Query about 1300 SP rebuild, heads and other improvements..

Just a few general engine questions ..

I have a mint standard 66' beetle with a stock 1300 SP down to the original solex 30 pic and oil bath air cleaner.

Once I've converted it to 12v and done all the usual things I'd like to get a little more power from it to help with keeping up with modern traffic and make it a bit more relaxed on the freeway.

I don't want to depart too much from original with this car, I quite like what sander288 has done to his 67 - basically a nicely rebuilt 69x77 1300 with dual port 1300 heads, a nice cam, exhaust and twin kadrons, sounds great and looks like it has a nice bit of power. I probably don't want to go quite that far though.

1300 dual port heads seem very difficult to find nowadays though. So I've been pondering a few different options. I kind of want to stick with a reasonably standard appearing engine.

One would be simply a rebuild, full balancing and weight matching, careful assembly of basically standard engine components, and having a cylinder head place do some machining and mild porting of the single cylinder heads, a little more compression (8.8:1 or 9 points?) port match the manifolds etc, a very mild camshaft perhaps (I'm told these engines are very under-cammed) and a better flowing exhaust (still with heat exchanger) and re-jetting to suit.

I'm not sure if the carb/manifold/heads would flow well enough to make use of the extra cam lift/duration but would it be reasonable to except a livelier engine from this work, perhaps an extra 8-10hp and a bit more torque and response?

Secondly .. Going to 1600cc pistons and barrels with the 1300 heads for slightly more compression or some machined 1600SP ones (they have slightly bigger valves don't they?) and a standard rebuild and the above - mild cam etc and upgrade the carb to a bigger pic.

The other thing I considered I I do go to a 1300 dual port motor was whether I could get some 1600DP heads and have them welded and remachined to suit a 77mm bore, and get the advantage of bigger valves and ports so the 1300 can rev and breathe better and make use of a bigger cam.

Would love to hear your thoughts!

Cheers,
Ben

PM sent

If the engine is not rooted and you have a mint 66' i would leave it right alone, a nicely tuned 1300 SP is hard to beat as a good street engine, my 1300 66' purred like a kitten and kept up with modern traffic on and off the freeway.
If you want performance, no use pussy footing around just get a 1776+ built.

If you really want to keep it a 1300 then a 100 grind cam would probably be as 'wild' as you want to go as IMO the 110 grind cams would make the smaller 1300 too peaky. The 100 livens things up but should keep the torque low down, which is what small engine need to get you moving.

A nice flowing exhaust is mandatory but do plenty of research on what actually works from owners on here, Samba, pre67 and Volkszone. There's a been a good few who say they've had heat issues with the vintage speed stuff but cream of the crop has gotta be the CSP Python but I think the pipe size may be too big for a 1300. Either way, bit of research and you should find something that suits your needs.

Then it's the heads and carbs. Staying single carb may make it look original but it really does strangle the engine. You need to let it breathe. Some ICT or Kads would be the best fit unless you can find some baby dells but then you'd have to choke them down to keep the engine torquey.
Heads is where the majority of an engines power comes from. Flow and air speed is what it's all about and not just flow as you can open the ports out to dustbins lids so they flow crazy amounts of air but the air speed will be crap and hence you won't fill the cylinders well. So nice smooth ports with knife edged point where the port splits into 2 and then 3 angle valve seats with radius'd outer edge of the exhaust valve and 3 angle on the inlet valve that gives a nice bit of back cut to the valve head.

All that should easily make the engine go more like a 1600 or better.

If however you want to keep the engine looking stock then with a single carb you'd need to go 1776 as doing a 1600 wouldn't be that much less in cost of parts.