Can Anybody Identify This Cam

[RLJ]

Bought an engine with this cam in it. Does anybody recognize these numbers on the back of the cam?

 

Engraved in: M# 227C-10  There is a B stamped in also and looks like it was stamped after the engraving. 
 

Base circle diameter is 1.188, lobe is 1.502, making cam lift .314 X 1.5(?)rocker giving .471 valve lift. 
 

Trying to determine if it’s to much cam for street driving

[datzenmike]

Lift is good and won't affect driving. Stock lift for L16 is about 0.409". A 0.471" lift just opens the door farther to let more air in.  Increasing duration will benefit high speed at the expense of low speed drive ability.

 

 

Cam makers specify the duration at 0.050" lift but back in the day they didn't. The duration of an L16 camshaft is 240 intake and 156 exhaust but I don't think at 0.050" lift. It's likely closer to 210-215degrees if it was measured. You have 227 engraved on the end so this is most likely 227 degrees at 0.050" lift. By Datsun measuring this is probably higher like 240. I don't know this for sure maybe someone else can say.

 

This, by my understanding (which could be in error) makes this cam pretty close to stock but with an increased lift. It should run like a stock cam but breath a bit better at higher RPMs.

[Stoffregen Motorsports]

That's a good street cam. Probably a Rebello built motor, or at least cylinder head. I think Cal Cams was the grinder.

 

The 227C was a mild street cam and worked well with dual Solex/Mikuni carbs, but best suited to a DGV. There are better, more modern cams, but I wouldn't throw that one away.

[RLJ]

Thank you Matt. 

 

Engine is supposed to be a Rebello “clone” for whatever that’s worth. What are the better more modern cams now?
 

Going to run with 44mm Datsun SU’s. 
 

It’s a 2.2 build on an L20b block.  Pretty sure it has 5-3/4” rods. Thinking of changing it out to 6” rods before installing it in the car. 
 

Thanks Mike. 
 

From what I’ve been told by a couple of cam grinders who regrind L cams the stock cams were 190-200 @ .050 lift. The factory duration numbers were at .010-.015 lift. ???

[Stoffregen Motorsports]

Clone? Rebello didn't build many short rod 2200s, mostly long rod. Actually, I can't remember ever building a short rod 2200 while I was there. I built a short rod 2150 with an L20B crank stuffed into an L18 block with 87mm bore and L18 rods. That motor had so much torque that you couldn't keep the tires from spinning.

 

The modern cams are what Dave refers to as "hydraulic" grinds. What that means is that the cam is ground with a slow ramp, which loads the valvetrain right before a massive jump in lift. This type of cam has a less violent opening event and will be more stable with higher lift numbers. I believe those cams ended with a D as in 45D.  I believe they had another variant with DE suffix and were even more stable. I actually preferred the older D cams with the huge lift numbers. They made for one helluva street driving experience, but if driven hard (like on the track), they would need constant attention. Broken valvesprings were common if shifting at 8k. The DE cams make more torque though. Almost all modern cams for just about any type of engine use this technology now, but back in the late '80s and early '90s, this was a breakthrough.

 

Note that this info is all dusted with cobwebs, and viewed through rose colored glasses. Actual events may have been less perfect.

[datzenmike]

Datsun lists the cam duration at 248 degrees but this seems way too high

 

 

 

 

[RLJ]

Thanks guy’s great information. 
 

Matt,

 

Which 6” rods were used for a 2.2 long rod motor? What pistons to get the different wrist pin height. 
 

Love your last comment about the cobwebs, etc. I can relate!
 

 

[Stoffregen Motorsports]

N85 rods from a Z20 and cut down KA24DE pistons. They are the ones with the big dish and the factory coating on top.

[RLJ]

Great. Now to find them!

 

Thanks again. 

[Stoffregen Motorsports]

Anytime.

 

Where did you get the motor? Are you putting it in a 510?

[RLJ]

Purchased from a Sacramento 510 enthusiast. Was told it was a copy of Rebello build. As I said previously for what ever that’s worth. 
 

Yes it’s going into a 510 wagon. 
 

Will be disassembling it soon. Not sure what the bore is. Appears to be a Z22 crank by measuring stroke. Was told 5-3/4” rods.
 

Was told by a seasoned respectable Datsun engine builder that the 5-3/4 rod and its relative piston speeds created a unique vibration. Not a balance vibration. The 6” rod was a nice smooth set up. Maybe you can confirm this. 
 

 

[datzenmike]

Use metric. There were no 5 3/4" rods. Closest were 145.9mm L20B or early Z22 rods. No way you can stuff 152.5mm (6") rods onto a Z22 crankshaft without a custom piston with a roughly 29mm pin height. Leaving 19mm for rings and ring lands between pin top and top of piston. Roughly 3/4"

 

Crank stroke sets the piston speed no matter the rod length. A shorter rod will have more side loading and friction than a longer rod. That must be it or it was out of balance.

[RLJ]

Mike,

 

Okay, the 5-3/4” rod is actually 5.744”. It’s easier to call it a 5-3/4” rod. The 6” rod is actually 6.004”. Still easier to call it a 6” rod. 
 

As far as needing a specially made piston you’re probably correct and would probably be best. VG30 piston would be the closest and probably not enough thickness in the top of the piston to machine it down enough to make it work for the longer stroke. 
 

Have to disagree with you, to a degree, on the piston speed statement and that the rod length doesn’t affect it. For mean(average) piston speed your statement is true, but it’s an average. At TDC the piston isn’t moving as it starts going down it is accelerating all the way to the 90 degree point of crank rotation. Then it is decelerating until it gets to BDC. 
 

The shorter rod is going to accelerate and decelerate faster than the longer rod. This start and stop is inertia and a longer rod softens it. 

 

Engine builders have known this and practiced it for decades. The other advantage of the longer rod is longer dwell time at TDC and BDC. Cam grinders take advantage of this fact. 
 

Will see what I end up doing as custom made pistons and possibly rods aren’t cheap!

 

[datzenmike]

1 hour ago, RLJ said:

. 

 

Have to disagree with you, to a degree, on the piston speed statement and that the rod length doesn’t affect it. For mean(average) piston speed your statement is true, but it’s an average. At TDC the piston isn’t moving as it starts going down it is accelerating all the way to the 90 degree point of crank rotation. Then it is decelerating until it gets to BDC. 
 

 

 

Can't slip nothing past you!

 

I think you meant to say it accelerates to the point the crank throw and the rod form a 90 degree bend, then it begins to decelerate. This would be different for longer and shorter rods. A longer rod would be farther down the cylinder. Only an infinitely long rod would form a 90 degree bend at 90 degrees crank rotation.

[RLJ]

I’ll post up what I find upon disassembly.

 

Hoping it’s only bored to 87mm. 4mm is a lot to be removed from a cylinder to make the 89mm bore. If it’s out to 89mm bore I’ll always be worried about the cylinders and how much meat is left in them since it’s an L20b block. 
 

Was told it has VG30 pistons which are 87mm. Thinking the pistons are below top of the block with the 5-3/4” rods. Won’t know for sure until disassembled. 

 

If just needed to buy longer rods and be able to modify the VG30 pistons to work with the longer rod shouldn’t be to crazy expensive. 

[datzenmike]

An 85mm L20B bored out to 89 is only 2mm removed from the walls. Z20 blocks (basically a recast of the L20B) are reputed to be thicker.  If going to 89mm on an L20B and it has a Z22 crank fit KA24E pistons for a 2.3 big bore engine.

 

Z22 crank stroke 46mm

L20B/Z22 rods 145.9mm

Early Z22 pistons 35.5mm

____________________________

 

227.4mm the L20B block height is 227.45mm so it fits with 0.005mm to spare.

 

The Z22 pistons are 87mm but you could go 1mm over to 88mm for extra displacement.

 

VG pistons would be 3.8mm below the deck. Terrible compression numbers.

 

 

Substitute 152.5mm long rods and VG pistons would need 2.8mm removed from the tops. Actually you can go 1/3mm above the deck safely so 2.5mm removed. VG are 87mm but you could go 1mm over.

[Stoffregen Motorsports]

On 8/27/2023 at 9:22 AM, RLJ said:

Purchased from a Sacramento 510 enthusiast. Was told it was a copy of Rebello build. As I said previously for what ever that’s worth. 
 

Yes it’s going into a 510 wagon. 
 

Will be disassembling it soon. Not sure what the bore is. Appears to be a Z22 crank by measuring stroke. Was told 5-3/4” rods.
 

Was told by a seasoned respectable Datsun engine builder that the 5-3/4 rod and its relative piston speeds created a unique vibration. Not a balance vibration. The 6” rod was a nice smooth set up. Maybe you can confirm this. 
 

 

Ok, that's not the "2200" I was referring to. A Rebello 2200 uses an L20B crank, while their 2300 uses a Z22 crank. 6" rods will work with the Z22 crank, but there is no stock piston that will work. You'll need custom pistons for that combo.

[Stoffregen Motorsports]

Hopefully I can put the bore size per block debate to bed here.

 

L20B blocks can be bored to 89mm, but it is risky. There were variances between block castings over the years and some blocks have thicker cylinder walls as a result.

 

Z22 blocks can easily take the 89mm bore, but there are "steam ports" between the 1-2 and 3-4 cylinders that can accidentally be cut into if the machinist is not careful. You can spread the bores to clear those steam ports. What I mean is, offset the bore so that you go more to one side of the bore to keep away from the steam ports.

 

Z20 blocks aree perfect for an 89mm bore because they do not have the steam ports and they do have thick cylinder walls. Thicker than L20B blocks. Boring a Z20 block to 90mm has been done, though I have no first hand experience there.