1.7 big bore P&C'S?

[rich]

Wayne or Anyone, Will the Big Bore P&C'S fit the case of the 1.7 with out boring? How about the heads? Does the injection work?
Will 1.8 heads with the 1.7 big bore P&C'S aid in any type of performance gain?

[rich]

Sorry for the dumb question. I just checked the specials. The add answered my question. Accept for the 1.8 heads. By using the 1.8 heads does this lower the compression?

[JP Noonan]

The 1.8L heads will NOT work with 1.7L P/C's. The spigot hole (the hole in the block) is the same, however the ring around the combustion chamber is not. The 1.7L jugs are 1mm (about that anyway) smaller, so to put 1.8L heads on you would have to weld/machine....it just ain't worth it.

On the other hand you can do what I'm trying out. I had some used 1.8L heads with good vavles (the PO blew up the motor from lack of oil) and some used 1.7L heads. Since 1.7L BB jugs are so much cheaper than the 1.8 or 2.0 sets I sent my 1.8L vavles (MUCH bigger than the 1.7L valves) along with my 1.7L heads to the machinest, he is putting in new guides and seats, as well as refaceing the vavles, checking the spring pessure, and doing a "three angle" vavle job. Problem is I don't have the short block together yet and the machinest is a friend doing the work for free, so since I don't have the block together he's in no hurry to finish the heads (and I don't dare pester him). From what I've read in Tom Wilsons book, my friends 15 years expert experience, and his NAPA books the combo should work fine.

The injection (acording to Kjnells article) can be adjusted to work with the bigger displacement and vavles by adjusting fuel pressure and the pressure sensor.

[halbl]

We did it this way to upgrade a 1.7 Bus (PO blew up) to 2.0, as follows: gave engine builder the 1.7 case, 2.0 914 P&Cs,push rods etc, and 1.8 heads. Then used progressive carb. The Westy/914 has over 30K "college" (son's) miles on it and, except for a bit of cold start, we are very happy. The tranny is out of a 76 Bus which makes it a fairly good freeway flyer. I have no idea how much HP or compression it has. The mechanic is a VW specialist who regularly works on vintage 356 racing engines. Permformance? Can hold 3rd gear to 65mph, holds interstate grades near 65, and top is about 75, but straining.

[Patrick]

I have the 96mm P&C's on my car. There are three different versions of them for the 1.7, 1.8 and 2.0. I had the choice of either the 1.7 or 1.8 versions because I had both freshly rebuilt 1.7 and 1.8 heads at the time. I went with the 1.8's because the cylinder walls are thicker and the bigger valves in the 1.8 heads. I am still wondering if that setup is carrying less compression than the 1.7's would have. At the time I couldn't seem to get a straight answer.

[rich]

I finnally found my way back to the bbs. I don't know about anyone else but I could access the bbs from the main page. Anyway thanks for the info. The thicker cylinder walls sounds like the logical choice. Is it better to have thicker walls with an air cooled engine? If someone had access to both 1.7 & 1.8 P&C'S with heads they could figure out the compression difference. Anyone know?
Thanks

[JP Noonan]

The 1.7 and 1.8 have the same crank (66 mm throw I think). While I've heard they have different PN's, the rods are also the same. I haven't seen every 914 piston out there, in fact not even half of them, but the ones I've seen all seem to have the same dish/crown. That leaves the heads, the combustion chambers look completely different, so you need some one with a kit to check the cc's using fluid and a graduated burette. You could use measurements from someone else's heads for a general comparison but not for bulding your motor. The reason is recessing the vavles (it is a normal part of a vavles job) changes the compression. The comparison would only really be valid if both sets of heads were factory fresh.

I was talking to someone else about removing the head gasket, common consensus is it raises it by half a point. I don't know how much sinking the vavles hurts it.

The piston walls being thicker can't hurt, but the main thing is what vavles are used.
BTW I haven't seen the 96mm jugs in 1.7L for a while, the 1.7L big bores most people sell are 94mm (same as the stock 2.0L I think).

[Paul]

I bought the 1.8 upgrade kit for the 1.7 case from pelican but i have not put my engine back togather yet so i don't know how well it works. I bought supposedly 1.8 heads from www.mofoco.com and they told me that the 1.7 and 1.8 heads were exactly identical in every way. So i bought the 1.8 heads from them to use on my 1.7. When I got the heads i took a look to see if they were the same and the were. Did they sell me 1.7 heads or did VW make 1.8 engines that used the same heads as the 1.7 914s but just the 1.8 914 didn't use those heads?

[rich]

AAAARGGGG!! As I have been reading, the 1.8 valves are supposed to be bigger. You should really consider checking in to this before you use the heads. We need the experts! I'm attempting to make an educated dissision based on the wide knowlage base contributing to this forum. I'm learning alot. I hope you got what you paid for. Anyone have the answer?

[Dave at Pelican Parts]

The heads are different part numbers. The 1.8 head is 022.101.351 C, while the 1.7 heads are 022.101.351 A, and 022.101.353 B. Note the last one has a different number group at the end.

I don't know part #s for heads from "actual" VWs, but the part numbers are definitely different.

The intake valves on the 1.7s are listed as 39.3mm (diameter, I assume); while the 1.8s are listed as 41mm. The exhaust valves are also different; 33mm for the 1.7 and 34mm for the 1.8.

From reading an OLD article in the Twin Trunks Tribune (Renegade 914 Club's newsletter), there is at least one "real" VW head (from the 412?) that is identical to the 914 1.8 head--except that it may need to be fly-cut for the compression.

Good luck! I've heard mixed things about Mofoco; I hope your story is one of the happy ones!

--DD