Bore + Cam selection - rebuilding a 200 I6

60sMustang

60sMustang

Well-known member
1966 Mustang coupe - 200 inline 6 C4 trans.

I've posted a couple other threads about some valve noise and cylinder head removal and got great feedback. Now that I have the engine torn down to the block basically I'm going ahead with a complete rebuild instead of just doing the top half(valve job, etc).

The head was well worn, which leads me to believe the bottom half is as well, no evidence of it being anything other than original. Replaced a couple valves and valve guides, rocker arm shaft was worn, valve seals leaking. I had hardened exh seats installed, 3 angle valve job, positive seals vs umbrella seals and upped the spring ratings to allow for a cam upgrade.

I'm looking at doing a .030 or .060 over bore with the comp cams 260H 110 degree LC. The head has been shaved down already to 48.5 cc chambers(already that way before I took it apart, they just took off the min to make it flat again). CR should be in the high 9's:1 when done, depending on the bore selection and gasket thickness.

Does anyone have experience with this specific cam in a 200? What's the idle like, Etc.

Recommendations on .030 over or .060 over on the bore and why?
 
there are a few people that have experience with the comp 260 cam, and they all like it.

as for boring the cylinders, always use the smallest overbore possible. all you want to do is clean up the bores and make them round again. this will allow you to rebuild again in the future as needed.
 
I have the same engine, same cam, same C4, - it does what it is supposed to do. Currently my car starts right up, gets warm, idles nicely, doesn't stall at lights, and no vaccum issues. I'm happy with it.

Are you retaining the original 1V 1100 carb and distributor with the SCV port?

I am using a 1101 carb which doesn't have SCV and a DUI distributor. At some point I need to get the DUI re-curved, but I didn't learn of it's potential shortcomings until some issues were brought to light here on the forum.

Best,

Perry
 
rbohm":2jeknh5x said:
there are a few people that have experience with the comp 260 cam, and they all like it.

as for boring the cylinders, always use the smallest overbore possible. all you want to do is clean up the bores and make them round again. this will allow you to rebuild again in the future as needed.
Click to expand...

That's what I was thinking on the bore as well, just wasn't sure if it would make a noticeable difference.

Thanks!
 
1966Mustang":vkpbbaf7 said:
I have the same engine, same cam, same C4, - it does what it is supposed to do. Currently my car starts right up, gets warm, idles nicely, doesn't stall at lights, and no vaccum issues. I'm happy with it.

Are you retaining the original 1V 1100 carb and distributor with the SCV port?

I am using a 1101 carb which doesn't have SCV and a DUI distributor. At some point I need to get the DUI re-curved, but I didn't learn of it's potential shortcomings until some issues were brought to light here on the forum.

Best,

Perry
Click to expand...

Did you see a noticeable difference in the performance or idle with the 260 cam?

Yes, Keeping the 1100 carb for now since it is freshly rebuilt also, may go 2V at some point but not sure.

I have the Pertronix ignition and coil setup, so sticking with the stock distributor as well.
 
60sMustang":1l7et22z said:
Did you see a noticeable difference in the performance or idle with the 260 cam?
Click to expand...

My engine was pretty jacked up when it went in for a rebuild, so really I don't have a good comparison for before and after. It ran before but it ran a whole lot better after. It's been layed up for... too long due to other projects on it - suspension rebuild, metalwork, etc. I might be able to get it started up next week.

Here are some old pictures of the engine getting pulled out - There's some bent pushrods I think because the rocker arm shaft was pretty locked up - I'm thinking some first start attempts after a long sit did those in. Another issue was the rocker arm shaft was packed solid with old grunge.

Oh, and make sure to check your fuel system - I didn't do that until I tackled my trunk a couple months ago... The amount of junk in the old tank was astounding... I should have done that before while the engine was out.

https://www.flickr.com/photos/10338575@ ... 589220934/
 
1966Mustang":35yzfd4v said:
60sMustang":35yzfd4v said:
Did you see a noticeable difference in the performance or idle with the 260 cam?
Click to expand...

My engine was pretty jacked up when it went in for a rebuild, so really I don't have a good comparison for before and after. It ran before but it ran a whole lot better after. It's been layed up for... too long due to other projects on it - suspension rebuild, metalwork, etc. I might be able to get it started up next week.

Here are some old pictures of the engine getting pulled out - There's some bent pushrods I think because the rocker arm shaft was pretty locked up - I'm thinking some first start attempts after a long sit did those in. Another issue was the rocker arm shaft was packed solid with old grunge.

Oh, and make sure to check your fuel system - I didn't do that until I tackled my trunk a couple months ago... The amount of junk in the old tank was astounding... I should have done that before while the engine was out.

https://www.flickr.com/photos/10338575@ ... 589220934/
Click to expand...

Looks good now though!

Mine is not in near as bad condition to start, I've been taking pics though to document progress. I'll post an album like this when its all done, great idea. My fuel system is all new already, but thanks for the tip.

I almost bought those same wheels. Ended up going with a Drag Wheel brand wheel instead that I will post also. Not many choices in the 4 lug pattern.
 
So this is what I have decided to do with my rebuild.

Head:
3 angle valve job with back cut intakes, positive valve seals vs umbrella style, hardened exh seats, replaced a few worn guides, upgraded springs to accommodate the cam I'm using in the bottom end, some port work to smooth out airflow as much as possible, new rocker arm shaft and resurface the rockers, mill head as needed to get CR right.

Block:
I've also decided to go ahead and do the bottom end while its torn down, I believe it to be original also. There I am doing the Comp Cams 260H cam and lifters and timing set, boring .030 over, grind crank as needed, new bearings, etc.

Also I already run the pertronix ignition system and flamethrower coil, dual outlet header and exhaust from Classic Inlines, and the autolite 1100 with cold air induction kit from CI. I don't see where a 2v carb will give me much difference in HP with the small log manifold, but may make that change at some point down the road after further research.

Any other suggestions, while its torn down?
 
IMO While it's down why not upgrade to the large log head?
Also double ck the avialabity of Classic Inlines web site.
 
CCs95GT":1kjag3ju said:
IMO While it's down why not upgrade to the large log head?
Also double ck the avialabity of Classic Inlines web site.
Click to expand...

My original plan was to just do a valve job to fix some ticking noise that recently developed, so money has already been invested in it before I decided to bite the bullet on the bottom half too.

Now that I am doing the bottom half also I'm having the builder do some port work, back cut valves and upgrade springs to match the cam. Also already have the port divider installed in it. I see where you're coming from but think I'll stick with the original head.

Also I already have the CI parts, I know they aren't taking orders on the website now. Thanks for the heads up though.
 
The 260 comp cam is an antiquated design.
Comp makes upgraded cams as well a Clay Smith264 & Schneider has several grinds.
When you see a camshaft which needs at least 100# seat spring tension you know it will outperform one which only needs 50# spring tension.
 
wsa111":1bj0or2x said:
The 260 comp cam is an antiquated design.
Comp makes upgraded cams as well a Clay Smith264 & Schneider has several grinds.
When you see a camshaft which needs at least 100# seat spring tension you know it will outperform one which only needs 50# spring tension.
Click to expand...

I haven't purchase the cam yet, I also looked at the Clay Smith 264 110 and the Howard 267 110. From what I see the durations at .050 are within 1 degree of each other and the valve lift is very similar on all three as well. What do you dislike about the Comp 260 and how is it different from the Clay Smith or Howard if the numbers on duration, lobe center, and lift are basically the same? Not trying to argue the point, just saying what I used to come to the decision on the Comp 260. Please let me know if I'm missing something. Thanks
 
Sure, faster valve opening produces more area under the curve. To achieve you have control the faster rate of lift with valve springs with have more tension.
If you want a grandmas cam go with the 260.
The faster rate of lift, providing you have the proper carburetion & exhaust mods will give you another 15-20 HP.
 
wsa111":3rheinyn said:
Sure, faster valve opening produces more area under the curve. To achieve you have control the faster rate of lift with valve springs with have more tension.
If you want a grandmas cam go with the 260.
The faster rate of lift, providing you have the proper carburetion & exhaust mods will give you another 15-20 HP.
Click to expand...

Where would I find the rate of the valve lift in the specs so I can compare? Or are you just comparing the spring ratings on each?

Do you have any opinion or experience on the Howard's Cams 267 - 110? This is what the builder is recommending based off recent experience with another 200 build.
 
60sMustang":26o84k6i said:
wsa111":26o84k6i said:
Sure, faster valve opening produces more area under the curve. To achieve you have control the faster rate of lift with valve springs with have more tension.
If you want a grandmas cam go with the 260.
The faster rate of lift, providing you have the proper carburetion & exhaust mods will give you another 15-20 HP.
Click to expand...

Where would I find the rate of the valve lift in the specs so I can compare? Or are you just comparing the spring ratings on each?

Do you have any opinion or experience on the Howard's Cams 267 - 110? This is what the builder is recommending based off recent experience with another 200 build.
Click to expand...
Call Howard & ask what are the springs specs. They do say stock springs are not adequate.
Do you have a stick shift or a C4, if so what converter do you have stock or one with a higher stall speed.
If its a C4 with stock converter I would go with a 112L/C.
Nothing worse than an engine with a narrow L/C with a stock converter.
 
wsa111":3lnvofre said:
60sMustang":3lnvofre said:
wsa111":3lnvofre said:
Sure, faster valve opening produces more area under the curve. To achieve you have control the faster rate of lift with valve springs with have more tension.
If you want a grandmas cam go with the 260.
The faster rate of lift, providing you have the proper carburetion & exhaust mods will give you another 15-20 HP.
Click to expand...

Where would I find the rate of the valve lift in the specs so I can compare? Or are you just comparing the spring ratings on each?

Do you have any opinion or experience on the Howard's Cams 267 - 110? This is what the builder is recommending based off recent experience with another 200 build.
Click to expand...
Call Howard & ask what are the springs specs. They do say stock springs are not adequate.
Do you have a stick shift or a C4, if so what converter do you have stock or one with a higher stall speed.
If its a C4 with stock converter I would go with a 112L/C.
Nothing worse than an engine with a narrow L/C with a stock converter.
Click to expand...

I noticed that also about the valve springs on their site. I'll call them tomorrow and ask though. The builder will be checking them as part of the head work he's doing also.

I currently have a C4 trans with stock converter, but I'm considering the T5 swap while I'm into it this deep. I made another post earlier seeking info about this; parts list, Etc.
 
HI, You don't get much out of boring.. Boring should only be used to clean up the cylinders. On my 460 I only gained 6 cubs with a 30 over bore. If you bore it too much you well start having overheating issues because to to thin walls. I would not go 60 unless you have to..
good luck
tim
 
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