cams

[stubby]

i am on with building a motor at the moment for predominatly fast road use.
1460 cc block and now looking at cam choices.
have seen some 470/500 lift cams for sale but are these a bit severe ?
would a set of milder cams say 420 lift be a better choice for this type of motor. ?

[zed1015]

470/500 lift for road use is too much, that's serious all or nothing full/drag race cam territory and the result will be unrideable , unreliable and spend more time in bits than on the road.
What head have you got as even a wild ported z9/1000 head with o's valves won't flow enough for a 1400cc + whatever cam you have.
You need a 'J' or better a Unitrack head to get the most from that capacity and have it ported with bigger valves so it can actually flow the extra air at say 410 to 435 lift.
You don't want more than a fast road profile, make the extra capacity do the work rather that spinning the crap out of it.
Remember no matter the capacity you will still be limited by the rpm's and the top speed won't be much different to a good 1075 motor, you will just get there faster.

[buzzard]

First off I would'nt go as big as 1460cc, not alot of base gasket left, 1325cc .@ 10.5CR is perfect, cams selection, Andrews 3X, 0.418 lift good duration and you can still use shim on top, pit stop performance are now making these again, PSP 3X I think.GPZ1100 cylinder head is a must as you can go much bigger valves and the inlet track goes out to 38mm for big carbs, I have done quite a few big valve GPZ heads lately, got all the seat cutters etc and I machine it on my milling machine, comes out real good. Buzzard.

[Fred the Zed]

First off I would'nt go as big as 1460cc, not alot of base gasket left, 1325cc .@ 10.5CR is perfect, cams selection, Andrews 3X, 0.418 lift good duration and you can still use shim on top, pit stop performance are now making these again, PSP 3X I think.GPZ1100 cylinder head is a must as you can go much bigger valves and the inlet track goes out to 38mm for big carbs, I have done quite a few big valve GPZ heads lately, got all the seat cutters etc and I machine it on my milling machine, comes out real good. Buzzard.

Hi Buzzard

Theres three GPZ 1100 heads on ebay at the moment.... is there a particular model thats best or are they all the same? Are these a bolt on replacement for Z1R heads?

Fred

[zed1015]

Theres three GPZ 1100 heads on ebay at the moment.... is there a particular model thats best or are they all the same? Are these a bolt on replacement for Z1R heads?

Fred

The unitrack head is the best one as it the largest valves and improved twin swirl combustion chamber (bathtub) however depending on the level of tune the earlier GPZ and J heads work just fine for road motors.
Although they do bolt straight on NON of the J/GPZ heads are a straight replacement as they need a top idler conversion for the roller camchain and you also end up with a lower compression ratio due to the larger combustion chamber volume unless you compensate.
The Unitrack head has a slightly smaller combustion chamber than the J so the compression drop is not so severe.
Later Z1100 heads are also the same as the unitracks but retain the earlier shim on top valve adjustment.

[Fred the Zed]

Theres three GPZ 1100 heads on ebay at the moment.... is there a particular model thats best or are they all the same? Are these a bolt on replacement for Z1R heads?

Fred

The unitrack head is the best one as it the largest valves and improved twin swirl combustion chamber (bathtub) however depending on the level of tune the earlier GPZ and J heads work just fine for road motors.
Although they do bolt straight on NON of the J/GPZ heads are a straight replacement as they need a top idler conversion for the roller camchain and you also end up with a lower compression ratio due to the larger combustion chamber volume unless you compensate.
The Unitrack head has a slightly smaller combustion chamber than the J so the compression drop is not so severe.
Later Z1100 heads are also the same as the unitracks but retain the earlier shim on top valve adjustment.

Great stuff.... knowledge like this is priceless. I was thinking of putting 1075 wiseco or similar pistons in, which would have a raised compression ratio, so this would all work nicely. Fred

[zed1015]

You will lose around 2 points of compression with a J head depending on bore size etc , slightly less with the Unitrack.

The usual wiseco road 1075cc kit is 10.25 to 1 and will end up at around 8.75 to 1 with the J head.
Ideal for a turbo but not so great for normally aspirated.

You will need to either cc then skim the head or fit higher compression pistons to begin with.

With a unitrack head you may also have to check valve to piston clearance as the uni's exhaust valves run at a steeper angle to the z1r wiseco's piston valve pockets.

[buzzard]

Nothing to add to what zed1015 has posted, obviously been their and done it before, but with a bit of machining work it not hard to fit any of these heads, you've just got to decide what you want to do with the motor. Buzzard.