273 head choice ?
- Thread starter stoot
- Start date
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Haven't but they work.
302's are a power loss compared to early 273 heads, unless they are ported. Magnum intake valves are too large @ 1.92". From the guys who race, 1.84" intake valve is optimum for the 273. If you don't have any heads, any 318 heads will work.
66-67 #920 heads are probably the best 273 heads. They are closed chamber like the earlier heads.
234 273 (also used on 318 truck/industrial engine) work too. Also closed chamber.
Just curious, do they go up to 1.60 exhaust valves to bring the seat height back up? I imagine if they’re using some of the value priced 5/16 stem Chevy 305 valves they’re getting really good bang for the buck.
65TerrorCuda
Well-Known Member
302's on 273, I like them. Not a huge difference from the original '65 closed chamber that had been on there
I believe @perfacar raced 273's and I think he would know. I'm not sure you would need the 1.60 exhaust valve. I'm just getting back into research, but I am looking at 5/16 or 8mm valves for cheap, light, and quality alternatives for valves. The +.100 Magnum valves look interesting. I always used Chrysler or aftermarket stainless steel valves with 3/8 stems, but that was a long time ago.
One of the bonuses about Magnum heads is the smaller stem size.
What year 273? 66 and newer heads will need a intake to match in case you have a 64 or 65 engine.
It's a 65 block I don't have the heads but I do have several options with stock 318 heads
It depends on what level of performance you are going for. The 273 bore is quit small and many 340-360 heads with 2.02/ 1/60 valves don't play well with those small bores.
What I was thinking was to go with the 302 heads with 1.88 1.60 valves
If you want to go with 1.88 intake valves, I'd go with milled 360 heads. Much better flow.
MOPAROFFICIAL
Oogliboogli
With all the right work done... that's the best bet for the 273, aside from the 920/234 heads.
It's time consumption is similar to turning 1.88 360 heads into well flowing 2.02 pieces.
bigrobsRT
Well-Known Member
I have 302 heads on my 273 with a weiand stealth intake.
How much power you looking for stock heads are good for about 300 hp mild porting get ya 20 hp more. I’d go with milled 1.88 valved 360 your gonna need less cam to get to get the power and be more overall streetable. As long your not shooting too high. 300-350 hp.
Don’t forget 273 are gone need to rev to reach those numbers.
Your not gonna find too many 273 builds look at 2v 4.6l ford builds for something you want and translate it to Chrysler parts.
Don’t forget 273 are gone need to rev to reach those numbers.
Your not gonna find too many 273 builds look at 2v 4.6l ford builds for something you want and translate it to Chrysler parts.
I don’t know how the the early 234 head ports compare to the 234 industrial 318 heads, but the industrial head ports look immeasurably better than 302 casting heads. My machinist confirmed that he can block the water crossover on them. They look like some 11/32 stem 1.82 (305 Chevy) /1.60 exhaust stainless valves and some porting could make them very good for a 273.
Yeah, I would run the 920 or the industrial heads over the 302 castings. On my engine I blocked the water crossover with 0.010" shim stock and rtv and used the thicker felpro 1243 gasket to take up the variance on the gasket face and it sealed up well.
To the OP I'm not saying the 302s won't run well but they would probably want a bit of work done. if your set on using them check out moparofficials thread - some good info there.
perfacar
Well-Known Member
the poly head 318. had 1.84 int and 1.56 exh valves, by using this size ,you don't have shrouding around the valves down in bore,. shrouding causes flow loss and port velc.,i test on a flow bench. also, i cut the margin back on exh valve , helps int flow. and radius the edge of valve. just food for thought.
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