly even 5s.
Is there any easy way to check for vacuum leaks besides a smoke machine?
Spray carb cleaner, but it eats paint. Even better propane torch (not lit).
When you find the leak, the engine will smooth out.
A flat tappet camshaft can have the lobes wiped out in 20 minutes without proper break procedures and oil additives.
It should have been broken in with weak break-in springs, or reduced ratio rockers.
Without actually looking it up, that cam will begin to pull at about 4000 rpm.
With a combination like that, your rear gears need to be in the 4s, possibly even 5s.
Last edited by NoEmissions84TA; 03-21-2017 at 10:48 PM.
#18
Re: Fresh 383 but no power!
Joe Gibbs break in fluid was used and the cam was broken in properly. That's coming from the builder. Im thinking I'll pull the cam if I can't figure this out soon. If the lobes are wiped out I'll take it down to his shop and beat him over the head with it.
#19
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Re: Fresh 383 but no power!
Just pop valve covers off and either crank it over off the starter or turn by hand off crank bolt. Watch the rockers and see if each makes a full lift cycle. If one is wiped it wont be moving as much. If thats the case the motor is likely shot and gonna require rebuild and cleaning. Metal in oil passages needs flushed. Bearings likely taken out.
But if it sounds good and seems to drive fine then it sounds like it isnt a worn lobe. Plugs would also likely show it. Pull them and check. Make sure they are all looking same.
But if it sounds good and seems to drive fine then it sounds like it isnt a worn lobe. Plugs would also likely show it. Pull them and check. Make sure they are all looking same.
#20
Re: Fresh 383 but no power!
Ok I will do that also , the only thing odd I noticed also is that my spark plugs were fouled before. Put brand new NGKs in and the strap looks white??? I've checked the oil ton make sure nothing crazy was happening. No metal or anything other than oil. It looked really good. I would think white means too lean but my fuel to air ratio is rich.
#21
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Car: 84 TA orig. 305 LG4 "H" E4ME
Engine: 334 SBC - stroked 305 M4ME Q-Jet
Transmission: upgraded 700R4 3200 stall
Axle/Gears: 10bolt 4.10 Posi w Lakewood TA Bars
Re: Fresh 383 but no power!
ANY glitter in the oil and YOU HAVE a problem.
I hope not for your sake.
The slight bit of oil that is sitting under the valve covers will tell the story.
I hope not for your sake.
The slight bit of oil that is sitting under the valve covers will tell the story.
#22
Re: Fresh 383 but no power!
i looked in the valve covers and no glitter whatsoever. Oil looks great. Interested in starting the car at night to see the spark plug wires. They are newer wires but hey you never know. I hooked the timing light up and checked each wire that it was at least firing and they all were.
#23
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Re: Fresh 383 but no power!
I think there may be potential that you are floating the valves. If those have the .575 lift hyd flat tappet springs they probably float the valves over 5800 rpm. You need one of their upgrade springs. They have a 143 lb seat 325 open spring that would be better, but i'd prefer to see more open pressure. But not sure how much pressure a mech tappet core cam can handle
#25
Re: Fresh 383 but no power!
I will get the car fired up here tomorrow hopefully and give you guys an update. My throttle linkage was kinked and could have been a problem since I don't think it was fully opening the throttle. I have also went down to a 4.5 power valve and haven't run it since then. Wondering if the 6.5 was kicking on while idling? Also going to replace the header gaskets . Will update soon. Thanks a lot guys.
#26
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Car: 84 TA orig. 305 LG4 "H" E4ME
Engine: 334 SBC - stroked 305 M4ME Q-Jet
Transmission: upgraded 700R4 3200 stall
Axle/Gears: 10bolt 4.10 Posi w Lakewood TA Bars
Re: Fresh 383 but no power!
to the floor while you are looking down the carb for full throttle. Just working
the linkage by hand at the carb won't cut it.
#28
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Car: 82 Berlinetta/57 Bel Air
Engine: LS1/LQ4
Transmission: 4L60E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Re: Fresh 383 but no power!
"Luck", or "experience"?
I got it to run. Actually did well at the track. But driveability was poor.
I started with a used 650 Holley DP. Put a Proform 750 main body in it before starting the conversion. Not much was available in 2006 for E85, so I started with rejetting and air bleeds. Wouldn't idle worth a hoot - didn't idle well with gasoline, either, discovered the throttle body was poorly made. I tried fixing what was wrong with it with limited success, so I got a stainless throttle body made for alcohol - that helped. Not long after that Quick Fuel came out with E85 metering bodies - that helped a lot, party because I now had 4-corner idle mixture adjustability. By that time I had as much into that carb as a carb built for E85 costs new. All I had from the original 650 was the float bowls.
Which is why I say it makes much more sense to just buy a carb built for E85. Sell your current carb to offset the cost of the new E85 carb, you'll be dollars and headaches ahead.
I got it to run. Actually did well at the track. But driveability was poor.
I started with a used 650 Holley DP. Put a Proform 750 main body in it before starting the conversion. Not much was available in 2006 for E85, so I started with rejetting and air bleeds. Wouldn't idle worth a hoot - didn't idle well with gasoline, either, discovered the throttle body was poorly made. I tried fixing what was wrong with it with limited success, so I got a stainless throttle body made for alcohol - that helped. Not long after that Quick Fuel came out with E85 metering bodies - that helped a lot, party because I now had 4-corner idle mixture adjustability. By that time I had as much into that carb as a carb built for E85 costs new. All I had from the original 650 was the float bowls.
Which is why I say it makes much more sense to just buy a carb built for E85. Sell your current carb to offset the cost of the new E85 carb, you'll be dollars and headaches ahead.
#30
Member
Re: Fresh 383 but no power!
How much stall are you running? That camshaft will require quite a bit of stall with an automatic transmission. Does it bog off the line then run stronger at higher rpms?
#32
Re: Fresh 383 but no power!
Ok guys, new air filter , throttle adjusted properly, and embarrassing enough to say but my plugs wires were crossed..... obviously that scenario proved to fix the problem. Before you say I'm an idiot the wires crossed behind the engine and I didn't see that....yea I'm an idiot . Anyways thanks everyone!!!! One last question. What a/f ratio should I be looking to achieve for maximum power? I picked up some new jets and will mess around with it this weekend. Any recommendations on oil also?
#33
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Car: 1984 Pontiac Firebird Trans Am
Engine: 383 SBC
Transmission: 700R4
Axle/Gears: 3.73
Re: Fresh 383 but no power!
Good to hear you got it figured out. I am dropping a fresh 383 in mine hopefully next weekend and like to read about the issues guys are having in case I run into problems. Right now trying to decide how big of a mechanical fuel pump I need. I would like to keep using the return line.
#34
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Re: Fresh 383 but no power!
Good to hear you got it figured out. I am dropping a fresh 383 in mine hopefully next weekend and like to read about the issues guys are having in case I run into problems. Right now trying to decide how big of a mechanical fuel pump I need. I would like to keep using the return line.
#35
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Car: 84 TA orig. 305 LG4 "H" E4ME
Engine: 334 SBC - stroked 305 M4ME Q-Jet
Transmission: upgraded 700R4 3200 stall
Axle/Gears: 10bolt 4.10 Posi w Lakewood TA Bars
Re: Fresh 383 but no power!
and embarrassing enough to say but my plugs wires were crossed
Let me guess #5 & #7.
Let me guess #5 & #7.
#36
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Car: 84 TA orig. 305 LG4 "H" E4ME
Engine: 334 SBC - stroked 305 M4ME Q-Jet
Transmission: upgraded 700R4 3200 stall
Axle/Gears: 10bolt 4.10 Posi w Lakewood TA Bars
Re: Fresh 383 but no power!
http://www.jegs.com/i/Carter/180/M6626/10002/-1
Less than $20. You can get it even cheaper on ebay.
Specifications: Free Flow Rate 120 gph
Inlet Attachment Stock
Maximum Pressure (psi) 5.5 to 6.5
I have not had the chance to try it yet.
I also will be keeping the return line.
In the past, when I was doing 1/4 mile runs on the highway, I was running out of fuel as I shifted into drive. I band-aided that by installing a small electric Purolator #12S near the tank to give the fuel a push up to the STOCK block mounted mechanical FP.
If you are getting rid of your emissions stuff - charcoal canister, don't just cap off all the vacuum lines.
You will prevent the tank from being vented and any fuel pump will have a hard time of supplying fuel
because a vacuum will be created in the tank.
Last edited by NoEmissions84TA; 03-25-2017 at 06:37 PM.
#37
Re: Fresh 383 but no power!
You would think it was 5 and 7 but it was 2 and 4... it must of got crossed when I was changing the spark plugs out because I know I checked it at least 3 times. Prior. The car wasn't running great beforehand anyways. I honestly think the new air filter and sealing the headers and collectors improved a ton!
#38
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Car: 1984 Pontiac Firebird Trans Am
Engine: 383 SBC
Transmission: 700R4
Axle/Gears: 3.73
Re: Fresh 383 but no power!
I bought a Carter M6626.
http://www.jegs.com/i/Carter/180/M6626/10002/-1
Less than $20. You can get it even cheaper on ebay.
Specifications: Free Flow Rate 120 gph
Inlet Attachment Stock
Maximum Pressure (psi) 5.5 to 6.5
I have not had the chance to try it yet.
I also will be keeping the return line.
In the past, when I was doing 1/4 mile runs on the highway, I was running out of fuel as I shifted into drive. I band-aided that by installing a small electric Purolator #12S near the tank to give the fuel a push up to the STOCK block mounted mechanical FP.
If you are getting rid of your emissions stuff - charcoal canister, don't just cap off all the vacuum lines.
You will prevent the tank from being vented and any fuel pump will have a hard time of supplying fuel
because a vacuum will be created in the tank.
http://www.jegs.com/i/Carter/180/M6626/10002/-1
Less than $20. You can get it even cheaper on ebay.
Specifications: Free Flow Rate 120 gph
Inlet Attachment Stock
Maximum Pressure (psi) 5.5 to 6.5
I have not had the chance to try it yet.
I also will be keeping the return line.
In the past, when I was doing 1/4 mile runs on the highway, I was running out of fuel as I shifted into drive. I band-aided that by installing a small electric Purolator #12S near the tank to give the fuel a push up to the STOCK block mounted mechanical FP.
If you are getting rid of your emissions stuff - charcoal canister, don't just cap off all the vacuum lines.
You will prevent the tank from being vented and any fuel pump will have a hard time of supplying fuel
because a vacuum will be created in the tank.
#39
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Car: 1984 Pontiac Firebird Trans Am
Engine: 383 SBC
Transmission: 700R4
Axle/Gears: 3.73
Re: Fresh 383 but no power!
What branch of the service were you in? Semper Fi.
#40
Member
Re: Fresh 383 but no power!
I did 24 years as a Crew Chief in the USAF, my father was a Marine, so back at ya Brother! You will enjoy that engine, these cars are a blast with that much torque. By the way, unless that 700r4 is beefed up a lot, it won't last long behind that motor, my stock transmission didn't last two months behind my 383. I replaced it with a level three Raptor 700 and was amazed at how much power I'd been losing through the stock transmission.
Last edited by MSgt Luttrell; 03-26-2017 at 01:44 PM.
#41
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Car: 1984 Pontiac Firebird Trans Am
Engine: 383 SBC
Transmission: 700R4
Axle/Gears: 3.73
Re: Fresh 383 but no power!
I did 24 years as a Crew Chief in the USAF, my father was a Marine, so back at ya Brother! You will enjoy that engine, these cars are a blast with that much torque. By the way, unless that 700r4 is beefed up a lot, it won't last long behind that motor, my stock transmission didn't last two months behind my 383. I replaced it with a level three Raptor 700 and was amazed at how much power I'd been losing through the stock transmission.
#42
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Car: 86 Z-28
Engine: 355 small block XR276HR roller cam
Transmission: TCI built 700r4 2000 lockup stall
Axle/Gears: moser axels auburn posi 3:73 gears
Re: Fresh 383 but no power!
70/70 probably the jet you want our elevation is similar.