170 head question

[nater200]

i have my old 66 170. is there anything i could use off it for future upgrades upgrades (like mod log, multi carbs, direct mount 2v...) on my 69 250?

 

[FALCONAROUND]

NO, that 170 head will choke the schitt out of the 250 head.... Even modded for an offy. The 69 250 head pulls a lot more cfm than the 170.

 

[wallaka]

I would disagree. Bigger valves, port 'n polish, a big cam and the offy setup would flow pretty well and keep compression up. The '69 head isn't THAT much better than the '66 one. Stuff like intake log volume doesn't matter much when you have that much direct carburetion.

If nothing else, it's something you could experiment with.

 

[powerband]

I would disagree. Bigger valves, port 'n polish, a big cam and the offy setup would flow pretty well and keep compression up. The '69 head isn't THAT much better than the '66 one. Stuff like intake log volume doesn't matter much when you have that much direct carburetion.

If nothing else, it's something you could experiment with.

Sure seems there's many answers to the same question. I have a Dxxx head with Offy Tri-Power. It runs great and the advantage of carbs sitting on the intake ports is evident at WOT. I always remembered a remark made to me by an old-timer supposedly "In the know". He basically said : the larger volume intake runners of the later heads were not as good with the Offy causing low vacuum at low rpm. . I never tried to tune an earlier 3X1 setup but any tinkering will cause hours of fun stabilizing my setup. 8)

2Bbl's through adapters seem to work well , Maybe try a direct mount 2Bbl mod and maybe small 4Bbl for 250...

Have fun

 

[CZLN6]

Howdy Nater and all;

Ironically, the '66 170 and the '69 250 share the same exact valves and valve sizes. So if you're looking to glean parts for future build the valves, spring (?) and retainers could be used on a 250 heads.

Some 170 heads, commanly referred to as the "Kidney Bean" chambers are likely the best head choice if fuel economy is the priority. They have an as cast, tighter combustion chamber for higher CR. And the smaller volume intake tract makes for higher vacuum and velocity. So when you're saying "For future Upgrades", what is the goal of the upgrades you are planning?

What is the casting code of the 170?

Adios, David

 

[nater200]

c6de is the number on the block

 

[FALCONAROUND]

c6de is the number on the block

Velocity of the air charge is not as important as the AMOUNT of air you can get flowing into it... At higher rpm's that is... velocity is great at lower rpm's say 1,000 to 3,000 rpm's but volume makes a BIG difference from 2,500 to 6,000 rpm's

 

[wallaka]

Yep, and having big holes full o' carbs open right at the valves will let a bunch of volume through. Since the valve sizes are exactly the same between the two, there shouldn't be any appreciable difference. If you're gonna cut the log off like he suggests later in the post, the point is even more moot.