Hi does anyone have some ideas for a normally aspirated a14..I already got some twin webers dceo28 with intake manifold but not sure on the correct jet sizing..was thinking on gasflow and skimming the head but my friend has an a15 head that he's selling so i was thinking on buying it and tuning that one,would the a15 head make a difference??and the valve springs,can I keep it standard or should I get other??and cam degree??plz i'm a newbie to tuning motors..any suggestions would be appreciated..aiming for 15sec 1/4 mile

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DCOE 28s? Never heard of ones that small. We normally run DCOE 40s on the A-series.

A15 uses A14 cylinder heads. No difference. There are several different design A14/A15 heads though. Which one do you have?

Skimming the head to go from 9:1 to 10:1 will give about 3% more power. That is 2hp.

Yes, if you want to rev the engine higher than 6000 RPM, get double-valve springs. For that you will need DCOE 40s, and a better camshaft. Better to swap in the entire A15, and use a GX camshaft (256/256 degrees). Most A14 and some A15s use 248/256. Later A15 uses a very mild cam.

i have an A12 with twin DCOE42's ... unsure of the carby internals, it's been so long since i had it set up.

It's got oval port head and double valve springs, larger inlet valves, balanced bottom end and lightened flywheel

revs out to over 8,000

I have a completely stock A12, revs out to over 6500 RPM, but accelerates a bit faster if I shift at 6000. Well not completely stock. It has electronic ignition, tubular header and 2.5" exhaust. It got stock balanced bottom end and the head has never been off.

You don't mean dcoe48's do you? If you are keen on building an engine, first know it's not a cheap exercise.
What head do you have currently? If it's an h75 it's a low comp head.
I you want to build a decent engine with good comp I would eithe look at buying an h89 or GX head, neither cheap however both high comp with the GX head being double valve springs.
You can have the h89 head seated for double valve springs for not too much money. Otherwise you can do some porting on it with bigger valves.
As for the block you can just bore the s**t out of the block and put a nice set of flat top pistons on. You can look at lightening the flywheel and crank, and have everythig balanced.
I don't know enough about what cam degree to use however have a good look at what your driving this engine will be use for. There is no point putting in a race cam that only starts to pick up at 6-7 grand that's meant for speedway racing if it's going to be a daily driver....
Also you can prob just have the cam you already have reground by a decent machinist in your area. There is usually a cam specialist near by....
Honestly I don't really know enough with specs and what not your best to have a chat to member "bige" (Earnie) he's more than happy to chat...
As for 15 seconds 1/4 mile dunno if that's achievable with a worked a14, have a look on YouTube there is an a15 turbo ute running good times from memory... Pretty sure one of the videos is datsun 1200 ute eats gtr skyline....

Yes, all true that. Certainly fitting 79 mm pistons will return far more HP than shaving the head and double-valve springs -- or even changing the camshaft.

Note that H75 and H89 can both have the same compression ratio depending on the year/region of the H75 (there are many H75 heads). For best power and fuel economy go with a closed chamber head. Control your compression ratio with the piston dish -- using flat-tops to raise compression often results in better power than milling the head.

I've always found and read a motorsove high comp and can rev out to 9 grand... This whole engine depends on how far and how much money you want to invest into the project. Don't get me wrong it a lot o money but the finished product is near always awesome and sounds great with some extractors and decent exhaust!! The weber induction noise is a unique sound by itself I love it!!

Quote:What?

Whoops was my phone. My bad. I meant to say that from past experience and reading worked A series engines can happily rev out to 9 grand (more so speedway motors...)

Good topic. I'm about to rebuild my A15. It's got the H89 head and I will be using 40mm twin dellortos