Bigger pistons and cylinders

[wreck]

It’s a sliding scale going larger , the 40s will be small and what size BAS header ?

[pnikas]

It’s a sliding scale going larger , the 40s will be small and what size BAS header ?

It is bolting up on stock oval port heads, it has thin walls though , I will have to measure it.
Will the 40 drlas restrict it a lot?
At least they can be replaced after, do you agree with the displacement heads and cam in general terms ?

[wreck]

yes a 2400cc with a 86C cam will be restricted with 40mm carbs and 42mm intake valves . this 98mm cylinder kit with a 71mm crank will give you a 2143cc engine that will work with the 86C and your heads as they are with better springs and the carbs will be a little small but still work . I'd recommend 10.0 to 1 comp . If you have good fuel then 10.5 to 1 .
It still won't have a lot of low end torque because of the cam .

http://vwparts.aircooled.net/Piston-Cyl ... t4b-je.htm

springs
https://www.thesamba.com/vw/classifieds ... id=2077442

[pnikas]

yes a 2400cc with a 86C cam will be restricted with 40mm carbs and 42mm intake valves . this 98mm cylinder kit with a 71mm crank will give you a 2143cc engine that will work with the 86C and your heads as they are with better springs and the carbs will be a little small but still work . I'd recommend 10.0 to 1 comp . If you have good fuel then 10.5 to 1 .
It still won't have a lot of low end torque because of the cam .

http://vwparts.aircooled.net/Piston-Cyl ... t4b-je.htm

springs
https://www.thesamba.com/vw/classifieds ... id=2077442

Would it be a good idea to add 44mm intake valves and 38mm exhaust valves ? If not mistaken vw had 38mm intakes , can they be installed as exhaust valves ?

[pnikas]

yes a 2400cc with a 86C cam will be restricted with 40mm carbs and 42mm intake valves . this 98mm cylinder kit with a 71mm crank will give you a 2143cc engine that will work with the 86C and your heads as they are with better springs and the carbs will be a little small but still work . I'd recommend 10.0 to 1 comp . If you have good fuel then 10.5 to 1 .
It still won't have a lot of low end torque because of the cam .

http://vwparts.aircooled.net/Piston-Cyl ... t4b-je.htm



springs
https://www.thesamba.com/vw/classifieds ... id=2077442

This combo you propose seems great . The only reason I am still thinking about a 2.4 is that I want to do the job once . The engine is in a convertible so torque is greatly appreciated . What 2.4 would you build around the parts I already have ? Bigger valves and carbs ? Both intake and exhaust valves ?

[pnikas]

yes a 2400cc with a 86C cam will be restricted with 40mm carbs and 42mm intake valves . this 98mm cylinder kit with a 71mm crank will give you a 2143cc engine that will work with the 86C and your heads as they are with better springs and the carbs will be a little small but still work . I'd recommend 10.0 to 1 comp . If you have good fuel then 10.5 to 1 .
It still won't have a lot of low end torque because of the cam .

http://vwparts.aircooled.net/Piston-Cyl ... t4b-je.htm

springs
https://www.thesamba.com/vw/classifieds ... id=2077442

Also another question , should I expect 22mm pins or 24mm ones for the pistons ? 2l 914 engine mostly

[wreck]

stock 914/ type4 rods and stock length rods use 24mm pins , the cam is the wrong choice for what you want to achieve . It works from over 3000 to over 7000. If you go with 104mm bore , change valves /seats, get minor head port work for 46 /38 valves . 44 or 48mm carbs . better rod bolts or rods (if not already fitted). you will need a minimum of a 1 5/8 header . those are the components to match that cam and a 104mm bore .
What revs do you want the power to start ?

[pnikas]

stock 914/ type4 rods and stock length rods use 24mm pins , the cam is the wrong choice for what you want to achieve . It works from over 3000 to over 7000. If you go with 104mm bore , change valves /seats, get minor head port work for 46 /38 valves . 44 or 48mm carbs . better rod bolts or rods (if not already fitted). you will need a minimum of a 1 5/8 header . those are the components to match that cam and a 104mm bore .
What revs do you want the power to start ?

Around 2000rpm , I think that’s the best for a daily

[pnikas]

stock 914/ type4 rods and stock length rods use 24mm pins , the cam is the wrong choice for what you want to achieve . It works from over 3000 to over 7000. If you go with 104mm bore , change valves /seats, get minor head port work for 46 /38 valves . 44 or 48mm carbs . better rod bolts or rods (if not already fitted). you will need a minimum of a 1 5/8 header . those are the components to match that cam and a 104mm bore .
What revs do you want the power to start ?

The combo I have now will be better with 104 pistons or worse ?

[wreck]

It will be better but a 96 mm bore , no machining , a better matched cam will give the same output for a lot less work

[pnikas]

It will be better but a 96 mm bore , no machining , a better matched cam will give the same output for a lot less work

If I end up building a big engine with the associated parts, what should I choose between 1)AA 104mm pistons and cylinders 2)JE 105mm pistons with usa provides cylinders ?

[wreck]

check out "Get Back On Track" on FB and PM Jakob , he has a lot of big bore experience and will most likely have used both sets in engine builds .

[cal 67]

86C is a huge cam and needs stiff springs, like CB650s. Also, the larger the engine, the lower the RPM your peak power will be with the same heads. Just installing a 44 doesn't really help. It needs to flow well enough to support however many ccs at whatever rpm the cam is meant to peak at.

Sealing: six studs. There are other ways, but six studding is proven and reliable. It's not cheap. The heads need to be disassembled and welded to accept more studs. I recommend not going into the rocker box with the center bottom studs. Use those little rows of fins near the exhaust port. Fill them in, mill the seating surface flat, drill for a stud.

[pnikas]

86C is a huge cam and needs stiff springs, like CB650s. Also, the larger the engine, the lower the RPM your peak power will be with the same heads. Just installing a 44 doesn't really help. It needs to flow well enough to support however many ccs at whatever rpm the cam is meant to peak at.

Sealing: six studs. There are other ways, but six studding is proven and reliable. It's not cheap. The heads need to be disassembled and welded to accept more studs. I recommend not going into the rocker box with the center bottom studs. Use those little rows of fins near the exhaust port. Fill them in, mill the seating surface flat, drill for a stud.

what is your opinion on 105mm pistons and cylinders ? Je pistons with usa provided cylinders?

[cal 67]

I’m personally having a hard time finding someone to bore/hone my barrels in a torque plate. Round in your hand means nothing. It needs to be round when torqued on the case. I need to keep pestering a friend till he gives me his honing contact. Anybody that’s honing by hand is giving you warped barrels. They need to stay in that fixture till they’re complete.