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Posted by: computers4kids Feb 28 2008, 07:48 PM

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

Posted by: Brando Feb 29 2008, 03:23 AM

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.

Posted by: alpha434 Feb 29 2008, 04:26 AM

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?

Posted by: computers4kids Mar 1 2008, 09:46 PM

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

Posted by: toon1 Mar 2 2008, 12:54 AM

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

Posted by: alpha434 Mar 2 2008, 08:29 AM

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...

Posted by: jr91472 Mar 2 2008, 12:40 PM

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.

Posted by: sean_v8_914 Mar 2 2008, 12:48 PM

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

Posted by: Brando Mar 2 2008, 09:46 PM

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

Posted by: HAM Inc Mar 3 2008, 08:35 AM

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.

Posted by: computers4kids Mar 3 2008, 08:52 AM

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...

Posted by: HAM Inc Mar 3 2008, 10:32 AM

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.