Anyone running The GSCA Pop Mech cam in thier 455?

I presently am running the GSCA Pop Mechanics cam in my otherwise stock small valve 455. I have seen claims (mainly GSCA ) say this cam is capable of supporting almost 500 hp. I chose this cam to replace the KB 118 that was bad because of a worn gear due to a HV oil pump. The HV pump was removed along with a total rebuild of the engine. The block was bored .30 and decked .20. I used the GSCA hyper pistons and installed new valve springs (GSCA), new stock aluminum rocker arms and shafts and port matched and bowl blended the heads. They are the 70 model 786 castings. Since the rebuild it has about 1000 miles on it has already broke 2 rocker shafts.:eek2: It fells like a total dog compared to the KB cam. No longer does it have the top end charge that it used to. I took the car to the drag strip a while back and its best was a pathetic 14.20 @96 MPH. The car also has stinger electronic ignition with the distributor recurved and timing set between 34 to 36 deg advance. I try to keep reminding myself that it is a fully equiped GSX, with A/C,P/B, P/S, P/W, and is an Auto. It still seems off the mark compared to the other cars I have seen on the board. I keep reading that these fast ramp cams are junk and I totally agree! If anyone has any experience with this cam, be it good or, like me bad I would like to hear from you.

 

Had the same cam, along with some other work on the heads done through the GSCA.........wouldn't rev past 5000 rpm. Pulled pretty strong to that point, then died. I won't go into the rest. :af:

My engine is now going through a complete rebuild at Tri-Shield Performance. Can't wait 'til Spring!:Brow: :bglasses:

 

Mine won't rev over 5 grand either. I already ordered some TA 1 7/8 headers and 3 in exhaust. I found a low mile 68 430 found that hopefully will have the big port heads. If so, I 'm going to install some STG 1 valves, do a little porting and deshroud the valves and slap them on. I also going to use the 430 rockers, slip in a TA 413 cam, put on a Performer and an 800 cfm Q-Jet. Hopefully it will break into the 12s no sweat and be able to drive it anywhere.

 

I'm going with the new aluminum Stage 1 heads:Brow: , so getting into the 12's should be a piece of cake! Good luck on your build....it sounds like a good plan!:TU:

 

Thanks SmittyDawg. I also have been eyeballing those heads for awhile now. I for now, have decided that they might be a little overkill for what I have got in mind. For the cost of a complete set the beer can heads, I can do a little work on my 430 or 455 heads, buy an intake, carb, and a set of headers and have money left over. Good luck to you also on your new engine.:beer

 

Thanks! Are you anywhere near St. Louis? I get down there occassionally since my company has a large facility in Greenville, IL, about 45 minutes east of St. Louis.

 

I'm in the middle of MO right off of I-44. About 120 miles west of St. Louis.

 

I am running the Popular Mechanics cam also. Motor is a 462 with fresh AMP Stage 1 heads, stock intake, stock carb, HEI (timing @ 33*), headers w/3" exhaust, 4:10 gears and BB trans. Car went 12.50 @ 108 at Cecil County this fall. Car does not want to rev past 4700. It falls on its face like it is running out of fuel. Stock S1 fuel pump. Considering a Carter electric pump or the new JW billet pump.
Car weighs 4080. I also broke a rocker shaft within 500 miles.

Cole - "Fast ramp" :laugh: :laugh:

 

Tip Height....

When you get your heads off to play with them, with the valve springs/shims off the heads, but the valve in place and on the seat, take a veneer caliper, or a depth mic, and measure from the tip of the valve, to the valve spring seat on the head.

If it is higher than 2.100 inches.. then the use of an aggressive ramp camshaft can give you fits.. as you describe..

If that is the case with your engine, give me a call at the shop, and I can tell you how to fix it.. When you convert to the larger valves.

There are a few versions of this cam, and the tip height deal is what makes some of the versions of this cam work on some guys cars, and some guys have issues like yours..

I have had a motor with a 2.080 tip height on the valves, and a fast ramp cam, and that engine was rpm limited to 5500.

We are dealing with an engine right now in the shop, that was rebuild elsewhere, and was a real mess when we got it.. Failed cam, failed cam bearings, and failed main/rod bearings to boot... I have been exploring what can be done at what tip heights on the dyno, and have come to the conclusion that we have to get rid of this high tip height deal, to make this engine live a long happy life. I have everything "living" on the dyno, but don't yet trust this motor to ship it back to it's owner in St Louis..

That motor, with standard lifters, high ratio rockers and .005 preload, was limited to 4600 rpm, with race hydraulic lifters, and the high ratio rockers, it would go to 5100.. and with standard ratio rockers, and the race lifters, it would rev to 6000..


This particular motor has a tip height of 2.125..

The issue here is that the fulcrum position of the rocker on our motors is fixed, and if the tip of the valve gets too high, then more force is required by the valvetrain to open the valve. It has nothing to do with lifter pre-load, as that is just a matter of the correct length pushrod. This issue is a contributing factor to all kinds of failures... cam bearings, camshafts going flat, lifter failure, rocker shaft breakage ect..

There is no real good, inexpensive way to shim up the rocker shafts to raise the fulcrum point of the rockers.


Problem is typically when a machine shop that does not realize how critical this engine is on that tip height.. and then sinks the new oversize valves so they "look good" in the chamber, and they don't even consider the tip heights.

But we have a way to take care of this deal now, without putting seats in the heads.. Takes some special parts and machining work, but it is do-able.

Moral of the story.. be very careful on who you let put your new Stage 1 valves in.

I am convinced that overlooking this issue has cause more cam bearings to "fail" than any other single issue. I did not even attempt to put "hard bearings" in this motor.. it is living (just barely) with stock bearings, which are softer, and can take more abuse. This particular block has other issues, that often contribute to cam bearing failures.

Hard bearings are any of the grooved back bearings..

When we do the aluminum heads now, we use this new valve treatment, and end up with a 2.050-2.055 tip height, and we have had excellent results. I completely disassembled one we had on the dyno a couple weeks ago, that made 600+ HP, and 23 full throttle pulls, just for a durability check, of all the bearings, and the cam bearings (the harder ones) looked like they had not even been run. Best set of new bearings I had seen in a long time.


JW

 

sigh...

Can't wait unitl spring... All these comments sound like the questons I've had with my combination for the last year or so.

#1 Car doesn't want to rev past 5000 rpm

#2 Feels like maybe a fuel shortage (kind of but not quite)

#3 car runs well but not as well as I feel it should. Especially after you read about the kind of power certain people are claiming to get out of this cam.

#4 broke 2 generic rocker shafts, on 2 different sets of heads. Do yourself a favor and order a new pair from TA and use the generics as a trunk spare.

and a couple of my own...

#1. gross Cam lift #'s don't jive with specs that the pop mech cam I bought from GSCA several years ago "should" have! Not sure if the cam is ground wrong or if they sent me the wrong cam with the right cam card.

#2 excessive difference in length between stock push rods and my adjustables with .020 pre-load. Where did this variation come from??? Yes I'm running chevy lifters and yes I know there is about .060 difference caused by using them, but...


Ultimately I just don't feel up to swapping a cam and breaking it in with the cold weather coming. By spring I'll have a new cam picked out and may have to yank the heads (or at lease check the installed height of the valves in the car, by the sounds of it. WAY more work than I want to do with questionable weather coming just around the corner.

Keep the comments coming folks, theres no telling what we may learn and be able to fix on our cars!!! :Comp:


regards!

 

Yep.....running out of fuel....that is the feel....

And John, I had forgotten Dou: ) about the infamous, incredible, all powerful "fast ramp" cam!:laugh:

Senility must be setting in already....

 

What are the specs on this cam if anyone has them handy ? Just want to know to commit to memory. Also I assume that my old 107 is of your "fast ramp" design too, but I don't have any problems. In fact if you don't get any traction with my slicks this thing zings right up and hits the chip really fast lol. Just wondering how close the 2 really are ............... o No:


later................................

 

I've been doing a lot of reading lately on cams. It seems like the 107 (if you're talking about the KB or Poston versions, not the TA) actually have a very soft ramp on the intake, and a little more aggressive, but still soft on the exhaust. If you look at the advertised duration vs. the .050 duration, there is a bigger difference than any of the TA cams, which to me means they have a less aggresive lobe design, at least in the low lift areas. I don't know how fast they ramp up from there, but the lift is so low that I can't imagine it being too aggressive.

107 ADV- 320, 322
107 @.050- 244, 264
difference is 74 deg. intake, and 58 exhaust.

compare that to the TA 413-
adv- 284, 294
@.050- 234, 244
difference is .050 on both int/exh.

I would like to see the advertised duration on the pop mechanics cam compared to the .050. Does anyone have these numbers?
I know there is no such thing as a "magic" cam, but that 107 seems to make more power and torque out of a nearly stock lower compression motor than any of the TA cams. I would love to know why that is, but no one seems to know. That, and most people on here subscribe to the 290-08HL theory of street/strip motor design (not that there's anything wrong with that). The 107 seems to be thought of as old technology. Still, I see plenty of people on here running slower with the TA cams than they would with a 107 with stock heads. Just what I've observed.

 

Street Strip.... and "Window Rattler" (KB 107) in the same sentance?

Look at the overlap numbers of a 107... not something you would want to think about running in a car that sees really any amount of street use.. and it's pretty tough to compare that to a cam with specs like a 413.

20* overlap is my threshold for a street cam.. any more than that, and it's really "too wild" for convienent street use.

And your correct.. a 244* cam, will outrun a 234* intake duration cam, but cams are always a compromise.

Could you explain the "290-08H way of engine building" as you percieve it?

I am assuming your proposing that the bigger cam, with stock heads, will out run the smaller cam, with ported heads?

Am I correct in that assumtion?

JW

 

Yeah, it's bold to use those 2 as a comparison. Window rattler, it is. But it sure makes some power!
I guess you could say my definition for street/strip is different. My car has manual drums. I don't need the vacuum. What I want is a motor that kicks butt and sounds good, and is driveable on the street on pump gas. Oh yeah, and I don't want to put over $4K into it.
The point is not whether it will outrun the 413 with ported heads. But, from what I've seen, it might be possible, or at least close. How many people are dissappointed that their cars aren't running the number they thought they should?
Let's compare apples to apples here. How about a stock motor with a good rebuild, unported heads, and the 107. I know of a 430 with 8.95:1 actual compression with this cam (107), a B4B, MT SS headers, quadrajet, 3500 stall and 3.73's that has run a 12.20 best time, and will run 12.30's to 12.50's all day long... with unported heads. Just a gasket match. And we have driven it 1 hour to the track (Cuyahoga Falls Ohio to Dragway 42). Car with driver 4100+ lbs! These are REAL numbers, no BS.
Sure, you might be able to pull that off with a motor with a 413 and a lot of head work. But, let's compare these two dollar for dollar.
If it works for me, why would I go with the 413 / 290-08h combo? The point being that I can save a heck of a lot of money if I don't want to run power brakes. I like the obnoxious idle. It sounds pretty darn cool!
My point was that everybody on here is convinced that you have one type of combination to a low 12 second car, that being the 290-08h combo. I believe that your developement of this has brought about a super-refined, fast as heck, well mannered street motor. I just have a problem with anyone thinking it's the ONLY way to do 12's. I would be willing to bet there are a lot of people here that don't know you can build a low 12 second buick for $3-4K. I talked to one guy a few weeks ago that was dissappointed with his motor's performance, and was talked into getting the 290-08H combo with aluminum heads. From what he was saying, he didn't really need it to acheive his goal. His budget was tight like mine. He wanted a car he could take out on a cruise on saturday that would run 12's. It can be done with the right combination, cheaply. He had no idea, and maybe would have considered going that route if he had known.
My point is- the 290-08H combo is not a cost effective way to a 12 second street car for everyone.
Your point is well taken- steetable and streetable with good manners are two different animals. Just not to everybody.
I hope you don't see my post as a personal attack, as it was not intended as such.

 

gsca 230 240 cam chart

i was sold this by the gsca as the low-comp pop mech cam
hope this will help

 

I guess there is something more to ramp speed that can't be seen in the advertised duration compared to the .050 duration, since these are the same difference in degrees as TA cams.
Can anyone explain what makes it a fast ramp cam?

 

My cam is a little different than yours. Adv. Duration is 280/295, @.50 is 230/245. Lift is .507 in. and .517 ex. Lobe sep is 116 and 112 centerline. p/n is 33399.

Thanks for the advise on the valve tip height JW. I seen the same problem on Mopars which are set up about the same.

 

Steve,

No, I did not take as a personal attack at all..

But I will question if you can really rebuild any motor for $4 K..

With everything re-machined properly, all new good quality parts.. Everything new, except the rods and crank, head castings and block.

My average engine, has almost $2K worth of machine work alone, and I have not even bought a part yet..

That is a block that is as clean as the day it left the foundery, has the decks cut for zero deck height, and the intake re-fit.. no slotted intake holes allowed! That process alone is $400.. as it takes a lot of time to mock everything up, cut the decks, the head deck and intake manfold surface, and the end rails of the block, so it fits all together, without a half tube of silicone..

RE-Sized rods with bolts, block bore and hone with plate, line hone, balancing, and misc rod/piston work.

I have those 4K motors here... that we are re-doing.. to the tune of 5 or 6K..




I will agree there are plenty of ways to go fast, it all depends on what you want to live with.

Also, drag strip times for comparing a cam, or even an engine build, can be very misleading..

There is a whole lot going on there, besides the engine, or any component.

And yes, 12.30/20's with a good working combo and no porting work to the heads is certainly possible.. I ran a car with 235 cfm stage 1 heads, but with more of a "race setup", at 4100 lbs, all the way down to 11 teens, with a big cam and race fuel. Nothing we would drive to the track, but that's what you give up to go a second faster.

Getting a street car, that will run the power brakes, operate on pump premo, and be reasonably easy to live with, to run those times, is the challenge.

Your buddy with the 08H cam and the alumium heads needs to figure out what is very wrong with his combo..

Not two weeks ago I had an engine on the dyno, with those heads, on pump gas, with enough vacuum to run the brakes, and a smaller overlap cam than the 08H.

It made 610 torque, and 604 HP..

That's enough power to put a 3800-4100 lbs GS into the low 11's/high 10's.. with a minimum of "race prep".

Heads are everything to making power.. and the most important factor for guys that want the power, without paying the driveablity price.

JW

 

Hi guys,

I'm not going into the specifics on the cams, but what caught my eye was the cost of building a 455 on a tight budget.

Well I can say that I'm building two different engines, one an all out racing engine "mega bucks" for my GS and the other a very low budget stocker with a towing cam for my Centurion convertible tow car.

I have to say the costs does climb. On the stocker I am doing the complete assembly of course with the all out race engine I farmed it out as it is beyond my experience. I always remembered what Clint Eastwood said, "A man's gotta know his limitations"

The stocker so far has cost me $1,150 that was for stock replacement cast .030 pistons, bore and hone, balance the block, press "my" new rods onto the pistons (I already had the stock rods and they were new from years back) also included is all bearings and rings and lifters along with cutting the crank .010 under.

Now I still have to buy a gasket set, oil pump, timing chain and gears, fuel pump and cam (a good used tow cam from Doug Hecker) and rebuild the distributor.

As for the heads I already had a set of very good Stage 1 converted heads so no work is needed, I already have a B4B intake and a good carb also and I don't plan on installing headers...at this time.

What I'm getting at is after I am done it will cost "me" close to 2 grand and that was with NO head work, or additional parts as the carb, intake, rods, flex plate not to mention a good mild ported heads and me doing all the assembly. Had I needed these items and had an engine builder build the engine for me I would figure this bare bone 455 would cost an easy 3 grand or most likely more.

Now with that all done comes the rest of the game...your converter.. another few hundred bucks and not to forget a decent trans and rear. Without these items set-up with your engine combo, you will no doubt hurt your performance.

Don't get me wrong here, I am just adding some of my experiences with engine building from a racer's view, not an engine builder or parts guy's view. So it does add up. I will no doubt keep a break down as both engines progress for an exact cost to me. A great comparision from both ends of the coin.

As with the cost of the race engine...ou: For now my only advise is to do it right spend the extra cash and do it once. Saving a few bucks on a race engine will no doubt come back to bite your wallet big time down the road.

Thanks for the time, just some of my thoughts, and best of luck for those with their projects.

Rick