PDA

View Full Version : VW GTI Head disaster



MiniStocker
07-15-2002, 02:55 AM
Hello, I have a VW GTI head that suffered a difficult night Sat. On my first lap of qualifying, the engine sounded like it loaded up suddenly going into the first corner and then quit. After removing the valve cover, I found one of the lifter bore holes cracked and it has a rather large hole in the side of it. I am running a large Crane cam and stronger valve springs with the solid lifters. 3 intake valves are bent, but the exhauste ones are all fine. The lifter itself basically fragmented. The skirt is stuck down in the hole and the top is in good condition. There isn't anything wrong with the spring, cam or the shim. It seems like the timing belt may have jumped, or a valve stuck in a valve guide (brand new 6 races earlier). The motor turns 7700 at the end of the straight and is still pulling. My big question is, is this breakage common? Was something done wrong? What do you think happened first, the belt jumped or a stuck valve, etc.) I'm going to build a new head for the weekend. I'm the only VW ministock in a crowd of 2.3 mustangs and people are starting to worry about me. I've gone from being lapped in the feature to improving my lap times 1.3 secs per lap on a 1/4 mile asphalt oval in 6 nights. I'm concerned about the heads though...

Thanks for any input... I know that I'm not an IT racer, but the best vw information on the net is right here on the IT Board.

Thanks alot,
Scott

Bill Miller
07-15-2002, 11:52 PM
Scott, what's the lift on the cam you're running? What kind of clearence are you running between the valves and the pistons? I suppose that it's possible that one of the valves stuck in the guide in the down position, but I don't know. Sorry I'm not more help.

------------------
MARRS #25 ITB Rabbit GTI

MiniStocker
07-16-2002, 12:30 AM
Hey Bill, I'm running a .465" lift and .012 intake lash and .018 exhauste lash. These figures are from the spec sheet. I am also running the Crane double valve springs. I talked to my machinist today and he said that the skirt on the lifter broke off and that allowed the top of the lifter to go down the bore "crooked" and damage the wall. He said that he had never seen a lifter do that before and told me that it was just a "freak occurance". I have another GTI head being built, but I'm worried about finding GTI heads around here. I am wondering if I can convert a Golf Hyd. head to solids if I swap the springs, valves, retainers, and lifters. Then I would have the larger intake valve and still have solid lifters.

Thanks,
Scott

racer_tim
07-16-2002, 12:19 PM
Scott, I don't think that you can convert a hydro head to a mechanical. I have a couple of hydro heads, and the differences are: Hydro head has shorter valve stems, and a larger lifter. The actual height of the base of the spring seat is also different. You can get the hydro head with 40mm intake valves, so the real question is at what RPM do the valve float?



------------------
Tim Linerud
San Francisco Region SCCA
#95 ITB GTI, GP for 2002

ITC Mercury
07-16-2002, 10:23 PM
MiniStocker-
I have an ITC rabbit. But also put together an '84 GTI to run At our local oval. If you have an e-mail address fire me off an e-mail. I would love to pick your brain about chassis set-up for rabbit circle trackers. [email protected] Thanks

Bill Miller
07-16-2002, 11:37 PM
Scott,

I'm w/ Tim, I don't think it's possible to make a hydro head a solid head. For one thing, the #4 cam cap is 'missing' in the hydro heads, there's a oil squirter there instead. Kind of makes you wonder if you could run a solid lifter cam w/ only the #1,3, and 5 caps in place!!!!

Yep, I've never heard of a lifter skirt breaking. Sounds like a freak thing. As far as big-valve, solid lifter heads go, keep in mind that all the 1.8 8v Sciroccos had them (up to '87), and all the 1.8 Cabrios up to '89 or '90. And so did the '84 Jetta GLI (but they're not very common).

------------------
MARRS #25 ITB Rabbit GTI

Bill Gotwalt
07-17-2002, 01:19 PM
I know a little bit about the combo you are running---having built several mini stock VWs--including Joe Nemechecks first 3 cars(pinto-Scirocco-rx-3)
I have all the notes--spring rates/shocks/engine settings---if you want feel free to call me here at work 8-4 est
800-682-1202x6181(will be at the beach thur and fri)

joeg
07-17-2002, 03:17 PM
I've seen this happen on a Rabbit ice racer and an IT car--OverRevving!

mogren
08-29-2002, 10:18 PM
I think that ALFA lifters are the same size and take the shim in the bottom . The adjuster shim comes out and hits the side of the bucket. Messit up good.
Check with Darrel at Techtonics, It has happen to one of my icer motors. cold oil can do it. MM