1700 dome top?

[grandfatherjim]

I recently picked up an EA series (1973 1700 cc FI from a 411 or 914) engine, which was said to have been recently (25,000 miles ago) rebuilt "by VW", thinking I'd refurbish it at my leisure and gradually get it ready for the bus.
Today I got the urge to look inside, even though it's -20C in the garage. So I took off one cylinder head only - too cold to do both - and it looks really good - no scoring or other weirdness. It has head gaskets, and you can see where one at least was leaking at the top.
Are these "dome top" pistons?



Here are the valves. My rough measurements give me about 39.2 and 32.8 mm.



So what I think I'm dealing with is an 8.2 CR engine in decent shape. I have two sets of intake manifolds with injectors, but no computer or FI wiring harness.

If I decide to go with carbs, could I use the same model as on my existing '72 1700cc engine, which has lower CR (I guess)? If so, would I need to re-jet? This engine was rated at 80 hp vs my 68 .... albeit there is the hp rating methodology confusion from that era ... anyway, it seems to me that 1700cc is 1700 cc so the overall volume of air/fuel mix being sucked in should be the same.

Thinking of going down this path, maybe, as sourcing all the missing bits for the FI feels like work and expense that may not benefit me me enough to be worth the hassle. If, that is, it is primarily the higher CR that gets me the extra hp.

Well, OTOH, fuel injection seems mighty cool, and stable once it's working....but arrrrrggghhh I have taken on enough projects here to last many lifetimes....

Part 2: re the valves. If it turns out that they're burnt and I need seats, is it worth it to bump them up a size while I'm at it because it's easy, or is it a waste of time unless I then dig in and change the cam, and maybe open up the exhaust ports, and maybe the intake too, and will doing this also give me carb grief?

TIA for your thoughts,
Jim

[dingo]

the one on the right looks dished...the one on the left could go either way depending on how you focus...like one of those optical illusions !

[grandfatherjim]

The centre is definitely sticking up. I have found on the internet now that these are indeed "dome top" - wasn't sure if perhaps these are what constitute flat, and I should have expected a hemispherical shape.

I have just read through this site where a guy is rebuilding his 914 engine

http://www.ephotomotion.com/914engine/

and he is saying how he does not have head gaskets. This engine does; they are 0.030" or about 0.76 mm thick.
So....this would take the compression down somewhat. What's the conventional wisdom on head gaskets vs. not?
Yeah, I suppose there will be answers on the net if I search....

Thanks,
Jim

[Amskeptic]

The centre is definitely sticking up. I have found on the internet now that these are indeed "dome top" - wasn't sure if perhaps these are what constitute flat, and I should have expected a hemispherical shape.

I have just read through this site where a guy is rebuilding his 914 engine

http://www.ephotomotion.com/914engine/

and he is saying how he does not have head gaskets. This engine does; they are 0.030" or about 0.76 mm thick.
So....this would take the compression down somewhat. What's the conventional wisdom on head gaskets vs. not?
Yeah, I suppose there will be answers on the net if I search....

Thanks,
Jim

My first 100,000 miles after buying my bus from the dealer with a dealer rebuild had the domed pistons. You can use them. The carbs do not need to be rejetted. You may get a few opinions that domed pistons are too much compression, but my engine ran well and it ran cool, and it did not ping. You want a clean engine with good 1700 heads. I have a set of new domed 1700 pistons that I was going to use on my upcoming Road Warrior engine rebuild, but those plans have changed.
Colin

[grandfatherjim]

Excellent. Your thoughts on the head gaskets? I'm wondering (assuming there is no interference with valves) if I can delete them, and lap the mating surface using valve compound with the cylinders as the guy does on the 914 website I reference. A little extra compression, I'm thinking.
Jim

[Amskeptic]

Excellent. Your thoughts on the head gaskets? I'm wondering (assuming there is no interference with valves) if I can delete them, and lap the mating surface using valve compound with the cylinders as the guy does on the 914 website I reference. A little extra compression, I'm thinking.
Jim

I used, and shall use head sealing rings when necessary. I do not want to tell you what to do, because you have to figure it out for yourself. You do not know the flycut depth on the heads, you do not know your deck height, you do not know your cc's. They are only a weak point after an overheat.
Colin

[Bleyseng]

The Djet ECU for that FI is available for $50 usually as there are tons of them around. You can buy a new FI harness from Jeff Bowlsby.. The MPS is the tough one but you can get a rebuilt from Performance Products..
The DJET FI in a 1700 80hp motor is very smooth and I would really think about installing it if you really want a nice driver..The dual carbs are nice but the Djet has built in altitude compensation and in 914 or 411 got 30 to 35 MPG..
Those heads don't drop the seats either unless you really cook the motor to hell and gone.

[Amskeptic]

The DJET FI in a 1700 80hp motor is very smooth has built in altitude compensation.

And any vacuum leak sends the mixture rich! A failsafe for the exhaust valves.
Colin