Cam Regrind specs needed??

Tech tips and how to's

Moderators: notoptoy, garth, S Allen

mok662
Roadster Newby
Posts: 8
Joined: Wed Aug 22, 2018 11:47 am

Cam Regrind specs needed??

Post by mok662 » Fri Mar 01, 2019 4:08 pm

Hello there guys. I am having my U20 camshaft Regrind while the engine is getting overhauled.

I would like to know what success you have had with the camshaft. I have a U20 with SUs.

What would you recommend? What specs should I have this cam meet?

User avatar
Gregs672000
Roadster Fanatic-Site Supporter
Posts: 6643
Joined: Fri Aug 07, 2009 11:47 pm
Location: Tacoma, WA

Re: Cam Regrind specs needed??

Post by Gregs672000 » Sat Mar 02, 2019 12:24 am

Well.... lots of variables there regarding recommended grinds. The cam is the brain of the engine, and tells it where and how to produce power. Assuming stock engine and carbs, I don't think you would want to go much more than the "B" cam with SUs for a street car. Higher duration and a little more lift will give you a bit more power with a slight loss of low end torque, typically comes on at about 3200 rpms or so, a little later than the A. What rear end gearing are you running? Do you like to rev an engine or more used to torque? Honestly, I've haven't ridden in an A or B cam SU car much, so others should chime in who have. Also, the final drive gearing may make some difference in what the car feels like with A or B cam. Deans site has lift and duration info on his regrinds. You will also need to regrind or replace your rockers.
Greg Burrows
'67 2000 #588
Tacoma, WA

User avatar
nismou20
Roadsteraholic
Posts: 1242
Joined: Thu Jul 07, 2005 2:16 pm
Location: Pasadena, Ca

Re: Cam Regrind specs needed??

Post by nismou20 » Sat Mar 02, 2019 12:50 am

Dave Rebello grinds one, a happy medium between A and B. Stock A has a 256 Duration and B @280. His street is a 270 with a tad more lift than B Cam but complements the SUs. You want to capture as much cylinder pressure so I wouldn’t go crazy for street and drivability. Put in a 1600 rear end too and thin the SU throttles shafts. With longer dura cams you will have a bigger hole to climb out of.

User avatar
ACote
Monthly Subscriber-Roadster Enthusiast
Posts: 780
Joined: Mon Mar 28, 2011 11:01 pm
Location: Winnweiler, Germany
Model: 2000
Year: High Windshield-68-70

Re: Cam Regrind specs needed??

Post by ACote » Sat Mar 02, 2019 2:27 am

Here's my old A cam dyno. SU's a little rough with an unknown needle. No point revving it past 5k but great for normal driving. Something slightly hotter and a nice tune with an Air/Fuel meter sounds like a good combo with SU's to me. Of course with the right needle and oil weight I heard they used SU's in the D-class racing making good power.
Image

User avatar
keith0alan
Roadsteraholic
Posts: 772
Joined: Wed Sep 22, 2004 10:07 am

Re: Cam Regrind specs needed??

Post by keith0alan » Sat Mar 02, 2019 8:15 am

On thinning SU throttle shafts. When I flow bench tested SU carbs that I modified I found that totally removing the throttle shaft and plate did not improve flow. After I did a bunch of other stuff then working the throttle shaft helped. If the only thing you are doing is thinning the throttle shaft then don't bother. Why is this? Quick answer, take your calipers and measure the inlet and outlet diameters.

JT68
Talented Enthusiast
Posts: 1863
Joined: Sun Jan 27, 2013 9:43 am
Location: Cumming, GA

Re: Cam Regrind specs needed??

Post by JT68 » Sat Mar 02, 2019 8:24 am

Personally, I think the B cam is a terrific all-around street cam. We grind a lot of C cams, but mostly because people ask for them.
The B is certainly smoother at idle than the C which has a noticeable lope. Whichever you prefer, there is only a moderate power difference between the two. We seldom use A cams anymore since there is really no downside to a B. C is a great street cam too if you prefer the lope.
Either will work well for you!
JT/LT
Datsunrestorationproducts.com
The very finest parts for your 311!

User avatar
Gregs672000
Roadster Fanatic-Site Supporter
Posts: 6643
Joined: Fri Aug 07, 2009 11:47 pm
Location: Tacoma, WA

Re: Cam Regrind specs needed??

Post by Gregs672000 » Sat Mar 02, 2019 11:55 am

If you want a B cam profile cut on your current A, one source is Delta Cam in Tacoma, WA. They have several grinds and are set up to regrind your rockers if they are the two piece. Otherwise, Dean at Datsunparts.com has everything you need and is now accepting one piece rockers as cores as he's figured out how to regrind and rechrome the one piece (well done Dean, more options!).
Greg Burrows
'67 2000 #588
Tacoma, WA

mok662
Roadster Newby
Posts: 8
Joined: Wed Aug 22, 2018 11:47 am

Re: Cam Regrind specs needed??

Post by mok662 » Thu Mar 14, 2019 9:19 pm

Sorry for my late response.

I am not building a SCCA race car. I'm looking to restore this to its glory days and give it some extra ponys.

So I agree with you guys on the B cam. So if ai understand rhis right, .478 lift @ 290 duration? That's the best specs I can find on my own.

I have no idea about the rear end. Its all stock. The car has been in the family since 1970.

User avatar
spyder
Roadster Fanatic-Site Supporter
Posts: 2065
Joined: Tue Apr 12, 2005 1:43 am
Location: Live Oak, TX.

Re: Cam Regrind specs needed??

Post by spyder » Fri Mar 15, 2019 1:12 am

When you start regrinding cams, keep in mind that this will alter the contact patch on the cam followers. The more aggressive regrinds may require taller lash pads.

User avatar
SLOroadster
Roadsteraholic
Posts: 5298
Joined: Sun Dec 08, 2002 2:53 am
Location: Napa Ca

Re: Cam Regrind specs needed??

Post by SLOroadster » Fri Mar 15, 2019 2:18 pm

mok662 wrote:
Thu Mar 14, 2019 9:19 pm
Sorry for my late response.

I am not building a SCCA race car. I'm looking to restore this to its glory days and give it some extra ponys.

So I agree with you guys on the B cam. So if ai understand rhis right, .478 lift @ 290 duration? That's the best specs I can find on my own.

I have no idea about the rear end. Its all stock. The car has been in the family since 1970.
The B cam had several lifts, all about 0.46 at 280 degrees. I ran a B cam with SUs when I first got my car and it was great. If I were in your shoes, I'd find myself a B cam and call it good.

Will
Sorry, I find modern engine swaps revolting. Keep your G, R, or U series in your Roadster!

mok662
Roadster Newby
Posts: 8
Joined: Wed Aug 22, 2018 11:47 am

Re: Cam Regrind specs needed??

Post by mok662 » Fri Mar 15, 2019 5:18 pm

Awesome. Thanks for the insight guys.
I will keep you posted.