angcobra

Should be okay, just won't see the gains you expect until you get the air and fuel to the heads and exhaust out of the heads.

RR69

Thanks, I'll prob do it in two stages. So hopefully by the end of the year it'll be done.

Mustang88LXKid

go with 1.6 rockers, there have been tests done that the 1.7 loses some of the low end the 1.6's have.

comp XH270 cam
holley upper and lower
afr 165's

sounds like an awesome combo (I'd recomend that cam, but you can go with what ever you want)

matt

91hatchgt

Well if you get the right cam with the right duration, you should be able to keep the bottom end, and gain a lot of mid and top with the 1.7's... This is why the stock cam works so well with the 1.7's because of the duration match.. The stock cam is great for bottom end, I am not touching my cam, and doing about the same mods.. 1.7's Trick flow up/low and AFR 165's ... 58cc versions..

RR69

I may keep the stock cam depends on its condition though. I'm not sure why one oy sets of valves don't operate. So when I have so time I'm crank the engine over when the intakes and valvecovers off to see if the pushrods are moving. How come you are choosing the 58cc heads, won't that raise the compression more? I'm just wonderinh how much it raises it. Thanks for all the help guys

91hatchgt

Yes it will raise the compression. It will raise it to about 9.65:1 CR... From a 9.0:1 So It will change noticably, this makes for more compression in each cylinder which = more power! the 62cc's are good too though, just not as high of compression.

RR69

Will rinning the 58cc heads make a noticeable amount more power? Do you have to run higher octane fuel for the 9.65:1, or can you get away with only midgrade, just wondering.

angcobra

You should be okay either way on premium fuel. The difference is if you want to add force induction or put more timing into your tune. The higher compression is more likely to have detonation with FI or higher timing. That's why many folks stay with the lower compression. The dyon tuner I use said, with the lower compression and NA he could put more timing in and have more HP gains than the additional compression gave.

RR69

Alright, I'll probably stick with the 61cc heads then. Thanks