273 buildup

[dtack64]

Hello
Was just wondering if I could get some input on an engine buildup for a 69 dart.
The proposed combo is as follows
-'65 273 block crank and rods
- approx 10-1 compression
-late (308) heads
-mopar single plane intake
-600 cfm carb
-1-5/8" headers
-mechanical cam with yet undecided specs
I know this will be a high rpm engine, and I am hoping for a vehicle weight around 3000
thanks for any help as this is the first hipo engine I have built

[toolman]

Do you already have the 273? Why not use a larger smallblock? Even a 318 could get you more power.

[GEARHED]

unless you already have a 273 or you are really attached to it, I would step up to a larger smallblock 340/360. You can make good power and not have to rev it to death to do it.

[Head Crash]

I say go ahead with the 273. I did one for my '67 Belvedere and had a barrel of fun with it. Everybody is building 340 or 360 small blocks. Seeing what you could squeeze out of a 273 is a challenge. One fellow here races a '67 Dart in the 12.20 range with his 273.

[rumblefish360]

To be honest with you, that single plane may be a bit much for the little eng. The intake has large ports where the head dos not.
The intakes range is on the strip side of its performance level.
A better intake would be a Torker II or Holley street Dom. The rpm range is more suited for what you allready have. Even if the cam is undecided. Remember that because the eng is smaller, it will react differantly than a 340-360.
The cam that gos rumpty rimp in the larger eng. will be much more radical in the 273. It's rpm range will also go up because its smaller.
The 600cfm is a lot for it. You would need a lot of gear and rpm to use that much. A 500 would be better. (for the street)
Also, the 1.88 intake valve will hit the side of the cylinder bore if you do not notch the bore.
Let us know what your thinking of useing for a cam. (specs)

[dtack64]

thanks for the intake tip. as I said this is the fisrt hipo engine i have built so I'm not certain on anything. cam wise I was considering mopars 276 duration .490 lift cam or trying to find a copy of the old hipo cam. either way since the mech. rockers are there I will probably run a mechanical cam
(sorry meant to say rockers instead of lifters)
[This message has been edited by dtack64 (edited February 02, 2001).]

[This message has been edited by dtack64 (edited February 02, 2001).]

[cuda367]

You can't us your old lifters. The new cam will be gone before you can road test the car. Use a 318 block with your heads, the compression will come up. Have the 360 valves installed, and then all of the rest of your plans will come together nicely.

[rumblefish360]

That MoPar cam would work well in there. The HI-PO cam was rated @ 284 duration. Since the cam tech of the time wasn't as good as now, that 276 is probrly larger.
Given that size cam in the 273, it will probroly make power from 3000-6000rpm.
To make good use of this cam will erquire a rear set like 4.10 's w/ a 26inch tire. There are variables to this as well.
NOTE...the Torker II is a large port intake as well. It will work the rpm range of the intake is better, but, a good dual plane thats modifided will work better. If you want the single plane, A numeric HI gear ratio is needed.
Also look at 1.6 rockers if posible.

[dtack64]

what do you think about the 308 heads, are they worth the trouble or should I look in another direction. I am trying to stay within a reasonable budget so aluminum is out of the question.

[BugEyedValiant]

Dont build the motor just yet. Check the pilot hole for the torque converter. If you are using this crank, the 67 and earlier had a smaller diameter hub. And dont think that you can use the early model tranny because if I am not mistaken, the early trannies had a fewer spline count on the input shaft and you would need and even harder to find converter. I may be wrong about the spline thing. I know it holds true with the 727s, but I also think that it goes with the 904s too. I am sure about the hub diameter.

[pishta]

Go with a 302 head, smaller valve, better velocity, more punch. Don't if it was a 4bbl motor due to pop up pistons and quench on 302 heads! Watch the intake bolt angles, 64-some 65's 273 heads had a diffrent intake bolt angle, requiring you to clearance each intake bolt hole with a grinder. And remember to remove the intake manifold dowel(s) before putting on that (too big) aluminum intake on.

[rumblefish360]

dtack64;

pishta wrote about pop up pistons. Do your pistons pop up out of the cyl. bore. If there flush or pop out of the block, a open chambered head will need to be used. If the piston is down in the cyl. bore, a closed chamber head can be used. This will effect compresion ratio. Lets keep it under 10.0-1 for ease of fuel.
And a smaller valve will keep the velocity up for better throttle response. (smart) A 1.88 can be used if the build up is to be one of higher HP. This is where the larger valve will pay off.
The 308 cyl. head is fine. A braket valve job should be all (at most) you need to start. The head - intake combo he's talking about is a point to watch if your useing the stock heads and a aftermarket intake combo. If you use other heads and intake together, theres nothing to worry about.
If your going to use your stock heads with the oddball bolt angle, (if thats what you have) I know where to get this intake. A local speedshop has one NEVER used. The intake was purchased by mistake. Then put on a shelf. The intake is an Edelbrock dual plane for the oddball bolt angle.
BugEyedValiant made mention to a possible tranny problem. There have been posts about this before. Look for them. The old trannys are a little differant. I don't know the fine points about it. Some have had trouble with them lineing up or was it hooking them up. I forget. Go look.
It has to do with newer crank to older trannys I believe.

[RDABIKE]

I had a 67' 273 that was built quite a bit. I even had a set of Mondello ported and polished heads and intake. As mentioned earlier the crank has an extra small piolt hole and will not fit a standard torque converter. I was able to put a 727 behind mine by having the converter custom made with the small end on the front to match the crank. You could also use a forged 318 truck or 340 crank in this one. Doing it over I would use a built 904 trans. While it was fun to run fast and have people amazed that it was only a 273, I would do a 360 or even a 360 stroker again. You can run just as fast for far less money invested with the extra cubic inches. Ex even built to a conversative level of 1hp per cubic inch, a 360 will make 87 extra hp, a 408 stroker 135 extra hp.

[dtack64]

shouldn't there be enough material on the crank to drill it out? the engine was originally the low compression two barrel, but I am planning on aftermarket pistons (probably flat tops), so i don't think chamber design should be a problem. as far as heads go no matter what i am upgrading to the later heads so the oddball intake bolts wont be a problem.

[Billydelrio]

Yes, you can open the hole on the end of the crankshaft to fit later torque converters. I did it to mine a few years ago.
Billy

[Duffys Ramcharger]

If you go to the scrap yard and get a set of heads off of an 89 to a 91 318(pre magnum) would be your best bet. Mostly because of fewer valve jobs and being newer, their design is as good if not better than the 70's. Also ported, they flow better than the 360 heads.

[Alan627B]

As far as smallblocks go the Edelbrock heads aren't a bad deal at all. Consider that if you have to have a lot work done on used heads you could burn up a grand fairly easily. Add porting costs and the Aluminum heads look pretty good. I am pleased as punch with mine even though I won't know for sure until I gwt them in the car and get them to the track. I haven't heard anything bad about them yet though.

[rumblefish360]

Alan;

You can't put 202-valved heads on a 273. He can only go as far as 1.88.
A grand should cover the cost of rebulit heads with a pocket porting job. Even springs and valves.
More than enuff for a 273.