Can't rev past 4400rpm: what's wrong?

yelowjaket · 05-19-2003, 03:11 PM

we just got done putting in a new timing chain set on the 302 but i don't know if this is the problem i don't think it is. But i got on the gas today when i was coming home and it was like hitting the rev limiter, got up to 4400-4500 and wouldn't go any further. I usually shift around 5000 rpm's when i'm racing. So i tried from a stop, 1st gear i got it to finally go 5k but 2nd, 3rd, it WOULD NOT go past 4500. So what the heck? I think maybe it's either the valve springs are getting weak and need to be replaced. Or what about the summer heat here in Arizona? could that be a possibility? Not really sure what's going on but i bet it's probably the valve springs because the engine is original and it has close to 180,000 miles on it. Can someone give me any other ideas of what it might be? or is it the valve springs getting old & weak?

84LX89GT · 05-19-2003, 04:09 PM

If this happened right after replacing the timing chain i'd have to say it's a problem with cam timing. If you don't build enough cylinder pressure/airflow your engine won't be able to rev past a certain point, sort of like a rev limiter. Unfortunately i'd have to say go back and double check that the timing chain is installed correctly or check and make sure it's the right timing chain and/or that it's not adjustable.

tireburner163 · 05-19-2003, 08:12 PM

My GT was doing the same thing. I'm pretty sure it's valve springs, I'll let you know wehen I get mine back together later this week.

yelowjaket · 05-20-2003, 12:51 PM

well my dad is the one who installed it, (he's a mechanic for Goodyear) so i know it's installed correctly. He thinks it might be the timing also, like what you said. He says we may have to adjust it a bit. But thanks for your input.

393Clevor · 05-20-2003, 05:27 PM

Check the fuel psi. also try a new filter.

Jeff Chambers · 05-21-2003, 07:35 AM

Been there done that. I'll bet $10 that you're off a tooth on the timing chain. Better pull it all apart and check it again. Did you verify timing events before you reassembled it? It happens to the best of us so bite the bullet and pull it apart.

yelowjaket · 05-23-2003, 12:56 PM

adjusted the timing, tried it out, it's good to go now. thanks for the input though guys.

05-19-2003, 03:11 PM	#1
yelowjaket Registered Member Join Date: Aug 2002 Location: Phoenix, AZ-USA Posts: 114	Can't rev past 4400rpm: what's wrong? we just got done putting in a new timing chain set on the 302 but i don't know if this is the problem i don't think it is. But i got on the gas today when i was coming home and it was like hitting the rev limiter, got up to 4400-4500 and wouldn't go any further. I usually shift around 5000 rpm's when i'm racing. So i tried from a stop, 1st gear i got it to finally go 5k but 2nd, 3rd, it WOULD NOT go past 4500. So what the heck? I think maybe it's either the valve springs are getting weak and need to be replaced. Or what about the summer heat here in Arizona? could that be a possibility? Not really sure what's going on but i bet it's probably the valve springs because the engine is original and it has close to 180,000 miles on it. Can someone give me any other ideas of what it might be? or is it the valve springs getting old & weak? __________________ 90redGT -Flowmaster mufflers -BBK 2.5" H-Pipe w/cats -BBK equal length shorty headers -K&N -BBK 65mm Throttle Body -Edelbrock performer 5.0 intake -3.73 gears

05-19-2003, 04:09 PM	#2
84LX89GT Mustangs Join Date: Jul 2000 Posts: 1,938	If this happened right after replacing the timing chain i'd have to say it's a problem with cam timing. If you don't build enough cylinder pressure/airflow your engine won't be able to rev past a certain point, sort of like a rev limiter. Unfortunately i'd have to say go back and double check that the timing chain is installed correctly or check and make sure it's the right timing chain and/or that it's not adjustable. __________________ 2005 Suzuki Hayabusa GSX1300-R 1980 Ford Thunderbird - 255 V8 ported heads, 5.0L ported stock headers, O.R. H-pipe and Flowmaster 2-chambers, dual roller timing chain hi-po Mack Truck hood emblem 1985 Mustang GT 5.0L T5, F-303, GT40p, headers, off-road h, flowmasters, MSD stuff, etc. Sold 02/06/04 1989 Mustang GT ET: 13.304@102.29 mph (5-24-03) Sold - 1998 Mustang Cobra coupe, 1/4 mile - street tires: 13.843@103.41 (bone stock)

05-19-2003, 08:12 PM	#3
tireburner163 It's a lot like a race car Join Date: Aug 2000 Location: Meridian, MS Posts: 4,130	My GT was doing the same thing. I'm pretty sure it's valve springs, I'll let you know wehen I get mine back together later this week. __________________ 1987 Buick T-type 1998 HD Electra Elide

05-20-2003, 12:51 PM	#4
yelowjaket Registered Member Join Date: Aug 2002 Location: Phoenix, AZ-USA Posts: 114	i talked to my dad. well my dad is the one who installed it, (he's a mechanic for Goodyear) so i know it's installed correctly. He thinks it might be the timing also, like what you said. He says we may have to adjust it a bit. But thanks for your input. __________________ 90redGT -Flowmaster mufflers -BBK 2.5" H-Pipe w/cats -BBK equal length shorty headers -K&N -BBK 65mm Throttle Body -Edelbrock performer 5.0 intake -3.73 gears

05-20-2003, 05:27 PM	#5
393Clevor Registered Member Join Date: May 2003 Location: NH Posts: 5	Check the fuel psi. also try a new filter. __________________

05-21-2003, 07:35 AM	#6
Jeff Chambers Moderator Join Date: Aug 2000 Location: Milan, OH Posts: 2,699	Been there done that. I'll bet $10 that you're off a tooth on the timing chain. Better pull it all apart and check it again. Did you verify timing events before you reassembled it? It happens to the best of us so bite the bullet and pull it apart. __________________ Jeff Chambers 1990 Mustang GT 10.032 Seconds / 137.5 MPH 14-time Street Warrior World Record Setter CRT Performance 2001 Tropic Green Mustang GT - 12.181 / 113.2 MPH 2002 Ford F-250 Crew Cab 7.3l Power Stroke - 17.41@77.2 "There's nothing boring about a small block automatic shifting gears at 9400 rpm!"

05-23-2003, 12:56 PM	#7
yelowjaket Registered Member Join Date: Aug 2002 Location: Phoenix, AZ-USA Posts: 114	good to go now adjusted the timing, tried it out, it's good to go now. thanks for the input though guys. __________________ 90redGT -Flowmaster mufflers -BBK 2.5" H-Pipe w/cats -BBK equal length shorty headers -K&N -BBK 65mm Throttle Body -Edelbrock performer 5.0 intake -3.73 gears

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