1296 vs 1493

[waltesefalcon]

Hi Everybody,

As some of you know I am building my spitty to race. I am thinking of replacing the 1493 with a 1296 for the cam bearings it offers and more importantly the stronger bottom end. Any thoughts from those who have run spits as racers would be appreciated.

Cheers,

Walter

[ 08-06-2003: Message edited by: waltesefalcon ]</p>

 

[britishcarfreak]

Have a look at the racing spitfire on www.triumphowners.com owned by Ian Cowie.

Its an orange one with green on it.

You can email him via the site.

He's spent about $60,000 Australian on it and gets a fair bit of competition results.

Here's a direct link to his car on the triumphowners site IAN COWIE

 

[Bugeye58]

Walter, I'm assuming you meant a 1296, commonly called a 1300, rather than a 1275. The 1275 is the venerable BMC "A" series from Spridgets, etc.
The 1300 is a much better engine to race than the 1500, as the stroke is .440" shorter, and here in the states, you are allowed to run the dual carb setup, and the 1500 is limited to a single 1.5" carb, at least for SCCA road racing.
We touched on the relative merits of both engines in the thread entitled "High Compression Spitfire 1500 engine", a few days ago. You may want to look at that, and then come back with any specific questions you have.
As I said in that thread, "If I had had a 1300 to build, the 1500 would have been gone in a heartbeat"!
Jeff

 

[tony barnhill]

I've got several old 1275 long blocks, carb setups, etc in my MG Graveyard!

 

[waltesefalcon]

Thanks Bugeye,

1296 is what I meant I didn't even notice the error till now. I didn't realize that in the SCCA only allowed for a single 1.5 on the 1493 just another reason for me to go with getting a 1296. Also does anyone know how far you can mill the head on one? I seem to remeber someone saying .125" but that seems rather alot. Can Anyone clear this up for me?

Cheers,

Walter

 

[Bugeye58]

Walt, I just measured the spare race head, and it is 2.900" thick. The build sheet on the current engine shows a head thickness of 2.860", but I have to admit, it's been so long since I've seen a stock head, I can't remember what the original thickness was. I know we took a ton off the head to get a decent chamber volume. If I can find the original head thickness, I'll post it, but maybe someone out there knows, and can bail me out.
Jeff

 

[waltesefalcon]

Jeff,

Thanks for the help. I really appreciate it all its nice to have someone who has raced these before around to pick his brain.

Cheers,

Walter

 

[Bob Claffie]

OK, I'm the guilty party with the VERY milled cylinder head. In my MK3 SCCA racer, I had .125 taken off it and never had a problem (at least with the cylinder head). Ran pump hi-test LEADED. No idea what the compression ratio ended up at but that milling spec was right out of the Triumph competition manual. Should also shorten the pushrods to avoid goofy rocker geometry. Bob

 

[Bugeye58]

Bob,and Walter:
Taking .125" off the head, and assuming flat top pistons, should give you a compression ratio in the neighborhhood of 10.6:1. Driveable on todays premium (93) octane gas, but you may want to run a lead replacement additive, or a booster, such as 104 Plus.
After taking .265" off the cylinder head on my current "F" Prod 1500 Spit, the compression ratio is 14.7:1, and runs just fine on 110 octane leaded race gas. I tried to kick it up to over 16:1, but didn't "O" ring the block, and couldn't keep a solid copper head gasket in it. After I melted two pistons, I went back to the Cosworth flat tops, and haven't had a head related problem since. But, to maintain proper valve geometry, I did have to modify the pedestals on the roller rockers, and had Crane make pushrods of the required length. The thing pulls like a freight train up to the 7650 RPM redline, but, it can be a high strung, tempermental beast at times. All in all, it hasn't been too bad, as fully race prepped engines go.
Jeff

[ 08-09-2003: Message edited by: Bugeye58 ]</p>

 

[waltesefalcon]

Jeff and Bob,

Thanks guys for all the help. I am gonna try and find a 1300 now. and I'll probably go with milling the head .125"

Cheers,

Walter