upgrade from 1.7L to 1.8L flycut ?

[ty901]

all;
i'm changing out the heads on a type 4 (dropped seat). as it turns out 2 of the pistons are pretty beat up as well. i have a set of 1.8L P&C (also low compression). is there machining required in order to use these w/ the 1.7L heads ? (022.101.372)
TIA
is this a great board or what ??!! ;-)
cheers
jerry

[Dave at Pelican Parts]

You will have to cut the "head registers"--the areas where the cylinders go onto the heads. The OD of the 1.8 cylinder sealing area is lrager than that of the 1.7 ones, and they will not fit the 1.7 heads without making that cut.

You do recall that the 1.7 has smaller valves and a different combustion chamber design, yes? The 1.8 pistons will give you lower compression than the stock 1.7, but I'm not sure what the compression will be.

--DD

[ty901]

Dave;
thanks !
jerry

[hardflex]

from the tech specs at Pelican, an EC engine (1.8) shows at 7.3 compression, same as 1.7 unless it was an EA (8.2 to 1).

Many moons ago, when I put bigger jugs into my EA 1.7, I recall a satisfying increase in pep. It may have been the freshness of the engine, but I did feel a difference.

I'd suggest if you go to the 93's, adjust your MPS if you have DJet to account for the larger displacement.

[ty901]

...and if i'm putting them in a carburetted slug ?? (bus) ;-)
p.s. thanks for the tip on Jim Cooper. we had a nice chat yesterday.

[Dave at Pelican Parts]

Only the EB motor had the 7.3:1 compression, and that was a CA-only 73 1.7, which made 72 HP versus 80 for the rest of the 1.7 engines. The W and EA motors both ran 8.2:1 compression.

--DD

[ty901]

hi Dave;
would you happen to know if the 1.7L T4 & 914 heads are the same ?
i'm beginning to think that this "upgrade" may not be such a good idea.
thanks again
jerry

[Dave at Pelican Parts]

I think they are the same, or at least close enough to swap around. But I am not sure on that!!

--DD

[Dave Bell]

I used T4 1.8 bus heads on my 1.8L 914 with no issue... the Tom Wilson VW engine book has a decent section detailing the various T4 heads, valve sizes and ID numbers. I found it useful when shopping in the junk yard.

- Dave

[ty901]

thanks Dave !
my machinist says there's a couple of different combustion chambers as well. i'm gonna flycut the 1.7L heads for 93MM & give it a shot. if this was a 914, i might skip it.
thanks again
jerry