Boring and PRC classes

[JohnnoEH]

OK, so I've decided that I want to use the L16 in my Stanza for now and run in P2 instead of P3. ATM the log book says it has an L20B for some reason, so I have to get that amended.

I know standard bore/stroke L16s were 1595cc, so that would be right for P2, but pretty much any boring out (as per reconditioning) sends it over 1600cc. I can't find the bit in the CAMS manual that says how much you can bore without it affecting the class (from memory it does exist ). Does anybody know?

I dunno if the car is bored out or not, so it probably doesn't matter, I have my doubts as the engine number matches the tags (ie it's the original block) and there are no stickers or marks from workshops to say it's been reco'd. I don't have to get the block sealed by a CAMS engineer do I? I can just send off the logbook with a form stating the changes, and that will be right to compete with?

[afifield]

In a nutshell if it's 1601CC then it's P3, no matter what the donor block.

For capacity increases, you fit in the class for the new capacity. It's worth the effort to find out the capacity, more so you're doing the right thing from the start.
It's highly unlikely that someone is going to protest against you for a few CC, unless you're setting the world on fire.

[Warps]

Also, for a 30+ year old engine, there's a fair chance it's been bored at some stage. I've never seen a reco sticker on a single rebuilt engine I've seen. Remember, for every workshop rebuild engine, there are probably ten home rebuilds (some good, some no so good)

Only (easy) way to tell is to whip the head off and see.

If it's logbooked with an L20, then why not keep an L20 in there? (I know you probably have a valid reason, just had to ask)

[Kaptainballistik]

Run as P2, Thats what you think it is , So it is then!

[vkdude]

just run it with the L20, I'm trying to recall a conversation with Boris when he originally got the car, where he said he was going to put a stock L20 in it to make it easier for his son to learn to drive with than a peaky worked L16.

[CraigW]

I ran a Datsun 1600 in state championships with a L16 for 13 years. When we originally built it we wanted a P2 car and a L16 - Datsun 1600 fit the requirements back in the late 80's.

I was still competive with the majority of L18 engined cars, but with less HP/Torque, it sure teaches you to drive better with neater lines and keep the momentum up.

When I rebuilt it, I had to sleve the bores to make sure I stayed < 1600cc as I think 1 overside sends it > 1600cc. But from my dim dark memory, the sleving didn't add too much to the cost.

As a L16 1600 was fairly rare in competition, when I rebuilt it I decided to get the bore measured and bottom end sealed so no one could say I was running illegally in P2. But that was my choice.

cheers
CraigW (still with the P2 Luv)

[JohnnoEH]

Originally Posted by CraigW

It sure teaches you to drive better with neater lines and keep the momentum up.

^^^^ That's part of the reason why I want to run with the L16, although it's mostly because I haven't got a L20B to put in it and am only running stock brakes (for now). I just want something to learn in for now, and later on when I get a bit faster and get more money I'll build a decent 2L and get bigger brakes, and fit the lot all at once.

Originally Posted by Warps

Also, for a 30+ year old engine, there's a fair chance it's been bored at some stage. I've never seen a reco sticker on a single rebuilt engine I've seen. Remember, for every workshop rebuild engine, there are probably ten home rebuilds (some good, some no so good)

That's very true, I'm too used to playing with early Holdens where nearly every single motor you see has a Repco or Gem sticker on it (same with my Bluebird, it has one). The car was made in '82, so it would be 26yo, I don't think it's done too many miles (speedo doesn't seem to work properly) and it is the original engine that came with the car so could it very possibly be unopened. In the little bit of driving I've done in it, the motor seemed pretty healthy, especially for a 1.6L, it doesn't blow smoke and behaves pretty well when warmed up.

Boris did say that he was going to put the L20B in, but didn't seem to get why they had already put the details in, maybe they just put that down to save him work later. The engine number is actually stated as 'Various' in the logbook so I could, in theory, put in any old L20 I pick up and not worry about it.

I have one more question, save making another thread - I have a spare U67 Bluebird head (the open chamber type), would it be worth getting it shaved/machined a few mm to lower the chamber cc's, and put it on the L16? I'm just thinking of the larger ports and valves vs the W53 head that's on it now, would I see any type of gains or would I not be able to get the chambers small enough to get any usable compression? I'll be running with twin SUs and a '68 works rally cam (Tighe 812C grind), if that helps.

[brendan]

Originally Posted by JohnnoEH

^^^^ That's part of the reason why I want to run with the L16, although it's mostly because I haven't got a L20B to put in it and am only running stock brakes (for now). I just want something to learn in for now, and later on when I get a bit faster and get more money I'll build a decent 2L and get bigger brakes, and fit the lot all at once.



That's very true, I'm too used to playing with early Holdens where nearly every single motor you see has a Repco or Gem sticker on it (same with my Bluebird, it has one). The car was made in '82, so it would be 26yo, I don't think it's done too many miles (speedo doesn't seem to work properly) and it is the original engine that came with the car so could it very possibly be unopened. In the little bit of driving I've done in it, the motor seemed pretty healthy, especially for a 1.6L, it doesn't blow smoke and behaves pretty well when warmed up.

Boris did say that he was going to put the L20B in, but didn't seem to get why they had already put the details in, maybe they just put that down to save him work later. The engine number is actually stated as 'Various' in the logbook so I could, in theory, put in any old L20 I pick up and not worry about it.

I have one more question, save making another thread - I have a spare U67 Bluebird head (the open chamber type), would it be worth getting it shaved/machined a few mm to lower the chamber cc's, and put it on the L16? I'm just thinking of the larger ports and valves vs the W53 head that's on it now, would I see any type of gains or would I not be able to get the chambers small enough to get any usable compression? I'll be running with twin SUs and a '68 works rally cam (Tighe 812C grind), if that helps.

Your still better off with a closed chamber head on it. If you want an L18 head i have 2 to choose from currently nothing on them but have the parts around to fit to them. Im happy to trade heads in any case. they run the 35mm exhorts valve where they W53 seams to be the 33mm exhort valve.

It comes down to what static compression your running with the U67 or V91 you will get pinggin with a lower compression then you will with the A87 or W53. I even have 2 U67 with 44mm intake valves as well. If thats the way you would like to go. you would have to find new valves for them tho

Also stick with the cam you have if your using SU's have heard they don't work to well with 72+ cams

[JohnnoEH]

Originally Posted by brendan

Your still better off with a closed chamber head on it. If you want an L18 head i have 2 to choose from currently nothing on them but have the parts around to fit to them. Im happy to trade heads in any case. they run the 35mm exhorts valve where they W53 seams to be the 33mm exhort valve.

It comes down to what static compression your running with the U67 or V91 you will get pinggin with a lower compression then you will with the A87 or W53. I even have 2 U67 with 44mm intake valves as well. If thats the way you would like to go. you would have to find new valves for them tho

Also stick with the cam you have if your using SU's have heard they don't work to well with 72+ cams

I thought that might be the case. I've only had one person say he likes the U67 heads (something about being able to port them out more, he runs 40mm ports with EFI on his 1600 rally car). Everyone else has said they ping real bad and I tend to agree since the Bluebird has one and I'm pretty sure the pistons must look something like the surface of the moon by now.

By a 72+ cam do you mean the exhaust opens/inlet closes at 72 degrees? The cam I've got is a 31/61, 272 total duration and 495 thou valve lift, I thought it would be OK? Doesn't seem too big to me, might be a bit lumpy/peaky in the 1.6L but IMHO a smooth idle and quiet running is for suckers.

I lied when I said I have one more question, I have yet another to annoy you with. I've heard SUs don't like the mechanical fuel pumps on L motors, will I have to get an electric one or is this full of it? I've run triple CD Strombergs (pretty much the same thing) on my Holden for nearly 6 months now, with the stock mechanical pump, with no problems at all, would the Datto be the same?

[brendan]

Originally Posted by JohnnoEH

I thought that might be the case. I've only had one person say he likes the U67 heads (something about being able to port them out more, he runs 40mm ports with EFI on his 1600 rally car). Everyone else has said they ping real bad and I tend to agree since the Bluebird has one and I'm pretty sure the pistons must look something like the surface of the moon by now.

By a 72+ cam do you mean the exhaust opens/inlet closes at 72 degrees? The cam I've got is a 31/61, 272 total duration and 495 thou valve lift, I thought it would be OK? Doesn't seem too big to me, might be a bit lumpy/peaky in the 1.6L but IMHO a smooth idle and quiet running is for suckers.

I lied when I said I have one more question, I have yet another to annoy you with. I've heard SUs don't like the mechanical fuel pumps on L motors, will I have to get an electric one or is this full of it? I've run triple CD Strombergs (pretty much the same thing) on my Holden for nearly 6 months now, with the stock mechanical pump, with no problems at all, would the Datto be the same?

Not sure where the 72 comes into it every one just seams to know what im talking about what i say that. Thats the only think i know about datsun cams or any cams for that matter. and i don't know much about carbies speaking of carbies i will have some pair of 45 for sale soon they might be a bit big for a 1600 .

[DaveTrees]

Originally Posted by JohnnoEH

I've heard SUs don't like the mechanical fuel pumps on L motors, will I have to get an electric one or is this full of it?

I would have thought a mechanical pump would be fine ... in fact SU-type carbs don't like electric fuel pumps in many cases, because the fuel pressure is often too high. You only want ~3-5psi fuel pressure for SUs .... just make sure the pump is providing enough volume.

[CraigW]

If you go for a different head, just remember that bigger valves (even L18 size) may not fit inside your L16 bore.

I had to eyebrow my L16 block to get clearence for bigger valves.

I used to run SUs with a different profile needle on my L16. I'm not sure if it made too much difference as I think the needles are hard to find.

Craig

[DaveTrees]

Originally Posted by CraigW

I used to run SUs with a different profile needle on my L16. I'm not sure if it made too much difference as I think the needles are hard to find.

SU needles are readily available, in the full range of sizes (assuming that the needles for Hitachi SU-copies are the same as the needles for real SU carbs).

Here is as good a place to start as any.

The trick is knowing exactly which ones you need .....

[DaveTrees]

Originally Posted by afifield

For capacity increases, you fit in the class for the new capacity.

The exception is if you are running under Historic Rally Car regs ... in your case (potentially) Category 2 - Post Historic.

From the CAMS HRC regs :

"4.2 The original type of cylinder block and crankcase must be employed. The bore may be varied, provided that the swept volume of the engine remains within the same cubic capacity class as the original engine supplied by the vehicle manufacturer. Stroke may not be changed. Where an engine is close to the capacity limit of the class, and reboring (which is permitted only to a maximum of 1.5mm in this case) causes the engine to pass into the next capacity class, the engine will be deemed to conform to the original class."

[JohnnoEH]

Ah well, in that case I might play it safe and stick with the head I have. I'm hoping I won't need to change the jets in the SUs (they are the 'real' SUs, not Hitachi copies) either. Probably would be a good idea but it's only going to be a el cheapo job for now, put a kit through and be done with it. I wouldn't have thought that I'd be exceeding the stock pump's capacity, it won't be that hot of a motor, so I guess I can only try it and see what happens.