fwd roller and non roller cam parts in gn motor w/pictures

Are you sure you can use the 980 valve springs with a roller cam??? I thought that you had to use a WAY stiffer valve spring with roller cams...

And for curiousity sake, where did you get the Comp Cam 258HR came at??? Do most of the GN/TR vendors carry it???


I agree... 980's are flat tappet springs. I am under the impression you need around 135# on the seat or so..... 980's should be in the 100# range on the seat....... not nearly enough seat pressure IMHO for even a baby hydraulic roller.
 
I know one person who is working on fabricating the fwd roller cam to fit the gn motors.still in testing phase.
been using then on 4.1 with 3800 heads and intake, in my buggies for a while now. use the g-rotor oil cover/ convert also. no low oil pressure when hot.
 
Iwill give you a call.

did I understand that YOU installed USED and cleaned lifters on a different cam. a Comp. being no statement of refacing the face of the lifter, and a statement of putting rollers on a standard cam. I have a few muffler bearings i need cut and spun in a lathe? take pay-pal
matt
 
Update on my HR conversion project.

My motor is ready to be installed..... I have my tranny torn apart and I am in the process of beefing up a few components.... hopefully to be going back in the car within the next few weeks.
 
I am on the verge of starting the assembly of my engine also--its taken a long time to assemble the parts because its suck a bastard combination---a 4.1 block with a stroker crank, Carillo H-beams, Diamond pistons and adapting the 3800 heads and g-rotor oil pump, block girdle and roller cam and lifters---obviously many parts are being custom built so its not quick (or cheap), and I have yet to decide for sure if I am going to be going with one BIG turbo or two smaller ones but I am leaning towards the two smaller ones to keep it more drivable on the street---we should soon see what our labors have yielded.....................Dan
 
It looks like there are a few of us working on this project:) I'm waiting for my block to come back from the machine shop. I will be using a custom ground 206/206 Comp roller cam with Champion iron heads. I will post pictures when I get the long block assembled. :cool:
 
Alright, I am seriously considering doing this project. My engine and transmission are out of the car right now because of the trans.:mad:
If I understand this right this is what I need;

The lifters out of a 1995 Chev Lumina 3.1L V-6 measure .842" wide and 2.228" high. The stock lifters are .842" wide by 2.005" high. When used with a Comp Cams 258HR (ductile iron) specs. 206/206 .498 lift, 110 LSA ......there is lots of ramp-up clearance (where the roller touches the cam,) lots of shoulder clearance top at max lift (.160" to be exact....... so the shoulder doesn't hit the dog-bones) and bottom or base circle ( .115" above flush deck....for the dog-bone retainers to stay in place) Use the retainer and bones out of a 1986 Vin "3" 3.8 roller block as shown in the photo's above (personally I would shorten the length of the spacer a little to put a little more pressure on the dog bones, but only about .200" inch less than the 1.00" suggested, you don't want too much pressure on them either)...........the only thing left to get are pushrods.

This would be Wonderful!!! I am really concerned about wiping a cam with the recent changes in the properties of motor oils. Yes I know, there are additives that address this but for the money required for this mod, and having the engine out, why not???

Skids, have you fugued out what length the push-rods need to be yet?

Thanks fellas!!!!
 
I haven't built the engine yet...........it happens this week. I was hoping someone had a similar project on the go and would chime in. I'm picking up a 7.80-8.80 pushrod length checker tomorrow, and will start the build this week. Stay tuned for cam install pics.....I'll have lots of measurements to the 1000th of an inch as well. Cheers!

As for the 980 springs.........the plan was to use the cups, so the pressure on the seat should be around 110lbs.......I'm going to look into other economy Z-28 springs in the 130lb range as well......will post soon.
 
I haven't built the engine yet...........it happens this week. I was hoping someone had a similar project on the go and would chime in. I'm picking up a 7.80-8.80 pushrod length checker tomorrow, and will start the build this week. Stay tuned for cam install pics.....I'll have lots of measurements to the 1000th of an inch as well. Cheers!

As for the 980 springs.........the plan was to use the cups, so the pressure on the seat should be around 110lbs.......I'm going to look into other economy Z-28 springs in the 130lb range as well......will post soon.


IMHO... 110#'s isn't enough seat pressure for any hydraulic roller cam... unless maybe it is stock or smaller...
 
O.K......so we know what may not work.......but could you suggest a spring in the 130lb. range with similar coil bind properties to the 980 that would work?
 
I'm running the Comp 26918 beehives.... they are "new" technology. Mike Licht sells the kit with springs/retainers/keepers for our cars. I found a guy on here that had bought a kit... decided to do something different.... and listed the spring kit on eBay.... worked out great for me.... I got like $70 or so in the whole spring kit.

I am sure there are other alternatives that can be had new for similar or less money.. but they would likely be a conventional spring type.....

I think mine worked out to 140# or so on the seat..... and maybe 300 # or so across the nose... can't remember exactly....

HTH
 
Watching Skid's progress

130# or so is what the installed seat pressure usually is from other posts.
You might want to do a search for roller valve spring pressure or something like that to ease your mind.

I'm trying to find all of my parts now to do the same conversion.

Appreciate your willingness to share this information
 
Did you have to modify the T & D rockers with the "compact" beehives?.

Could I use stock rockers with beehives?
 
Did you have to modify the T & D rockers with the "compact" beehives?.

Could I use stock rockers with beehives?

I didn't have to mod my T&D's for the beehives.... but had to cut my rocker pedistal to clearance for the T&D's.

Not sure about the stock rockers....

FWIW... I think my springs will relax a little after breakin... I am thinking they should settle in the 130's.....I just didn't want to start at 130 and end up at 115-120....
 
I hate it when guys just quit posting half way through a build.........so sorry I haven't posted an update on my build lately. The whole idea is to keep this upgrade cheep........and beehive springs kind of wreck that idea.......... I stopped the build because I don't want to spend $180 on beehive springs and retainers, so I asked a bunch of builders at local speed shops what to do. They told me 980 springs (1970 LT-1 Chev 350) should be good just north of 5000 rpm with the CompCams 258HR.......... anything more aggressive would probably require beehives. How do they know, well, they're Chevy guys who know Z-28 Chevy springs, and that's what we are putting in our Buicks. They told me that they use a similar spring in the Vortec head upgrade using the GM-HOT roller cam (LT-4) specing out at 218/228 @.516ish lift.........substantially more agressive than the Comp 258HR..........and those thing will run to 5 grand all day. So I'll be the Guinea Pig and be the first to risk 980's on a roller setup. Stay tuned for pics, and pushrod length specs.:) They'll be along soon.
 
I'm still posting,just started new thread with pictures due to size of this thread...I'm using bee hive springs and due to my turbo size we bumped spring pressure up to 140-150 range with about 360psi open pressure.I'm using a weber billet 218 roller cam,but will run a ductile roller on my next build.

I hate it when guys just quit posting half way through a build.........so sorry I haven't posted an update on my build lately. The whole idea is to keep this upgrade cheep........and beehive springs kind of wreck that idea.......... I stopped the build because I don't want to spend $180 on beehive springs and retainers, so I asked a bunch of builders at local speed shops what to do. They told me 980 springs (1970 LT-1 Chev 350) should be good just north of 5000 rpm with the CompCams 258HR.......... anything more aggressive would probably require beehives. How do they know, well, they're Chevy guys who know Z-28 Chevy springs, and that's what we are putting in our Buicks. They told me that they use a similar spring in the Vortec head upgrade using the GM-HOT roller cam (LT-4) specing out at 218/228 @.516ish lift.........substantially more agressive than the Comp 258HR..........and those thing will run to 5 grand all day. So I'll be the Guinea Pig and be the first to risk 980's on a roller setup. Stay tuned for pics, and pushrod length specs.:) They'll be along soon.
 
I'm still posting,just started new thread.......

Oh, I wasn't refering to you, I was refering to me.........I haven't posted any info for a while due to a couple of issues. I gave the impression I would provide info on my build in timely order.

P.S. How long are your pushrods, how much were they, and where did you get them? Cheers, Randy.:)
 
heads at machineshop.once we bolt heads on and get pushrod length I will post for you.I'm running rjc bullet proof head gaskets.

Oh, I wasn't refering to you, I was refering to me.........I haven't posted any info for a while due to a couple of issues. I gave the impression I would provide info on my build in timely order.

P.S. How long are your pushrods, how much were they, and where did you get them? Cheers, Randy.:)
 
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