TT5.9mag
Two atmospheres are better than one
That’s an upgrade from a magnum stock spring but not by very much. That might be light for a 224 hyd roller cam, depending on how aggressive the ramps are.
High RPM Backfire when fully warmed
- Thread starter TheGrimSpeed
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TheGrimSpeed
Well-Known Member
Dang, something in the 115/320lbs valve spring would be more adequate?
The camshaft grind is 1341 from Oregon camshafts
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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IDK
what your problem is.
I just wanted to say that my Second cam was a Hughes FTH 270/276/110 (223/230@050), and I absolutely loved it.
What I can say with a very high degree of confidence is that timing is NOT your issue, nor are your jet sizes.
I'm gunna guess that when you find your problem it's gunna be the Ignition amp, or valve-spring related.
*****************************
> by empirical seat of the pants testing, The reluctor gap can run anywhere from ZERO to 030, and the amp doesn't even miss a beat. The factory spec is IMO, just there to prevent the vanes from rubbing on the pole-piece, over time, as the top bushing wears out. I have seen vanes wore half way down, so I mean, that proved it for me.
> I highly recommend that you run the VA, it will make a world of a difference at Part Throttle, and yur fuel-economy will drastically improve.
I modified mine to get 22 degrees, by filing the external stops to fit. My 223 cam, with overdrive, was good down to about 2000=65mph, where it got gas mileage rivaling any modern EFI 4-cylinder. The timing at 2000 was in the range of 56 to 62 degrees, depending on what she asked for, on any particular day.
********************************
As for my combo;
This is on a 367LA, with alloy heads, TTIs with dual 3" exhaust, the AG, and an ancient 750DP. Plus; I run fresh cold air straight down thru a big hole in the hood., and the carb has one of those short phenolic air straighteners on it, I forget what it's called.
>She liked 32>34 degrees Power-Timing and
>the DP ran 72/80s with a 10.5 PV. Sometimes I run 70/78s knowing it will be lean on top, but she sounds so good ripping up to 7200.........
This DP carb does NOT have a choke either.
and mine revved to 7200 and more with ease.
>You want a good coil?
I highly recommend the big square-top Accel SuperCoil, with it's matching ballast-resistor. It's been on my LA since about 2000.
>My valve springs are the Hughes recommended 1129s, and I bought the "hughes" 5003 circlip lifters, which I run preloaded from zero to 1/2 turn.
>My rockers are 1.6 roller-tipped, blue-anodized, that I bought at the Mopar dealer in 1999.
>My pushrods are Mopar cut to length big boys, 3/8ths IIRC.
Btw; I tried to use a CDI-type, E-core coil, with a standard NON-CDI amp, and that was a bust.
Happy HotRodding
what your problem is.
I just wanted to say that my Second cam was a Hughes FTH 270/276/110 (223/230@050), and I absolutely loved it.
What I can say with a very high degree of confidence is that timing is NOT your issue, nor are your jet sizes.
I'm gunna guess that when you find your problem it's gunna be the Ignition amp, or valve-spring related.
*****************************
> by empirical seat of the pants testing, The reluctor gap can run anywhere from ZERO to 030, and the amp doesn't even miss a beat. The factory spec is IMO, just there to prevent the vanes from rubbing on the pole-piece, over time, as the top bushing wears out. I have seen vanes wore half way down, so I mean, that proved it for me.
> I highly recommend that you run the VA, it will make a world of a difference at Part Throttle, and yur fuel-economy will drastically improve.
I modified mine to get 22 degrees, by filing the external stops to fit. My 223 cam, with overdrive, was good down to about 2000=65mph, where it got gas mileage rivaling any modern EFI 4-cylinder. The timing at 2000 was in the range of 56 to 62 degrees, depending on what she asked for, on any particular day.
********************************
As for my combo;
This is on a 367LA, with alloy heads, TTIs with dual 3" exhaust, the AG, and an ancient 750DP. Plus; I run fresh cold air straight down thru a big hole in the hood., and the carb has one of those short phenolic air straighteners on it, I forget what it's called.
>She liked 32>34 degrees Power-Timing and
>the DP ran 72/80s with a 10.5 PV. Sometimes I run 70/78s knowing it will be lean on top, but she sounds so good ripping up to 7200.........
This DP carb does NOT have a choke either.
and mine revved to 7200 and more with ease.
>You want a good coil?
I highly recommend the big square-top Accel SuperCoil, with it's matching ballast-resistor. It's been on my LA since about 2000.
>My valve springs are the Hughes recommended 1129s, and I bought the "hughes" 5003 circlip lifters, which I run preloaded from zero to 1/2 turn.
>My rockers are 1.6 roller-tipped, blue-anodized, that I bought at the Mopar dealer in 1999.
>My pushrods are Mopar cut to length big boys, 3/8ths IIRC.
Btw; I tried to use a CDI-type, E-core coil, with a standard NON-CDI amp, and that was a bust.
Happy HotRodding
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TT5.9mag
Two atmospheres are better than one
So 218/224 @050 and 270/276 @006 .482 lift on a 110sep. Not what I would call overly aggressive but more than a stock style spring can handle. I’d be looking for about 130lbs on the seat.
The Hughes 1110 would be a good place start if that ends up being your problem.
The Hughes 1110 would be a good place start if that ends up being your problem.
It does not matter what springs you used if the seat pressure is weak due to incorrect installed height. When installing springs installed height is critical . If the valves are sunk in the heads this will also affect rocker geometry. That is why when ever you get heads freshened there is a process to bring them into spec. You just can't throw springs on and think they are good to go. Stem height , spring pressure, and proper lifter adjustment all play a role in performance.
Also when ever you install a larger cam. you usually need to idle off the secondaries or drill holes in the primaries when using a holley style carburetor. Playing with jetting should be second after using air bleeds. I ran an out of the box 1050 quick fuel on my 416 . Bigger slow speed air bleeds and smaller high speed . Squared the primaries and idled off the secondaries. Air fuel ratio was perfect through RPM ranges. The timing was locked a 35 and I used a digital 6 MSD with 20 retard for start up.
Also when ever you install a larger cam. you usually need to idle off the secondaries or drill holes in the primaries when using a holley style carburetor. Playing with jetting should be second after using air bleeds. I ran an out of the box 1050 quick fuel on my 416 . Bigger slow speed air bleeds and smaller high speed . Squared the primaries and idled off the secondaries. Air fuel ratio was perfect through RPM ranges. The timing was locked a 35 and I used a digital 6 MSD with 20 retard for start up.
I don't know if valve springs are your issue, but that's terribly light on the seat and pretty weak open as well especially for a hyd roller. I'd like something about 125 or even 130 on the seat with 230-250 open. I don't think a little more open would hurt a thing. Certainly what you have now is not enough sprAng. Whether it will solve your problem is unknown, but I'd put more sprAng in it "just because".
You’d poop your pants if you see what my basic 750 tuneup looks like for jetting. You might faint if you see my 750 tuneup with annular boosters.
I sweat it still but I’m getting used to it.
That plug is on the hot side for me. If you are running a timing curve you can increase the initial and reduce the total some.
If it’s locked out you need to pull some timing out of it ASSuming pump gas.
TT5.9mag
Two atmospheres are better than one
Maybe but I’ve seen a lot and rarely poop my pants. I like when guys do crazy stuff and it just works out. I was tuning (his carb not mine) a friends stroker mustang yesterday and the damn thing wouldn’t idle for the life of me. Had jetting where I wanted it, TSR where I wanted it, pcvr where I wanted it, hsab where I wanted it, and it wouldn’t freakin idle. Finially looked at the iab and some asshat previous had drilled them (I measured once I started screwing with em) to .130. Once I stuck some 10ga wire in em it ran like a top and idled at 600rpm with a 262@050 cam.
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MOPAROFFICIAL
If it has tits, it's a liabilititty.
The 901 is stock 340 cam spring and
won't work.
What installed height are you at?
1.64 or so?
I like to use 145 lbs or so on the seat and around 300-360 open for up to .500-.550 lift hyd rollers turning 5500-6000 rpm.
Stock reground core?
Yours shouldnt need more than 300-330lbs open.
Did you know you can pull them out and thread the holes for replaceable air bleeds. We did that to this 500 2bbl on this Omni to get the air fuel ratio correct. Most speed shops have different sizes in stock.
TheGrimSpeed
Well-Known Member
Okay, so I guess there’s my issue. Not sure on installed height. I just had bought Hughes locks and retainers and those 901 springs and gave them to the machine shop to slap them together. So I’m probably going to have to pull the heads it’s crazy that I been running the car like this for a while now.
Another question Hughes 1110 springs would be the cure for this? How much more lift would these handle just in case later down the road I install a hotter camshaft?
MOPAROFFICIAL
If it has tits, it's a liabilititty.
To my knowledge the Hughes Spring drops in at about the same installed height as those 901s are recommended to be installed at. They are a higher lift spring and would work a lot better than what you have. You don't have to remove the heads in order to change the springs. So don't worry about that. You can bring the Piston up to TDC on each cylinder and hook a leak down tester to it and pressurize the cylinder to hold the valves closed and then use a screw down type spring compressor to then remove the springs and swap the new ones in place.
TT5.9mag
Two atmospheres are better than one
Oh yea I’m well aware. I do it to all of the stock Holley main bodies that I use. This was a friends car and he didn’t want to get that deep in it just yet. He had a brawler 750 new in the box and we tossed that on it instead of drilling tapping more on this one.
TT5.9mag
Two atmospheres are better than one
All the info on the Hughes spring.
https://www.hughesengines.com/Index...bnVt&level1=VmFsdmUgU3ByaW5ncw==&partid=35162
Personally I’d throw jet in it first just rule that out. The temperature variation still has me worried. Why would it float the valves hot but not do it when cold? Seems like if the spring looses control of the valve it’ll do it at any temperature.
TheGrimSpeed
Well-Known Member
How much PSI would I need in each cylinder? Do you have a link to the spring removal tool. I have never had good luck with a spring removal tool, but this is a pedestal mounted rocker maybe those type of removal tools work better!
TheGrimSpeed
Well-Known Member
Imma do that as well before!
TT5.9mag
Two atmospheres are better than one
I use the hose from my compression tester and just plug it in to my air compressor. It runs at 120psi.
Search here there are threads about valve spring compressors.
Magnum Head Valve Spring Compressor
mygasser
Well-Known Member
i know many prefer it but i don't trust/like the air pressure method to hold the valves up when swapping springs/guide rubbers myself. i have a length of cotton rope (washing line pulley rope, lol) that i work into the bore through the spark plug hole at bdc. then turn as close to tdc as i can at which point the rope jams the valves shut. no possible chance of losing air or having the compressor noise in the background while you're working so for me it's better. the cotton rope is chosen as any tiny 'threads' that come off in the bore will burn away cleanly.
neil.
neil.
MOPAROFFICIAL
If it has tits, it's a liabilititty.
Valve springs lose pressure due to heat cycling after running to the tune of around 7 to 9 PSI.
When you have a spring that is short on pressure, heating that spring up will make it even shorter on pressure.
I had a motor that ran pretty good until it was fully warmed up, then it kind of went flat at the top. Turned out to be the springs, too light
When you have a spring that is short on pressure, heating that spring up will make it even shorter on pressure.
I had a motor that ran pretty good until it was fully warmed up, then it kind of went flat at the top. Turned out to be the springs, too light
MOPAROFFICIAL
If it has tits, it's a liabilititty.
90 psi is well into good enough.
I've done it with 60
TheGrimSpeed
Well-Known Member
I clicked on that link but nothing pops up that would work, one link is dead, and the other member made a tool. I see that Mancini has this MRE - Valve Spring Compressor
$125 But I rather not buy from him I have seen that he charges a lot for shipping for profit.
Is there a generic brand of this type of valve spring compressor?
TheGrimSpeed
Well-Known Member
This looks like it would work, but I would need a stud that I could bolt on were the rockers mount?
Summit Racing SUM-906784 Summit Racing™ Valve Spring Compressors | Summit Racing
Summit Racing SUM-906784 Summit Racing™ Valve Spring Compressors | Summit Racing
mygasser
Well-Known Member
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