stereomandan

I'm seriously looking at these for my GM 845 cam install. I just want to know if anyone has had bad experience with them. They seem very nice for my application. They are $99 complete, and I can use the stock retainers and seats if I want. Single spring with damper. My max rev range will be 6200 rpm, no more.

Isky 235-D
Outside Diameter of Outer Spring (in): 1.260 in.
Inside Diameter of Outer Spring (in): 0.886 in.
Damper Spring Included: Yes
Seat Pressure at Installed Height (lbs) 130 lbs. @ 1.750
Open Pressure (lbs) 320 lbs. @1.200
Coil Bind Height (in): 1.150 in.
Spring Rate (lbs/in): 350 lbs./in.

The GM 845 cam is 214/224 0.521/0.543 lift.

I'm considering installing them at 1.78" stock height, which will give me about 120 lbs of seat pressure. A little low, but is it enough with this mild cam? Open pressure would be about 310 lbs on the exhaust side and 302 lbs on the intake side with this setup. Coil bind is going to be o.k. with these springs.

I'd rather spend $99 if this spring will work than the $300+ for the 26918 beehives.

Dan

MachinistOne

The 235-D is a very good spring, I use it all the time. But you cannot use the stock spring seats - it looks like they fit, but the spring ID is too small and the spring sits on the radius of the seat. You need to use Isky #255-VSL as your bottom locator and then check your installed height and use the correct retainers/locks to get the pressures right, a 707-STA should put you in the correct range I think, but I don't remember if I have to use +.050" locks for that combo...

stereomandan

Thanks for the great reply. That's good to know about the springs.

One thing I know is that if I use L98 locators (part# 10185066), that supposedly fit well with these springs, then the installed height is 1.76", according to measurements from truedualws6 who has mocked up this combo. I believe that this is with the stock retainers and locks.

Are the stock, or LT4 retainers and locks o.k. for the Isky's? I have both, and I think they are identical.

Dan

MachinistOne

Yes - the stock retainers will fit ok, but the ISKY locator's are .075" thick and may make your installed height too short, that is why I was saying you may need to get some +.050" retainers(STA)

The L98 locator's may fit, I know that several years ago I was able to setup a set of heads with those springs and a set of off the shelf GM locator's, but the last time I did it I couldn't find the part number for the ones I used and the LT1 and LT4 locator's have the same part number and neither one fits. It may be that the L98 ones are different and were what I used.

stereomandan

Thanks again. Yeah, I think the L98 locator is around 0.046" thick, so it helps with installed height.

Dan

Bersaglieri

stereomandan, how'd that install go? I was looking at using these springs with a mild cam as well, seems like a good buy since you can reuse most of the stock stuff.

MachinistOne, in your opinion how aggressive can you go on the lobes with these 235D springs? I assume they would handle Comp Magnum and XE lobes just fine, but not XFI series or stuff like that.

-Dustin-

MachinistOne

I've used them with the XE lobes quite a few times, but I would step up to the toolroom 295-D spring with the XFI lobes.

Another option that I like is using the dual PAC springs designed for the LS motors - I'm trying to use them in as many application as possible.

Bersaglieri

Thanks MachinistOne. I wonder if I could just toss a shim them to the correct installed height with stock retainers/locks, alot better on the wallet than a full set of locators, those L98's have gone way up in cost.

I'll be running em with a XE502 cam 218/224 .528/.536 112LSA.

-Dustin-

MachinistOne

The problem is that like I put in an above post, those springs don't sit on the LT1 locators properly and instead ride on the radius rather than the flat of the bottom coil. The cheap alternative in the past was to use the slightly different stamped steel locator from GM, now I have different spring setups that I use so I haven't looked into it in a while.