10.8:1, 264/256° Bigport
06-05-2017, 09:48 AM
Post: #1
10.8:1, 264/256° Bigport
I have some engine issues and I'm going back to a bigport in my Carina. The engine is rebuilt with smallport pistons and I'm going to use a 0.8mm TRD headgasket. This should get the compression up to 10.8:1 right?
The head is fitted with 256/256 HKS cams (8.1 lift i think). I might swap the intake for a 264° cam.
It will run with a redtop ECU and intake manifold.

Will a bigport work at that high compression? Would you suggest adjustable camgears?

Give me your input and experience!

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06-06-2017, 08:24 AM
Post: #2
10.8:1, 264/256° Bigport
I haven't run that particular combination of parts, but essentially it is no
different from putting a bigport head on a smallport block, and that has
been done many times. You end up with a high compression bigport that
will respond well to bigger cams.

Since you will be running it on a bigport ECU the fueling won't be far off. If
you have an O2 sensor plugged in, the ECU should be able to compensate
well enough for the modifications. Better still if you have an AFM setup.

And you will need to experiment with cam timing to get the best results
for you style of driving, so definitely a good idea to get some adjustable
cam pulleys.

Cheers... jondee86

PS: By redtop I take it that you are referring to the later TVIS engine and
not to the smallport engine ?

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persists in trying to adapt the world to himself. Therefore, all progress
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06-07-2017, 12:18 AM (This post was last modified: 06-07-2017 12:20 AM by oldeskewltoy.)
Post: #3
10.8:1, 264/256° Bigport
clear up "redtop" and we can better assist. (ECU AND manifold)

additionally... your Carina would be rwd... so using either "redtop" manifold may require some modifications as both "redtops" would be fwd.....

Dan -

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06-10-2017, 09:54 PM
Post: #4
10.8:1, 264/256° Bigport
(06-07-2017 12:18 AM)oldeskewltoy Wrote:  clear up "redtop" and we can better assist. (ECU AND manifold)

additionally... your Carina would be rwd... so using either "redtop" manifold may require some modifications as both "redtops" would be fwd.....
Its a smallport ecu and intake. I've had a 4age in my carina for 2-3 years so the intake is already flipped. Everything is smallport (injectors and such) except for the block and head basically

Engine started today with 256/256° cams, but it knocks a bit..

Since bigports don't have a knock sensor I welded a nut to the block in the same positions that the smallport block has the sensor and put it there. I've had this engine in my car before, only difference was it had a regular head gasket. So I assume that the sensor works. Gonna try and adjust the distributor a bit more tomorrow..
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06-12-2017, 09:57 AM
Post: #5
10.8:1, 264/256° Bigport
Can't hear any knocks anymore but there's a very noticable dip in power above 5000rpm.

I tried to tinker a bit with the knock sensor and the respons felt better for a while then it went back to a pretty sluggish state. I'm thinking the sensor or the connector is bad and the ECU is overcorrecting because of it?

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