Engine rebuild advice? Suggestions?

[rdefabri]

All:

New to the forum, made a few posts. I am 20+ years out of the Z game, but recently purchased a 1972 240Z, numbers matching. The previous owner kept it mostly original, but did add a 5-speed and a 4.11 R180.

The car needs a rebuild, it doesn't have spunk to it. I considered doing a resto on it, but given the tranny and rear-end, perhaps a "resto-mod" or stealth Z is in order.

I considered the idea of the Rebello 2.7L, but searching this board indicates this is a $4,000- $5,000 expense :eek: So I started thinking I could do this on my own if I were to obtain a 260 crank and rods, add higher compression pistons, and maybe have Rebello do an Improved Touring job on the head.

Yes, this is only a 2.6L, but for maybe $2,000 plus my time, I am thinking I could come close to the 200 or so HP Rebello advertises.

Any thoughts? Am I a nut? I don't want to pull the block and rebore if I can avoid it, my funds are low.

Thanks in advance!

[Arne]

If it's worn bad enough to require a rebuild, it probably NEEDS to be bored anyway.

If you're not going to be stuck on numbers matching, find a decent 2.8 from a 280ZX and use it as your starting point. You should be able to get an '82 or '83 with flat-top pistons for a few hundred bucks. Then put your IT head on that instead.

While the following site may not have perfect info, it can be used as a good starting point.

http://www.geocities.com/zgarage2001/engine.html

[rdefabri]

Arne,

Thanks for the feedback, I know Bryan Little's site well! Unfortunately, I want to keep numbers matching. Otherwise, his site was what kept me motivated to someday get back into the Z game!

I know these motors fairly well, I only have 148K miles on it, so I don't think it needs to be re-bored. When I tear it down that should indicate whether or not I should.

Assuming I don't need a rebore, and I want to keep my numbers matching, am I still crazy or does this sound like a reasonable plan to getting some more oomph out of my 240?

[rdefabri]

I should add that I'd be looking for 180 - 190 rwhp if possible

[ZSaint]

I just got home and read your post. I know it is important to some restorers to keep the numbers correct. I know the value of these cars will be greater if you have the original engine in the car. Here is what I would do. Take you engine out and buy yourself a 260 engine long block. If you install the 260 crank and rods and bore the 240 block .060 over with a new set of standard pistons, you will have 2658 cc's with about 10:1 compression. (Or, install the stock 260 pistons with new rings. CR will be 9.6 and you will still have 2565 cc's) It will essentially be a 260 engine in your 240 block. Do a head rebuild, take .010 off and bolt on your 240 head. 280 valves are another option) It will have a lot of torque and be fun to drive. Your stock SU's and exhaust manifold will work fine with a mild cam. It will perform and look stock for the "purists". Just an idea from the old racer!

[rdefabri]

Nice suggestion! But how about just dropping in a L28 crank in the original motor?

That gives me the extra torque, but numbers would still match. I'd also be around 9.5:1 compression, so I think I could make some decent power like that.

Visually, it would still be numbers matching with no modifications to the block (I'd store the 240 crank).

[Arne]

You'd need the L28 crank and rods both. The result is the same as the 260 crank and rods, as they are the same.

[rdefabri]

Yep, that's what I meant!

Still debating whether it's worth it. The added displacement may only be worth 10HP at crank, so it's not much. I think with a cylinder head job from a good supplier, I could squeeze decent HP while being streetable and getting more ponies.

[ZSaint]

If you want HP, you will need to spend money. By placing a 260/280 crank with rods in your 240 block, you will have a bit more then 10 hp. You will also be increasing you CR by nearly 1 point. With a bigger cam and some head mods you could be looking at 20-25 hp. When you say you want 175-180 hp w/o spending any money and using the 240 engine, we have a problem. I don't think you can have it both ways. I would just rebuild your 240 engine and put it in as a new stocker. IMHO, You cannot get any better then that.

[rdefabri]

Well, I am not saying I won't spend money, I don't want to drop $5K into a full blown Rebello/Sunbelt motor.

About 20 years ago I had a 280 that I modified a bit and it responded well for little dollars (sort of the Bryan Little/Z Car Garage thing).

I am budgeting about $2K or so on engine work. The car has good compression, and doesn't burn oil, but seems a bit sluggish off the line. The previous owner told me that the guy he purchased it from put in a new cam. If he did, I can't tell, or he just dumped in a cam without other mods (porting, etc.).

For $2K, I think I could get a first rate head re-work. Maybe specify some mods, but I think that's reasonable. If I do that + the 280 crank and rods (which I already have in my possession), I think I could get to the 180 mark.

[ZSaint]

Did you really say you wanted 190 hp to the "Rear Wheels"? Wow, I have dyno'd a couple of cars and you will be looking at crank HP rating of 220-225 hp. Doubt if you can get that out of a "stock" 240 no matter how many mods you make. You are stymied be the exhaust manifold, the SU's and port size. How about just putting a rebuilt 240 engine in your car and being satisfied. Think how smooth that baby will run!

[ZSaint]

Did you say you cannot get your 'Z' off the line with a 4.11 diff? That thing should be a tire smoker!