Slant *        6        Forum
Home Home Home
The Place to Go for Slant Six Info!
Click here to help support the Slant Six Forum!
It is currently Thu Mar 28, 2024 10:19 pm

All times are UTC-07:00




Post new topic  Reply to topic  [ 10 posts ] 
Author Message
PostPosted: Thu Dec 07, 2017 6:20 am 
Offline
4 BBL ''Hyper-Pak''

Joined: Wed Feb 15, 2017 6:57 am
Posts: 49
Car Model:
Hello Everyone,

I am currently building up my Slant Six, using the Clifford 6=8 Kit as a guideline. Clifford recommends milling the head .100

I am interested to see what others have done, as well as do a second check on the outcomes of how the engine performed afterward.

My Goal:
Creating an engine that has a respectable torque/ hp and can get out of it's own way when accelerating.
Drive car somewhat regularly in California traffic and in the mountains
Air Conditioning
Still Interested in Reliability and MPG

Not My Goal:
Racing/ Competition
Needing Octane Boosters
Pinging and Detonation
Broken Down on side of road

My engine:
1970 Engine & Head
Oversized valves, minor clean-up porting
Clifford Dual 2bbl intake/carbs
270 Duration Cam .495 Lift


Top
   
PostPosted: Thu Dec 07, 2017 6:59 am 
Offline
Board Sponsor & Moderator
User avatar

Joined: Mon Oct 21, 2002 11:08 am
Posts: 16451
Location: Blacksburg, VA
Car Model:
If you want to run 87 octane, then mill 0.080" and make sure your ign timing (advance) curve is properly set up.

Clifford has not been helpful to Slant 6 owners for many years, as far as I know. Their 4bbl intakes and shorty headers are great. Otherwise, I don't know about anything else.

What transmission and torque converter do you have in there? What kind of car? That cam would be too big for a stock converter. The head porting and valve increase will have more effect than anything else.

There are many unknowns here, so please help us to help you by giving more info.

Thanks and Slant on!

Lou

_________________
Home of Slant6-powered fun machines


Top
   
PostPosted: Thu Dec 07, 2017 7:47 am 
Offline
4 BBL ''Hyper-Pak''

Joined: Wed Feb 15, 2017 6:57 am
Posts: 49
Car Model:
Thanks for the reply. I am working on a 1965 Dart, 225, A904, 8 3/4 3:23 Truetrac. It has been completely torn down and now getting close to completion. e.g. - all new paint inside and out, all trim polished and anodized, new full Interior, Firm Feel Stage 3 Suspension, Disc Brake Upgrade - etc -etc. So, basically - I am way over invested in the car and want to make sure I can drive it day to day and do an occasional burnout to make me smile and remember the good old days of muscle cars. :)

I am not too worried about using any grade of pump gas (87, 89, 91 is what is available here). I just don't want to deal with adding supplements if the compression is too high. I don't want to rumble like crazy at street lights.

I rebuilt the transmission using Oregon Performance Transmission HD rebuild kit and added a Stage 2 shift kit. I also worked with PTC -Performance Torque Converter to get spec'd unit to match cam and 3:23 rear-end.

I surely need to learn more about properly setting up my ignition timing - when I get to that stage. I did buy the Later Electronic Ignition Distributor and related parts for then.

* Also, for what it is worth - Larry at Clifford has been very helpful and invaluable to me in many many ways. My engine was essentially stolen from the machine shop with many of the Clifford parts with it. I bought all new replacement parts from Clifford and I just recently recovered my missing property. Larry is refunding all my duplicate parts nearly 8 month after the debacle.


Top
   
PostPosted: Thu Dec 07, 2017 9:25 am 
Offline
EFI Slant 6
User avatar

Joined: Thu Jul 24, 2003 4:51 pm
Posts: 465
Car Model:
What's a truetrac?


Top
   
PostPosted: Thu Dec 07, 2017 12:10 pm 
Offline
Board Sponsor & Moderator
User avatar

Joined: Mon Oct 21, 2002 11:08 am
Posts: 16451
Location: Blacksburg, VA
Car Model:
OK, that is very helpful information! Glad to hear that Larry at Clifford Perf has been helpful, and that he has been a good resource. Sounds like he is working harder for the Slant 6.

It sounds like that cam should work well then, assuming you have a 2400 RPM stall converter or a bit higher. Assuming you have a stock head and block (uncut), then I would mill 0.100". It would be better to cc your head and measure the piston-deck height and then plan your head mill exactly, but you will be 99% likely fine with a 0.100" head mill, if you head and block are uncut. I would probably get custom pushrods from Smith Bros that are 0.080" shorter than stock. You could try with stock pushrods first, but the valves (rockers) may not hold adjustment well if the screw runs out of "tightness" range.

Sounds like a plan on ign timing curve and fuel use. We can help with recommendations on that once you get the car together and running.

Best,

Lou

_________________
Home of Slant6-powered fun machines


Top
   
PostPosted: Thu Dec 07, 2017 3:06 pm 
Offline
TBI Slant 6
User avatar

Joined: Mon Aug 03, 2015 2:39 pm
Posts: 221
Location: Dallas Texas
Car Model:
69a100 wrote:
What's a truetrac?


It's an Eaton limited slip differential.


https://www.youtube.com/watch?v=lZmsY2YvVsc

_________________
1976 Feather Duster /6 4sp
1984 W100 318 727 np241
1972 'Cuda 340 4sp
1985 D250 360 46RH


Top
   
PostPosted: Thu Dec 07, 2017 6:15 pm 
Offline
Triple Duece Weber
User avatar

Joined: Tue Nov 23, 2004 6:05 pm
Posts: 2011
Location: Desoto Texas
Car Model: 1972 Dodge Colt
I just cut my 1975 head .100. There are two different numbers in the Direct Connection manual for CC's to cut number. Anyway you need to CC your head before and after the cut. Mine was at 60 CC's before, I was looking for 43 after, but got 45 CC's. I used Summit's compression ratio calculator, not the most detailed but good enough for what I was trying to do. My little 170 looks to be around 9.5 after the cut. I was looking for around 9.75.

_________________
Hyper_pak


Top
   
PostPosted: Thu Dec 07, 2017 6:15 pm 
Offline
EFI Slant 6

Joined: Thu Jun 04, 2015 6:19 pm
Posts: 317
Location: Florida
Car Model:
I would think with that much cam, and the fact Op doesn't care about which pump fuel he uses, no racing, but mileage is still a concern, max amount of mill (.100") would be the target. We also assume the head has been uncut previously. And Any headers would sweeten all your other nice upgrades, since i see no mention of exhaust concerns.


Top
   
PostPosted: Thu Dec 07, 2017 8:37 pm 
Offline
4 BBL ''Hyper-Pak''

Joined: Wed Feb 15, 2017 6:57 am
Posts: 49
Car Model:
Thank you for all the input. I am very appreciative. This is not my 1st Slant Six car, but the 1st performance minded build.

I forgot to mention that I do have the Clifford shorty headers and will be doing 2 1/4 dual exhaust.


Top
   
PostPosted: Thu Dec 07, 2017 9:06 pm 
Offline
Board Sponsor
User avatar

Joined: Tue Oct 29, 2002 8:27 pm
Posts: 9760
Location: Salem, OR
Car Model:
Unfortunately without some numbers like deck height, and combustion chamber volume before milling but after new seats and OS valves... kind of leaves a lot of "guess work"....


Just to "throw" a WAG into right field here is a scenario based on some variables I could come to a close guess on:

Assumptions due to lack of real world constants (remember WAG...LOL):

mid-60's 225 block at .185 original deck height being cleaned with a .05 cut for straightness (this deck height can vary between .2 in 1963 trucks, and .175 in the late 60's)...

Assume 1970 head is about 58cc original chamber (mopar head castings more consistent about 1972+... and valve recession is a big ??? in this era)... with a .100 cut cleans up to 43cc (round ot the nearest (if new seats and OS valves riding a little high it might be closer to 38-40).

The .1 cut will produce an engine with a 9.08 SCR...

Assume it's a Comp Cam Chevy Lobe special (I can't find any other lobes profile close in my library, and clifford's website no longer lists slant six cams... this lobe is common for a 292 Chevy Cam). 270/270 adv dur /108 LSA .495 lift @ 1.5.... we do a "Lou" and index the cam at 100 intake centerline (this will lower the torque band... but peak torque will occur about 3000 rpm).

This finals out to about 7.78 DCR which will run on low end to mid range pump gas.

Not sure on tire choice... average recommended 205/70R14 would put the car about 73 mph in 3rd at 3000 rpm with some convertor slippage...

Distributor would have to be recurved for a faster advance (you will want a late short slot super six distributor for best performance), and you would have to check your dual Weber DG's for a ported vacuum nipple to take advantage of highway economy (some do not have this option...).


Getting the deck cut to .160 bumps the SCR to 9.4... gets a nice street DCR of 8.05...and a little more "umph"...which with a proper recurve can run on low to mid range pump gas...

Just doodling out loud and hopefully you can advocate your machinist to keep the build in the goal posts so you achieve what you want.


Top
   
Display posts from previous:  Sort by  
Post new topic  Reply to topic  [ 10 posts ] 

All times are UTC-07:00


Who is online

Users browsing this forum: No registered users and 47 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Limited