Head & rocker arm questions

[Guest]

New to rebuilding, but here is my plan.

I’m going to do a build-up on a stock 67 Mustang w/ 200 I6. The car will be a summer daily driver. I’ll be picking a 77-83 head from a bone yard. Planning on using a 264 110* cam. Already have the flat top pistons, .030 over. Will go with headers. Not sure yet what I’m going to do for carburetion.
I’ve contacted a machine shop that was recommended to me to mill the head .060, boar and deck the block (not to zero… .010 to .020 or so. have to measure first) dip, press, and do all the things a machine shop does for us.
From my reading here I see that a 250 head bolts up to my block. I’ve been told that a 250 I6 came standard with 1.6 adjustable rocker arms and was planning to use them. The owner of the machine shop is recommending that I use a head from a 200 and the arms that came with my engine because the higher lift will change the dynamics of the cam. I thought it would just improve the flow.

Has anyone ever done this here?
Any thoughts on this?

Next:
Should I open up the ports on the exaust?
If so, how much?
Does anyone have pictures of how they should look when finished?

Thanks... I Love this site
Tom

 

[addo]

Tom, the 250 head uses (to my knowledge) the same rocker setup as the 200 head - either adjustable, or non-adjustable.

As to the exhaust ports - use the exhaust header or manifold as your guide there; make sure to maintain at least an average 1/32" oversize on manifold or header openings. You can usually hog a bit out from cast manifolds, but less with headers.

Cheers, Adam.

 

[Guest]

I was thinking of ordering the 1.6 rockers from Classic Inlines and the guy at Clifford told me that this was a way to save some money. He was also looking to sell me a new head. My question to him was about the springs on their head and possible binding.

OK… For the extra lift I’ll need to buy rocker arms.
Has anyone out there placed a set-up like the one I’m planning here on a daily driver?

Tom

 

[JackFish]

Next:
Should I open up the ports on the exaust?
If so, how much?
Does anyone have pictures of how they should look when finished?

Thanks... I Love this site
Tom

This is a gasket-matched port:

 

[Guest]

Thanks Jack!

Love the way you can click on the pics to get a larger view.

 

[fordconvert]

Make sure and CC the new prospects before you get too far into things and also know what your bottom end is going to be so you can get the CR you want. I am now on my 4th head and only one of them is close to what it should be for size, the other 3 have had a lot of work done to them over the years. My largest one is 61cc's. Smallest is 40. Both same casting numbers! The 61 looks like it may not have been shaved, it doesnt have seats or guides in it but it but who knows. When its been 25+ years since a motor has been built especially in common man daily drivers like fords I have found most (if not all) of them have had some sort of motor work done on them by this time and you wont know for sure till you get them apart. I dont have my notes handy but at the bore and stroke of the 200 10-15 cc's is all it takes to make a whole point change in compression. I have $200 of work into a head I cant use for my current bottom end because it will give me 7.2:1 compression. I will just leave that one on the shelf while I look for more parts to go with it.

 

[Guest]

Mustang Geezer had a website a few years back where he showed how to measure the cc’s of each chamber. Glad I read that page several times.
I’ll be going to a very large bone yard and will be looking for a car that has the lowest mileage and appears to have the original .025 gasket installed. Hope that this will be the best way to find one that hasn’t had any work done to it as of yet.
I know the cc’s on the newer head is around 62cc and my head originally was 52cc. From my reading here, by milling the head .060 my chamber size should be at 50cc’s in a perfect world. I’m expecting to have to even the chambers and if I end up with 52cc’s or less I’ll be quite happy.

Is anyone here using the 1.6 rocker arms with a similar cam to the one that I will be using? I would like to know how it is working for you.
If not I guess that I can try the 1.6s and go back to the original if I don’t like what I end up with…

Tom

p.s. I’ve spent years thinking (dreaming) about this build. It’s fun to be finally starting it.

 

[CZLN6]

Howdy Tom and All:

FYI-
*The 200 and 250 heads are the same after about 1970.
*All 144. 170 and 200s prior to '65 had adjustible 1.52:1 rocker arms.
*Many 1965 engines also had adjustible rocker arms with hydraulic lifters.
*You'll be wise to convince your machine shop to deck the block to achieve zero deck height. The composite head gasets available will give you more than enough cleanance.
*The stock type dished pistons, all else being equal, will give more power in a wedge shaped combustion chamber engine. And be more knock resistant.

What is your CR goal for this engine?

Check the advertized lift on the 264 degree cam you're planning to use. if the Lift is over .400" you don't need and will likely not benefit much from 1.6:1 rockers- without a great deal of flow work on the chambers, valves and ports.

Keep it coming!

Adios, David

 

[Guest]

*You'll be wise to convince your machine shop to deck the block to achieve zero deck height. The composite head gaskets available will give you more than enough clearance.

OK… This sounds good.

*The stock type dished pistons, all else being equal, will give more power in a wedge shaped combustion chamber engine. And be more knock resistant.

I already have the Flat-Top (30 over). Still think that I will use them. What does a wedge shaped combustion chamber look like. Does anyone have a few pics?

What is your CR goal for this engine?

10:1 to 10.5:1. I’ve been playing with the compression calculator for a while. Boar=3.71, chamber vol=50, gasket=.05, deck=.01, and piston=Flat Top. I don’t yet understand what the “Dish/Valve Relief/Dome Volumeâ€￾ is but it is set at 0. Ditto for the “Volumetric Efficiencyâ€￾, that is set at 80%. This gives me a compression of 10.1:1.
Changing to a zero deck height gives me 10.3.

Check the advertised lift on the 264 degree cam you're planning to use. if the Lift is over .400" you don't need and will likely not benefit much from 1.6:1 rockers- without a great deal of flow work on the chambers, valves and ports.

Planning on getting the SCS-264/274(110*) from Classic Inlines http://www.classicinlines.com/proddetai ... 2DHDP%2D10 . I’m planning to open up the ports on the exhaust side of the head. Besides evening out the cc’s on the chamber, I think that I have no business trying to change the chamber on the head I’ll be using. With that being said, I’ll still have my original head to try something new. Does anyone have some pics of changes to the chamber that are effective?
I know sooner or later I’d like to try.


Tom

 

[addo]

The chamber shape referred to (wedge) is what's cast into the head. It's more or less fixed in overall profile and may only be reduced by skimming, or increased by grinding.

Flat top pistons have no "dish" - hence your dish volume is set at zero.

You can go to negative deck heights, but it's advised to leave up to 15 thou clearance between the head and piston top. Deck height would be determined/altered after the block is bored/honed and the rods resized. Both of these influence it.

 

[Guest]

To be sure that I’m understanding you… Theoretically if I went with a minus .035 deck height taking into account the .050 gasket, this would be possible while leaving 15 thou for clearance. Would give me 11.4:1 compression. Sounds like fun, but I think that I will stay around the 10:1 area.

Any idea what the “Volumetric Efficiencyâ€￾ is?


Tom

 

[addo]

You'd be brave to go that far! But yes, that's the idea.

VE will reflect the flow abilities of your motor. Headers and improved carburetion (larger venturi) allow a potentially greater VE to be approached.

 

[mugsy]

I agree with David: zero deck the block and then change the combustion chamber volume to get the ratio you want. I did something very similar to my engine a few years back and ended up with a 0.030 cut on the block (to zero deck) and 0.040 on the head. Also the new composite head gasket the crush is around 0.048 to 0.042 if my poor memeory serves me correctly. You might want to check around.

Personally I would target a lower compression ratio; something in the low 9.X:1 range. On my "other" project car ('68 Catalina) the engine was rated at 10.5:1 and it sparked knock like hell. I tried all the tricks to reduce/eliminate the knock (lower temp t/stat, cool air intake, jet changes, etc) and nothing worked. If you are off on your calculations and/or machining it's tough to put material back on. And personally I don't think your butt-o-meter will tell the performance difference with a 10.X:1 versus a 9.X:1 ratio in your engine.

And lastly, I bought adjustable rockers off of evil-bay. They work fine and I think are needed with all the material that has been removed.

 

[Guest]

Correct me if I’m wrong… I thought that placing my cr around the 10.x range from the machine shop would be my best choice. If it is working great after the build, well then, great!
I’ve also contemplated the possibility that the compression could cause a pre-detonation knock, even with mixing my own fuels. Or after a while of mixing fuels the car might not be as much fun to drive on a regular basis. If this was the case I could remove the head myself, clean up the chamber while adding a few cc’s to the chamber and drop the cr without going to a machine shop.

Is this a bad plan?

 

[addo]

It'll work. You might find just backing off the timing fixes light pinging - if it happens.