Which heads will work better on a 318? 340 or 360?

 

I would have to look into the bore to valve sizes, but, 340s will flow more than the 318s. Same with the 360s. The more cubes you have, the more you have to inhale and exhale. I have some 360 heads in the shed that I could measure the valves at some point for you. I wish I would have kept my 318 heads though for comparison!! I dont have a CC-ing tool though, I will not be able to give you chamber sizes. If you just want to bump up a little bit of horsepower & torque having a light porting on the heads will improve your engine even with your current valve sizes. That is if they were ported correctly!

As for now, I don't have a clue of valve sizes that are present. Your bore is 3.91" btw.

 

http://www.geocities.com/alwest_83/318 was posted by NEMESIS SS on another thread but answers all your questions.

 

Thanks for the info. I want to get some sick H.P. out of my 318

 

as far asi can tell, this is the cheapest, easiest way to do it. There is another that uses junkyard parts, but by the time you get all the machining done, these new heads are almost as cheap, and they are better. also much close to being bolt on then anything ive read that claims to be bolt on

http://www.popularhotrodding.com/tec...ine/index.html

 

Thanks for the info.

 

I remember reading that article a while a back. Everyone is obsessed with forged production crankshafts. Kinda like how some buy heads because they supposedly flow that "big" amount. But, like the article says in the third paragraph. The cast crankshaft will do just fine and last long. That is if the engine does not have a detonation problem. If an engine has a detonation problem, the cast style crank will break earlier because of its rigidity (not very flexible) compared to a forged crankshaft which can flex more.

Depending on where you go, depends how much you will spend machining wise. Basic valve job is essential. Leveling the Block & heads is not necessarily a "need to do" type of work. The racing heads for my sisters race car didn't need a resurfacing so we didn't. "Shaving" you cylinder heads or decking your block (if already level) is mainly to boost your compression ratio. There are limits on these. Its all up to your budget from beginning to end though.

I would just start with the easy stuff, exhaust and induction along with the general valve job. Have Backcuts put on the valves.

 

One other thing you can put in your engine is a Windage tray to free your crankshaft of the oil "stucK" to it during operation.

 

but if you put the 360 or 340 heads withoutshaving a bit wont your compression go really low?

 

Depending on the chamber CCs. If there is a drastic size difference, yes. If there isn't, using a thinner headgasket can make up for some of it.

Same with using valves that are larger (margin thickness not head diameter) that protude more into the chamber. But that has to be more closely calculated and watched for preventing any damage. Especially with a longer con-rod.

Could the 340s and 360s have a close if not same chamber size? I have no clue Nemesis. Do you know their differences?