250ci turbo questions

blackbird64":1wlp5m3b said:
where do buy parts from then and ones that arent Chinese crap or over priced
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It doesn't look like you are reading the info I'm posting.
It will be twice that I have made reference to buying rods and pistons.
I also told you that Does10s on this site has the remaining CI inventory.

Each type of part will come from a different place and we can discuss where to buy each type when the time comes.

The most important question that I previously asked you is Do you have a trusted machine shop to machine your block and parts?
 
blackbird64":j6075d69 said:
yes i know of one that my dad and granfather go to
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Good.

The first step is to talk to him about the project.
You will need to strip the 250 block of everything including freeze plugs and oil passage plugs.

Then the shop can clean and magnaflux the block and the crank to check for cracks.
The cylinder bores also need to be checked to make sure they only need a small bore increase to clean them up.
A turbo engine needs as much cylinder wall thickness as possible.

If all are OK then he can bore or hone the block mainline for straightness then take a cut off the block deck to true it up with the mainline as well as give a clean deck to work with.
Then the cylinders can have the initial bore cut done so you know what size piston you need.
The deck height also gets measured after it has been machined so you know what the piston compression distance needs to be.

This is a start and the first money that gets spent.
 
now i have another question idk if the black has to be bored but i would only want to go mabe 20 over also you say to take a cut off the block deck is that to lower c/r and what about my head do i need to zero it
 
The cylinder bore wears from the top piston ring on down to the bottom.
With your fingernail you can feel a ridge in the cylinder about 1/4" from the top.
The end cylinders usually have the most wear.
The cylinders are bored so they are round again and there is no ridge.
Hopefully it doesn't take more than .030" over to clean them up. The less the better.

The crankshaft line is bored first so it is straight then everything else is referenced from that.
The top of the block is machined so it is flat and parallel to the crank line.

Once you have the rods and know what the rod length is then you can figure where the piston pin needs to be in the piston so the piston top ends up be even with the top of the block deck at TDC.
Rod length is measured from the center of big hole to the center of the piston pin hole.
The block deck height is measured from the center of the crankshaft bore to the top of the deck.
Piston pin height = (Block deck height) - (1/2 the crank stroke) - (the rod length).

Example: Lets say that after the block is decked the height is 9.460".
You decide to use an after market rod that is 6.00" long with the stock 3.91" stroke.
9.460" - 1/2 of 3.91" - 6.00 = 1.505"
When you order the pistons you would specify on the order sheet a Compression Distance of 1.500" which gives you a .005" margin to work with.
You don't want any of the pistons to go above the block deck.

The piston size is determined by the overbore needed.
The dish volume in the top of the piston is determined by the combustion chamber size in the head and the head gasket thickness.
Those 3 volumes along with the bore and stroke are used to calculate the Static compression ratio.
This means the head needs to be finished before the piston dish volume can be figured.

The Static compression ratio is a function of the Dynamic compression ratio which has to do with the intake valve closing point.
That involves cam timing. The cam choice is also needed before the piston specs can be finalized.
 
so if just drop at the machine shop they should know what to do and i know the 250 had to c/r 9.5 to 1 and 8.5 to 1 idk what my is but if it is 9.5 you think i should have it lowered down to to 8.5 and lower to 8 later in life
 
Before you do anything you need to visit the machine shop first and discuss the project with them.

As you remove engine bolt and nuts, place each set in a zip lock bag and label the bag with a permanent marker.
Example: Valve cover bolts in one bag, side cover bolts, oil pan, timing cover, distributor clamp and bolt and so on...all in separate bags.

When you remove the timing chain put the cam gear back on before you pull the cam. This way you don't have to worry about losing the plate and spacer.
Also the plate only goes on one direction so you will have that for reference when you install the new cam.

Piston compression ratio is for a later discussion. Get the block and crankshaft work started first.

Do you have anyone with experience that can help you?
 
I know im new to this forum but I have been building turbo cars for some time now and my take on this is. If your running good internal and have a well thought out turbo kit 10's are no problem. You might have to make some of your parts but its worth all the time in the end.
 
hey so you say that classic inlines is no more will they becoming back to business in the future or are they permanently gone because it was sort of the last hope for my engine if im going to have to hunt for each specfic part and there isnt a constant stock of them and everybody here is trying to buy parts then there will be issue: high demand+few parts=expensive prices which i might switch to a 302 or maybe a 351
 
Please read this link.
/viewtopic.php?f=2&t=73807#p567170

Any parts that you need for a turbo 250 six can be ordered directly from the original supplier for the same or less money than if you could purchase from Classic Inlines.
CI supplied forged pistons form Racetec or JE and you certainly can buy directly from each of those companies.

CI did not supply aftermarket connecting rods.
Your choices are to polish, shot peen and resize the stock rods with ARP bolts or Use the Scat Chevy 250 six 6.00" rods.
The Molnar BBC 6.135" small journal rods are also a possibility.

You have the 250-2V head.
You would need to make an intake and exhaust manifold to fit the head
 
yea thats the big stuff what about cams, valves, rollers, pushrods, and other wierd little things they had where can i find where they bought those so i can by them
 
blackbird64":1kq2veqd said:
yea thats the big stuff what about cams, valves, rollers, pushrods, and other wierd little things they had where can i find where they bought those so i can by them
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Almost every item shown on line at CI is clearly marked as to the source supplier.
Cams and other valve train components were supplied by Clay Smith. You will see the Clay Smith emblem.
Valves are clearly marked as SI Valves and so on.
Take the time to look over the Classic Inline online parts listing.

One of the reasons for posting here is to also find out what the best parts are for what you are doing and it may not be what CI had to offer in all cases.

I'm hoping at this point you have at least talked with the machine shop about your project?
Have you started to take apart your 250 yet?
 
i have not talked to the machine shop because i dont have the budget im trying to find out what i am going to do for sure then get a game plan and start budgeting for the project i expect this to a few years and 10s of thousand of dollars in the car and engine i made parts list once for just the engine and was close to 5000
 
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