As a few of you know from last year I had a problem with my new 290hp crate blowing smoke. I brought it to the dealer and without a problem the repaired it. It ended up that the stem seals were being crushed by the retainer on 3 valves. Well I'm looking into doing something with a new cam so I did some checking.

Pulled off a spring and checked the clearance from the retainer to the seal. Spring height and piston to valve clearance. Here's what I got....

-Retainer to seal = .470
-installed height = 1.75
-Top of valve stem then top of valve stem dropped into cylinder = .970 ( plenty of clearance for a cam)

Look at the specs for the seal! The lift on the stock cam is .450 intake .460 exhaust. I'm looking into a cam with .479 intake and .465 exhaust. Question is could I get a retainer about .050 shorter so I won't be so close to the seal?

Marc,
A lot of the aftermarket retainers will give you a little more installed hgt and clearance to the seal. Problem is you have to have a "stash" of them to try until you find one that will do what you want. What heads are on the engine ? Vortecs ?

I know there not Vortecs. Whats the stock head on a 290hp crate? Here's the head number...93438648 Iron 76cc.

Marc,
Is that the actual casting number on the head, or a part number ?? The part numbers really dont mean much, you need the actual casting number off the head itself.

Marc,
Is that the actual casting number on the head, or a part number ?? The part numbers really dont mean much, you need the actual casting number off the head itself.


yea, casting number. I don't have the head number off hand. Maybe someone knows what heads came on the 290hp crate?

14034808 I believe is the casting number (heads) on the 290hp engine. I could be wrong tho....

14034808 I believe is the casting number (heads) on the 290hp engine. I could be wrong tho....


That could be it. Here's what I found.
14034808...96-up...350..........76cc chambers, 1.94"/1.5" valves, Gen.I Goodwrench crate motors

Earlier ones are "Hecho en Mexico"...doesnt change quality or anything tho. Like Bill said youll have to find a 'stack' and see which seals and retainers would fit best.
IMHO tho, I think you would be ok with that cam. I was looking at specs for this motor at pace parts and scoggin-Dickey and I think a little more lift and duration would be a nice upgrade for this particular engine. Just my .02 :thumbsup:


edit: are you planinng any future upgrades?

Earlier ones are "Hecho en Mexico"...doesnt change quality or anything tho. Like Bill said youll have to find a 'stack' and see which seals and retainers would fit best.
IMHO tho, I think you would be ok with that cam. I was looking at specs for this motor at pace parts and scoggin-Dickey and I think a little more lift and duration would be a nice upgrade for this particular engine. Just my .02 :thumbsup:


edit: are you planinng any future upgrades?

Thanks. I keep going back and forth. Comp just came out with the hydraulic thumper cam. The whole kit cost around $380. It's not gonna work with my retainers. . The clearance is too close to the seals. I only have .460 clearance and the cam is .479. My local engine shop said today he could mill down the retainer up to .100 on the bottom as far as the keepers. That would give me the clearance. The problem is the exhaust. They have the spinners. They can't be milled. If I use the intake retainers on the exhaust the installed height comes out to around 1.876. thats .100 too much. I can't use that many shims. http://www.compperformancegroupstores.com/store/merchant.mvc?Screen=PROD&Store_Code=CC&Product_Code=K12-600-4&Category_Code=ThKFT I know many will say Noooooo. I think this will make me happy while my 496 is being built. Around 2 years. The cam shoud give me better power and a nice sound. I have a 2500 stall and 3:25 gears. here are the specs. http://www.compcams.com/Cam_Specs/CamDetails.aspx?csid=107&sb=2

You can buy a cheap tool that will shorten the guides and size them for proper positive seals. I've heard it can be done with the heads on the engine. (I wouldn't...) And you can lose the rotators.

Thanks. I keep going back and forth. Comp just came out with the hydraulic thumper cam. The whole kit cost around $380. It's not gonna work with my retainers. . The clearance is too close to the seals. I only have .460 clearance and the cam is .479. My local engine shop said today he could mill down the retainer up to .100 on the bottom as far as the keepers. That would give me the clearance. The problem is the exhaust. They have the spinners. They can't be milled. If I use the intake retainers on the exhaust the installed height comes out to around 1.876. thats .100 too much. I can't use that many shims. http://www.compperformancegroupstores.com/store/merchant.mvc?Screen=PROD&Store_Code=CC&Product_Code=K12-600-4&Category_Code=ThKFT I know many will say Noooooo. I think this will make me happy while my 496 is being built. Around 2 years. The cam shoud give me better power and a nice sound. I have a 2500 stall and 3:25 gears. here are the specs. http://www.compcams.com/Cam_Specs/CamDetails.aspx?csid=107&sb=2
Are you dead set on the Thumper? There are cams out there that perform much better and still have the same sound. My advice if yoyu want sound and performance is to get the 276 from Comp. The 280 might work ok too, not sure. Good
luck!!

You can buy a cheap tool that will shorten the guides and size them for proper positive seals. I've heard it can be done with the heads on the engine. (I wouldn't...) And you can lose the rotators.

Got several of these tools in my tool box up to 1.625 id. They not only mill down the stem boss height but also they will cut the id down to either .500 or .530 to fit good PC or band clamp type seals. Most head shops have these tools. You will beat yourself silly looking for the retainers you were talking about.

^^ come to think of it Don, your right. May be hard to find...

Did a little more measuring on the intake and exh. Here's what I found. The intake seat is a bit higher than the exhaust. Switching retainers around here's what I got.

The way it is now....

Intake installed height = 1.742
Space between seal and bottom of retainer = .450

Exhaust installed height = 1.741
Space between seal and bottom of retainer = .461

Cam specs now .450 intake / .460 exhaust ( this is why I had a seal crushing problem !! They just replaced the seals....I could see it happening again!)
New cam specs .479 intake / .465 exhaust

Here's what I need to be safe.
.030 on the intake
.055 on the exhaust

Now measuring the thickness of the retainer I found the rotator retainer on the exh is .052 thicker than the standard intake. So I took the intake and tried on the exh. Here's what I got.

Intake installed height = 1.840
Space between seal and bottom of retainer = .510
Now the installed height is .100 too much. How could I get my correct installed height without using different keepers? Is .100 shims too much?

As for the intake side. I could just shave .060 off the bottom of the retainer and be fine or even up to the keepers. Thats around .100. The exh..I dont want to keep the rotators with a bigger spring. Hope I didn't confuse you guys?

Shave off bottom of retainer?? Remember that any stress risers will allow retainer to split. OPPS, there went the valve. Just a precautionary note. Don't know what material your retainers are. Also don't know how far you keepers fit into the seat area.

Here is what I'm going to do DEPENDING if I use my 305HO, -601's to make a 292 or my god big valve -291's to make a 301.

292 motor here!!!

I'm going to using Elgin's .600" lift springs and some shims on the exhausts less rotators and then .050" taller locks on the intake's to mix and match to take care of ditching the rotators on the exhaust vs having too much pressure on the intakes!!

Here is how you do this!

Spring rate = open height #s - seat #s/ seat installed height - max lift height!

Then you take seat pressure + (spring rate x lift) to get max pressure at lift to make sure you DON'T over spring her and wear the lobes and lifters down!!

(Seat pressure is rate x seat height).....

pdq67