When Stroker Motors Go Bad.... - Page 2

BDR561 · #21 (**permalink**) 10-14-2007, 07:02 PM

He had new springs and work done to support the lift of the cam...

What head would you recommend as a replacement, I believe I will de-tune the motor and drop the c/r to 10:1 and a more civilized street cam

blykins · #22 (**permalink**) 10-14-2007, 07:03 PM

Those heads are good heads....hard to beat them.

jwd · #23 (**permalink**) 10-14-2007, 07:37 PM

AFR heads are fine, it's their hardware that sux. Edelbrock Victor or Victor Jr. heads are as good or better PLUS the hardware is quality stuff.

Excaliber · #24 (**permalink**) 10-14-2007, 07:52 PM

I dropped the compression and went with a milder cam in mine as well. Couldn't be happier! Oh sure the really BIG motor was fun, for a little while, mostly a pain in the butt for street use.

I guess just because you give a carpenter a set of blueprints, don't mean he can build a house.

BDR561 · #25 (**permalink**) 10-14-2007, 08:14 PM

Must admit, will be nice to use pump gas...

blykins · #26 (**permalink**) 10-15-2007, 05:14 AM

Yes it will. I would think about switching to a hydraulic roller cam as well. That way you won't have to worry about the lifters failing (technology has improved, but there is still a risk) or having to change valve springs every so often.

BDR561 · #27 (**permalink**) 10-15-2007, 06:22 AM

I like the 205 heads so will probably just order another set. Unfortunately there isn't a great selection of pistons for a .40 over using 6.2 rods, most of what are available have a high c/r and I would like to stay around 10:1. Looks like the JE 232464 will give me close to a 9.5:1. Cam??? Thinking the CC 249-35-770-8, 602/608 lift.

Trying to get everything in time for the 27th....

blykins · #28 (**permalink**) 10-15-2007, 06:36 AM

I ran a Probe dished piston in my 425W. It was a 22cc dish and they do offer it in .040" overbore. With a 60cc head (and my other build characteristics), it gave me 10.3:1...which is very doable with aluminum heads and a cam with a decent duration. I also ran a 6.2" rod.

If you're wanting to run pump gas and use the Probe pistons (they're a lot cheaper BTW), you should probably go with the 35-771-8 cam. My CR calculator says that with a 4.040" bore, a 4" stroke, 58cc chambers, and Probe pistons with the 22cc dish, that your SCR would be at 10.36:1. I guessed at your deck height and put the pistons .005" in the hole.

The DCR with the 771 cam would be 8.2:1 running it at 110/106.

IMO, the 35-771-8 cam would be a little better match for the combo and for the car. You could very easily run pump gas....probably 89 octane with that DCR. I would guess that the hp peak would be at around 6300-6400.

If you used the 770 cam, I think you'd have to find another piston to get the DCR in the right spot to run pump gas.

blykins · #29 (**permalink**) 10-15-2007, 06:42 AM

BTW, the part number for those pistons is 12360-040. They're about $455 through Flatlander Racing. Keith Craft can get Probe pistons as well.

blykins · #30 (**permalink**) 10-15-2007, 06:49 AM

Sorry for all the edits up above....I was off a few cc's on the piston dish.

greg schroeder · #31 (**permalink**) 10-15-2007, 07:37 AM

Looks like a mess

turnpike boy · #32 (**permalink**) 10-15-2007, 08:22 AM

Quote:

Originally Posted by jwd

Unfortunately, AFR uses hardware made in China and there are alot of problems being reported all over the internet. They used to be the best product on the market but that has changed.

Uh huh.

.

As the industry leader for 35 years, doubtless they're not concerned with their standing and reputation and are going to provide less-than-adequate equipment. As to the "lot of problems", equally doubtless these are the fault of AFR as well, and certainly not related whatsoever to "quality" builders and enthusiasts.

You might want to look at the pictures again.....and you might want to ask the builder just what he provided. With those cam specs and control over both the machine work and construction, he's eminently qualified to answer that question, as well as just exactly what he bought for the build.

RedBarchetta · #33 (**permalink**) 10-15-2007, 09:14 AM

Looking at those pics, we all feel for you.

There's also something to be said for buying a stroked motor from one of the mass-production houses (Ford, Roush, RDI, World Products, etc.). Aside from any warranties, at least the experience and volume tells you that these kind of things shouldn't happen with someone that deals with building these motors daily. That doesn't mean that $#it won't happen...just less likely and better odds.

Hope you get her back together soon.

-Dean

Madmiles442 · #34 (**permalink**) 10-15-2007, 09:24 AM

Yowzers. Feel for you, man. I've been without my Cobra for 4 weeks and the withdrawal is getting bad.
Hope she's back on the road soon.

Jerry Clayton · #35 (**permalink**) 10-15-2007, 09:25 AM

The stroke didn't have any thing to do with this--the cam was timed wrong or the crank key sheared and the cam retarded. The piston is chasing the exhaust valve as it closes and there was inadequate clearance probably at around 10-15 degrees before tdc

Jerry

BDR561 · #36 (**permalink**) 10-15-2007, 11:46 AM

Haven't seen the crank key yet, that was a possibility that I thought of, but after seeing the DVD of my actual motor being built and the claying of the piston/valve clearance it's pointing to inadequate clearance...

Does anyone know what the .039 gasket actaully is at 10lbs vs. 75lbs?

BDR561 · #37 (**permalink**) 10-15-2007, 11:48 AM

blykins,

I have a block with a 9.480 deck that has been decked .015. I will look into the probe pistons... I'm running Oliver rods if that makes any difference.

turnpike boy · #38 (**permalink**) 10-15-2007, 11:49 AM

It would be worth your while to get the degree wheel out and actually check what was done - there is reason here to suspect the veracity of that video. As to the rods; 6.200" is 6.200", regardless of whose make they are. Check with the piston mfgr. also and find out their recommendations on what they were designed for, lift-clearance-wise. They can tell you a good ballpark number based on compression height of the piston and relative position within the block - example, if the block is zero-decked (top of piston flush to deck), then piston would provide adequate clearance for a lift of 0.XXX".

blykins · #39 (**permalink**) 10-15-2007, 11:56 AM

I don't know what you're referring to with the head gasket. As long as the head wasn't rising up off the deck, there's no reason to check out how much torque would compress the gasket. You're talking about probably less than .010-.015" between install thickness and compressed thickness. The only concern here is that if the bolts were loose, the head was way off the block when the pushrod was going up. But there again, he was using checking springs, so it wouldn't have raised the head off the deck anyway. You just want the head to be sitting down flush where it should be. Once it contacts the metal and the fasteners are tight, there's no use in torquing them down to the correct torque until final assembly.

I never check piston/valve clearance with the head gaskets on anyway. There's no use in it.

If you're thinking that if he had torqued the heads down to the torque spec that it would have changed something....but if he was measuring .200" clearance, a few more wouldn't have been noticeable to him. Also, if torquing the heads down brought the piston/valve clearance out of spec, then you were way too close to begin with. See what I'm saying?

As for the pistons, these were for a 9.500" deck....I don't think the Probes will work for your deck height, but you can check. It would be a cheap alternative for you.

BDR561 · #40 (**permalink**) 10-15-2007, 12:10 PM

I'm trying to get a screen shot of the video... As I previosly mentioned, the clay had been pushed out of the way and I could see the piston showing through in the valve relieve, (it was NOT .2100 in that area). I'm assuming with the crush depth of the gasket it would make it worse...