I have a GM goodwrench 350 with a mild cam in it with iron heads. Im looking at doing 113 heads and a comp XFI-268 cam. Im leaving the bottom end alone. Will compression be an issue switching to those heads? Is it worth it? Or leave the iron heads and do springs for that cam?

 

Fu&% yes its worth it. 76cc garbage iron deadweight versus 58cc aluminum and way more flow. Do it. Compression should be no issue cause the GM Goodwrench has dished pistons if I recollect anyhow. I imagine with that cam and 113 heads that engine will pickup 60-75HP over stock goodwrench engine atleast. Throw some flat top pistons in there you would pick up another healthy gain.

 

The Goodwrench 350 is usually a flat-tappet block and the XFI268 is a roller cam, unless you're using the flat-tappet version.

Either way, double check the cam lift, because those heads are usually good for about .510 to .525" lift max.

 

Yes it is flat tappet. And I was planning keeping it that way. Im pretty sure it has the valve relief pistons in it.

 

There is no reason to keep it flat tappet. Do a roller conversion.

 

I wouldn't build a non roller cammed engine for a daily driver i would be looking to put 100k on but for a weekend cruiser i wouldn't hesitate if that's what I had. LO5 trucks had them and they run forever.Just use the right oil.

 

Budget would be the only reason. And I dont drive it much weekend cruises and car shows.

 

The heads are on their way to me. They are fresh from the machine shop. Can they take the XFI268? or do I need to replace the springs?

 

That would depend on what springs they put on them. I would bet NOT however.

Any highly aggressive modern roller cam like that will need far more spring then is likely to come on heads not specifically prepared appropriately. IOW if you don't see a large upcharge on the invoice with a part # called out, you'll be needing to buy and install better springs.

Most likely the heads themselves probably won't either. Most likely, the valve guides need to be machined down. Like the above, if you don't see that on the invoice, accompanied by an appropriate charge, it hasn't been done, and needs to be. The retainers will crash into the top of the guides and destroy the seals, or worse.

 

great info. I have found the 113 heads will max out at .525 of lift and the 268 is .52 with 1.6 rockers. So i should be good with 1.5 rockers and the beehive springs recommended? If not I may step down to the XE274 and maybe LT4 springs. It has a little less lift and may be harder to tune.