What would you do?

[terryst]

Hello
I am going to try to rebuild my 200 6cyl in a 65 Mustang soon.So my question is. should I use the current head on the car which is part # c9de-6090m or I can buy a head off of a 200 79 fairmont for $70.00 (that needs rebuilt)or purchase a rebuilt head for 189.00 off the web.
What would the cost be to rebuild the head or the fairmont head.
my car currently has a autolite 1100 carb.
I will be building the engine back close to stock cr

Thanks

 

[Anonymous]

Hi terryst,

The C9-M head is the first year 250 head. It has the 1.75 carb bore and larger manifold. The 79 head, probably a D7 or D8, would have the 1.75" intake valve. This valve can be put into your C9-M head at rebuild. Bottom line, since you are doing a "stock" rebuild I would stay with the C9, do a 3 angle valve job and add the 1.75 intake valve. Save your self $70 and/or the cost of shipping your core back to the rebuilder.

Steve

 

[CobraSix]

If you are worried about money, buying the rebuilt 79 head may be the way to go. The C9 and D7- D8 heads are not the concours correct heads for the 65, so it doesn't matter in that regards. Comes down to cost of rebuilding a head in your area. I know where I live, just a simple regrind, new valves, and replacing only 2 guides, runs about $250 plus parts, and remember, that's only replacing two guides. In that case, I would buy the rebuilt one if the person has the receipt that it was indeed rebuilt. Don't trust the "rebuilt 2 years ago, only 500 miles" lines. But, it that head is indeed rebuilt and only costs $189, go for it. Doubt seriously that you can get your head rebuilt for a better price. But you also have to figure shipping charges. shipping heads isn't cheap. Also, if you have to pay to enlarge the valves on the C9 head, then that will cost more too.

Slade

 

[CZLN6]

Howdy Terryst:

Steve and Slade have laid out some good guidence. I have just a few more questions. Is your goal to maintain stock performance? Was the "M" head installed as a performance increaser? Was the head milled to reduce the larger chamber? Are you just doing the head, or a complete rebuild?

The big differences between the two heads is that the "M" head has aprox 1,365 cc of volume, while the '79 head will likely be about 1,245cc. Both are larger volume then a stock '65 head which has about 1,100cc. Both will have a stock combustion chamber size of about 62cc as opposed to 52 in a stock '65 head. Either would have to be milled about .050" to maintain stock CR. The difference in gasket thicknesses would also have to be compensated for, by milling, to avoid losing Compression. The '79 head will have hardened valve seats and a 1.75" intake valve. The "M" head will have a 1.69" intake and no hardened seats.

Hardened seats would be necessary for hard driving, lots of miles. Not necessary for a weekend cruiser. The difference might mean that you will need to do a valve job in 60,000 miles as opposed to 150,000 miles, depending on your driving situation.

Greater intake volume would be helpful in high rpm, compnesating for a too small carb situations. Less volume might be better in low rpm use giving slightly better throttle response.

The difference in valve size between a 1.69" and a 1.75" intake valve would be negligible in low rpm, stock type application. A three angle valve job and back cutting the intakes would make a difference in the case of either size valve.

Maintaining stock, true 9:1 compression is very important and easily missed because folks don't take the time to measure and compute the actual dimensions. If you installed an "M" head on a '65 block and exchanging the stock type shim gasket for a composite, aftermarket gasket you will have lost a significant amount of power due to lost CR- even compared to a stock 200. Please reread the sticky post at the top of this forum for a detailed description.

There are the variables Terry. Now you need to decide what's best for you and your situation. You really need to set some long range goals and plan to spend what you need to, to get what you want.

Adios, David

 

[terryst]

Thanks Steve,Slade,and David
David I purchased the car with the m head in place.I do think I have an issue with the size of the head gasket now.I plan on using this car as a daily driver.
For now I plan on rebuilding the head,add headers,and sometime go with a two barrle carb.
Later I will rebuild the lower engine.

Thanks

 

[CZLN6]

Howdy TerryST:

If I were in your shoes, I'd buy the '79 head, assuming it is in rebuildable condition. But, I'd try to buy it for $50.00. That will get you the largest valves from the factory, the larger carb hole and hardened seats.

I'd assume, for head rebuild planning, that your '65 200 block has a deck height of .025" and build from there. To get back to stock CR get the head cc down to 50 -52cc with a shim type gasket or 45 -46cc with a composite head gasket. This will require milling aprox .050" for 52cc or .080" for 46cc. It is best to measure yourself. Fit and install an exhaust port divider now, even if you can't afford the headers now. Specify to your head builder that you want a three angle valve job, and the intake valves back cut. The back cut gets you the performance gain of 1.6 rocker arms at a fraction of the cost.

If you're able to do some clean up, polishing and grinding, just let me know and we can get detailed.

That's my two cents.

Adios, David

 

[Anonymous]

For now I plan on rebuilding the head,add headers,and sometime go with a two barrle carb.
Later I will rebuild the lower engine.

Look into modifying the M head to mount a 2bbl Holley with a flat spacer. The Schjeldahl Bros and Mustang Geezer have successfully done the same modification.