I have this rebuilt motor that is offered at a reasonable price to me. It has oversized pistorns and 1.8 heads.

As I understand it, a 1.7 and 1.8 have essentially the same stroke, just different bore.

How do 1.8 heads effect a 1.7 motor?
Thanks

I think the question should be "how do 2.0 heads effect a 1.7/1.8 motor?"

To answer your original question... they won't too terribly much. They might flow a little better.

valve sizes for 1.7:
In: 39.3MM
Ex: 33MM

valve sizes for 1.8:
In: 41MM
Ex: 34MM.

Lol.

Flow= HP

The problem with 1.8s isn't the heads. Well. Spark plug location plays a part. It's mostly the funky fuel injection setup. Is the rebuilt engine going to come with FI? What type?

The motor is setup with djet injection for a 1.7 (not L-jet) and is suppose to run very good. He can't find the MPS, and I forgot to see what color the injectors where...should be yellow. The MPS and injection came from a 73 1.7. The guy spent a lot of money having the motor professionally rebuilt years ago.

Anyway...should I get excited

If I'm not mistaken, the registers is the 1.8 heads are too big for the 1.7's

1.7=90mm bore
1.8=93mm bore

It's close enough.

Hey. A deal is a deal. It might run pretty strong. It might just be good for a lot of spare parts...

Just a thought...

Don't assume they are 1.8 heads. I have the same setup, but the 1.7 heads were simply opened up to accept the 1.8 cylinders by the PO.

I have heard this is (or was) as fairly common thing. I have no way of telling you how to tell the difference between and 1.8 and a 1.7 head without taking them off and measuring the valves.

in post 1 he states it has a big bore. remove the valve cover and read teh casting number does it end in 371 S

go with a pair of happy 2.0 heads and race your shorts off.

The 1.8 heads do flow a little better than the 1.7 heads. If the last four digits of the casting # in the rocker chamber are 371s then they are 1.8's. The increase in flow is enough to make a difference if the cam is updated. With the stock cam you won't see much difference.

Yes, the heads are definitely 1.8, in fact the owner has reciepts for all the work...the heads are brand new (not rebuilt).

Thanks all for your input...

If your heads are new AMC heads that are stock then you will see no difference as compared to a 1.7. All of the T4 AMC heads are cast with identical intake ports, regardless of engine size.