OK, this is for my LT1 383 build up I am doing.

So far, I have heard you need to do head work for the 383 so it won't choke the motor, correct. So, how much work? Are we talking like a valve job and some gasket matching good enough? I am not going for extreme power here, I just don't want to hurt the new motor. I was thinking of buying an abbrasives kit and doing the before mentioned items to them. Or how about LT4 heads. I could afford to do the same thing to them. The thing I don't want to do is spend thousands of dollars. Oh yeah, and I will be using the LT4 hot cam w/1.6 rockers

I am only looking for a nice street motor with good torque. Maybe around the 400 flwywheel HP levels. Last question revision. Is this level possible with the home porting job, I have all the bolt on goodies: headers, elec. water pump, 52m TB, etc.
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Thanks for all the help so far guys, this motor would probably never happen without everyone's help on this forum. I have already saved myself from lots of trouble.

 

Increase valve size to 2.00 intake and 1.56 exhaust. 400hp should be no problem. With good porting and a 58tb and maybe even with that lt4 cam you can hit atleast 440hp.


[Modified by BAM92, 11:56 PM 9/9/2003]

 

Sweet. That's what I like to hear.

Do you really think the 58mm TB is worth it over the 52mm. I saw that the 350 on HP tv didn't gain anything going from a 48mm to a 52mm. But however, I am going to a 383 so I understand the need for it. But wouldn't 58mm be overkill? I can get a 58 no prob, I just don't want to go overboard on if it is not going to make any more power.

 

Do a search on porting; might be something on "pocket porting"which is where you'll get the most improvement. If not there, try Chevy High Performance web-site on the subject.

:chevy

 

1) The concensus of opinion is to mod your LT1 heads rather than purchase the LT4 heads. It will be less expensive. If you go with LT4 heads, you will need the LT4 intake manifold, too.

2) Fully ported LT1 heads from major tuners run $1400 or more. This normally includes new valves and springs. The Hot Cam kit comes with springs and you may see if you can use your old valves although it would not save you that much.

3) Pocket porting generally involves smoothing the bowl area just below the valve seats, smoothing the short side radius, and a 3 angle valve job. This really improves the low lift flow and torque. Expect about 10% flow improvement for about $500+-. This is what I had done to my LT4 heads and I picked up 22 rwhp with no other mods. Since I stayed with the stock LT4 cam, it did not make sense to spend big money for fully ported heads since most of the flow improvement would only be realized over .500 inch of valve lift. I found a local head porting shop by asking the local dyno shop who they recommended. You may want to ask around in your area.

4) You need to understand what kind of flow numbers do you need for the HP. 400 flywheel HP is not that big a deal with a 383 and Hot Cam. But in my opinion, if you have the head off the vehicle, you are foolish not to have them ported.

For more information, see my website shown in my signature.

 

You should use springs tougher than what the Hotcam comes with, the LT4 has different valves than LT1 (the lt4's are lighter) and you would benefit from a tougher spring. Especially if you want to rev it up any. Though you can use those springs if you want. If you went with the tougher springs you can go to 1.7rr.

Pocket porting would greatly benefit that motor, even porting on a 350 will free 20hp up with the hotcam. Dont buy the LT4 heads.

Dont mess with a 58mm TB, the 52mm will feed the 383 well.

 

Cool. What about prices for getting them ported by someone. I am not in the price ability to spend $1500-2000 for some CNC heads, but any ideas for places to go.

Has anybody found an inexpensive place to get LT1 heads mildly ported.

 

Contact Trevor Johnson at http://www.tjcylinderheads.com. He is just outside of Dallas.

You may be able to have a local shop do a simple pocket port and 3 angle and save yourself the shipping cost.

 

Any machine shope will do pocket porting and a 3 angle, but if you want P&P take it to the pro's. When it comes to port work its not just gasket matching and grinding away. It has a lot to it.