Amazon: B18 Engine

[DOGSTAR]

I am taking my engine out over winter.
I am going to give it an overhaul, but whilst it is out i wish to enhance the perfomance.
Any thoughts advice on polishing heads, cams flywheels pistons painting the block please most welcome.

[Clan]

Originally Posted by DOGSTAR

I am taking my engine out over winter.
I am going to give it an overhaul, but whilst it is out i wish to enhance the perfomance.
Any thoughts advice on polishing heads, cams flywheels pistons painting the block please most welcome.

I suppose the obvious is fit a B20...?

[Rustinmotion]

Originally Posted by DOGSTAR

I am taking my engine out over winter.
I am going to give it an overhaul, but whilst it is out i wish to enhance the perfomance.
Any thoughts advice on polishing heads, cams flywheels pistons painting the block please most welcome.

Get hardened exhaust seats if not done and new shells for the crank and con rods, a light smooth out of the intake and a good 3 angle valve and seat grind, don’t polish the intake port you want it smooth as in no abrupt changes or bumps and lumps but the surface should be a sanded finish not mirror like to prevent fuel dropping out of suspension and pooling in the port bottom
If you can’t get the crank balanced at least balance the pistons and con rods
Aim is to get every piston within one gram, every small end and big end within 1 gram
It won’t be a lot more powerful but a good smooth engine, a cam will give more power but it’s a trade off be sure what you want from the engine before selecting, large lifts put a lot of strain on the valve train and big overlap causes a lumpy idle, if your going for more overlap you need a good exhaust manifold to make full use of the overlap

[blueosprey90]

My understanding is that the best money spent will be on the head. Find a place that can modify your head properly.

I had a head ported as part of a race engine build. It was great, but I didn't know better. Later, I cracked that head and slapped on my spare "flowed head", i.e., ported on a flow bench. That head was noticeably better and allowed the engine to continue to pull to 100+ mph. I could suddenly catch and pass cars that were always out of my reach.

For a street build, I would try to send out to a qualified shop.

You might also consider a lightened flywheel.


This is not a recommendation for a shop, just a place to start looking.

http://www.v-performance.com/product...formance_heads

Also see http://www.v-performance.com/article...h_updates.html

[blueosprey90]

I'm going to supplement my prior post. I'm not sure what you are looking for, but you might also try to match a camshaft with whatever head work you have performed. A little extra lift and duration on the cam complimentary to whatever head work you have done. After that, compression is always a good thing, subject, of course, to what fuel you might be limited to by budget or otherwise.

[Rustinmotion]

This link from Amazon Cars gives a good idea of getting the best out of a standard B18 without spending lots of cash, rally spec rather than race
https://www.patreon.com/posts/543766...=postshare_fan

[Burdekin]

What B18 do you have? If it's a A engine then there's a good amount of added HP by going to the later B18B spec or even D cam with 10:1 CR with twin SUs. Tidying up the ports directly under the valves and removing the step on the valve stems is probably far enough for a nice street engine. Going oversize for the bottom end will help with torque but I think you need to be careful with the B18 as you might hit a water jacket due to the poor castings. Engine work isn't cheap.

[142 Guy]

If the engine is close to original then chances are the camshaft and lifters are due for replacement because of surface spalling. This was a B18 / B20 materials flaw right up until the early 70s. If you are replacing the camshaft, then consider contacting Tinus Tuning and ask for his recommendations on a suitable camshaft. They should ask what compression ratio, what carb arrangement and what exhaust system. You may be able to engage them in a conversation as to "this is what I want, what do you recommend". Cam selection will be dependent on carb selection and compression ratio. In particular, SU carbs do not idle well with long duration camshafts. Twin SUs will work with a D grind cam; but, it won't be a nice smooth idle if that is important.

As Burdekin notes, if you have a B18A the simple path to more power would be change to a B18B spec or Clan's suggestion to just transplant a B20B into the car. A used B20B would probably be cheaper than the machine work required to upsize the B18 and a B20 head has larger valves (get a B20E head) and proper valve seals as opposed to those silly umbrella things on the B18.

Whether you currently have a high compression engine or want to increase the compression ratio, decking the block and machining the piston crowns so that the tops are flush with the deck will allow you to establish a correct squish band in the combustion chamber which will allow you to run the correct amount of ignition advance without incurring detonation.

Unless you have access to a technician with a flow bench and prior knowledge of old school head modification, don't bother with modifying the combustion chamber and the ports. The #1 problem with B18 / B20 head design is the exhaust port and the > 90 bend the exhaust gasses take exiting past the valve. Fixing that problem is a lot or work which requires welding in filler on the bottom of the port floor.

Checking the combustion chamber volumes to make sure they are matched which means matched compression ratios on all four cylinders would be a good thing. As noted by Rustinmotion a multi angle valve job with hardened inserts on the exhaust valves are a given if not already fitted.

I recommend against a light flywheel unless this is going to be a race / rally car. With any cam with longer duration (like a D grind camshaft) and twin SU carbs the idle will be erratic. The RPM fluctuations will be significant and make setting ignition timing with a timing light interesting.

[DOGSTAR]

Originally Posted by Burdekin

What B18 do you have? If it's a A engine then there's a good amount of added HP by going to the later B18B spec or even D cam with 10:1 CR with twin SUs. Tidying up the ports directly under the valves and removing the step on the valve stems is probably far enough for a nice street engine. Going oversize for the bottom end will help with torque but I think you need to be careful with the B18 as you might hit a water jacket due to the poor castings. Engine work isn't cheap.

Thanks for getting back to me.
I already have a 123 ignition and upgraded from single zenith to twin su's with a custome made inlet/outlet and straight through stainless exhaust system so i went from 60 hp to 80 so big improvment. i only have a 4 speed so i went for mid when getting the downpipes designed so after that grunt rather thsn the top end. I have a good guy who restores and builds engines. Has done a lot of work for Boyd Coddington, so lucky to know him!

[142 Guy]

Up sizing a B18 bottom with larger pistons has its issues. Because of the larger swept volume you will get an automatic bump in compression ratio. If you are already running a higher compression ratio you will need to open up the combustion chambers to reduce the CR to something manageable. At that point, setting up your squish band depth becomes even more important.