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All about the Head...
https://slantsix.org/forum/viewtopic.php?t=9361		 Page 1 of 2
Author:  '65 Dutch Dart [ Thu May 20, 2004 6:56 am ]
Post subject:  All about the Head...
Hi again,
I'm working on my 1972 head right now, I just wanted to check a few things before I go on.

Here's a drawing:

<img src="http://picserver.student.utwente.nl/view_image.php/H4D81MMLKH4K/picserver.jpeg"width=400>

Ok, I nicely smoothed the bump ( B. ), I just smoothed the curves, is it better to delete the whole bump ( valve support?) I thinking to keep it like this.

And can I completely grind away A. ?

And another question, in 1972 they put hardened valve seats in, mine is a '72 head, but I'm not sure if I've got them,... I guess there was some overlap in production.

This is the number of the head: 2843163-4.
Anyone who knows?
Author:  Dart270 [ Thu May 20, 2004 8:07 am ]
Post subject: 
The seats were hardened, but they were not pressed-in hardened seats. They basically just hardened the metal at the seat using an electric current heating device. You will probably cut through that hardening when you do a valve job.

Most people say not to remove the whole valve guide boss hump, but I bet it will not make that much difference. I'm no expert on this, just a feeling. According to Doug's cutaway head pics, I believe you can remove all of the A bumps in your (nice!) pic.

Lou
Author:  mnecaise [ Thu May 20, 2004 9:27 am ]
Post subject: 
Here's the link to Doug's cross section pictures.

Doug Dutra Head Cross Section

You can see the water jacket clearly and It's safe to remove the material at 'A'. For a street rod, it's not necessary to remove all the material at 'B'; just smooth it out like you talked about.
Author:  70valiant [ Thu May 20, 2004 1:12 pm ]
Post subject: 
I used a 79 head and I removed all of "A" all the way around and most of "B". when I started I couldnt get my thumb knuckel past the valve bump and when I was done I could with out touching anything. I used a dremmel with a tungsten carbide cutter and several different size and shape stones. I dont think I'm getting the full benifit of the porting and compression jump because I'm still running the pitiful stock 1970 cam w/ 93,000 miles on it. I did go from 123 horse last year at Englishtown to 151 horses this year.
Author:  '65 Dutch Dart [ Thu May 20, 2004 4:11 pm ]
Post subject: 
Thanks!!

I'm going to keep the compression stock, I'm running on both propane and pumpgas, I was thinking the propane and higher compression isn't going to be really healthy for the engine,.. Any thoughts on that?

Other items in my buildup:
CompCam 264s Cam, prolinefuel dual webers, msd6al, blastercoil2, 8mm plugwires, clifford dual headers, stainless allenhead bolts, etc.
Author:  Charrlie_S [ Thu May 20, 2004 5:26 pm ]
Post subject: 
Propane actually likes more compression then gasoline. Propane has an equivilant octane rating of about 104.
Author:  DusterIdiot [ Thu May 20, 2004 6:54 pm ]
Post subject:  Cam...
Your cam choice may not like the 8.4:1 either....

-D.Idiot
Author:  '65 Dutch Dart [ Fri May 21, 2004 3:32 am ]
Post subject: 
Hmm,.. food for thought,... please explain some more.
How much should I take off? And how/where to measure if someone took a bit off in the past? (flattening it twice (for example) before assembling might take of a bit right?)
Author:  Dartvader [ Sun May 23, 2004 5:31 pm ]
Post subject: 
I ported the head on my slant just as you are proposing after I read a British book about headporting. Most of their examples were small CC in line engines, and they recommended taking the valve guide boss completely away. That is what I did, and even with a small cam specifically ground for future turbo use, it reved freely to 5k RPM, something it never would do with the stock head configuration. Will it affect the durability of the engine? Maybe, but maybe not. Roller rockers would reduce the side pressure on the guide. But, after all, I don;t put that many miles on her any more.

DI, do you think the 264cam is too small or too big for 8.4 compression? I have heard good things about that cam.
Author:  DusterIdiot [ Sun May 23, 2004 10:05 pm ]
Post subject:  Peak or Peak...
The cam might be too big...

The 252 seems to have a low rpm torque peak (good for mileage and off the line grunt at street revs...) the 264 seems to 'come on' later (higher rpm, late torque peak and higher top end horsepower). If I highly modified my slant and was running more than 9:1 and some low gearing the 264 might work good, but with 8:1 and no boost and 3.23's the 252 might be better if you're idling at the light at 800 rpm and leaving at 1500 rpm, and running it up to 2000+ at highway speeds....

-D.Idiot
Author:  '65 Dutch Dart [ Mon May 24, 2004 6:27 am ]
Post subject: 
Hmm,..I've been back and forth between the two comp cams a thousand times, reading all posts a million times and finally decided to order the 264 instead of the 252.

It's quite a shakealottamoneyoutofyourpocket thing, so research was needed. I arrived at a point at which I felt save to order the 264,...

And know you got me wondering if I made the right choice! :shock: :wink:

I wanted to keep the bottom-end stock, keep compression stock, get the max out of the head, but stock valves, add a MSD6al, blastercoil2 and 8mm plugwires, chuck a proline dual weber setup on there, bolt on the clifford headers and
last (and least?) the compcam 264 with new timing set, springs.

I run on regular gasoline and on propane, well not me, my engine does,.. :lol:

I could use some real good opinions on the above combination of parts!

Remember my goal was to built an engine that's capable of running with the European BMW's, Mercedes' and Audi's, etc. (Both at the stoplight and on the highway)

Will higher compression be the key, or do I have to do more?

Help! :?: :o :?:
Author:  72Duster [ Mon May 24, 2004 1:24 pm ]
Post subject: 
dutchdart,

when you´re doing the head anyway, I don´t see a reason for not raising compression, except budget limitations.
Raising compression will increase engine efficiency at all rpm´s, that is, give more torque at any rpm. With thel fuel qualities available in Holland (92, 95 and 98roz, right?) you shouldn´t have any problem. You can take .100" off of the head which gives you about 9.2:1 cr if I remember right. This should be fine even with 92octane gas. (but you may need shorter pushrods). My VW Polo runs 95octane and has 10,5:1 compression. And when it´s payday, get a tank full of Super or Superplus and advance the timing to take advantage of the good stuff.
When you´re running on propane, higher compression makes up for the power loss in comparison to fuel. and, as before mentioned, propane loves high compression.
With all the components you described, I´d say raising compression is a MUST. A stock bottom end can take loads of power, don´t worry about little added stress due to higher compression.
Raising compression+252 cam will give more streetable results than running stock cp and the 264 cam. You will enjoy about the same hp but at a lower rpm level (engine friendly; nothing stresses a slant/any engine like high revs) Raising cp will take full advantage of what the 264 has to offer.
Before you tell your machinist how much to take off the head, cc the head volume. This will give you an idea of how much has been shaved off previously.
Head work is the key to wake up a slant... will you have new stock size valves installed? Then go for bigger valves. Do it once, do it right.
Christian
Author:  Dartvader [ Mon May 24, 2004 5:29 pm ]
Post subject: 
I agree with everything Christion said. There is nothing wrong with that cam, although it might work a little better with a 4 spd OD tranny which has a very short 1st gear, It is not compression ratio as such that causes detonation, but cylindar pressure. With the bigger cam, you lose cylinder pressure over the smaller cam, because the exhaust valve remains open for a longer portion of the compression stroke, referred to as over lap. In order to make up for this loss of cylindar pressure with the bigger cam, you must increase the compression ratio. The net result with a bigger cam and higher CR is the same cylindar pressure right before ignition. Ask the cam manufacturer what compression with the 264 cam equates to 8:1 with the 252. They should be able to tell you exactly what CR will seem like stock to the combustion chamber right at ignition. Once you have that information, you can calculate exactly how much to mill the head. There are those on this board, who carry that kind of information in their heads, and others who can look it up for you as well.
Author:  Dart270 [ Tue May 25, 2004 6:15 am ]
Post subject: 
My vote is to mill the head 0.060-0.070" (1.5mm), which will put your static compression ratio close to 9:1 and will work very well with that 264 cam. Any more milling may require shorter pushrods.

Lou
Author:  '65 Dutch Dart [ Tue May 25, 2004 7:50 am ]
Post subject: 
Christian: We don't have Super fuel anymore, they stopt selling that about 2 years ago, they said it was an environmental thing, but I'm sure their targetgroup just became too small. But 95 and 98 octane is sold everywhere.
Quote:
Raising compression+252 cam will give more streetable results than running stock cp and the 264 cam. You will enjoy about the same hp but at a lower rpm level (engine friendly; nothing stresses a slant/any engine like high revs) Raising cp will take full advantage of what the 264 has to offer.
Did you mean you get the same HP @ lower rpm with the 264 cam when raising the compression?

DV: I'm sure you mean the 4 speeds in general are best with this cam, instead of just the OD box right? They both have the same first 'SpeedyGonzalez' gear (3.09).
I'm indead running a 4 speed ( more gears will come later but I decided to take one step at a time,..). The 4speed is the reason I picked the 264.

Dart270: That's how I like to get information, in milimeters! :D Great service, thanks!

All: Thanks! I'm convinced and I will raise the compression! Unless someone tells me I can take of lot's more without problems, I will go with the 0.060-0.070"(1,5mm) that Lou suggested.
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