Thats why I said I like Grahame's 348 system better. Looks a neat installation too which is appealing. Since a motor rebuild is so often the decider point between an upward or downward spiral, having funds for all the while we're here things seems important to me. Rather have the suspension feeling great too than a set of individual bodies to gawk at when the bonnets up.
Like the no motorsport bit!! Can't imagine having that car so close to the Targa and not having an eansy-teensy run.
Fantastic motor - well done!! Very tidy as well! Looking forward to the dyno sheets if you can find them! Believe me, I also know about a project spiralling once you get started. I am not sure if for the cost of his (although also wonderful), I might prefer your single tb doing quite well on its own in more street rpm ranges. If his 300 hp claim is to be believed, though, achieving 100 hp/liter in a streetable na car is great.
Thanks Russ - from you that is a great compliment! I will keep scratching around for the dyno sheets but they are not hiding in any of the obvious places! Cheers, Grahame
Well folks, The damage was not due to a old sodium valve. It was a $50 synchrometer by EMPI. I found a small brass cylinder in the exaust pipe of #2 and wondered where it could have come from. Then it all added up. The day before the compression test I was checking the carb balance with an EMPI air flow sync meter. The sync meter was in #2 carb barrel and I was attemping to raise the RPM to 1500 when it may have hit upwards of 3500 rpm. After this the sync meter would not read 0 any more it was reading 5 kg/h with no air flow. As it was not servicable I threw it away and ordered another. I got my new sync meter today and low an behold, there is a small brass cylinder part in the sync meter that is used as a counter weight on the air flow flap. This brass conterweight has fallen out of the plastic air flow flap and into #2 pot. It must have bounced around there for a while before it got caught under the exaust valve and then that was the end of the valve/piston. Please be careful when using such meters, maybe a gauze filter is required. See attached pics of meter and said brass part. Image Unavailable, Please Login Image Unavailable, Please Login
WOW! I'm glad that you found the cause, however, I'm sorry to hear that this was the cause!!! Maybe you could write the company and explain what happened....who knows... JIM
Thanks Jim, I'll give it a go. It's just frustrating, the motor probably had plenty of life left in it. BTW I don't think my valves are sodium as the broken stem piece is not hollow.
It depends on how far up the stem it broke. They are not hollow all the way down.... Good luck! I'll send good vibes your way. JIM
http://www.prahranair.com.au/cars/gt4/rebuild/images/DSCN0475.JPG http://www.prahranair.com.au/cars/gt4/rebuild/images/DSCN0477.JPG http://www.prahranair.com.au/cars/gt4/rebuild/images/DSCN0479.JPG http://www.prahranair.com.au/cars/gt4/rebuild/images/DSCN0482.JPG
Thanks PP for the valve pics. Here's what's left of mine. The stem piece is 30mm long and not hollow. I don't think they're hollow sodium so I think the head has been done before. When you say the damage do you mean to the air flow tool? The pic of the air flow tool shows a good one with the brass in place - look in the middle of the dial you can see the brass bit in the air flap. The broken one I threw in the bin the day it broke but it was missing the brass weight and hence would read 5Kg/h with no air flow. I didn't notice the brass weight missing at the time I just assumed the spring in the tool had failed. I ordered another air flow tool that day. I'd say that the valve head broke off during the carb airflow testing @ 1000-3000 rpm but did not do much damage till the next day when we were doing the compression test. Thats when the stem broke loose and went through the piston. If only I checked the compression on #2 first but it was #8 that was suspect. Image Unavailable, Please Login
Judging on how easy you were able to remove the heads,there is a chance that they have alredy been done.Any documentation?
whilst mine came off quite easily after 30 years, apparently that's a fair call. it was unusual, i'm told, that they came off so easily,.
PP & Maurice, Plenty of doco on the car but nothing on the engine. Damage appears to be only one piston at this stage but I haven't pulled the engine out to see if there's any damage below (the piston is holed and I haven't found all of the valve yet. I invited my neighbout (a mechanic by trade) over to have a look. 1/2 and hour later all the valves were out. His comments were, the valve guides are good (other than the damaged one which isn't that bad either). There appears to be some exaust valve "strech". The motor has been worked on in the past. The heads have been resurfaced. The #1 cam bearing caps have been welded to reset/reduce endfloat of the cams. The copper head gasket is probably thicker than stock to deal with the amount on material that was shaved of the heads. He advised to have the head rebuilt/repaired with at least new exaust valves and one new inlet valve (as #2 inlet valve was slightly bent). He did question if the head could handle another surface machine. The head is very straight (using a straight edge) but will need to be welded near #2 exhaust valve seat due to the damaged caused when the valve head embeded into the head. My question is how can you tell how much has been machined off a head? In the twin cam alfa's there was a bevel edge around each combustion surface, so if there was still a bevel then the head could still be machined. Cheers George
Hi, Measures 127mm top to bottom of head, maybe a fraction more but I was only using vernier so not super accurate. But according to the WSM I have the measurments are 127.2-127.0mm Given that the heads have been machined I'd say they are at 127.0 but they're not warped.
Well the engines out at least. With the rear head removed it was pretty easy to get the engine out but I still had to remove the 5-8 exhaust headers. The biggerst pain in the butt was undoing the battery feed to the starter. I think I might put the 1-4 head back on in the car as having it off during the removal was great. I guess the only down side is I'll have to set my cam timing in the car. I'll pull the other head off and remove the broken piston next week. I'm hoping to take both heads to an rebuilder to see if they are still servicable. Cheers George Image Unavailable, Please Login Image Unavailable, Please Login
WOW, not wasting any time there! That is great. I hope the rest goes very smoothly for you. I had to get at that starter wire a couple months ago...what a pain without a lift! Good luck. JIM
