1200/1300

[greeny89]

just wandering if somebody could give me the low down on why to put 1300 crank and rods into a 1200 ?? any ideas?

[Copers]

longer stroke

[mowgli]

i did it about 20 years ago. i used a 1300 engine & rebored it, and fitted 1200 pistons (with the tops machined) and ended up with a 1400 with about 90hp. it made a very tractable engine, with lots of torque for its size. nowadays the 1400 original gm engine is readily available, so by getting a 1400 bottom end & fitting a 12/1300 top end to it, you will end up with a similar result.

or you don't machine the 1200 piston tops & end up with a 11.5:1 compression ration, and with a big valve head & a cam & twin 40's, you will end up with a monster.

ps. i was rebuilding an engine anyway, so it was a cheap deal for me.

[greeny89]

iv got a 1200 on dellorto 40's and obviously standard it doesnt make much difference so was going to put 1300 crank n rods in it

[SR-Rally]

I have 2 of these engines, both 1300 blocks rebored. One I used for last years rallying which was built by me in my shed and was/Is good engine. Although I've just took one out of a stage car that has been built by an engine builder up north and will be rolling roading it in next few weeks. Expecting some very good figures for "1300" 8v :)

[garyc]

its about time one of the dreamers actually did this and wrote it up as a guide.

[grooge]

i'm sure mowgli has written it all up before or at least that somebody has. i considered building one and got all the info i needed off here.

[mowgli]

when i did mine, the internet was not about. i have written it up many times.....

it really isn't a case of slapping some different rods & a 1300 crank in.. it will need a rebore, a crank grind, a new oil pump etc, or it will simply blow up.

but if you know how to rebuild an engine, then it is a doddle, as long as you know how to make a drift & have a decent vice or a hydraulic press.... or know a good engineering shop....

[greeny89]

if you could email me the details that would be great thanks

[rallycraig]

I ran a screamer of a small block for 10 years in rallying. Take a 1300 block, machine it out to take mahle 1200 pistons. I had the 1300 rods shotpeened for strength. Fitted arp bolts, lightened and balanced bottom end. Added a big valve, ported and polished head, ast2 cam that was further profiled, twin webers, solid lifters, and heavy duty valve springs. It regulary reved to 8k, pulled 130 bhp on the rollers and won the 2003 emamc championship outright. Coupled to a straight cut with a 4.5 cwp it would outrun most rally cars to 60 ( including bda's, n10's, e8 & 9's)

[mowgli]

if you could email me the details that would be great thanks

the png is a public forum, so i can't see the point in emailing:

1. strip engine
2. get it rebored to fit some 1200 st oversize pistons
3. get 1300 crank reground
4. fit new oil pump
5. assemble as per haynes.

the clever bit was the dummy build & a stack of measuring to calculate the desired cr, then convincing an engineer to actually machine my pistons.. he wouldn't charge me in case they went bang. they didn't.

obviously i did it with a replacement short engine, so the car was only off the road for an evening when i fitted it.

also never rebuild an engine in your bedroom, it was chiffing heavy to carry down the stairs.

[greeny89]

so whats better;
1200 with 1300 crank n rods or;
1300 with 1200 head and pistons?

[garyc]

a C14SE, the stroke is the same and the bore is more or less the same and the head is better.

[mowgli]

well, it ends up as the same. the 1300 cam is bigger as std, compared to the 1200,
the blocks are the same height, so the 1300 crank & rods ends up with the same tdc height as the 1200 crank & rods, and the pistons are the same height, so there are no clearance issues. all the outer ancilliaries fit on.

not that i'd recommend such a thing, but a 1200 block has a 1200 engine number on it.........

[mowgli]

a C14SE, the stroke is the same and the bore is more or less the same and the head is better.

and you try & find a distributor to fit one for a carb conversion then........

the point is that the 1200+1300=1400 is that it is a high compression engine.