You had an adapter plate on it today when I looked at it?

If MPG is the goal H pipe as close to the collectors as possible. 2 1/4" - maybe 2 1/2?"

What is the specs for the valve lash? Set it cold tomorrow to the hot spec. If you get out there when it warms to 20*

Where did you set the cam?

I do have an adapter on it, never got around to machining the manifold for the TQ.

I set all the valves to .010 when I built it just to get it going, I know that isn't quite right but wanted to get it going and didn't have time to look up the specs. I will find the specs today and re-do them.

The cam is in it's factory position. I could not find real good specs for it so I put it in how the factory would.

I'd be hesitant to put a header with a 3" collector on something that small. It will kill torque. For what you are attempting I'd either build a custom set of 1 1/2" primaries with 2 1/4" collectors or I'd go back to manifolds. That is way too much header for that engine. This is fuel economy err on the small side rather than the big side.

How about a set of Spit Fire Tri-Y headers. I think they are 1-1/2" primary and a 2.25 or 2.5" collector,

Low rpm tq is great, it is when it starts turning over 3000 that it just falls flat on its face

I put 2.25 duals with an H pipe on it today, no muffs yet.

The exhaust smells like exhaust from a new car

I pulled a couple plugs and they look better than when I put them in.

May be pick up a LM1 to tune the carb with ?

I missed a few posts when I read it before. I dont see a problem with the TTI's. Maybe they are a little big but I wouldnt go and replace it.

I still think the LM1 is the way to go with tuning but I would also get a hold of Demon Sizzler and ask him for some TQ advice.

For mufflers I would add some straight throughs.

On my totally-stock 74 318, I installed TTI's step headers AND their 3" H-pipe duals. These goodies replaced my previous 2" duals w/o x-over, and 318 logs. Carb at the time was a cruddy TQ from an emissions 440 that ran pig-rich, and I can tell you there was NO loss in bottom end with the new way-oversized (by conventional wisdom) pipes. I think the benefits of the headers vs. mani's will far outweigh any potential loss due to oversized pipes. If I was building the 273, I'd either run a big fat single exhaust with a Flowmaster Y-pipe, OR duals using some long cone reducers from the headers down to like a 2.25" tubes and an X-pipe.

If you know how many HP you're working with, you can hit the Dynomax catalogs and find mufflers that provide unrestricted flow up to that number for singles or duals. Very helpful info.

Clair

Hey hotroddave how low do you figure the torque peak on that motor is?

I have found with my 5.0 mustang that if I can only go 65 mph, it actually gets worse mileage in 5th gear than in 4th. This is with a .69 overdrive I think and a 3.08 rear-end. You said you were considering installing an overdrive. The 518 is a similar ratio and you have 2.73s. If I am going 80mph the mileage picks back up in 5th gear, but I have found when I spin under 2k rpm at cruise, or especially under 1800 rpm, the mileage drops off.

Be interesting to see what you come up with.

The way I figure, the tq peak on the 273 motor the cam came from was 1600rpm. I have a few more cubes. I think relistically it should peak about the same but make a few more pounds when just running on the primaries. I do have headers and a 4bbl so it might make turn a little higher but not much and only when the secondaries are open (very rarely during cruising). Right now going 75 I am turning over 2500 so I don't think an OD will hurt me, it should drop me right around 1750. The headers are staying because this car is eventually destined for a 500hp 416 stroker after a few months of this experiment

Very good thread. You lean burn guys , would an MSD ignition setup help on getting a clean burn?

I think it would help, if I had a few bucks I would try one but I am jobless nad broke right now.

A couple other things I am going to try when I make a little more money is screens over the intake ports, an MSD, and an Offy dual port manifold.

I am really suprised how clean it smells, almost no odor at all! I am not takeing any chance and running it in a closed garage or anything.

I have done it before with aluminum window screens and it did not cause a problem even when one of them did go through the engine I never knew it till I was swapping manifolds . If I do it on this motor I will use the gaskets that have the screens built in.

i think the intake you are looking for is in the trade and swap section

Well aparently somehow while the distributer was out of the car from the last engine to this engine the points gap was messed up. tightened the gap a ton to a .017 gap and now it pulls hard to 5000 with only the primaries hooked up

The intake in the trade section is a port-o-sonic, I am looking for a dual-port.

Thanks though.

sorry about that

Speaking of intakes, I know that in order to use a later model intake on a '64-'65 273, the bolt holes need to be modified. Can anybody guide me through the process, step by step?

My curiousity is piqued...how long till you have some mileage #'s...cause I get to add almost 30% to them! (The US gallon is 3.78L...the CDN/Imp gallon is 4.54L)

OH! And gas here is about $4.45/US gallon, and our dollars are near equal...

Might be a while, the headers just burnt through the speedo cable and no money to replace it, if it ain't one thing it's another.

I think I will go out and reset the valve lash .010 intake and .020 exhaust, that is the factory 273 lash specs and I set them all at .010 when I put the motor together.

I am not super concerned about the miledge till I get everything sorted and the motor is broke in real good. In all my tinkering and peeling out and such it has not moved from the full mark yet