Inliners International Forums General Discussion Hi Performance Head work

I was wondering if anyone knows of a good place around Western NC to have headwork done on an inline. I was thinking of having them ported and polished because I know this is one of the weaker links in the inline and I still haven't done it. What kind of gains would I be looking at by doing this. I have a 270 Clifford cam, Clifford intake and a Weber 38. Last I would like to know what is a reasonable price to have decent work done.

Check with Precision Engine Service in Waxhaw, NC. It's near Charlotte, not exactly in Western NC but well worth a trip. PES is run by the Norwood family who have done fantastic work on Inline heads for many years. Head work tends to be costly because of the hand labor involved, but the improvement in flow is very worthwhile.

Back in the mid 1970s Street Rodder magazine had a story on porting 235 and 261 Chevy six heads.For oversize intake valves use the ones for a 1950 to 1952 Powerglide engine (1.92).For oversize exhaust valves,use ones for a SB Chevy V8 (1.60).
EvilDr235

Okay, here's a question that is not to far off topic. I am getting ready to warm up a 1970, 250 six. When I switch to the 1.6 exhaust valves do I have to put in bigger seats, or can the originals be machined to take the larger valve.

According a dyno-simulator computer program the bigger exhaust valves add 6 hp.

If you can get 5 hp at the carb, 5 at the exhaust, 6 at the valves, 8 at the cam, et, pretty soon you've gained 50 hp, and you still have a very drivable/depedable engine. 50 hp is a 30% gain on an average 250, and that is a BIG bump.
Thanks,
Bob

The problem with using a 1.60 exhaust valve in the 235/261 is that the valve shrouding will get much worse and you will need to remove enough chamber to cause at least a 1/2 point drop in compression. If you are going to use forced induction or custom pistons, no big deal, but do the head first before ordering pistons so you can get an acurrate volume measurement on the "new" chambers.

Considering the potencial costs of significant head work as well as custom pistons, you may want to concider turbocharging. It would prove to be more bang for the buck, in my opinion. 300 hp should be doable on pump gas, but you'll never get close normally aspirated.

the 250 inlines have bigger valves from 78-80 so rather than upgrade the valves to 1.6, just get a newer head and problem solved...I'll be doing that soon, getting a used head, getting it magnafluxed then if its good i'll port'n'polish it and custom fit a 2BBl to it....

The only problem with the newer heads is that they have intergral intake manifold. From what I hear, they are very prone to cracking. Not to mention that you'd be stuck using that intake and couldn't go to an aftermarket one. John

it is true that the head has an integral log, but i have never heard of a log cracking and i am a member of three different inline forums, and have read almost all the posts...if your mechining skills are ok and you are sorta creative, then if u want to add an aftermarket intake all u gotta do is get a shop to cut the log off, then tap and bolt on a custom plate, made of aluminum and u can easily bolt on an aftermarket intake...or even make your own intake...enough people have customized their integral intake to accept 2 and even 4 BBl carbs...i still think it would be a better way to go than have to worry about valve shrouding...check out my website and then click the link that says 'inline fever' that takes u to the main page and then look at the stuff he made for his engine...

Remember guys, both Ford and Chevy made 250's. Clarify which one you're talking about.

thats true...i'm talking about ford...i dont know if chevy heads are the same or not, just with the intake on the other side...

I was talking about the Chevy 250.

The integral Chevy heads are rather thin castings and do crack. If they have ever been hot, they are most likely cracked.

I guess thats why they say 'built ford tough' and not 'built chevy tough'...hehe...

No, that's whay they say "Built Ford tuff, with Chevy stuff."

nice try...hehe...got no chevy stuff on mine or any other ford i seen...so there...