Perfect timing. Just acquired a 1994 Mustang GT convertible 5.0l aode. Engine and transmission showing their age. In the olanning stages now. Thanks for this vid!
I've freshened several with 100+ miles. All speced out fine. Biggest thing is timing chain wear Cam likes 4* more advanced.. and the chain will settle in with 2* wear... So set it up at 6* adv with a very good chain.
The cam on the 5.0 H.O is the last thing you need to change for 300hp. The wimpy e7 cylinder heads and choking lower intake are the main things. My car ran 12.60s with it.
ezcondition not at all to make 325 hp you will need a 230-236 camshaft trick flow heads the biggest ones higher flow intake upper and lower and maybe a 75 shot of nitrous on top of that lol
Hi guys, Before getting a union job to raise family, I was a serious engine builder and really like that you look at how a simple cam change can have far reaching effects on the rest of the system. Good job! After reading the comments, your tech dept must have some serious patience.
Been around the block with cams and heads. Ended up going all ford. aluminum gt40 heads and the Z cam. sounds great, runs great, lots of power, AND 22mpg
thats a great video ! lots of info for someone just getting into the sport, and or just getting into Mustangs. Thank you for providing these quick vids !
I have a stock 85 Roller Motor with that X303 stock .444 cam and - stock Bottom end and I want to slap on some aftermarket heads (170cc 2.02 / 1.60 valves 300 springs 1.6 Roller Rockers) for more flow ... Lookin for about 280- 300 HP that's all... Think I can get there or close without a cam? No valve to piston issue until I go large on Cam correct? Car already has BBK Long Tubes, Demon 625 Carb and RPM Intake ...T-5 World Class , 8.8 rear 3:73 gears ....
I have a near Mint 1988 Lincoln Town Car with 5.0. I would like to do some things, trying to minimize efforts, mainly just make it sound and run better than stock, not looking for extreme performance. With the Automatic transmission and gears that are from factory be compatible with any kind of after market cam? Can other Transmission options work? I dont mind doing what needs to be done as long as its not too far down the fabrication road, its not intended to be a daily driver and I know it sounds like a useless endeavor but its all I got and its what I want to do.
Why don't you guys offer a idle to 5000 RPMs roller cam for 351 Windsor 94 297 Motors I've been looking for one for my truck and you guys don't have one if you do let me know and I have a fuel density sensor so it has to be density friendly
I want to get to that 280-300 HP with my AOD, can a Ecam get me there? Also have gt40 everything on the top end. I don’t plan on going any further then gt40 parts. I’m looking for simple, smooth, fun.
What Cam Lift or KIT would I need to reach 325 hp keeping stock bottom end and it;s a 1985 so carburated NOT EFI ? "M code Roller Motor" Kinda need to be Budget build though ~ Willing to do new Aftermarket Heads, Roller Rockers, Lifters, Push Rods ($1,500. in parts) ***Car currently has orig. Holly 600 Carburater, Edelbrock Performer RPM Intake, 8.8 Rear with 3:73 gear, BBK Long Tube / Flowmaster exhaust, T5 "World Class tranny, MSD Dizzy, (Frame Connectors and Torque Boxes) A/C and Smog Pump Delete
The duration on my E cam is advertised at 282° Intake and Exhaust. I feel like that’s hurting my 302 with GT40 heads and GT40 intake. Also have aftermarket exhaust, bigger throttle body, but still 19lb injectors and it feels like it leans out at the 5000-5500 rpm mark which is where the cam stops making peak power.
sounds like a valve spring problem, known problem with the stock e7 heads and gt40/gt40p heads. a valve spring upgrade lets you rev cleanly out farther than you can dream without dropping too much power. source is Richard Holdener, he has a youtube channel and has done probably thousands of dyno runs and he shows all the charts and what hes done. look at his SBF N/A playlist, it has over 50 videos in it on sbf 302 and 351
@@alexdollen1787 nah, we figured out the problem lol. Tore it down a couple of months ago. Cam looked great, lifters looked great (no wear) heads looked great. We think the issue was that every single cylinder had the piston loose enough that every one of them could rock in the bore a good amount. Pulled it apart, found out the crank had been turned .010/.010 and still had factory rods and pistons but new piston rings, and all new bearings (obviously). This is a 1991 E7TE so it had the TRW pistons in it but after we got a few of them out, measured the skirts where they were worn really bad, and turns out they were worn .016 causing piston slap. 😂😂😂 so much slack in the cylinders you could literally see the ring around the piston so I’d imagine I was losing a good amount of compression. Oh well, onto 331 Scat stroker kit lol
You didn’t give a lot of information so I’ll need to make some assumptions, sounds like you have a fuel-injected Explorer 5.0L engine/transmission combination. If you’re looking for a camshaft that makes an adequate vacuum to sustain power brakes and does not require tuning, I recommend Lunati EFI Compatible Camshaft LUN-20350613. This cam operates in the 1,600-5,200 rpm range and should work with your stock springs, but at .477" lift, you're getting close to coil bind, and you will need to check this. If you’re wanting something a little more aggressive, check out Lunati Street/Strip Camshaft LUN-20350514. This camshaft operates in the 2,000-6,000 rpm range and delivers more midrange power complementing your 4.10.1 gear ratio. There will be a reduction in vacuum at idle with this cam, but it should still deliver enough pull for power brakes. A 2500 rpm stall speed converter is suggested, and this cam will require an upgraded spring kit like TFS-2500100. Computer tuning is suggested but not required. www.summitracing.com/parts/lun-20350613/make/ford www.summitracing.com/oh/parts/lun-20350514/make/ford www.summitracing.com/oh/parts/tfs-2500100
I have a 1994 get Mustang has a small re cam and cold air intake. and some shorties. shoring for 300 to 350 hp from it thinking about a trick flow top end. what else's what be needed to make it run right .
Recently bought a Crane hydraulic flat tappet cam from Summit. Engine would NOT start, then discovered after 30 attempts, the cam firing order did NOT match the cam card!!!! It was ground on the wrong firing order!!! Ground on the 351W firing order not the 302 firing order. It went flat from so many attempted starts and Crane only wants to replace the cam if I pay to ship it to them! What about the lifters? The clean out rebuild? This was negligence, pure and simple. Engine long gone out of shop with Erson cam. No more Crane in my shop.
@@hotrodray6802 You are WRONG. It will not and did not start with the cam card firing order. It was incorrect for what was ground for the cam. Gee only been doing this for 55 years! Instantly started on correct order. The engine was disassembled TWICE to confirm correct assembly.
Two options, the first one I would suggest is CCA-31-238-3 (XE262H-10 grind), this camshaft has an operating range of 1,300-5,600 rpm but will require a 3.23-4.10 gear ratio. While it will work with the stock converter, the engine will behave better, and the car will accelerate faster from the start with a 2000 stall converter. The second option is CCA-31-234-3 (XE262H-10 grind), this cam has an operating range of 1,000-5,200 rpm, and will work with a gear ratio of 3.23 and down, it will have a smoother idle. Both cams will require spring upgrades. Click on the suggested parts for information. www.summitracing.com/oh/parts/cca-31-234-3 www.summitracing.com/parts/cca-31-238-3
I have a stock motor 94 f150 4x4 what cam setup should I do it's my everyday driver since I put my 33x12.50x15 on there is lost every bit of power it had the motor has 144 im looking to get some power but it can still be driven daily
Hey great informative video. I have a 89 GT drop top I got BBK headers 17 mm BBK cold air intake MSD ignition with 2-Step rev limiter Cobra intake manifold speed I want to get the B cam Ford and I can get a really good deal on some 4.10s you said that could hinder me can you tell me how so please so I shouldn't do?
hi, i have a fox body that im rebuilding and im running a carberated 302. besides that, it has a 8.8 posi rear end and im not for sure on the gearing i think the guy i bought it fron said it was a 3.83 but it's manual, i was looking at a summit cam that has a lift of .520/.542 it being manual drive train would i have to change the gearing? every bit of information helps since this is my first car and im still learning,thanks.
Yes it can run good, but the bore/stroke ratio is completly different from the ford. Look for a 302 cid chevy. It has a 4.00 bore and 3.00 stroke just like the ford. High revving hp is how the 302 makes a good platform to build off of. Just get a 350 block and a rotating assy with a 3.00 stroke. Unfortunately, The aftermarket dosen't cater too much to this so you might have to get a custom piston.
U dont need all that, a stock short block is more than enough, and 4.10s are a waste, 3.73s are the way to go, any more than that and u r losing torque
If you want nice street motor build it 11:1 compression 306, with trickflow 185 head. 240 110lsa on the cam around 600 lift. Rpm air gap 1 inch spacer. sump the tank and go external pump. 410 gear in the rear 275/50/15 float aftermarket forged pistons on stock rod and factory crank balance use sfi balance and turn big rpms. Valve trains needs set up professionally
Or class you can put a 5.3 ls in it and hit 300 hp with Texas speed stage 3 truck cam kit with springs Texas speed headers tune oh and will idle nice good luck getting anywhere near 300 hp with a 302 5.0 without changing the whole top end
Help, pulled the motor on my 87 mustang, buying parts soon. 4k budget. Is demon 650 carb, weiand intake, AFR 165 heads, e303 cam, bbk shorty headers a decent combo???
Great combination, should have good street torque and higher RPM horsepower. If this is an aod, you will need to lower the gears to 3.73 or better 4.11 to stay in the power band at cruise speed. If 5 sp. you'll want 3.55 or 3.73 for street action and 3.23 if you want a road burner.
Just a thought, with the carb setup you do not need such a large separation angle the letter cams have, a separation angle or lobe centerline of 108 degrees will give you a wider power band. The wide separation angle is for to not confuse the fuel injection but it narrows the powerband.
the e303 cam is a smog approved cam, it is an upgrade for a computer controlled car. That cam was also developed over 20 years ago and cam shaft technology has advanced alot since this cam was developed. You are leaving a lot of horsepower on the table with those afr heads if you go with the e303. I would call the tech line for all the major cam manufacturers and tell them what your building and they will recommend a cam. Afr will also be able to recommend a cam.
No, you're wrong. Because from 57 all the way up until 86. 4.11 was a factory gear ratio available for vehicles equipped with the Ford 9 inch, and available after market for newer rear ends 8.8/10.5 etc. So no, it's not as simple as you stated.
Hi Zach, We would be happy to help but this is a complicated topic to discuss here. Can you give our tech department a quick call? 1-330-630-0240. We look forward to your call. Thanks for watching!
I recommend a 2,500 rpm stall converter and a 3.55 gear ratio. Below are the links to some recommendations. Stall Converter www.summitracing.com/parts/hup-51-25lwww.summitracing.com/parts/hup-51-25l Ring and Pinion www.summitracing.com/parts/sum-748803
Great info delivery 👍
Thank you for watching!
Perfect timing. Just acquired a 1994 Mustang GT convertible 5.0l aode. Engine and transmission showing their age. In the olanning stages now. Thanks for this vid!
I've freshened several with 100+ miles. All speced out fine.
Biggest thing is timing chain wear
Cam likes 4* more advanced.. and the chain will settle in with 2* wear... So set it up at 6* adv with a very good chain.
Great video. I learned quite a bit just from this short clip.
Thanks for that video👍🇵🇷
🔔Timely for me and one of the better Fox explanation videos Ive seen.
👍😎
Thank you for watching!
The cam on the 5.0 H.O is the last thing you need to change for 300hp. The wimpy e7 cylinder heads and choking lower intake are the main things. My car ran 12.60s with it.
Matt King dynoed 400 with the stock HO cam carbed.
Evan Smith ran 12s without touching the HO engine except timing.
so you think an explore intake with 160 aluminum heads 1.7 and the stock cam can crack 325/325 range? thanks
ezcondition not at the wheels. That’s more than most H/C/I stock cube stock compression make.
ezcondition not at all to make 325 hp you will need a 230-236 camshaft trick flow heads the biggest ones higher flow intake upper and lower and maybe a 75 shot of nitrous on top of that lol
Okay, I see you are 5.0L friendly - nice! We have not covered a build or cam selection to this level yet; thank you for the recipe and insight.
Great job, very informative kind of goes back to a basic formula of for every action there's an opposite and equal reaction!!
Hi guys, Before getting a union job to raise family, I was a serious engine builder and really like that you look at how a simple cam change can have far reaching effects on the rest of the system. Good job! After reading the comments, your tech dept must have some serious patience.
Been around the block with cams and heads. Ended up going all ford. aluminum gt40 heads and the Z cam. sounds great, runs great, lots of power, AND 22mpg
89 mustang gt convertible 5.0 ho stock how can I add more power wat is a good set up and exhaust?
thats a great video ! lots of info for someone just getting into the sport, and or just getting into Mustangs. Thank you for providing these quick vids !
I have a stock 85 Roller Motor with that X303 stock .444 cam and - stock Bottom end and I want to slap on some aftermarket heads (170cc 2.02 / 1.60 valves 300 springs 1.6 Roller Rockers) for more flow ... Lookin for about 280- 300 HP that's all... Think I can get there or close without a cam? No valve to piston issue until I go large on Cam correct?
Car already has BBK Long Tubes, Demon 625 Carb and RPM Intake ...T-5 World Class , 8.8 rear 3:73 gears ....
I have a near Mint 1988 Lincoln Town Car with 5.0. I would like to do some things, trying to minimize efforts, mainly just make it sound and run better than stock, not looking for extreme performance. With the Automatic transmission and gears that are from factory be compatible with any kind of after market cam? Can other Transmission options work? I dont mind doing what needs to be done as long as its not too far down the fabrication road, its not intended to be a daily driver and I know it sounds like a useless endeavor but its all I got and its what I want to do.
Why don't you guys offer a idle to 5000 RPMs roller cam for 351 Windsor 94 297 Motors I've been looking for one for my truck and you guys don't have one if you do let me know and I have a fuel density sensor so it has to be density friendly
I agree, I ran TW heads and a RPM intake with the on my old stock shortblock and I had it on the limiter all the time!
Some good pieces of information. I'm a Chevy guy but I'm seriously considering building a 300 hp 302 5L
+Matt Leonard ,
Thank you, Matt. Let us know if you have any questions.
alright i cant think of any at the moment
I want to get to that 280-300 HP with my AOD, can a Ecam get me there? Also have gt40 everything on the top end. I don’t plan on going any further then gt40 parts. I’m looking for simple, smooth, fun.
What Cam Lift or KIT would I need to reach 325 hp keeping stock bottom end and it;s a 1985 so carburated NOT EFI ? "M code Roller Motor" Kinda need to be Budget build though
~ Willing to do new Aftermarket Heads, Roller Rockers, Lifters, Push Rods ($1,500. in parts)
***Car currently has orig. Holly 600 Carburater, Edelbrock Performer RPM Intake, 8.8 Rear with 3:73 gear, BBK Long Tube / Flowmaster exhaust, T5 "World Class tranny, MSD Dizzy,
(Frame Connectors and Torque Boxes) A/C and Smog Pump Delete
Hey MetallicaDave,
Can you be specific? We are not sure which cam you are referring too? We would be happy to help so let us know!
The duration on my E cam is advertised at 282° Intake and Exhaust. I feel like that’s hurting my 302 with GT40 heads and GT40 intake. Also have aftermarket exhaust, bigger throttle body, but still 19lb injectors and it feels like it leans out at the 5000-5500 rpm mark which is where the cam stops making peak power.
sounds like a valve spring problem, known problem with the stock e7 heads and gt40/gt40p heads. a valve spring upgrade lets you rev cleanly out farther than you can dream without dropping too much power. source is Richard Holdener, he has a youtube channel and has done probably thousands of dyno runs and he shows all the charts and what hes done. look at his SBF N/A playlist, it has over 50 videos in it on sbf 302 and 351
@@alexdollen1787 nah, we figured out the problem lol. Tore it down a couple of months ago. Cam looked great, lifters looked great (no wear) heads looked great. We think the issue was that every single cylinder had the piston loose enough that every one of them could rock in the bore a good amount. Pulled it apart, found out the crank had been turned .010/.010 and still had factory rods and pistons but new piston rings, and all new bearings (obviously). This is a 1991 E7TE so it had the TRW pistons in it but after we got a few of them out, measured the skirts where they were worn really bad, and turns out they were worn .016 causing piston slap. 😂😂😂 so much slack in the cylinders you could literally see the ring around the piston so I’d imagine I was losing a good amount of compression. Oh well, onto 331 Scat stroker kit lol
@@nexgencarguyscraig331 that’s precisely my thinking lol, when this motor blows up, 408 stroked here we come
Great info. Thanks for sharing.
Good video, informative.
With a stock 5.0 gt40p head 410 gears and jmod 4R70W, what cam from lunati would benefit the build?
You didn’t give a lot of information so I’ll need to make some assumptions, sounds like you have a fuel-injected Explorer 5.0L engine/transmission combination.
If you’re looking for a camshaft that makes an adequate vacuum to sustain power brakes and does not require tuning, I recommend Lunati EFI Compatible Camshaft LUN-20350613. This cam operates in the 1,600-5,200 rpm range and should work with your stock springs, but at .477" lift, you're getting close to coil bind, and you will need to check this.
If you’re wanting something a little more aggressive, check out Lunati Street/Strip Camshaft LUN-20350514. This camshaft operates in the 2,000-6,000 rpm range and delivers more midrange power complementing your 4.10.1 gear ratio. There will be a reduction in vacuum at idle with this cam, but it should still deliver enough pull for power brakes. A 2500 rpm stall speed converter is suggested, and this cam will require an upgraded spring kit like TFS-2500100. Computer tuning is suggested but not required.
www.summitracing.com/parts/lun-20350613/make/ford
www.summitracing.com/oh/parts/lun-20350514/make/ford
www.summitracing.com/oh/parts/tfs-2500100
I have a 1994 get Mustang has a small re cam and cold air intake. and some shorties. shoring for 300 to 350 hp from it thinking about a trick flow top end. what else's what be needed to make it run right .
you'll never hear the end of people raining on your parade saying you can't make a 305 run good. It's just not a good place to start.
Recently bought a Crane hydraulic flat tappet cam from Summit. Engine would NOT start, then discovered after 30 attempts, the cam firing order did NOT match the cam card!!!! It was ground on the wrong firing order!!! Ground on the 351W firing order not the 302 firing order. It went flat from so many attempted starts and Crane only wants to replace the cam if I pay to ship it to them! What about the lifters? The clean out rebuild? This was negligence, pure and simple. Engine long gone out of shop with Erson cam. No more Crane in my shop.
Engine will run with either firing order, but one not well. There is only 4 cyls changed. You had other problems for a non start condition.
@@hotrodray6802 You are WRONG. It will not and did not start with the cam card firing order. It was incorrect for what was ground for the cam. Gee only been doing this for 55 years! Instantly started on correct order. The engine was disassembled TWICE to confirm correct assembly.
@@hotrodray6802 OK smart guy, I still have the cam and card. Put some money up and I'll ship them to you.
What camshaft can I put in a 69 302 that will have a LITTLE hit to it and do NOT have to run a stall converter??
Two options, the first one I would suggest is CCA-31-238-3 (XE262H-10 grind), this camshaft has an operating range of 1,300-5,600 rpm but will require a 3.23-4.10 gear ratio. While it will work with the stock converter, the engine will behave better, and the car will accelerate faster from the start with a 2000 stall converter.
The second option is CCA-31-234-3 (XE262H-10 grind), this cam has an operating range of 1,000-5,200 rpm, and will work with a gear ratio of 3.23 and down, it will have a smoother idle.
Both cams will require spring upgrades. Click on the suggested parts for information.
www.summitracing.com/oh/parts/cca-31-234-3
www.summitracing.com/parts/cca-31-238-3
-Dave
I have a stock motor 94 f150 4x4 what cam setup should I do it's my everyday driver since I put my 33x12.50x15 on there is lost every bit of power it had the motor has 144 im looking to get some power but it can still be driven daily
Good video, doing a heads cam swap on my 91 Tbird, I bought it off the guy and he gave me a B303 and GT40 heads
roller cam overlap is key. 112* is smooth, while a 108* is really rough.
good info.
Hey great informative video. I have a 89 GT drop top I got BBK headers 17 mm BBK cold air intake MSD ignition with 2-Step rev limiter Cobra intake manifold speed I want to get the B cam Ford and I can get a really good deal on some 4.10s you said that could hinder me can you tell me how so please so I shouldn't do?
Bruce Wayne I got a 90 lx drop with bbk headers, bbk 70 mm throttle body, upper and lower edlebrock intake manifold with 4:10 gears in the back
Thank you for watching!
hi, i have a fox body that im rebuilding and im running a carberated 302. besides that, it has a 8.8 posi rear end and im not for sure on the gearing i think the guy i bought it fron said it was a 3.83 but it's manual, i was looking at a summit cam that has a lift of .520/.542 it being manual drive train would i have to change the gearing? every bit of information helps since this is my first car and im still learning,thanks.
Zach Phelps no lol
Best cam shaft for 1986 GT with stock heads and still speed desity?
Yes it can run good, but the bore/stroke ratio is completly different from the ford. Look for a 302 cid chevy. It has a 4.00 bore and 3.00 stroke just like the ford. High revving hp is how the 302 makes a good platform to build off of. Just get a 350 block and a rotating assy with a 3.00 stroke. Unfortunately, The aftermarket dosen't cater too much to this so you might have to get a custom piston.
More on the trickflow packages like hp numbers
U dont need all that, a stock short block is more than enough, and 4.10s are a waste, 3.73s are the way to go, any more than that and u r losing torque
sure thanks for the reply
If you want nice street motor build it 11:1 compression 306, with trickflow 185 head. 240 110lsa on the cam around 600 lift. Rpm air gap 1 inch spacer. sump the tank and go external pump. 410 gear in the rear 275/50/15 float aftermarket forged pistons on stock rod and factory crank balance use sfi balance and turn big rpms. Valve trains needs set up professionally
for 400 hp what cam plz? i have gt40 intake AFR heads 2.02 .70 mm TB 3.73
+karla Garcia ,
We need some additional information from you. Can you give our tech line a call? 1-330-630-0240.
I'd run a x303 personally
We would be happy to help but, due to the complexity, it is best that you call our tech department at 330-630-0240.
Or class you can put a 5.3 ls in it and hit 300 hp with Texas speed stage 3 truck cam kit with springs Texas speed headers tune oh and will idle nice good luck getting anywhere near 300 hp with a 302 5.0 without changing the whole top end
Hi, our tech department has several questions for you. Would it be possible for you to call our tech department? 1-330-630-0240
Help, pulled the motor on my 87 mustang, buying parts soon. 4k budget. Is demon 650 carb, weiand intake, AFR 165 heads, e303 cam, bbk shorty headers a decent combo???
Going to bore itto a 306 unles it already is, no idea the history of thia motor
Great combination, should have good street torque and higher RPM horsepower. If this is an aod, you will need to lower the gears to 3.73 or better 4.11 to stay in the power band at cruise speed. If 5 sp. you'll want 3.55 or 3.73 for street action and 3.23 if you want a road burner.
Just a thought, with the carb setup you do not need such a large separation angle the letter cams have, a separation angle or lobe centerline of 108 degrees will give you a wider power band. The wide separation angle is for to not confuse the fuel injection but it narrows the powerband.
the e303 cam is a smog approved cam, it is an upgrade for a computer controlled car. That cam was also developed over 20 years ago and cam shaft technology has advanced alot since this cam was developed. You are leaving a lot of horsepower on the table with those afr heads if you go with the e303. I would call the tech line for all the major cam manufacturers and tell them what your building and they will recommend a cam. Afr will also be able to recommend a cam.
Bueller.....Bueller???
4.11 gear is Chevy 4.10 is FORD
No, you're wrong. Because from 57 all the way up until 86. 4.11 was a factory gear ratio available for vehicles equipped with the Ford 9 inch, and available after market for newer rear ends 8.8/10.5 etc. So no, it's not as simple as you stated.
Quiero vel ma's caro Para yo quiero mucho vel la condition.
Hi Zach,
We would be happy to help but this is a complicated topic to discuss here. Can you give our tech department a quick call? 1-330-630-0240. We look forward to your call. Thanks for watching!
Summit Racing i
the first minute im out
To run the fcam with a aod transmission gt40 setup what stall and gear would to be a redlight to redlight car thank you
I recommend a 2,500 rpm stall converter and a 3.55 gear ratio. Below are the links to some recommendations.
Stall Converter www.summitracing.com/parts/hup-51-25lwww.summitracing.com/parts/hup-51-25l
Ring and Pinion www.summitracing.com/parts/sum-748803
I got an 86 302 Mustang 5 speed with 355 gears and want to know what cam I should go with using stock heads for the "300 horse 302 package"??
Limited heads.
‘86 heads are limited in capability. ‘87s had different heads and were rated at +25 HP vs. ‘86. Change the heads first.
If I change from a stock cam on a 5.0l HO to an E303, do I need to change the valve springs?
Calvi Heaps, yes you need to change valve springs on a stock head, the reason is valve float or the binding of the springs
Thank you for watching!