engine building on paper. A+ and pre-A parts combination?

[DarkHelmet]

I am faced with a conundrum. I have a pre-a 1098 and a A+ 998. I do wish to build a great overbore Calver parts 1098 (1218), but when faced with the benefits the A+ has in its evolution I am now thinking of putting the 1098 bottom end in the A+ block and trans, and the A+ bottom end in the A- block and trans and eventually moving that along. I may be crazy, but I may not be surprised.

I guess the A+ has a stronger block, Spring loaded tension unit for the timing chain (really?), plus detail changes. I recall the Transmission casting is also stronger from removing some webbing holes where things can crack. So is this a crummy idea? It would be an overbore with Russell pistons and a Calver worked 202 head/lifters/rockers/pushrods.

With what I want to achieve, what is the strongest combination? In the end ill have a spare 998 with a 202 head.
(dave may enter this chat, I would welcome that, he's seen the 1098)

[MiniDave]

I'm not sure why folks go to this trouble instead of just building up a nice 1275, overbored 40 thou with a good cam and about 10.3-1 compression? That will be a durable engine with plenty of life left for the next build too. Add the Calver head and you have a strong motor!

Yes, use the later model rod change gearbox - it's a solid easy shifting box.....I think the issues had more to do with race cars breaking them than street driven cars, but you might as well take advantage of the latest technology.....but not all A+ rod change boxes had all that - it was developed over the years. The easy way to tell is that the latest ones only had 3 bolts retaining the bearing on the final drive end of the mainshaft.

I'm all about working with what you have, but I would sell both of those and see if you can find a late model 1275 from someone who went Vtec or something.

Just my humble opinion of course.

To address what you want to do. everything you wrote is workable, except there will be some mix and match to get it all to work together.....for example, the drop gears shafts and bearings are different on the late model rod change gearboxes.

If you're going to all this trouble I would def get the cross pin diff too, and put in a set of 3-1 final drive gears, although for mountain driving 3:44 might be the better way to go.

[94touring]

I like the 1098 bored and built idea.  It can be a very nice motor with great power and torque (Calver has a writeup on this) that runs smoothly and should be about bullet proof and get great mileage. If you have the block and crank then I think building it up would cost about the same as doing a 1275. Go 10:1 or 10:3:1 on compression, especially at your altitude.

Gearing, decide if you're driving around town more or plan on doing 70mph on the highway.  If most your driving is 70, then do 3:1. If it's primary around town or roads up into the mountains, do 3.44.  You can also split the difference and get a 3:20, which given altitude, power output, and hills, maybe the best way to go.