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turbogrill

Any cam experts? Colt Cams adv duration vs @0.05"

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Hi,

 

Most camshaft has a pretty similar ratio between advertised duration and @0.05". However Colt Cams differs:

 

Colt (C542): 

 

Duration Adv:     280     

Duration @0.050: 224

 

Isky / Schneider:

 

Duration adv: 280

Duration @0.050: ~232

 

Almost 10 degrees difference!!!!

 

Just looking at the advertised duration the Colt cam looks aggressive, but the 0.050" tells a different story. Could probably even use stock EFI with it.

 

Is the C542 just a minor upgrade from stock? Or is there more to it.

 

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Posted (edited)

I have the C.542s.

 

 

I can only compare a 10.5:1 combo with a stock cam, to a much lower compression (8.6:1) with the C.542s.  Less low end grunt with the colt cam (Compression was probably a good portion of this), but pulls hard to red line.  Different engines, same car, but not a great comparison.

 

It has a fairly lumpy idle.  

There is another user local to us Vancouverites, who has a c.542s and tried to use it with stock EFI.  It didn't like it.  Colt Cams reground, I believe the intake side down to one of their less aggressive profiles.  They left the exhaust side the same.   It then worked with the stock EFI.    I could be backwards with that, but you get the point.

 

 

To add to this.   Shadbolt is another local Vancouver company who actually was the original maker of this grind (So the rumours go).  They will do the same grind for much less money. I think $160 Canadian.   

Edited by HuD 91gt

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Posted (edited)

Hi

 

 

 

Thank you for that.

 

I am hopefully getting the SHADBOLT M455, I think that is the same one as what you have. 

Planning on using MS as well.

 

Noticed you are running MS timming, what do you have for timing related sensor? Turbo dizzy or crank trigger?

Edited by turbogrill

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Posted (edited)

You'll like the M445 from Shadbolt. One of their proven Classic grinds and good for just about any L-serie's for a Weekend warrior or Autocross car. L28 should pull hard to from about 3,500 to 7,000 with this cam. Can comfortably putt around at lower RPM's as well. Very, very popular grind in the PNW. Easy on valve train as well.

 

Edit: New  Stock Roadster Outer springs and Roadtser stock inners are all that are required for 7,000 RPM. You may have to trim the bottom of the retainer for seal clearance or run shorter seals. Lift is in the .0480" range if memory serves me correct.  Will really wake up an L-28 without being too lumpy or a fuel pig. It's in the " GoldiLocks " zone  :D

 

Check with Shadbolt to see if they still re-surface rocker arms. 

Edited by Chickenman

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You'll like the M445 from Shadbolt. One of their proven Classic grinds and good for just about any L-serie's for a Weekend warrior or Autocross car. L28 should pull hard to from about 3,500 to 7,000 with this cam. Can comfortably putt around at lower RPM's as well. Very, very popular grind in the PNW. Easy on valve train as well.

 

New Stock Outer springs and Roadster inners are all that are required for 7,000 RPM. You may have to trim the bottom of the retainer for seal clearance or run shorter seals. Lift is in the .0480" range if memory serves me correct.  Will really wake up an L-28 without being too lumpy or a fuel pig. It's in the " GoldiLocks " zone  :D

 

Check with Shadbolt to see if they still re-surface rocker arms. 

 

Sounds awesome.

 

I am getting it and a ported N47 head soon. 

 

Initially I will put it on my N47 block, so compression will be in the 8:1. I guess it will be OK for that? Will also do MS..

 

 

 

(I have a F54 flattop waiting to be built...)

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Sounds awesome.

 

I am getting it and a ported N47 head soon. 

 

Initially I will put it on my N47 block, so compression will be in the 8:1. I guess it will be OK for that? Will also do MS..

 

 

 

(I have a F54 flattop waiting to be built...)

 

An N47 block and N47 head should be around 8.3 to 1 CR.  At least you can run 87 Octane on that. May be a bit doggy on the low end. That cam is happier at 9.0 to 1 compression and more. 

 

F54 with FT pistons should give you around 10.3 CR. I have the same combo. Engine should really come alive with the M445 cam and higher CR.   

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Posted (edited)

An N47 block and N47 head should be around 8.3 to 1 CR.  At least you can run 87 Octane on that. May be a bit doggy on the low end. That cam is happier at 9.0 to 1 compression and more. 

 

F54 with FT pistons should give you around 10.3 CR. I have the same combo. Engine should really come alive with the M445 cam and higher CR.   

 

Do you use stock springs? Or would the M445 require different springs?

 

Seems like any lift over .460 and over ~7000 RPM requires new springs.

Edited by turbogrill

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Posted (edited)

Edit: Think I got the required Inner and Outer springs mixed up. 

 

Covered in Post #7. New factory Outer springs and new Roadster 2000 inners. The stock Z inners are the ones that will coil bind first. Roadster Inner springs ( 13204-25502 ) allow more lift and are a bit stiffer. Good to 7,000 RPM with a M445 Cam.

 

Roadster springs are listed as NLA from USA dealers, but NOS 13204-25502 springs can still be found if you search hard enough.... or you can find an aftermarket equivalent. Have to check if my Canadian dealers can still get them direct from Japan. 

 

Don't forget to check retainer to valve seal clearance. I like to use lightweight " checking "  springs. Basically just a compression spring that has a couple lbs rate. Just enough to  hold valve closed. Check piston to Valve clearance as well. Pretty sure you won't need to machine any Valve reliefs with the M445... but you should always check. 

 

No need to twist an L-28 street motor past 7,000 RPM. Intake won't flow enough to make any more Power above approx 6,500. I have a Rev limiter set at 6,800 for when I Autocross and have to run to Redline in 2nd gear. 

Edited by Chickenman

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Covered in Post #7. New factory Outer springs and new Roadster 2000 inners. The stock Z inners are the ones that will coil bind first. Roadster Inner springs ( 13204-25502 ) allow more lift and are a bit stiffer. Good to 7,000 RPM with a M445 Cam.

 

Roadster springs are listed as NLA from USA dealers, but NOS 13204-25502 springs can still be found if you search hard enough.... or you can find an aftermarket equivalent. Have to check if my Canadian dealers can still get them direct from Japan. 

 

Don't forget to check retainer to valve seal clearance. I like to use lightweight " checking "  springs. Basically just a compression spring that has a couple lbs rate. Just enough to  hold valve closed. Check piston to Valve clearance as well. Pretty sure you won't need to machine any Valve reliefs with the M445... but you should always check. 

 

No need to twist an L-28 street motor past 7,000 RPM. Intake won't flow enough to make any more Power above approx 6,500. I have a Rev limiter set at 6,800 for when I Autocross and have to run to Redline in 2nd gear.

 

Rebello suggest using stock INNER but aftermarket outer for their ~.480 cams. At least that is what their website says.

Seems to be confusion about this.

 

I am buying a head with this cam already mounted, the guy has been running it for a while but with stock springs.

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Posted (edited)

Ooops.. I think my memory is fading. dave is likley correct.  Maybe it was the Roadster Outers we were using.  I'll check with some of my buddies at " The 510Realm " to see if there memory is better than mine. Just dug this up from the archives. Valve lift of the M445 is higher than I originally recall. There also may have been revisions made over the years. 

 

http://www.the510realm.com/viewtopic.php?t=15931&start=15#p163338

 

 

 

Speaking of cams, i just found the Shadbolt grind slip for the cam in my(Byron's old) LZ22

cam was ground Feb 11 2003, so Byron can comment if it was his cam or installed afterwards

Datsun l20 sohc m.445

*[email protected]"(280d advertised) 340" com .510' valve lift clearance of .08 int and .12 exh

 

 

 

The M445 cam has the following specs;
445 Profile: 
Duration: 280 degrees (30-70-70-30) 
Overlap: 60 degrees 
Lift: 0.507” at the valve 
"Good for about 7200 rpm max" 
Works well with Roadster valve springs 
Edited by Chickenman

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Ooops.. I think my memory is fading. dave is likley correct.  Maybe it was the Roadster Outers we were using.  I'll check with some of my buddies at " The 510Realm " to see if there memory is better than mine. Just dug this up from the archives. Valve lift of the M445 is higher than I originally recall. There also may have been revisions made over the years. 

 

http://www.the510realm.com/viewtopic.php?t=15931&start=15#p163338

 

Awesome!

 

Thanks!

 

I was a bit concerned about valve to piston clearance given the high lift. However comparing it to other cams (Isky 490/Schneider 290F) it seems to open/close the valves much earlier/later.

 

I guess the the most critical is the time the valves open/close when piston is close to TDC, not the actual lift. 

 

It also seems to be a "slow opening" cam since the difference between advertised and @0.05 lift is so large. 

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Yes, it is a slow opening cam compared to some of the Modern stuff. But that also makes it easy on the valve train. It is the duration you have to be worried about. Fast acting ramps and longer .005" durations accentuate Piston to Valve contact  At maximum Valve lift the piston is well down the bore. Couple of interesting video's from Mahle Motorsports on checking Piston to Valve clearance

 

https://www.youtube.com/watch?v=PXzO9u93-n8 

 

https://www.youtube.com/watch?v=Dz7Fqo_oufU

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Ok, finally got some answers back from the Old Fart experts at The510Realm who use M445 Cams regularly. Yes you can use Flat Top pistons with no valve reliefs. Got that from any engine builder who regularly built 510 motors with L24 FT pistons. I would check the piston to valve clearance though, just to be 100% sure.

 

He also mentioned that new stock valve springs could be used, That I'm a little wary of. You do have to check for coil bind very carefully with stock springs. I think I would follow Rebello's recommendation on valve springs. You don't need anything super strong, but you do need a slight increase in pressure if you want to pull 7,000 RPM or so. IMHO that is. When I was Racing 510's and 240Z's back in the day, we always upgraded to the Roadster springs. The Roadster springs would handle more lift before coil bind and were a bit stiffer than the stock L series springs. They are still available at DatsunParts.com

 

Standard Roadster springs:

 

http://www.datsunparts.com/2109  

 

Uprated aftermarket Roadster springs:

 

http://www.datsunparts.com/1665

 

Of course you may want to pressure check the springs that are on that head. may have been upgraded already. That would be nice

 

.180" Lash pads are the size you need. Stock Steel retainers are fine. You may want to trim the bottom of the retainers for more retainer to stem clearance. Check your retainers first. PO may have already done that. Or you can use a shorter seal. Ford V6 are popular as are Datsun A12 seals. 

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Posted (edited)

DatsunParts won't sell you a split set? Did you call them?

Is something wrong with these?

http://iskycams.com/cart/index.php?main_page=product_info&cPath=99&products_id=2119

 

Isky used to make titanium retainers for these - looks like they don't any more.  Part number was 1624Ti-12, in case you can find some on ebay or someplace...

Edited by TimZ

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