More low end and milage street 1500

[Guest]

With the 3.55 gear I figure it'd be nice to move some torque lower in the rev range. I never go above 5K and rarly do I go that high. Most cruising I do is 3000-4500 and I usually shift at 4k. I've been thinking about mods for a bit better milage and more low end torque, seeing I'm now loosing ~500 rpm at any given mph in 4th. I considred going from 30mm chokes to 28's but the car runs pretty good like it is.

I still have the 7.5 dish pistons in this engine. The head has been cut but I don't know by how much. So, I was thinking about a 1300 head with the smaller valves and ports. That should bump up my compression w/o having to cut the head and get special push rods. The smaller valves and ports should move my peak torque down lower and aid in better milage as well.

Peak cruise rpm should be around 4k and I'll probabaly still shift at that point. Most of the time I'll be at 2000-3500. Still considering the 28's with that head too.

Whatchallthink? Hap?

 

[nomad]

Does the 1500 head have the Westlake style combustion chamber? Assuming that it does I would go with flat tops to take advantage of the squish on the "Westlake promontory". Then I would change cams to one with a shorter intake duration. Higher compression and a shorter intake usually translate to better gas mileage. Read an article once on cutting a V shaped trench across the "promontory" aimed directly at the spark plug. Guy claimed great improvement in gas mileage because the engine would fire a much leaner mixture. Course he was offering the service for a fee so it may have been hockem!

Kurt.

 

[Guest]

Kurt, I'm looking at low budget, bolt on, finished in an afternoon modifications.

 

[billspit]

If you are going to use a Mk IV head, go ahead and do hardened valve seats, new guides, etc. You can also go with larger valves at that time. I seem to recall the MkIV head on a low compression 1500 gives a bit less than 10:1 CR. So it would work with 93 pump gas. Everybody says stay away from that head and high compression 1500 pistons as it seems to provide a CR of 10.5:1 or more.

 

[Guest]

Did any of the 1300 heads have hardened seats?

This is to hold me over for a little while till I can build the engine.

 

[Scott_Hower]

Did any of the 1300 heads have hardened seats?

Nope. 1500 CA spec was the only head with hardened exhaust seats (TKC1410).

 

[Guest]

Never woulda guess that. So NONE of the other 1500 heads have 'em?

 

[regularman]

With the 3.55 gear I figure it'd be nice to move some torque lower in the rev range. I never go above 5K and rarly do I go that high. Most cruising I do is 3000-4500 and I usually shift at 4k. I've been thinking about mods for a bit better milage and more low end torque, seeing I'm now loosing ~500 rpm at any given mph in 4th. I considred going from 30mm chokes to 28's but the car runs pretty good like it is.

I still have the 7.5 dish pistons in this engine. The head has been cut but I don't know by how much. So, I was thinking about a 1300 head with the smaller valves and ports. That should bump up my compression w/o having to cut the head and get special push rods. The smaller valves and ports should move my peak torque down lower and aid in better milage as well.

Peak cruise rpm should be around 4k and I'll probabaly still shift at that point. Most of the time I'll be at 2000-3500. Still considering the 28's with that head too.

Whatchallthink? Hap?

What rpm is high torque on the 1500? On the 1275 its 3000 rpm. Im running 65-70 at 3k in 5th gear. With a 4 speed you would probably be 60-65 at 3k.

 

[Guest]

Depends on the cam and carb. Mine should be ~2500-3K. What I'm seeing w/ the 3.90 500 RPM= 10 mph in 4th.

 

[Morris]

I have read somewhere (though I cannot site the source) that the 1500 in relatively stock trim makes max torque around 3500.

 

[Guest]

I have read somewhere (though I cannot site the source) that the 1500 in relatively stock trim makes max torque around 3500.

Depends on the trim. From the wiki:

"The home market's dual SU HS4 carbs were swapped for a single Zenith-Stromberg 150 CD4 unit, and the power fell to 50 bhp at 5000 RPM and 67 lb-ft of torque at 2500 RPM."

Found somewhere the euro was a bit higher in torque and RPM.

67 ft lbs, isn't that what the mains are torqued at?

IMO, and engine should put out more torque than is used to hold it together. :laugh:

 

[Scott_Hower]

Never woulda guess that. So NONE of the other 1500 heads have 'em?

Nope. Only the Cali-spec heads had them. Triumph called them "inserted".