ding56

I have a 68 289 that I am looking at doing a cam and heads swap. I have already installed a performer intake and a Holly 4 barrerl 600 cfm carb on and I am going to be installing Headman shorty headers and a flow master exhaust. I am thinking of installing a comp cam xtreme energy can and trick flow street heat 170 heads but want some suggestions on of they are good combo or what. I just drive her on weekends and around but I want some more power in the normal street rpm range.

Thanks for your help.

67mustang302

AFR/TFS/Edelbrock are all good, and some others. I'd spend a bit of extra money and get a custom roller cam.

Starfury

I like the XE line of cams, but they are a little more temperamental than some of the other grinds. For one, you need to make absolutely sure you have the matching Comp Cams springs for the specific cam. The XE grinds have a really steep ramp to them, which can cause problems if the springs aren't correct for the cam. I wouldn't rely on the springs that come with the heads. Also, you need to be very careful with break-in, being sure to use the proper amount of zinc break-in additive in the oil, and run something like Valvoline VR-1 for the life of the motor to prevent future cam problems.

Which cam are you looking at? There are many XE grinds, each tailored to a specific driving application. Which cam you pick should depend on your transmission (a/t or m/t), rear end gear ratio, and your intended use for the car (cruiser, street/strip, etc). You also need to factor the bottom end into your choice. If the bottom end is stock/original, you won't want to push it much farther than 5500rpm (if that). If it's been rebuilt with ARP hardware, balanced, etc, you can safely consider higher rpm operation.

Twisted Wedge heads are pretty nice. I run them on my 331 and I like them. They'll allow you to run more lift than you would be able to out of a normal set of heads without valve reliefs in the pistons. The altered valve angles also allow for more flow at lower lift than a standard set of heads, which should help you more than, say, a set of AFR's. Trick Flow does recommend drilling steam relief holes in the deck of the block before installation. I did it on mine without any problems. Just make sure you get yourself a good carbide drill bit and keep it oiled with some penetrating lube (and keep the shavings out of the cylinders).

Keep in mind, you need to factor in some additional parts for the project, including new hardware. ARP head bolts (conversion bolts for putting 351W/aftermarket heads on a 289/302), roller rockers (not required, but recommended), lifters (you can buy them as part of a cam/lifter kit), and special length pushrods. You may also need thermactor emissions port blockoffs, unless you still have your car's emission system hooked up.

Pushrods are a little trickier with Twisted Wedge heads. Due to the altered valve angles, you're going to need 8 of one size and 8 of another. And you'll need a good adjustable pushrod length checker to figure out the proper length once the heads are bolted up. Comp Cams makes a pretty good one for ~$20.

barnett468

hello

are your pistons dished or flat top?

are they orig stock style with the small valve reliefs?

what are your rear gears?

are you willing to change them?

what is your trans?

do you want a fwy flier, drag car or inbetween?



AFR heads. you are looking at the 58 cc chamber 165 or 185 renegade heads. they will have to be milled slightly to get the optimum compression.

the xe cams are xlnt.

the xe268h is common for a moderate 289 - 302 bulid. the xe274h is WAY too big for a 289 and 302 unless you have over 11.0 static compression and at least 3.73 gears.

Starfury

I ran the XE268H in my 331 previously, and while it made good top end power, I'm actually happier with the Magnum 280 and Rhoads lifters I run now. The Rhoads lifters give me more low-end than I had before the swap.

barnett468

yeah, if you wnt a performance engine the xe268h is way too mikd for a 331. it is a bit mild for a 302 also.

for some reason, there seems to be a huge jump between the xe268h and xe274h cams in how they perform even though the specs are not that different.

the xr274h is great in 347 engines and in 331 if you have enough compression and want a "big" cam but i would advance it 2 degrees in a 331 to mellow it out a hair.