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leverhead 03-20-2012 04:21 PM

New Solid Roller Cam Question
 
2 Attachment(s)
Hello all. I just received a new Comp solid roller cam that I custom ordered - (steel billet small base circle, pressed on iron gear, 230/236 @ .050, .553/.565 lift, lsa @ 110, cl @ 106) for my 383 SBC in an effort to make my car more streetable (replaced my Isky RR-602 & SRP 13.1 pistons).

I opened the box and was surprised at the size and width of the lobes. I've been measuring with my calipers to check the lobe lift and base circle and still cant verify the same specs as the cam card. Also, the width of the lobes just barely matches the width of the rollers on my lifters, and there is almost no backside the the lobes at all....like the lifter will ride along the base circle itself as it travels around the lobe.

The lobes have an almost cathedral shape to them and with the narrow width, you would think any deviation with endplay would cause the lifter to hang off the lobe. I have a hydraulic roller cam for another motor in my truck (std base) that has less lift and duration but the lobes look bigger and encompass the entire base and are also wider.

Maybe its unjustified, but I'm a little concerned at this point and was hoping others could chime in. Anyone see a grind like this? (pics attached)

I should also note that Comp tech said it was based on thier Extreme Energy grinds, but none of the extreme energy cams I looked at looked like this.

Thanks in advance.

SPEED MASTERS CC 03-20-2012 06:55 PM

Send it back

68NovaSS 03-20-2012 07:16 PM

Quote:

Originally Posted by SPEED MASTERS CC
Send it back

That's a non-qualified response, tell us why you arbitrarily say that! I don't have an answer for the OP either. :rolleyes:

ap72 03-20-2012 07:17 PM

How wide is the face of the roller? How wide is the lobe? Is the alignment correct? If so then this really isn't that hard to figure out.

joelster 03-20-2012 07:51 PM

All small base-circle cams look like that. Nothing wrong with it. A cam that mild won't need much valvespring so you are in no need of having to worry about any flexing issues. I'm curious as to why you went with a small base circle? It isn't needed with a 383.

joelster 03-20-2012 07:53 PM

Here is a nasty .950" base for an LT1/sbc

http://i9.photobucket.com/albums/a76...rs/p_00436.jpg


Here is a really nasty .900" base for an LT1/sbc

http://i9.photobucket.com/albums/a76...ars/lsmcam.jpg

leverhead 03-20-2012 08:40 PM

The roller face is approx 11/32 and the lobes are about 15/32. The lobes on the cam I took out are 1/16" wider. The roller I checked seem to line up in the center of the lobe with a smidgon leftover on each side, so I assume as long as the endplay is within spec it won't be a problem...just a little close for my taste and dont know why they made them so narrow. Could not get a definitive answer from Comp.

Springs are 200 @ 1.9", 480 @ 1.2" (Motown heads / -3). Comp also recommended their springs if starting from scratch (210 @1.9, 523 @ 1.25) so I figure I'll use what I already have installed, as well as my rev kit - should be plenty without being excessive.

The pic of the bottom cam looks very similar. Comp doesn't tell you the base circle size but my measurements show about .908. I originally was going to go with an LT1 grind but lowered the duration a bit because of my elevation (5500-6000 ft) and compression ratio (9.8:1) . Also went with the small base circle as that was what the other cam was and looking down the cam journals the rods look really close (6" eagle H beam) so I felt safer that way. Thanks for posting those pics....I feel a LITTLE better now.

joelster 03-20-2012 08:48 PM

I would think those springs are overkill for that camshaft you are running. I ran a 242/248 duration with .584"/.579" hydraulic roller with a single beehive spring. It was 130 seat and 313 open (going off the top of my head here). You are running 480lbs with less duration and less lift, probably a lobe rate similar to what I was running. If you are running heavy rockers or heavy valves then they might be necessary but I bet it would be fine with a 918 beehive spring.

My new cam is 256/260 with lift near .700" with heavy Crower maximus roller lifters, shaft rockers, and big pushrods, and my springs are similar to what you have right now.

leverhead 03-20-2012 09:38 PM

I agree I could get away with lighter springs. They were installed by World Castings when the heads were purchased and rated up to .700 lift. (1.550 diam). The cam I removed was a 260 @ 50, .602 lift 108 lsa with rev kit , rockers are summit aluminum rollers (1.5) and the intake valves are 2.08 so they were sufficient. Comp suggested their springs (954-16) for the new cam which are actually heavier (but slightly smaller diameter) so I figure I would use what I already have and save the $$$.....probably more than I need but still in the safe zone. I may rethink the springs though...

Still dont get the narrow lobe thing...

BTW, what compression ratio are you running...and at what altitude? Is this a street car? Thanks.

joelster 03-21-2012 06:37 AM

Comp is 11.77-1, pump gas, street car, my altitude is around 700 ft.

ap72 03-21-2012 07:25 AM

Quote:

Originally Posted by joelster
Comp is 11.77-1, pump gas, street car, my altitude is around 700 ft.

with a 230/236 cam? You must have some amazing heads, an awesome EFI system, and a super light car! Any pics of the car? Is it a kit car?

SPEED MASTERS CC 03-21-2012 01:20 PM

If there is a dimensional problem. Send it back for a QC check... Maybe send some photos first... That's all I was saying...

joelster 03-21-2012 06:27 PM

Quote:

Originally Posted by ap72
with a 230/236 cam? You must have some amazing heads, an awesome EFI system, and a super light car! Any pics of the car? Is it a kit car?

Huh?

My cam is 256/260, EFI, AFR 227's, and race weight of around 3100. No tune either. Should be knocking on 9's either this summer or in the fall. It's a 4th gen f-bod, 94 Z28.


Idle video


http://www.youtube.com/watch?v=WAoR_DxZffU

leverhead 03-21-2012 10:33 PM

2 Attachment(s)
I mocked up the cam to check endplay and lobe alignment. Endplay with my roller cam button was excessive but worse was the lobe alignment. With the cam pushed back as far as it will go as installed, and a light film of red grease on the rollers, I can see a few of the lifters are directly centered on the lobe but most are off to one side (the inside edge) with many sitting right on the inside edge of the lobe. So any endplay will cause the lifter roller to hang off the edge. Pics attached. I'll give comp a call tomorrow to see about rectifying this.

raceman14 03-23-2012 06:15 PM

Lever,
You are going to kill 25hp with those springs and you will kill your engine oil and valvesprings with the heat they generate. If you were turning 9500 you might need that much pressure.

If you don't run stroker rods you can hit the cam in a couple places with standard rods. That looks like about an .850" base circle with the optical mics.
That cam will lose you about 2-3% of your duration at the valve unless it was compensated for in the grind ( usually not done ). You can check it with your degree wheel when you dial it in.

I might be tempted to go up from 1.5 -1.6 on the rocker to get some back.

That cam is similar to the GM ASA cam that I use in my "Outlaw" crates, with stock GM604 parts and the cam swap, those engines at 350" make about 475HP swapping in a 3.75" stroke and stroker pistons that same engine makes about 550HP. I use my "Outlaw" spring set on them and they are good to 7500 and are a German made 1.260" spring with 175# @1.800 and 425 open, I sell them **************

Cam end play is your responsibility not the cam manufacturers. I set mine as close to ZERO as I can get it. First you have to set your crank gear in place, then you put your cam gear in place those two have to be shimmed to vertical +/- .001" once you do that you shim your cam end play to zero with shims behind the cam gear / bearing and the nose bearing against the timing cover. If you can't find the stuff ************


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