It would be interesting to see it run but seems like a lot of work. The block will have to be notched for the intake valve at least, possible the reliefs in the pistons will have to be machined. There will be a mismatch on the chambers and bores along with the head gaskets. What cc are the chambers sizes on both heads?
I have the 920 closed chamber heads on the commando 273 now . I believe the chamber size is 57cc . stock standard bore 10.5:1 pistons size . appears tf's are 60 cc
And there isn’t a problem With what’s written in BOLD? Better yet.... the underlined.... faster with h a bigger engine.... I guess you gotta wanna do a 273. That’s OK though. Ya gotta wanna do a 6 pack too!
Your not gonna find to much on 273, I'd look up 4.8l LS, 4.6l and even 289 builds see what cams heads etc.. and how it effects the rpm powerband.
Trick flows won’t fit the small bore. An excellent idea for sure. Researching engine builds via old magazines or the current format of you tube videos of smaller engines is a good idea. To the questioner, @stroker402 , I’d just look carefully at the components used and how well they flow over your equipment. After all, the engine is an air pump and higher or lower flowing parts can have a big effect on output. Ported heads will extend the power band, as well as a better intake, bigger carb, header tube size and exhaust if dyno’d with it. On a 273, the limiting bore size will require a notch in the cylinder wall to run a 1.88 valve (IIRC) so a well ported head and a 1.88-1.5 or 1.6 valve will be about the best you can do which should be plenty.
The 273 small bore will eat a lot of the heads potential but there’s really no way you could come close to using it anyways you have to spin like 10,000 rpms to do so, 350 hp would be about 6000 rpm, 400 hp 7000 rpm, 450 hp 8000 rpm etc.. I usually think people over worry about velocity but in this case it would be definitely a concern, one good thing is you probably could make big power for a 273 with a relatively small duration cam with a .500 lift, solid would be a good choice.
At .500 lift, the heads would or could still be close to stock with the valve job being most important and then the bowl under it. I think ..... pretty sure of it.... Engine Masters used a “Isky Mega Cam” to good results. Long duration means deeper breathing but yet limited by the lack of valve lift which doesn’t mean low performance or the in ability to make power. I don’t understand the small bore will eat the heads potential. Which head? Trick Flows? Which don’t fit...
I agree the most I’d use on a 273 is Magnum heads, but the guy only doing this as an intermediate step on his way to a 416, I give a trying if I had a 273 and the heads.
According to my Moroso slide calculator it looks like about 1/4 mile ET is approximately 10.45, MPH = 127, HP = 590-600 These are not set in stone they are approximate, your results may differ. Have fun !
Well without going through all the threads this has prob been posted before but here it is again> Only a dyno number, track results may vary of course but in a 3200 car with a good chassis/proper verter 10.50's is on the cards as you all know. Hardly anyone over here in the UK has woken up to these heads yet, were still in the crappy Eddy head stage or perhaps just getting over it?,...I've posted this up on my FB page some time ago, cannot see why, apart from the cost of the heads, SB guys aren't going this route, thats good hp from a 360 and you don't necessarily need a solid roller, there's more power there with a better intake/carb etc.
@Hot Metal , A better intake besides porting that SV is down to the Indy and a Tunnel Ram. IMO, I think he is doing pretty good. I wouldn’t mind seeing two intakes I listed being run! That would be cool for sure. As far as a better carb goes... maybe just more cfm..??? He does street drive it. I have to agree with you on the heads. Definitely a better purchase for power over an Edelbrock head. Your UK buddies will pick up on it sooner or later.
I went from a 750DP on my stock headed '71 340 to an 850DP and picked up 1.8 10ths, that was back in 1983 when it still had a 484/284 hyd. in it!!... gotta think outside the box sometimes and try stuff. That 360 combo was crying out for an 850>950 carb or better still a TR would've been best. Yeah I hope the guys here wake up soon, I cringe sometimes when I see the money wasted on some combo's that don't work well and certainly don't make much power, and I'm talking from 416ci motors. I don't think anybody has heard that they make a cam for a SB with more than .550 lift, I ran a .590" SFT cam on the street and didn't think it was too wild...perhaps my thinking is too hardcore for these guys, who knows eh.
@Hot Metal Yea, sometimes people are happy swimming in the shallow end. It’s all good. It’s not he lift that is rough on people but the duration that’s out of there comfort zone. Most also think there’s no room. Good heads like the TF and a sub .550 lift is a waste of time IMO but some guys like it. Why? I do t know. Why would you not take advantage of the flow the head offers? They could have saved money IMO with a lesser head and a low lift cam and it would still perform great. The wife’s TF headed 360 runs high grade pump fuel @ 11.6-1 with a Hyd roller lifting the valve north of .575 on a short duration cam. Drives like butter and runs really good up top. She’ll be in it 5 days a week driving it to work and around town.
You guys are making my old pig 408 that ran 9.80’s on pump gas BP93 gas, 750 carb, and .520 lift cam feel bad.
The answer is probably the class, plenty of cars, good all round fun and some cool cars but there 80% street guys having a go@Racing which is what I did and thats fine but put "street" into the equation and you get what you have, 190's won't make a car un-streetable, put a small dur/lift cam in there if you must and you've still got 280cfm of flow, thats what I can't get through to them.....Move up a class or 2 to ProET or Super proET and now you've got the combo's that run. John, your just in another league, you were running times with your Duster with 906 heads that some run here today with 540 -1 motors and that includes our car, along with the combo you mentioned above.
i have talked to Dwayne ( PRH) many times over the years and one thing he hammers on a lot is more lift isn't a big deal. He said almost never does going from a 1.5 to 1.6 rocker to gain more lift make any more power, or ET at the track. I am keeping my 565 gross lift camshaft to put in my 418 that was in my 360. Eddie heads. Its far from an all out combo but i bet it will run good. I could have bought another cam, 1.6 rockers, etc, but didnt. The old stock shortblock 360 ran as good with near stock eddie heads as this 530 horse trick flow motor did everybody is talking about with a roller cam and trickflow heads. My heads went 255...lol
