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Which cam?
https://slantsix.org/forum/viewtopic.php?t=61126		 Page 1 of 2
Author:  coconuteater64 [ Thu May 11, 2017 10:09 am ]
Post subject:  Which cam?
Author:  DadTruck [ Thu May 11, 2017 10:32 am ]
Post subject: 
If the 2106r is the same cam as the 2106 with the intake and exhaust profiles swapped, be careful with that, cam grinds typically have a slower ramp (opening and closing) on the exhaust valve when compared to the intake valve action, so you could have a slow ramping intake and a fast ramping exhaust,, which is the opposite of typical valve action
The folks at Oregon would have that info, ask them.
Author:  coconuteater64 [ Thu May 11, 2017 10:38 am ]
Post subject: 
If I'm reading it correctly, the 2106R has a bigger lift on the intake side, right? I wasn't sure if I was reading that correctly. I know the slant head flows better on the exhaust side.

BTW: this is the 198 block and cam. It was in primo condition other than just being a little tired (the timing chain could be twisted into a figure 8!) and having a slight lip at the top of the cylinders. I found the crushed remains of a distributor gear in the bottom of the oil pan but otherwise it was free of debris and goop.
Author:  Dart270 [ Thu May 11, 2017 12:28 pm ]
Post subject: 
These are all basically stock cams in my personal book, which is probably what you want for a truck and towing and no racing. I'd really focus on headwork to make power. Personally, I'd go with the biggest one you stated. Oregon will put I lobes on I and E lobes on E and I don't think they'll let you grind an E lobe on I as Dadtruck suggests. Yes, confirm this with them. I always pick I lobes from their charts for I, and so forth...

One big unknown I see is pistons you want to use with those 198 rods and final compression ratio. Hard to pick a cam w/o knowing at least pretty close to what the static comp will be.

Lou
Author:  coconuteater64 [ Thu May 11, 2017 1:42 pm ]
Post subject: 
I am thinking about using KB268 pistons. I know that's not specific enough to calculate the true compression ratio, but it's a little less generalized.
Author:  Exner Geek [ Thu May 11, 2017 2:25 pm ]
Post subject: 
If I understand you right you have a 198 block which all used forged cranks, and a 79 crank which are all cast, and the two are not compatible.
Author:  DadTruck [ Thu May 11, 2017 2:27 pm ]
Post subject: 
get friendly with these

https://www.rbracing-rsr.com/compstaticcalc.html

or

http://www.wallaceracing.com/cr_test2.php

or just google 'compression calculators' and you will find others,,,

cams and compression go hand in hand,,

and start here:
http://www.hotrod.com/articles/0607phr-camshaft-basics/

Lou likes large cams, (he has also said he does not mind paying the $ for premium, my goal was good performance on regular,,and he drives light A body cars, I have a larger than stock but a smaller cam that what you are looking at in my 83 D150 ( 212/206 @.050 with 8.5 static and 180 cranking pressure that runs on regular gas) and I think its great.

with 198 rods and dished pistons you won't need to cut much if anything to get the compression up.

for D150 fun stuff you can also look here

http://www.slantsix.org/forum/viewtopic.php?t=56667

and

http://www.slantsix.org/forum/viewtopic.php?t=45826
Author:  DusterIdiot [ Thu May 11, 2017 4:09 pm ]
Post subject:  Correct...
Quote:
with 198 rods and dished pistons you won't need to cut much if anything to get the compression up.
I would have to find my original build notes for the 198 stock forged crank long rod build, but I seem to remember that after having someone cut the valve bathtub in the top of a KB piston it gave back something like 17-18cc...

You will need to look at the DCR calculator so you don't end up with lots of static compression and not much cam which won't play well...
Quote:
Oregon will put I lobes on I and E lobes on E and I don't think they'll let you grind an E lobe on I
This is correct, but they were able to do an RDP with that grind for a local guy building up a "better" than stock engine for his valiant...FYI.
Author:  SlantSixDan [ Thu May 11, 2017 4:14 pm ]
Post subject: 
Wait a sec, I'm a little confuzzed. I thought Oregon Cams № 2106 was the Dutra-spec RV10-RDP. This is the first I'm hearing of a № 2106-R…so…which one is the RV10-RDP?
Author:  Dart270 [ Fri May 12, 2017 2:01 am ]
Post subject: 
Yep, cast crank and 198 rods would not play together unless you have someone carefully cut the big end width of the rods down to cast crank width (with proper side clearance).

Lou
Author:  Rick Covalt [ Fri May 12, 2017 3:30 am ]
Post subject: 
Quote:
Oregon will put I lobes on I and E lobes on E and I don't think they'll let you grind an E lobe on I as Dadtruck suggests.
I have the 819 cam in my truck and Oregon did put the Intake grind on both the intake and exhaust.

Rick
Author:  Dart270 [ Fri May 12, 2017 5:00 am ]
Post subject: 
That's weird. Are you sure they didn't put the 819 I on I and 819 E on E? Some lobes may have similar/same profiles/ramps on I and E, I suppose. ;)

Lou
Author:  Rick Covalt [ Fri May 12, 2017 1:02 pm ]
Post subject: 
Lou take a look at my cam card in the FAQ "User cams" post. Pretty sure both are the same lobe.

Rick
Author:  DadTruck [ Fri May 12, 2017 1:22 pm ]
Post subject: 
for the 83 D150, I had Oregon put intake grind 1333 on the intake and intake 1527 on the exhaust,,

that is 212 duration for the intake and 206 duration for the exhaust @.050

and that is 256 and 250 at .006 (Hydraulic) with .447 I and .432 E lift at the valve.

when I was on the phone with Oregon they noted that I had specified two intake grinds,, after a discussion they agreed a fast ramping exhaust would have no probable negative impact. Very long term there could be additional seat / valve wear,,,,

what you would not want is a slow ramping (exhaust grind) on an intake
Author:  Dart270 [ Fri May 12, 2017 6:25 pm ]
Post subject: 
Thanks for the rundown, John. Makes sense.

Greg and I are here in my living room chatting about Slants, Darts, Valiants, and life... Nice to have a slanted visitor!

Lou
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