8 valve cylinder heads

[mk1nova_rich]

which is the best head to modify in terms of flow rate and power gains achievable that can be fitted to a 1300?

[comptoncj]

I believe its best to use a 1200 head is there is more meat to take off. but not 100% sure but i think thats been mentioned before.

[mk1nova_rich]

cheers, im sure someone else will be able to provide info

[garyc]

14SE as it ha bigger valves to start with. You can probably get the same size valves in a 1300 head but be prepared for a big cost.

[mk1nova_rich]

i was thinking more about porting rather than trying to fit huge valves

[REDTOm]

i have a good 14se head in the garage ;) lol

[mk1nova_rich]

i dont want to buy any worked heads just yet. I want to start designing a proper alloy inlet for my bike carbs, just want to know which head i should work with?

[Damo]

I think ive seen before that the 1200 head is the best flowed out of the small block ones equipped with a 1300cam etc and potrt matched 1300inlet can give good gains.

[mk1nova_rich]

whats the difference between the 1200 and 1300 heads?

[mowgli]

whats the difference between the 1200 and 1300 heads?
nothing as far as i know.

getting a big valve head, a decent cam & some better fueling, (twin 40's) is the way forward.

[mk1nova_rich]

bike carbs mate, i want to start designing a manifold but obviously different heads have different port shapes etc. Im thinking a round port head might be good if any will bolt to a 1300 bottom end??

[garyc]

the 14SE has round ports and they flow better then the square bottom on the 12\1300 heads. If you want to stick bike carbs on the that would be easiest as you have a round port to start with. If you dont know what your doing I'd start with the 14SE head and take out any lips and give a bit of a polish up on the inlet and take out the nasty step on the exhaust side. Look for a book by peter burgess as they detail a vauxhall head which is similar.

[mowgli]

its all down to combustion chamber volume.....

a lot of the later heads have much bigger chamber volumes than the 1.2/1.3

[mk1nova_rich]

this 14se is sounding like a winner, which models are these found on?

[mk1nova_rich]

will a higher CR be achievable by skimming a 14se head?

[garyc]

yes but you will have to measure it and work it out. Will be better decking the block to increase CR.

[mk1nova_rich]

why is decking the block better? Sorry for all the questions but i like to learn these things

[mowgli]

yes but you will have to measure it and work it out. Will be better decking the block to increase CR.

i think stuart had something with all the chamber cc's on it.

i'd say a skimmed head is much cheaper to do than a decked block...

[mk1nova_rich]

i can skim a head myself, only wanting in the region of 10-11:1.

[mowgli]

you could try my old favourite. bore it out to 77.8 mm & put some 1200st pistons in, you get a 1400 with more than 11:1cr, and tons of torque, then get a decent cam, 4-1 exhaust & some porting

[mk1nova_rich]

this sounds very interesting.... I really want to use bike carbs which coupled to the above mods could create a very strong engine. The attraction of the 14se head was the round ports though

[mowgli]

but the old 1300's were incredibly well tuned in their day. groupA on 40's with about 125hp (i believe), which is 55 odd hp up from std.

[mk1nova_rich]

yeh im looking for around 120-130. i have heard a lot of good things about the 1300 heads but the bike carb manifold will be easier to match to round ports, but if better overall gains can be had with a 1300 head then i will work round that.

[mowgli]

why not get a 1300 twin 40 manifold as a starting point for your carb manifold, there seem to be loads about on the bay & they aren't costly

[mk1nova_rich]

i was hoping to put my CNC skills to good use :d what is the best way to port the 1300 inlets?

[chrisnieldgte]

is 130hp reasonable from a 1300? it sounds a lot, thats all. im expecting the same from my 16se in my gte from a cam,porting/polishing and a 4 branch. i know the bike carbs bang in the juice but it just sounds a lot?

[mk1nova_rich]

its "achievable" with a fair amount of work. I want to spend a bit of time perfecting the inlet run from carb to combustion chamber which is where most gains will be had. Then a nice lairy cam and a head skim along with a 4 branch

[mowgli]

is 130hp reasonable from a 1300? it sounds a lot, thats all. im expecting the same from my 16se in my gte from a cam,porting/polishing and a 4 branch. i know the bike carbs bang in the juice but it just sounds a lot?

the gte is capable of more, but needs forged (expensive) pistons and a different ecu, so its not as cheaply tuneable, but it is really good on petrol.
the 1300 was from a time when emissions were much simpler & twin carbs chucking juice in was the way to do it

[mk1nova_rich]

im only 19 but i love the old school methods of tuning lol but im also a big fan of bike carbs rather than the twin 40s route

[mowgli]

but bike carbs are really not that suitable for a car, when compared to twin 40's.. a 1300 car engine revs to about 6500 & gets up to , say 120hp... a 600cc bike engine revs to twice that to get the same power. getting carbs to meter the fuel correctly for a 1300 will be a compromise...

[mk1nova_rich]

im using 900cc carbs, i suppose its an experiment really - to try and achieve 120bhp+ but with the increased fuel economy. I'm not trying to save the planet or any of that crap but Boffer8's 1200 Nova on 40s is ridiculously thirsty...

[tom reid]

Stick with the bike carbs mate, remember bike carbs don't know they're NOT on a bike.
Have a search on here, plenty of info to be found.

[mk1nova_rich]

yeh im definitely gona stick with them, but its not really the bike carb info im after now, more the difficulties of mating the manifold to the head. cheers anyway :)