Type 4: Whats the biggest stroke crank without case machine?

[Cragrobbo]

Hey guys.

What is the largest stroke crank I can use in a Type 4 case(W code) before it will need machining?

I am trying to save myself a bit of money but if nothing but stock will fit then I guess I'll have to dig deep.

Craig

[Piledriver]

Case clearancing is not usually the main issue on a T4--- Missing the cam lobes is.
You can hand clearance the case with a dremel, a coarse cutter, oil and patience.

The lobes on the cam are ... inconvieniently located... unlike a T1.

IIRC if you use chevy or T4 2L journals with the right rods 86mm is no issue.
Richard has much experience with long stroke/rod builds, I'm sure he will post up soon.

[Cragrobbo]

The crank I am looking at uses Chevy journals any way so I should be good to go?

I'm wanting to go 80mm

[Piledriver]

If my memory is working, that should drop in with Bugpack race rods and std base circle cam.

Again, I'm going from my memory of what Richard posted, so you may want to search a bit

[Cragrobbo]

If my memory is working, that should drop in with Bugpack race rods and std base circle cam.

Again, I'm going from my memory of what Richard posted, so you may want to search a bit

Sorry, I don't know why I put 80mm I ment 78mm (all these sizes and my head went for a walk)



I am looking at a 78mm crank & I will be using 103mm Pistons with it which will give me about 2600cc

The only thing is the carbs I am going to be using are 44's Really I should be using 48's for this size of an engine.

The 44's should give me an increased velocity and hopefully lower down power but will likley hurt top end revs and power.

I am wondering if I would be 'over' strangling the engine with 44's or if its just not 'ideal'. in theory the 44's will give beter fuel milage too over the 48's

Would it be worth while going to a 2.4 with the 44's or will I still see a power gain with the larger 2.6 with the 44's?


seeing as this will also be my Daily drive the lower end power with increased MPG should be much better.

Thanks

Craig

[Piledriver]

44 vs. 48 depends on the heads cam //power band etc.

Big motor needs big heads ($$$) for high rpm use.

There's no shame in a motor that pulls like a truck to 6500 and is done.

Richard posted a thread w/pics showing cam/rod clearance w/various setups awhile back.

[Cragrobbo]

Thanks piledriver.

I had a quick look but disn't find anything under 'Richard' have you got the link please?

[Piledriver]

Sorry, "Richard" is the type4ums moderators "Type 4 Unleashed" meatspace name.

T4-related questions are best posted to the type4um.
More likely to get a fast and complete answer.

[Cragrobbo]

Thanks for that.

From what I can gather from info from here and other sources a 78mm is a direct drop in with no machine work required.
I will have to do some machine work to fit the 103mm heads though.

Craig

[Steve Arndt]

78 stroke with 5/16 rod bolt thin rods will clear. Some rods have meaty big ends with cheaper 3/8" bolts and they may need clearancing.