PAC spring questions

PAC 1243 and pac 1343 have same dimensions so. What’s the difference and which one is best for street strip .680 roller? Also Howard’s has a pacaloy 98843, same dimensions, is this the same pac spring sold under Howard’s.

One is a 1200 series spring and one is a 1300 series spring
That Howards spring, Comp 943, Trickflow 16943 are all relabelled PAC 1243s

The 1343 is listed as "1.550 Dual Spring for Short Installed Height Roller Cams", the 1343 is listed as a "1.550 Dual". I'm running the 1396 on my small block.

The 1300 series “have the latest advancements” for higher endurance.

Take a peak at PAC web site on the differences in those two part #s
I've used both in the past on my old Duster, I'm sticking with the 1200 part series now

Ok, looks like the 1200 is good enough for what I’m doing. What application would call for the endurance of the 1300 spring?

A street/strip solid roller cammed, Indy headed small block that runs mid 6.20's on pump 93.

What does you cam look like?

263/271° @ .050" .711/.719" at the valve. The thought of the 1300 series endurance spring was that it would hold up better on the street.

That was my thought as well. After I subtract for lash I be about .668” lift if I can make that work with my victor heads and standard valves. I’m told .680 is max lift with this combo per Hughes Engines. May have to switch out the 1.6 arms for 1.5’s.

The cam that is in my old S/P motor with the Eddy Victor M.W. heads has a little over .700 net lift with the Harland Sharp 1.56 ratio rocker on it, it has .120+ V to P on both valves and it is right at .080 from coil bind with the PAC valve springs I put in that motor. I did replace the springs, retainers and keepers to a set of Comp Cams 10 degree tool steel retainers and keepers with lash caps

That part looks good. Hughes says my Victor heads with standard valves only allow 660-680 lift max. I don't know for sure. I believe my current springs are 1.550 flat tappet springs and hoping to reuse the spring cups, titanium retainer with locks on the new Pac springs. I see CNC motorsports has the 98543(1243) pacaloy springs for $280. UDHarold cam has been ordered, so i'm on my way to roller after the T ram test run in the spring.

I run the PAC 1243 on my hemi and have been very pleased w/ them. Dwayne recommended them 14 years ago.
.672"/.651", 276°/284° at .050" solid roller.

I believe the 1300 series are polished. Mine runs the 1224 Pac.. When swapped at 200 passes zero pressure loss. Current set has 300 passes. Stainless 2.25 x 11/32 intake valve. 285/292@.050, .800. 7100 every pass.
Doug

Sounds like the 1243 spring is plenty for racing. I do a lot of street so was just looking at 1343 as well. Thanks guys

You can get more installed height using +.050 retainers and locks. My 511 is over .700 net lift with standard length valves in my Victors. Hughes told me the same thing as you when I was figuring out the IH and camshaft. The problem I ran into was getting the roller tip centered on the valve at that lift. I used a b3 kit to correct it. Engine made peak hp around 7000-7100.

Wow, what size cam did you put in it? I went slightly conservative with 269/275@50 on 108.

I will dig out the specs. It is a little different that what you will want being a power adder deal with a small tire and a stick. .740 gross, 280's @ .050, 111 LSA from Mike Jones. Maded 686hp first pull. 750 on the last pull without n20.

Isky Tool Room is all you need ........Wink Wink .....

I used ISKY RAD-9998 1.600 OD springs with a 2.00ish IH.

Forgot my part # but after 9 years on the street they were all within 10lbs.....

I think the 1243 pac spring is a specialty spring for short install height. Can’t find anything like it on Isky site. $280 is not a bad price either.

Found my card they are part # 9385.....

Drag Week comes to mind.

Just FYI, I have ran Trick Flow TFS-16943-16 springs since 2013 on Edelbrock MW Victors with.674 Valve Lift. They are re-boxed PAC and I believe the 1200 series. The Trick Flow box says "by PAC". I pulled the heads apart a couple years ago (blew some metal out between 3 and 5) and when I checked the springs, was surprised how pressure readings (seat and open), didn't vary much from when I checked them when they were new out of the box. After fixing the head, I reassembled using same springs. . https://www.summitracing.com/nv/parts/tfs-16943-16

Cool. That’s an even better price yet. Thanks

I forgot to mention I've had and used a valve spring tester that shows Lbs. and distance when installing valve springs since the mid 1970s, on roller cam springs I shoot for .055 to .080 to coil bind on iron heads and from .065 to .085 on aluminum heads. I try to get the seat pressures within + or- 5 lbs. and shoot for between + or -20 lbs. open pressures by shimming or swapping the inner and outer springs to get what I want

I will check those best i can for coil bind and p-v, but thought if i set them up at 1.900 as they are spec'd by Pac, the pressures would be very close or close enough. I'm not removing the heads. I called Howards yesterday about the Pac 1200 and 1300 series springs and Eric tells me they never seen the 1300 spring last any longer than the 1200. He also said the 1200 is plenty for what i'm doing as some on he have said as well. Thanks guys