Stroke a Cosworth

[dindin]

Im thinking of maybe stroking my cosworth now that's its in the machine shop, any advise , benefits advise downfalls, whats needed ect...My head is now rebuilt and I have got new webers ..Guy at the shop is behind a couple months so I figure I have time to plan something maybe.

Al

[cosvega76]

Al,

The easiest thing to do is to get a regular Vega crank and have the snout machined down to CV size for the crank sprocket. Your rods will work, but you'll either need custom pistons (JE quoted me about $900/set) or try to find a set of TRW Vega forged pistons (nearly unobtanium) and have the valve reliefs machined in. You can't do this with cast pistons, though, the crown isn't thick enough. Plus, depending on whether you're using the aluminum bore or steel sleeves will determine whether you'll need a coating on the pistons or not.

Chuck

[dindin]

Chuck,

Have you ever driven one that was stroked??

Al

[hammerdown7]

Chuck,

Have you ever driven one that was stroked??

Al

I have driven them since 1979, gains in torque and drivability are hard to believe until you drive one. What you loose is the need to rev over 7000rpm's, it's just not necessary.

Dick

[cosvega76]

Chuck,

Have you ever driven one that was stroked??

Al

Al,

The engine I was building I sold to a friend who put it in his '73 Vega that he had already converted to a CV drivetrain. Yes, it is torquier, especially with the CVOA reindexed cam sprockets.

Plus, Dick has a lot of experience with them.


Chuck

[dindin]

Thanks Guys, So that's the new plan , now I need to find them parts..Do you know what the bore size should be for these pistons and what compression is best for a street car?? A regular vega crank should not be a problem I guess.

Al

[cosvega76]

Al,

Bore size depends on what condition your block is in. If it's standard bore and cylinder wear is within reason, you could certainly use a standard-size piston. If the block needs to be bored, you'd get the proper oversize piston to match. Just remember that you'd need pistons with the Vega pin height, not Cosworth. And if the block isn't sleeved, there's a special process to overbore and hone the aluminum cylinders. You can use moly rings on a sleeved bore, but you'll need chrome rings for an aluminum bore.

It was suggested to me that for the street - 9 - 9.5:1 should be considered max compression.

I don't know what your budget is for this build, but keep in mind that with the mods to the crank, special block work, and custom parts the cost can explode in a hurry.

Did you try the CVOA reindexed cam sprockets on the 2.0 L engine? I did that and swapped in a T-50, 5-speed trans and it favorably changed the character of the car.


Chuck

[dindin]

Hi Chuck, I have no budget but that being said, I am over my budget

I have the reindexed sprockets but I have my short block block at the builders and he has a backlog of a couple months or so, so I was thinking maybe I could change stroke it, but I think I may pass on all this and keep it a 2.0 cosworth instead, seems like a big job and expense for a weekend cruiser..I just got a new Hurst for my 4 speed so it will have to do also..

I actually was OK with the power before to be honest, but being in the builders shop and seeing all them big motors got me testosterone movin..

Al

[cosvega76]

I actually was OK with the power before to be honest, but being in the builders shop and seeing all them big motors got me testosterone movin..

Al

I understand!

Took a tour of the Corvette plant in Bowling Green a few years ago. By the time you leave you're wondering what color Vette you should buy!


Chuck

[mikeceli]

I actually was OK with the power before to be honest, but being in the builders shop and seeing all them big motors got me testosterone movin..

Al

I understand!

Took a tour of the Corvette plant in Bowling Green a few years ago. By the time you leave you're wondering what color Vette you should buy!


Chuck

TRUE! We toured it in 2002 and I bought a 2001 MAGNETIC RED Corvette, in 2003!

[dindin]

I ended up just keeping it stock although I did get everything I need minus a crankshaft from a 140 engine to make it work, I never realized how much other stuff is involved and how expensive it is to build a motor..I will be happy when its running stroked or not.

Al

[hammerdown7]

Where are you located Al?

Dick

[dindin]

Im in Connecticut

[hammerdown7]

I was wondering how close you may be to Ohio where a large number of the h-body group will be gathering in a couple weeks. There will hopefully be 6-8 Cosworth owners attending and a couple will have stroked engines. I'll only be able to be there Saturday but it should be fun.

Dick

[dindin]

A little to far for me at the moment, but it sure sounds like it will be a cool event.

Al