Solid Roller Cam Hellp

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douglas340

douglas340

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Brisbane, QLD
I`m looking at buying a compcam custom grind billet solid roller cam that's done 12 dyno pulls only for my engine, The specs are 246 int 250 ex at .050 110 isa .608 lift with 1.6 rockers. The guy that's selling it owns a engine shop and said it should suit my engine nicely?? I have a set of 1.5 rockers at the moment, Can anyone tell me what affect that will have with the cam?? I have no idea what cam to buy & if the above one will do the trick?? I`m not that knowledgeable with cams so any advice from you would be appreciated, I don't want to wast good money for a cam that's not getting the best out of my combo. The specs of my engine are:
factory 340 block bored 40 over, Vanola forged pistons, scat H-beam rods & factory steel crank. Heads are 6077 RPM`s with comp roller springs & titanium retainers 2.02 & 1.6, They have had a stage 2 porting job done by Ryan J, specs are:

LIFT--IN/EX IN EX
.100"--72.6/NA 0.1
.200"--146.9/110.8 15.8 3.8
.300"--196.3/150.1 13.4 -1.7
.400"--245.8/180.2 29.2 -1
.450"--259.0/193.8 31.3 9.9
.500"--268.6/203.4 32.7 17.8
.550"--271.8/212.9 33.1 27.3
.600"--276.6/218.6 34.4 33
.650"--283.5/221.6 40.3 36
.700"--286.6/223.8 43.4 38.2
Compression is 10.5
My manifold is a edelbrock victor junior single plain with a 850 demon carb. The block has had oiling mods done to it suggested by Guitar Jones.
http://www.forabodiesonly.com/mopar/showthread.php?t=103623&page=2
I`m running a 904 fully manualized auto, I haven`t chosen a converter yet but it will be around 3500 stall I think??. The cars weight is around 2900 lbs. The engine has been built to run around the 7000/7200 rpm comfortably(I hope lol). It`s a street, strip & weekend car so it needs to be fairly drivable around town to.
Thanks Doug
 
First it will lose a little lift 1.5 that you have versus the 1.6 as stated earlier. Personally I'd find out if it has an intergrated cast iron gear on it if not I wouldn't buy it. 3500 sounds about right.
 
1970Duster said:
First it will lose a little lift 1.5 that you have versus the 1.6 as stated earlier. Personally I'd find out if it has an intergrated cast iron gear on it if not I wouldn't buy it. 3500 sounds about right.
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How much lift will it lose?? I did ask if it needed a bronze gear & he said yes, Will that become a problem??
 
608/1.6=380.
380x1.5=570

Total loss is:
608-570=38.

The bronze gear is a wear item and will make metal shavings in the motor. The bronze gear works best for race motors because they are continuously being ripped apart and rebuilt. I wouldn't run a bronze gear because I don't like ripping and reinstalling motors, let allow rebuild them (I like to keep my money).
 
1970Duster said:
608/1.6=380.
380x1.5=570

Total loss is:
608-570=38.

The bronze gear is a wear item and will make metal shavings in the motor. The bronze gear works best for race motors because they are continuously being ripped apart and rebuilt. I wouldn't run a bronze gear because I don't like ripping and reinstalling motors, let allow rebuild them (I like to keep my money).
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simple math will get u the lift w/ 1.5 rockers. divide ur lift by 1.6, then multiply what you have ( which should be ur lobe heighth) by 1.5----- simple. I ran a bronze gear in the hemi (781 lift cam dynamics roller) back in the day, never did wear any at all, finally gave up on worrying about it! guess it depends on the way ur block was machined at the factory. if it wears it won`t put chunks or slivers(unless something is out of alignment) in it. just bronze dust most likely. there are hords of them out there.--------bob
 
famous bob said:
simple math will get u the lift w/ 1.5 rockers. divide ur lift by 1.6, then multiply what you have ( which should be ur lobe heighth) by 1.5----- simple. I ran a bronze gear in the hemi (781 lift cam dynamics roller) back in the day, never did wear any at all, finally gave up on worrying about it! guess it depends on the way ur block was machined at the factory. if it wears it won`t put chunks or slivers(unless something is out of alignment) in it. just bronze dust most likely. there are hords of them out there.--------bob
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1970 duster beat me to it, he`s right on---bob
 
With that cam, the power will top out and fall off well before 7000 rpm. You will probably see max power about 6000 rpm. It should still work well, but if you want to maximize what you've got I would start by talking to Ryan J about what cam he would recommend. He did the same stage 2 port work to my Edelbrock heads and I have an off the shelf comp cam that is about 1 size larger than what you described (XR286R, 248/254 duration with .576/.582 lift). I like the cam for my street/strip car because it makes good power and is easy on parts....but to be honest, it is too small, and my car would pick up probably 2 tenths (or better) with the right cam. I already had the cam before I started building this motor, so I just used it knowing it was going to limit it some...but hey, mid 10's for a street/strip car is pretty good in my opinion. :D
 
That's the information I'm looking for, just want everyone's thoughts on what size roller cam should I be looking at.
thanks Doug
 
1970Duster said:
First it will lose a little lift 1.5 that you have versus the 1.6 as stated earlier. Personally I'd find out if it has an intergrated cast iron gear on it if not I wouldn't buy it. 3500 sounds about right.
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Who makes roller cams with cast gears for small block Mopars?
 
grimreaper said:
Who makes roller cams with cast gears for small block Mopars?
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Seems like everybody now but when I was looking for one, only crane cams had one. When you go and order the cam, ask them (cam maker) does it have one on it.
 
flyfish said:
With that cam, the power will top out and fall off well before 7000 rpm. You will probably see max power about 6000 rpm. It should still work well, but if you want to maximize what you've got I would start by talking to Ryan J about what cam he would recommend. He did the same stage 2 port work to my Edelbrock heads and I have an off the shelf comp cam that is about 1 size larger than what you described (XR286R, 248/254 duration with .576/.582 lift). I like the cam for my street/strip car because it makes good power and is easy on parts....but to be honest, it is too small, and my car would pick up probably 2 tenths (or better) with the right cam. I already had the cam before I started building this motor, so I just used it knowing it was going to limit it some...but hey, mid 10's for a street/strip car is pretty good in my opinion. :D
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You have to remember that your running a stroker motor which will eat up more of the cam's duration than a stock 340. With your engine you could go a little bigger without totally losing street-ability. The OP however is running a .040 340 stock stroke, which a XR268R is probably right on the money for that combo he's running. A Lunati roller, 40200730, would also do the trick.
 
71Scamper said:
You have to remember that your running a stroker motor which will eat up more of the cam's duration than a stock 340. With your engine you could go a little bigger without totally losing street-ability. The OP however is running a .040 340 stock stroke, which a XR268R is probably right on the money for that combo he's running. A Lunati roller, 40200730, would also do the trick.
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Good point, I totally missed that in the original post. For some reason I thought there was a 4" crank involved...my bad....I really should finish my coffee before answering questions over the internet. :-D :coffee2:
 
flyfish said:
Good point, I totally missed that in the original post. For some reason I thought there was a 4" crank involved...my bad....I really should finish my coffee before answering questions over the internet. :-D :coffee2:
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hughs engines has had the coated cam gear for quitea while now. will run on any kind of cam.-------:blob:
 
so is it better to run 1.6 rockers rather than the 1.5 that i have now on a roller cam?? Correct me if I'm wrong, but Wouldn't it be less likely the lifters coming up to high & exposing the oil gallery?? Am I on the right track here or am I outside the ball park??
 
Get a set of MRL lifters (no more worries about exposed ring). The final lift rate is done but the rockers.
 
the trouble is its going to cost me another $800.00(buying, shipping & Aussie dollar)to get them over to Australia, I just can't afford them right now....I'm hoping to make do with what I've got.
 
douglas340 said:
so is it better to run 1.6 rockers rather than the 1.5 that i have now on a roller cam?? Correct me if I'm wrong, but Wouldn't it be less likely the lifters coming up to high & exposing the oil gallery?? Am I on the right track here or am I outside the ball park??
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The lifter will move the same amount of distance no matter what type of rocker you use. But to answer your question as far as 1.5 over 1.6; I would try what you have and mock up the engine. Put some modeling clay on top of a piston and run your crank over two revolutions by hand, then remove the head and see how much room you have before the valve touches the piston. Here's a link for better explanation:

http://www.enginelabs.com/engine-tech/engine-blueprinting-how-to-check-piston-to-valve-clearance/

You don't have to use a degree wheel and the testing springs like they do in the link to do this. You can just mock your engine up and turn it over by hand slowly. If you start to feel a little binding then the valve is more than likely touching the top of the piston. If you get done and realize that the 1.6 rocker is putting the valve too close to the piston then you will need to run 1.5's.
 
71Scamper said:
I never understood why Ma Mopar would chamfer them like that. It makes no sense :wack:
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Piss poor quality control, plus there isn't an issue if you use a flat tappet cam which all they had back then.
 
douglas340 said:
so is it better to run 1.6 rockers rather than the 1.5 that i have now on a roller cam?? Correct me if I'm wrong, but Wouldn't it be less likely the lifters coming up to high & exposing the oil gallery?? Am I on the right track here or am I outside the ball park??
Click to expand...

It is probably better to run 1.6 rockers for the added lift. The very minor extra intensity is peanuts. This extra rocker ratio will (or should) show a bennifit on any style cam.

Correct me if I'm wrong you say, OK, your wrong and he's why.

The extra rocker ratio effects the valve. Not the lifters because the cam makes the lifters rise. Not the rockers.
Check all parts before final installation and bolting it up. When the cam is installed, you start by decreeing the cam and then checking retainer clearance, then Valve to piston clearance, pushrod clearances, rocker contact patch and how far the lifter comes up out of its bore during the entire travel from when it is on the base circle to max lift on the lobe.
 
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