grannyknot

How can fuel pressure be a factor when many of the attempts to get an idle where done with NO power to the fuel pump? Using fuel in the bowls only resulted in the same symptoms. Fuel dripping out the front of the throttle body happened with the triple carbs which were replaced with SU's about a month ago and has not occured with the SU's. I know this thread has gone on too long and the facts are getting lost, it does need a spreadsheet sating what has worked and what hasn't but I don't have those kind of computer skills. Once ZTherapy actually ships the carbs there is a retired mechanic in our local Z club that will come by my place and we will have a go at it. I'll let you know. Thanks, Chris

Well I didn't find anything out of order. I checked the valve clearances, they are right where I left them .20mm IN, .25mm EX. Did a leak down test, all cylinders register very low, compression test was within 5lbs of the last test. I couldn't find the alternate compression gauge head so I tested my trusty Subaru Impresa and the gauge is accurrate. Besides, it's not the actual numbers on the compression test that matters but how close they are to one another. Just going to wait until I have the new carbs installed and I have a second person on hand. Chris

That's interesting, I did check the valve tolerances and a few were too tight, I loosened 4-5 and set them to the cold setting. That's certainly worth a second look in case a screwed something up in the adjustment but I should say again, it's not a stock engine. It was built by Whitehead Performance here in Ontario, they build street, strip and race engines almost exclusively for Nissan cars. F54 block,N42 head, 10:1 compression w/flat top pistons ... I have another pressure gauge head that I can swap, that should tell me if my first compression readings were off. Chris

Yoshi, the frame rails of the original Z only extended to the rear to the middle of the seat. There is a gap, a structural gap on the floor pan between the end of the frame rail and the subframe for the rear wheel arch. Many feel it is a flaw in the design. Zedd Findings is supplying original floor pans and rails albeit in thicker metal than original. Charlie's Zedd Findings floor pans and rails are first class and a deal at the price. If however, you want to fill that structural gap then have a look at Baddog, Bad Dog Parts, Specializing in Datsun Z parts BD rails are welded over top of the original rail for added rigidity. Have a very close look at the driver's side floors, it is VERY unusual for just the passenger side floors to rot out and not the rest of the floor pan. As for the Ebay floor pan, it looks like a picture of Charlies floor pan, but that's slease bay for you.

Hey Bart, still waiting on the carbs from ZTherapy, they haven't shipped them yet. I'm using the time to finish the restoration.

ggunder, just remember that the original tar mat was laid on top of bare steel, lots of restorers have found rust under the tar mat when it was removed. If your car came from a dry area you maybe fine.

Your right of course, I was picturing my Z body on it's side on the rotisserie. CEgg11 is probably doing this with wheels on the ground.

If by "front rail/brace" you mean the front seat support which sits about midway on the floor pan, then yes you can leave it in as long as you grind off the welds on the bottom of it. You can run a couple of self tapping screws through the bottom flange of that seat support and into your new floor pan so you can get a good weld then remove the screws and fill with weld.

So I have spent the last 2 months farting around with an engine that I can't get to idle but while I'm waiting for rebuilt carbs to to arrive from ZTherapy I manged to get some stuff done Here is the SU balance tube project I started last summer, then with a bit more smoothing, then I put it on the shelf because I thought I would use the triples instead, now that I'm back to using the SU's I finished it up. How is this for a smoothed balance tube? Throttle will be actuated by a cable instead of the old Mechano set linkage.

Here's a question, at some point in the future do you think this work you are doing could be used as the basis for a 3D printed version of a Z car?

Chas, I agree, that is one of the reasons I sent the carbs to ZTherapy, even if they were not the problem at least it will help me narrow it down by ruling them out, I'll recheck all gaskets surfaces and any possible vacuum leak. As much as I hate using silicone sealers and prefer a dry seal I am tempted to try some sealer this time just because I'm getting a bit desperate, would appreciate anyone's input. I knew what you meant Cap'n and at this point I'm starting to believe anyones skills are better than mine. And a good thought Colin, I'll call him and see if he's available. I called ZTherapy last night and Bruce P. said the carbs should be in the post next Friday and with a week for transit I should get them about the 8th of June, I've also ordered new plug wires and spark plugs to have them on hand if needed. I'm also going to rig up a gravity feed fuel source so as to rule out fuel pump/regulator and pressure.

Well I'm terribly sorry that this thread is not as rewarding an experience as you had hoped for Wade, I can just imagine how frustrating it must be for you. If you would bother to read those posts you would see that the basics is all I have been dealing with for almost 2 months. Keep your whining to yourself.

Captain, good question. I don't think the HEI unit regulates timing advance but not 100% sure. The vacuum advance is working but I plugged it off to try and eliminate any possible vacuum leaks, that leaves the mechanical advance that I assume is working. I did disassemble, clean, lubricate and put it all back together properly.

1976 distributor, Pertronixs HEI ignition, Pertronixs coil, NGK wires and plugs.

Zedyone, I think I might have done this test but in a different form, with the triples and the SU's I did a number of start tests with and without the fuel pump powered. The tests without any fuel pump, just using the fuel in the bowl to start the engine were really no different than with the pump. Both the triples and SU's have a normal air pressure vent tube so there would be normal atmospheric air pressure. Wouldn't that prove the pump and regulator aren't effecting these problems? I don't mean to be argumentative just trying to eliminate possible causes.

Your second pic shows a very common rust area and not hard to repair as long as the labour is free - DIY You might want to take a bunch more pics of other areas like under the carpets in the footwells, rockers and any shots you can get underneath the car. Don't buy it until you have seen under the carpets. Where is the car from, what part of the country?

I have a buddy that runs a cabinet carpentry shop and has an inline table belt sander that is 4'x8', 180 grit. I trued up the exhaust manifold before all of these tests and since dis-assembling the SU's I have trued up the intake manifold and there were no irregular wear patterns, it came off uniformly. I didn't know that! I haven't sent the carbs to ZTherapy yet so I'll reassemble them and try again with no regulator, with a new regulator and with the mechanical pump. see above see above Thank you gents Chris

Stanley, And the Cheeseburger Demon Squirrel Award goes to ...? Wade, the engine has not been loosened in any way, there is no way that I can see of that happening and the timing checks out. I have sent the SU's to ZTherapy with no illusions that it will solve the problem (but I hope it does) but it will eliminate the carbs from the equation. I have parallel ground the head side of the intake manifold and cleaned up both surfaces of the SU spacers. Also thinking about a adding a smear of silicone gasket sealer. There will be fresh gaskets, yada yada Every spare hour. You said it Steve, It's not just your luck you wonder about, you start questioning your ability and experience and the all the other guys helping you work through the problem. I talked to Steve Eperly of ZTherapy the other night (and this guy knows an L6 engine as well as anyone) he said "sounds like a big ol vacuum leak" just like so many of you have said and as I know from my own experience. While I'm waiting for the carbs to be delivered I'm going to try and finish the rest of the car. I WILL get this sweetheart running. I really don't know what in the hell I would offer as the CDS Award (Cheeseburger Demon Squirrel ) Chris

Hey Tom, front grill looks like a 510 but the car is too big for a Datsun. The door is original but front quarter panel and rear end look like they have been worked and maybe the roof. Kinda of looks like a Ford Falcon but the Australian market had all kinds of "North American looking" cars that we never got to see. You'll have to go to some local car shows this summer and see if he turns up. Do they still have that big cruise in at CND Tire on Yonge and Davis on Thursdays? Chris

I found that the fuel regulator was having no effect when I did the fill test at different settings, 5lbs or 1 lb the I'm getting 1.5L of fuel per min. The pump only pushes with 4lbs of force but to eliminate the fuel pressure as a possible problem I disconected the power to the pump and tried starting the engine with just what fuel was in the bowls, all the symptoms are the same. Thinking I might pull these SU's and pack them off to Ztherapy so I can start working on the car again. I'll let you guys know what happens when I get them back, thank you very much for all the help. Chris

Having cleaned out this past winter I couldn't believe how much junk was in there. Once you have it in hand there is a small spring clip holding the valve in place, there will also be a lot of grit built up around the base of the valve, needle nose pliers will do the trick, clean it out and reassemble. Once every 40yrs is the maintenance schedule I guess.

The exhaust manifold is a stock unit that I have bored out a bit, the flange thickness is the same as intake manifold, with new 1/4" thick washers on a new gasket, tight as drum. Great idea, had hopes for this one, ran a drain snake up the exhaust hoping I would brake up the demon squriels nest then I unbolted the down pipes at the exhaust manifold, it sounded good but changed nothing. Thanks, do you have a set of points? That might be worth a try. My last test of the pump was 1.5L per min. at 3.5 psi. I'll try the regulator at 1 and 6 psi in a fill test to rule that out. I have a mechcanical pump from the original engine, certainly worth a try. Plug cables are good. I wish, that would be so easy fix. I gotta say, this engine runs like a champ from 3000 - 4000 rpm, if only I could get it a little lower.

I had the vac advance plugged with triples and with the SU's I've had it with a hose to vacuum and plugged, it made no difference. It's plugged at the moment and will stay that way, one less variable. When the triples were on all the butterflies were in sinc.The SU's butterflies appeared also to be in sinc before I installed them. Just cranking the timing mark on the pulley is about at 10* with the timing light. Zed, your right it is all over the place, but people make a suggestion, I go and try it and report back, any one of them might be the fix. Demon Squirrels...THAT'S IT! fresh fuel going to both carbs, and yes that is a new hose and it's feeding the vacuum tester. I don't know what fuel pump he was using but the 1.5L per min. pump that I have now is enough for an idle. What has changed? He had a header on I have a bored out cast iron exhaust manifold, he was using a generic HEI module and a Bosch coil, I'm using a matched HEI module and coil from Pertronix. He had the triple carbs which I tried extensively, but spark plugs were always wet and fuel spilling out the front, since installing the SU's no wet plugs and only a bit of gas coming out the front when it back fires through the carbs on shut down. A little success today, I managed to get a very rough and low idle out of it twice, each time only lasted about 10 seconds and the timing light showed pulley mark at about 12* In between those 2 attempts were lots start and die immediately and the usual start and surge up and down like in the second vid. I changed nothing between these attempts as I was trying to get a reading with the timing light. Chris

Can I take a set of SU's off of a well running L24 and put the on an L28 with 10:1 compression and expect to get the engine running, even roughly? Thanks Chris