1800 or 2000 FI head

[So Cal Mark]

I only have carbed 2L heads on the shelf, no FI heads

[pope]

how does a 2.0 Carbed head compare to a FI head. Or are they the same in performance.

[BrianAz]

Hi Tom, Nice pool !
I maybe too late here as I see you posted your original question 28th Aug and perhaps you are finshed your engine rebuild. It has been a few weeks since I last checked the forum. I was in the same position earlier this year when I was rebuilding my 1980 2.0L FI Spider engine and had an extra head from an 1800 engine, along with HC pistons from Vicks and mild perf cams from Allilsons. I checked out the numbers on the workshop manual and did the math. The following combination of head and pistons give the following compression ratios:
2000 Head and Standard pistons CR =8.1:1 (as we are all aware)
1800 Head and Standard pistons CR = 8.95:1
2000 Head and Vicks HC pistons CR = 10:1
1800 Head and Vicks HC pistons CR = 11.4
The above calculations are based off the values of bore stroke CR etc in the workshop manual. The only measuring I did was the dome on the HC pistons, so the numbers should be pretty accurate.
Bottom line is that using the combination of HC pistons and an 1800 head will result in a CR that will be too high, regardless of what perf cam you use. The igniton will have to be set late to avoid detonation and that will cancel out any potential performance gains. Also with late ignition timing the exhaust temperatures will be higher than normal. I ended up using the 2000 head with the HC pistons (CR=10:1)

// Brian.

[TomS]

Thanks Brian, pools are what we do. I haven't even started the work yet, the information you have is very helpful, what size domes are you talking about?
Thanks Tom

[BrianAz]

I measured the dome on the Vicks HC pistons to be Height = 8mm, Diameter at top = 35 mm and diameter at the base = 62mm.

// Brian.

[TomS]

After looking at all options, I have decided to go with the IAP flat top HC pistons and the 1800 head. Mild intake cam, stock exhaust cam. Single plane intake and 34adf. Marks header and exhaust. Thanks everyone for all the input.

Tom

[So Cal Mark]

if you use both of my street perf cams you will have a very good street car with gobs of power from 2500 to 5000 rpm

[RJ80]

Mark, assuming a swap to the earlier air injection system to retain a functioning smog system, would a '79 2L have any chance of passing CA smog with an 1800 head, 40/80 cams, and a 34 adf? I imagine creative carb rejetting would be required at the very least, and of course the catalytic converter would need to be present...

[So Cal Mark]

the 40/80 cams are too agressive IMHO. For a Calif smog test all of the equipment needs to be in place, so the air pump, egr and catalyst all have to be intact. Fairly lean jetting is also needed for the test.
We have several customers with our exhaust, either 32/36 dfev or 38 dges carbs, our street cams and 1.8 heads that pass the smog test without much trouble. The cars are pretty fast as well.