inline6

I'm filling out the custom piston form for CP/Carrillo pistons and I'm not sure what info they are looking for in a couple of the boxes on the form. I'd like to complete the form and get it to them for rough estimate on pricing - I will have my machinist/engine builder look through all the info to confirm everything is correct before they start machining... But, I'd like to know what these are now: "Flat/Angle Mill How Much?" These will be flat top pistons with valve reliefs. I am guessing that "Flat" is what I put here. However, they will not be flat with the deck surface. With a 1mm thick head gasket, I want the pistons to be .015" above the deck... this gives .024" piston to head clearance, which from reading the forums here is pretty much the minimum that will work. By the way, I don't see where to put info regarding location of the valve reliefs nor depth of them... "Deck Clear" Elsewhere on the form, they ask for "Comp Dist" which I believe is compression height. Could "Deck Clear" be the amount the piston goes above deck (the .015" mentioned above)? "Lift/Lift at Overlap" followed by "Int" and "Exh" in close proximity on the form. I have various cam specs that came printed out on a sheet of paper with the cam I bought, but no "cam card"... Next is "Lobe Separation" which is 104º from the info I have on the cam. And next to that field is "Installed @". What is that? Then comes "Free Drop"... again followed in close proximity with "Int" and "Exh" I have no idea what that is. The rest I think I have figured out.

I found this thread in the other engines forum to be quite helpful: http://forums.hybridz.org/index.php/topic/96128-borestroke-and-strokerod-ratios/

So, I got my cylinder head back from the machine shop recently... New cam (kind of big). I put it on my F54 short block (which is stock) and I don't have enough piston to valve clearance. So, I had already planned to build a shortblock with forged pistons to work with the cam (rev limit of 7700 RPM). Lack of PTV and winter coming on makes the timing right to pull the bottom end apart and get forged pistons with the valve reliefs I need. So, I've been reading about strokers in the archives... Given that my cam is good for 7700 and the car is almost entirely for track use, what combination makes the most sense for the bottom end? A 3.1 stroker, or something else? I note with some interest, the following: The stock L24 bore and stroke is 83 x 73.7. Dividing bore by stroke, I get 1.126. The stock L28 motor, by contrast has an 86 bore and 79 stroke. Dividing bore by stroke, I get 1.089. It is mentioned in the archives, and of course it is fairly universaly understood that smaller displacement engines with smaller strokes tend to rev higher and typically make less torque over their given speed of operation. Now back to the stroker. Most commonly, the bore and stroke is 89 and 83. Dividing bore by stroke, I get 1.072, which is close to the L28 number. Again, interestingly, taking the same 89mm bore and dividing it by the standard l28 stroke of 79, I get 1.127 -- basically the same as the L24. So... would the characteristics of an 89mm L28 with the stock 79mm stroke be more similar to the L24, (i.e. be a more rev happy motor than the 3.1 LD28)? To be honest, my main concern with going the standard 3.1 LD28 route with this motor is that the cam won't work well with it. I've seen some comments in the archives about it being pointless to rev the LD28 beyond 6500. Is that the case? And if so, what about the 89/79 combo I mention? Would that be a better route if I want to turn some more RPM's (7700 to be exact)? Garrett

All good there. I got the head back from the machine shop recently. Valve springs are designed and intended for use with the cam. I'm using shorter valve stem seals than stock (Ford Capri V6 as mentioned in threads here on hybridz).

Thanks for the reply. By timing set, do you mean a degree wheel? I did not have anything like that on it yet. I just mocked everything up and rotated he engine around two full crank revolutions. I do have a degree wheel that I can use... But, I've been reading old posts and came across a comment from Tony that not having the cam dialed in when doing the clay test is ok as generally to get it dialed in usually involves less than 4 degrees one direction or the other, and that amount doesn't make much of a difference in PTV clearence. Thread where he mentions this is here: http://forums.hybridz.org/index.php/topic/84616-headpiston-clarification/page__p__802326__hl__%2Bpiston+%2Bvalve+%2Bdeck+%2B__fromsearch__1#entry802326 If I had something close to the right minimum PTV (whatever that is), I would go through the extra effort to go ahead and time the cam and remeasure. Of course, if I am now looking at putting valve reliefs in pistons, I'll need to do this as a next step anyway. Regarding the piston above deck being .030" - reading through several threads here at least, it looks like there are differing amounts for stock L-28 flat tops... However, Braap indicated in this post that he had never seen less than .019": http://forums.hybridz.org/index.php/topic/58127-best-way-to-achieve-piston-to-head-clearance/page__hl__%2Bdeck+%2Bbraap+%2Bpiston And then in this post, he gives a much larger range (.012-.022") but I haven't found reference to anything above .025" - until now that is :)http://forums.hybridz.org/index.php/topic/75849-warning-mn47-clearance/page__p__722093__hl__%2Bpiston+%2Bvalve+%2Bdeck+%2B__fromsearch__1#entry722093 Mine is measuring out to .017 - .018" above the block deck with my dial caliper and magnetic stand (again all carbon removed - with carbon it was .022")

I did some searching in the L6 forum and came across a post that said these were the minimum piston to valve clearances to run: .080" intake, .100" exhaust minimum Has anyone run anything less than this successfully? Here is some info on my combo: Stock bottom end - F54 L28 with flat top pistons. I measure .017" to .018" piston height above deck (all carbon removed from top of piston). The head (E-88) has been milled a few times over its life, just to straighten. I'm guessing .010 - .015" has been removed from stock. Anyone know the stock thickness? Manley stainless valves - stock exhaust diameter and stock l28 intake diameter. Cam: Intake Seat duration 320 degrees .050" duration 290 degrees Valve lift with zero lash .565" Hot valve lash .015" Net valve lift .550" Exhaust Seat duration 315 degrees .050" duration 274.8 degrees Valve lift with zero lash = .565" Hot lash = .015" Net valve lift =.550" I put clay on the number one piston. I put on the Nissan stock head gasket (a used one that measured .050" thickness). I put the head on with a couple of head bolts just to snug it down. I put the number one and two rockers in with zero lash... Looks like I have about .030" clearance on the intake valve and maybe .025" on the exhaust. By the way, while I was searching through old threads, I came across info that said I should run .022-.025" deck height. That is interesting, because with the stock head gasket from Nissan, I calculate that you end up with .050" minus .018" (piston pop up) which gives .032". A 1mm head gasket would put that around .022"... Garrett

Please let me know if you have one and how much you want for it. Thanks.

In case someone needs this info - My 12/70 240z has 5/16" OD (might be 8mm) supply, and 3/16" OD return, and 1/4" OD vent hard line (the one on the driver's side).

I'm burning up my Saturday searching for answers and not finding them... I've got a Mr. Gasket fuel pressure regulator. Thanks to a post I read, I now think putting it in the return line just after the carbs is the way to go, instead of on the supply line before the carbs. However, it is not clear to me based on what I found in the threads so far that you can do that with any fuel pressure regulator. Do I need a special FPR, or can I use this one? The regulator came with 1/4, 5/16, and 3/8 line fittings. Which should I use? The carbs each have T fittings on top of them that are 5/16", but... The final incarnation of the engine will hopefully be around 300hp. Will 5/16" on the regulator be big enough? What size are the stock supply and return lines in the transmission tunnel of the car (12/70 production date)? Do I need to increase the size of those? If so, what size should each be? As mentioned before, I will utilize a return line to the tank. I note that the stock fuel rail closes down to a "pin-hole" size (on the very end of the return line). This is undoubtedly to provide restriction of fuel flow and is perhaps a "regulator" of sorts? As recommended in a post, I plan to scrap the factory fuel rail assembly altogether. Thus, the pin hole will be gone. Does this harm anything? I am thinking that the fuel pressure regulator will serve the same function (essentially) as this pin hole does. Sound right?

I've been working on a project to install a cam and switch over to 44mm Mikuni's for almost a year now. I just got the head back from the machine shop yesterday and while inspecting things today, I found more and more that is upsetting. First thing is I provided the guides and asked for them to be shortened and tapered (I gave specific instructions on how much and where the taper should start and end). When I picked up the head, that had not been done because they didn't think it would be a good idea - the guides need the strength - they might crack, or something to that effect. Given all the porting I have done to make this thing breathe as much as possible, and that I have a 4 cyl head on a shelf where the guides were tapered just as I desire (and it ran for over 30k miles with no issues), I was disappointed. I only have machine work like this done maybe every 10 years, so I wanted it done right. Removed rocker arms and checked to make sure the cam rotated by hand. It does. Good there. Next, I cut a piece of hard wire to 1.68" length (spec provided for installed height by the cam manufacturer for the springs which they also provided) so I could quickly check the installed heights. Eyeballing it, I see some differences that look to me like possibly close to a millimeter. Really? .030" to .040" off? So, I decide to disassemble all the valve spring assy's to measure the installed heights. The first one I do is an exhaust. After removing the collets, retainer and spring, I push the valve down a bit to inspect the valve and seat work and The valve seat is galled on one of the cuts! I did the same for a second exhaust valve - ughh. Same thing. See the attached pic. I stopped there. Honestly, I think a shop that would let work go out like this isn't worth taking it back to. I mean, obviously I could go back and try to get them to do it right, but quite frankly, I am scared to let them try. Until I decide whether to give them another shot or not, they shall remain nameless. They don't know anything about my issues with the work yet, and the last thing I want to do is complain and moan on a forum about such and such machine shop and then not take it back to them so they never have a chance at correcting the problems. So, now I have tried finding a recommended machine shop near me and I am not happy with the result. Who are known performance Datsun head builders left that I can trust to do good work? Rebello and Sunbelt and BRAAP (don't know his business name) are options in my head at the moment. Also: I'd like to take the valves out, but don't want to wreck the seals... Do I need to find a straw or something to cover the collet grooves so I don't damage the seals? Can the intake guides be punched back out and machined the way I want and reinstalled? Or should I just leave them alone because the work to taper the guides isn't worth the increased flow difference?

I am looking for .180" - but just spoke with someone at Isky and he said they only have .175". Bummer. Next size up they have in stock is .263 I think he said. 3 seems odd... Maybe he said 260's Garrett

I checked with Courtesy Nissan and they don't have any. They said they can't get them from Nismo at the moment, maybe because they are in the middle of moving? Oh, and they are .180" - title is a typo. Garrett

Bumpy... Anyone? Do the valve job, then measurements for installed height is most likely the answer to the first question. If I go with the ford Capri seals, will they fit both types of valve guides that I have? Anyone used Goetze BMW seals?

Oh. Yep, that makes sense that the lube goes on the nuts that get torqued. Any problems putting some of the lube on the threads that go in the block? I wouldn't think so... Garrett

My cam calls for 1.680" installed valve spring height for intake and exhaust. I mocked up one intake valve and one exhaust valve assembly to check approximate installed height. The intake was 1.660" with the .039/.040 shim that was there with the stock spring set-up. The exhaust was 1.690" with it's same size shim. Since I am about to hand the head over to a shop to do a valve job, I'm guessing that these measurements are not meaningful yet - and obviously they can vary a bit for each valve, though the last engine builder likely set all of the intakes and exhausts at similar respective depths. When the next shop recuts the seats and refaces the valves, the installed height will change... How much can I expect the installed height to change (approximate given no odd issues with seats) with a valve job? Should I just wait until I get it back and then order appropriate size shims as necessary? Also, I have attached a picture showing the top of the guides where the seal goes on. The intake and exhaust guides are different. Looking at the invoice I was provided with when the engine builder last rebuilt the head, he indicated that he installed and sized 6 exhaust valve guides - "nissan comp". I am assuming the intake guides were not replaced - are stock. Can anyone tell by the picture? What valve seals do I need to acquire? The cam has .550" lift... From looking through forum posts, it seems a lot of people go with "A-series" seals. Additionally, some people use Ford Capri seals... I'm fairly certain my previous engine builder used neither and not stock L series either. I want to say he used BMW seals? "Goetze" I think. Has anyone used those with success? Year? Model? If the answer is go with the Capri or A series seals, will they fit both the stock intake guide and "comp" exhaust guides? Or is there some kind of compatibility issue with certain seals needing to fit certain valve guides -- I mean outside of being the correct diameter?

Reading the instructions... doesn't quite give me the info I need. Block threads are clean. I put a bit of the lube that came with them on the threads that go in the block. I installed each as far as they would go, finger tight. Instructions call for 60 ft-lbs instead of factory torque settings. That's it? Finger tight studs and 60 ft-lbs of torque once the head is in place? Garrett

I definitely appreciate the advice anyone is willing to provide. I was spoiled when I was a teen, as Dave Weber of Malvern racing was local. And Tom Howen, his long time friend, driver, machinist, is here as well - but no longer doing car work. So, I find myself without the readily available L-series expertise that I used to enjoy. Regarding the cam, it is not run of the mill, though perhaps as Tony said, I should have gone with something more common - a more typical off the shelf cam. It is from Sunbelt - same cam grind as Dan Baldwin I believe. Here are the specs: Intake Seat duration 320 degrees .050" duration 290 degrees Valve lift with zero lash .565" Hot valve lash .015" Net valve lift .550" Exhaust Seat duration 315 degrees .050" duration 274.8 degrees Valve lift with zero lash = .565" Hot lash = .015" Net valve lift =.550" I am not sure of the power band, but since I was told by Sunbelt not to exceed 7700 RPM, I'm guessing the power band goes somewhat north of 7k. Perhaps that is not the case. When I degree it and jet the Mikuni 44's, I'll know. Still looking for input on the euro dampner and the stock flywheel. I cam across a post that mentioned lightening the stock flywheel (done correctly) to 17 lbs is a good way to go. All other things equal, will a correctly lightened flywheel help with any crank harmonic issues? Garrett

So, I'll set it at 7,000 for this "season" and look to go forged pistons over the winter, if I like the cam. My season consists of a about 2 track weekends (usually VIR and Summit Point) a year at this point. So, I think I'll be ok. A couple of you mentioned dampners. I am running a euro single pully unit. Issues? The flywheel is stock, which is what, 23 lbs? The clutch is a 225mm Centerforce unit with probably 40k street miles, a pile of autocrosses, and a few track events. Again, is this a problem for 7k or for 7.7k for that matter? Garrett

I'm putting in a new cam and am wondering where to set the electronic stop (max rpm) on my Hi 6 ignition. The car is mainly used for track days. The cam set up is good to 7700 max. Anyone have some experience with max revs for the stock F54 bottom end? I realize that forged pistons are going to be necessary, but would like to wait a season. 7k? or can I get away with a bit more? Garrett

I don't want to have to drive it like a race car to keep it moving on the road, in traffic, at stop lights. I drive to and from the track plus put about 1000 street miles on it a year. I realize this is a question with what is likely to be very subjective answers... Hoping to get some responses from people that have something similar and their thoughts on driving on public roads.

About to pay a bunch for a cam from Kinetic Sunbelt (in GA). They came back to me with specs which are below. I've run a 490/290 in my 510 years ago (daily driver in college) which I liked... I've read some posts and tried to decipher what cam is really too radical. My car has an F-54 L-28 with flat tops, about 10 to 1 compression with E88 head (1 mm bigger intake valves). Switching from SU's with SM needles to a set of tripple 44phh Mikunis when I do the cam upgrade. So, is this cam going to be too radical? Can I still drive it to and from the track? It pretty much just sees autocross and track duty these days, but I don't trailer it. Intake Seat duration 320 degrees .050" duration 290 degrees Valve lift with zero lash .565" Hot valve lash .015" Net valve lift .550" Exhaust Seat duration 315 degrees .050" duration 274.8 degrees Valve lift with zero lash = .565" Hot lash = .015" Net valve lift =.550"