250 head questions

[RancheroBoy]

So I have finally made the decision to use a late model 250 head on my '66 200. I read the article on Classic Inlines but I still have some questions.

-Am I able to use the Autolite 1100 that was on my 200 or will the carb not work with the head? If not what carb do I use?

-So to make sure I keep my stock compression ratio I have to mill the head x amount for the difference in thickness in my gasket and for the difference in size of combustion? (62c to 52cc)

-Since I would be milling the head would I use the stock pushrods from my 200 or get the pushrods from a 250 engine or do I have to buy some from a V8?

Thanks

 

[CZLN6]

HOwdy Ranchero Boy:


Q-Am I able to use the Autolite 1100 that was on my 200 or will the carb not work with the head? If not what carb do I use?
A- Yes, you can use your stock 1100, but, the bolts will not line up with the carb mounting holes. The mounting holes on the carb can be slotted to fit, but the orientation will be different. Best solution here is to get a flat piece of aluminum stock and make the adapter you need. OR, you can find the correct Carter YF one barrel carb that came on this head. A key factor in which way you go is what distributor will you be using? the stock Load-O-Matic needs a carb with a SCV like the 1100. Later distributors like a carb without SCV and a ported vacuum source for vacuum advance.

Q-So to make sure I keep my stock compression ratio I have to mill the head x amount for the difference in thickness in my gasket and for the difference in size of combustion? (62c to 52cc)
A- Yes. That will be approximately .025" for the difference in head gasket thickness and .050" to reduce the chambers to 52ccs, for a total of .075".

Q-Since I would be milling the head would I use the stock pushrods from my 200 or get the pushrods from a 250 engine or do I have to buy some from a V8?
A- the stock 200 pushrods will work just fine. The hydraulic lifters will accommodate the difference.

by the way, what year/code is your new head? Are you planning on giving it a valve job?

Hope that helps. Keep us posted.

Adios, David

 

[rbohm]

david, rancheroboy, mike sells an adapter to put the early 1.5" carb on the later 1.75 head;

http://classicinlines.com/proddetail.as ... -200-1VA-V

 

[RancheroBoy]

Alright thanks for the info guys! I am getting them cleaned but not ported, I haven't decided on it. I don't have the head yet, I am just trying to get my homework done beforehand so I know what I have to get. I am going to get the later 70's or 80's head, because of the hardened valves and seats. The distributor i'm using is a HEI type. I think we are going to go for the Autolite, mostly because we have 2 of them, one from the engine i'm using and one from my parts car, and the adapter is affordable enough. Is there anything wrong with these theories?

 

[rbohm]

nothing i can see.

 

[Econoline]

There may be an issue with using the ported vacuum off the 1100 to the hei, b/c the 1100 most likely has a scv for the load-o-matic. I'd go with an Carter RBS or one of those new universal carbs Classic Inlines sells. Will bolt right on, linkage shouldn't be a problem. The RBS came on 70-73 250's. People are always looking for good 1100 cores, you could sell the 2 you have.

 

[my way]

If you can get the 250 carb carb with the head it would solve the vacuum timing issue and the cost of making-buying an adapter. Plus a little more cfm. Also the perfect time to do a three angle valve job being at the machine shop to mill
My way

 

[RancheroBoy]

if we're using a Carter carb that would be on the head, what size venturi do we use, 200 or 250? Because this is going to be used on a daily driver we want to have a little zip but be more econonomical. We also want this to be easy to start and drive with no flat spots.

 

[rbohm]

it actually doesnt matter which one you use, both will do just fine. remember the cfm ratings are not different enough, even if you pulled a carter YF from a 300 and put it on a 144 to cause any negative issues. it would be like putting a 735cfm carb on a stock 289. you will get more airflow capability, but not so much that it will cause issues, unless it is poorly tuned.

 

[CZLN6]

Howdy Back:

The 1st Carter to be used on the 250 engine was a Carter RBS. It is rated at 215 cfm. It is unique in that it is a very low profile carb. It will require adapting linkage but will be compatible with your DUI distributor vacuum advance requirements. THe other Is a Carter YF. IT was used on post '70 200s and began to appear on 250 engines around 1974. It is rated at 210 cfm. It also will require linkage adaptation. Both are good choices for your situation.

Adios, David

 

[RancheroBoy]

Alright cool, (we are probably going to sell our two Autolites to classic inlines for core charges) so we are going to get the carb that is on what ever head we pull. How long would it take for our hydraulic cam to adjust to the pushrods from the different height from the head? Is it good for the engine to do that? I am clueless when it comes to hydraulic cams. Thanks!!