need a type 4 guru, picking engine components

mike gilbert · mike gilbert's Garage

hello, i got a 1.7 and a 1.8..i want to rebuild the 1.7 because i cant line bore the mag. 1.8 case and the 1.7 is the original motor.i know the 1.8 heads have bigger valves and if i use them i need to use a 1.8 piston kit but i want at least 125-150hp..i want reliability and 50k lifespan..if i go for the big bore kit, say 96mm to 100mm do i have to use a aftermarket crank?I'm prepared to get machine work to clear the skirts, but I'm confused about crank length and rod, piston combinations..I'm needing a economical solution to my rebuild (around $2000) also what lift cam for good all around street performance and get the hp #'s I'm looking for.are the big bore kits 8:1 or less?also im going to use weber type dual carbs maybe 40mm?..thanks, mike

hardflex · 01-20-2009, 11:21 AM

1.7 and 1.8 crankshafts and rod assemblies are essential the same. You will need to bore the 1.7 case to fit larger cylinders, 96's are recommended by most. Use the 1.8 heads and 1.8 or 2.0 exhaust.

The cam will depend on whether you are using Carbs or Fuel Injection.

mike gilbert · mike gilbert's Garage

i have to bore the case even with a 96mm set?

hardflex · 12:22 PM

hmmm rethinking that. I know you have to bore the 1.7 heads to fit larger cyls, but maybe not the case. I think I was in error. I think the case boring is only for pistons larger than 96mm

Maybe someone else knows for sure.

Dave at Pelican Parts · Dave at Pelican Parts's Garage

All four-cylinder 914s used aluminum crankcases, not magnesium. They are almost completely identical, 1.7, 1.8, 2.0 alike.

No need to bore the case spigots for 96mm P&Cs. The 1.7 heads have to be cut for them, unless you get the very very thin 96es made specifically for 1.7 heads.

The $2K budget will rule out a lot of things, like a longer stroke-unless you get fantastically lucky in bargain-hunting. Remember that heads can take $1K of work to get into good shape on their own...

You can make 1.8 cylinders (93mm) or 2.0 ones (94mm) into 96es by honing them out in a fixture, held down by a torque plate. 96mm pistons can be had for decent amounts of money.

The 1.7/1.8's 66mm stroke with 96mm cylinders give 1911cc displacement. The bottom end will be really tough, and can be spun very fast. Making sure the heads can feed the motor adequately at high RPMs and making sure the valve train is up to those revs is another question...

If you have a decent set of carbs already, you can build the engine to rev and put a good aggressive cam in it, and probably get 100 solid HP or more. 150 HP is being really optimistic. Making your power goals will be easier if you have a tuned header exhaust, as well--and not just a Bursch muffler, I mean a real racing header. But those are relatively expensive...

If you're willing to pony up more than double your current budget, you can talk to Jake Raby and get a full kit ready to assemble that meets your power goals. No, it isn't cheap.

--DD