ive got an insane build planned and am still doing r&d work for my 81 i6 truck i was just wondering on the 300 which head flows more the carbed head or the efi head any inout will be apreaciated



mark

 

If there is any difference in the flow it wouldn't be enough to make a difference. The EFI might bump the compression ratio by about .5 and has a "fast burn" combustion chamber...which isn't necessarily detrimental to running on a carbed engine.

 

get a cylinder head from a 240 engine, those have smaller combustion chambers which will raise your compression up a good bit. find the head take it to the machine shop have them mag it and do a good valve job replace the seals and guides and you should have some good power outta that head. Dont know how high the compression would be or if you would need to run premium, i would doubt it but im sure someone else would chime in and give you a heads up on that.

ps if you plan on a "insane 300 build" note that the getting a radical cam will not be a good idea. it wont idle at all below 2k and iv heard of the high lift cams pulling the studs outta the head for the rockers. Dont go to insane unless you plan on spending a pretty penny on the bottom end to take the abuse. Also if this is going to be your daily driver i would not recommend going crazy. If this is for pleasure use or some type of racing then hell yea just be ready to spend the money, the 300 is not a high revving engine at all, its all low end torque.

a good ignition (msd)
a mild cam for towing, possibly comp or isky
a offy manifold and a 4 barrel carb with the 240 head maybe a little p&p job on the runners and a fresh bottom end will give you plenty of power you will be happy with.

 

The basic recipe I came up with a few years ago goes something like this:
Any carbed 300 head, just fully ported and polished
Shot peened 240 rods, bushed for smaller pin
347 pistons
Entire rotating assembly balanced
EFI with custom upper and smoothed lower
Custom mid-length headers with 2.25" collectors
Crossover pipe and 2.25" full dual exhaust
I can't remember the cam right now, but it was a custom grind from Delta in Tacoma
Or you could just piece together two 351/400 heads, or mill one out of a big chunk of aluminum and build your own chain driven DOHC setup...........
Alternatively, stop at the headers and instead bolt on a pair of T025 turbos and then run those into a 3" single exhaust, but then the cam and EFI system will be quite different.

I used to have a lot of wild plans way back when-

 

[QUOTE=8525ford;9201124]get a cylinder head from a 240 engine, those have smaller combustion chambers which will raise your compression up a good bit. find the head take it to the machine shop have them mag it and do a good valve job replace the seals and guides and you should have some good power outta that head. Dont know how high the compression would be or if you would need to run premium, i would doubt it but im sure someone else would chime in and give you a heads up on that.

So, let me make sure I've got this right. Whip off the 300 EFI head and fit a 240 carb unit which I spare lying around. That will obviously up the compression. Do I need anything else. I mean, could it be that simple for some bolt on additional HP? I already have a nice mild towing cam. Do I need to muck around with push rods or anything? How about the port match to EFI inlet and headers?

 

The 300 EFI head has the same 68 cc combustion chamber volume as the 240 head. There will be no compression ratio change.
The problem is the EFI head has high swirl chambers for faster combustion and if you change them out you will lose power because the ignition timing will be too retarded for the 240 head.

Which towing cam do you have and how does it perform compared to the stock cam?

I had a 1974 Z1 900 Kawasaki back in the day. I also had a 1977 KZ1000 Rickman with a supercharger.
Is your KZ1000 stock?

 

I loved my '72 Daughter. SIL came along and made me an offer I couldn't refuse.

 

Hi. I can't remember the specs of the cam. I switched it a few years ago along with steel timing gears. They are noisy so I plumbed a line directly from the pump to the timing case just to shut it up a bit.
So the yarn about improved performance from a 240 head is just a myth then? I won't go to the trouble. Thanks for the tip.
G.P.

I bought this in 1978 when I was just 23. I'm now 65.

Very stock Z1000. Fitted 900 4 into 4 exhaust just because it looks better.

 

A 240 head will raise the compression ratio of a carbed 300 engine about half a point - from about 8.4:1to 8.9:1. Carbed 300 engines have a bigger chambered head than EFI engines - 76 cc vs 69 cc.

Beautiful bike BTW.

 

Very nice looking truck.

As FTF replied, the 1965 to 1986 300s had the 76cc chamber volume and compression could be raised by replacing with the 240 head.
The 1987 and later EFI engines like yours have a 69cc chamber so no help in compression from a 240 head.

Beautiful Kawasaki!
What alloy wheels are those?

 

Factory standard alloy rims.

 

My mind reading pills ran out on what
Not any truck I know of
Dave ----

 

I think he's talking about the Kawasaki Dave.

 

You might be right
Dave ----

 

I was 23 in '78 also, turning 66 next month.

No fun trucks for me then, I was riding submarines. They didn't let me keep any of them...