Savetherock Posted August 1, 2011 Report Share Posted August 1, 2011 so I bought this 620 and the head seams like it was put on crooked. Ever seen this before? Driver side front of head: Passenger side front of head: Passenger side of head: Quote Link to comment
motavated Posted August 1, 2011 Report Share Posted August 1, 2011 What happens is this... The head has two shims... And if they are missing or bent, it could end up like that. My gasket would sit crooked. But two new shims from the dealer and its all good. I use the same gasket, felpro. It sits flush with the chain cover bolts holes. Quote Link to comment
Skib Posted August 1, 2011 Report Share Posted August 1, 2011 theres two dowels that align the head... apparently its missing one... or both. Quote Link to comment
motavated Posted August 1, 2011 Report Share Posted August 1, 2011 It looks like this... dang that is one blurry ass picture. But its small and cylindrical. Quote Link to comment
izzo Posted August 1, 2011 Report Share Posted August 1, 2011 Is the head bolted down? it shouldn't have that much room to move around when its bolted down and torqued? Quote Link to comment
Savetherock Posted August 1, 2011 Author Report Share Posted August 1, 2011 it is bolted and torqued on. I am in the process of taking it off right now, greasin up my keyboard as I type! Quote Link to comment
HRH Posted August 1, 2011 Report Share Posted August 1, 2011 Yeah, I'd say your head dowels are non-existent. It can move a lot without locating circles. Quote Link to comment
datzenmike Posted August 1, 2011 Report Share Posted August 1, 2011 Just imagine how far it went with the fire rings hanging over the cylinder. I wonder if the oil could get up to the head from the block???? Quote Link to comment
Savetherock Posted August 1, 2011 Author Report Share Posted August 1, 2011 It was over heating horribly when I bought it. I looked it over, but it was a greasy mess. I didn't even think to check the head alignment. As I was cleaning it up to diagnose the problem I noticed it was missing the two front bolts. When I blew carb cleaner in the holes I saw they were misaligned! I stripped the engine today, and will pull the head tomorrow. Quote Link to comment
wayno Posted August 1, 2011 Report Share Posted August 1, 2011 Guess this shows you what happens when someone that doesn't know what they are doing gets ahold of an engine. Seems like the rest of the headbolts would have forced the headgasket semi close. Good question datzenmike, was the topend getting any oil, good question. Quote Link to comment
datzenmike Posted August 1, 2011 Report Share Posted August 1, 2011 Guess this shows you what happens when someone that doesn't know what they are doing gets ahold of an engine. Seems like the rest of the headbolts would have forced the headgasket semi close. Good question datzenmike, was the topend getting any oil, good question. All the gaskets I've seen have an oval with a copper crush ring to seal it. (top middle) Would be directly above the oil pressure sender in the block. Quote Link to comment
wayno Posted August 1, 2011 Report Share Posted August 1, 2011 Hey Datzenmike, your photo of the headgasket peaked my interest in the headbolt holes in the gasket, so I pulled one of the old gaskets out and took a look, the holes are very big for the headbolts, so if the dowels were missing, I could see the gasket cutting off the water flow between the head and the block at least partially, and if the headgasket was moved towards the drivers side even an eighth inch, it will cut the oil flow off to the head, but only towards the drivers side, any other direction doesn't seem to be a problem with the oil supply to the head taking the headbolt holes in the gasket into cosideration, the gasket will move an eighth inch any direction without the dowels. Quote Link to comment
HRH Posted August 1, 2011 Report Share Posted August 1, 2011 I once had a customer at NAPA try and tell me his head didn't require locating dowels. :blink: Quote Link to comment
banzai510(hainz) Posted August 1, 2011 Report Share Posted August 1, 2011 I seen copper pipe that fits the dowel holes Quote Link to comment
datzenmike Posted August 1, 2011 Report Share Posted August 1, 2011 Yes!!! (didn't want to admit my shetchiness) My dowel was lost somewhere on the gravel driveway. The dowel does nothing anyway just fine tunes the alignment of the gasket over the holes. Quote Link to comment
pocket rocket Posted August 2, 2011 Report Share Posted August 2, 2011 I once had a customer at NAPA try and tell me his head didn't require locating dowels. :blink: Maybe not with a Datsun, but this would be true for a SBC when fitted with screw in studs. With something like 16 studs per head, the chances of getting all those lined up along with the gasket & dowels and still being correctly aligned over the block, is minimal. Both Felpro & ARP actually state to remove dowels when using head studs. Unfortunately mass produced stuff is not always that accurate. FWIW, when using studs, you should lay the gasket on the block deck, then install all the studs (through the gasket & into the block), then install the head down over the studs. Thought that might be useful information for someone. Quote Link to comment
motavated Posted September 1, 2011 Report Share Posted September 1, 2011 Soooo.... did you fix it? Quote Link to comment
HRH Posted September 1, 2011 Report Share Posted September 1, 2011 Maybe not with a Datsun, but this would be true for a SBC when fitted with screw in studs. With something like 16 studs per head, the chances of getting all those lined up along with the gasket & dowels and still being correctly aligned over the block, is minimal. Both Felpro & ARP actually state to remove dowels when using head studs. Unfortunately mass produced stuff is not always that accurate. FWIW, when using studs, you should lay the gasket on the block deck, then install all the studs (through the gasket & into the block), then install the head down over the studs. Thought that might be useful information for someone. True, but this guy didn't have head studs and was also wondering why his head gasket wasn't sealing. ;) Quote Link to comment
Savetherock Posted September 1, 2011 Author Report Share Posted September 1, 2011 Soooo.... did you fix it? YES! I pulled the head, measured the cylinder bores with a gauge to be sure they weren't egged and blowing by (they were square), cleaned everything up, threw on some new dowels I picked up from the Nissan dealership, and did a full gasket change. I also took the down time to have my radiator disassembled, boiled, and reamed at the local radiator shop for 80 bucks. Paired with a carb rebuild as well and converted electronic ignition, It is working great! Starts up immediately, idles perfectly smooth, and NEVER overheats now. The only thing I don't like is the harsh transmission. It is a truck that handles like a car but shifts like an old Hilux. I'll throw up an engine bay pic tomorrow. I have been super busy with school and work lately. Quote Link to comment
Savetherock Posted September 1, 2011 Author Report Share Posted September 1, 2011 True, but this guy didn't have head studs and was also wondering why his head gasket wasn't sealing. ;) Yes, no studs. I wasn't wondering why my gasket wasn't sealing though. In fact, I was wondering why my gasket was sealing off my oil channels so good that my engine was overheating! It was missing one dowel, and was torqued down crooked. Quote Link to comment
datzenmike Posted September 1, 2011 Report Share Posted September 1, 2011 Check clutch master fluid level. Quote Link to comment
Savetherock Posted September 1, 2011 Author Report Share Posted September 1, 2011 Check clutch master fluid level. I meant more along the lines of the gear ratio. Quote Link to comment
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