Hi this is Scott, i need some advice on this rebuilt 1975 360 small block that I got last week for 400 bucks. When i got the motor it was a long block with no oil pan, the block is 30 over looks like stock rods, stock pistons, the heads are i think the smog heads with the ports plugged. the cam is mopar N 1138 witch translates close to crane cams duration 288 / 292 lift 458 / 465 RPM range 2,500 to 5,500.

Ok my questions are do i use the windage tray?
the red 360 heads are what came on the motor looks to have a little port work, but the valves seem to be different on both heads, plus the smog holes are plugged.

OK I have a fresh set of 340 X heads but the springs seem to be a lot tighter, than what is in the red heads, can i use the Xheads on the stock 360?

would I need new pistons with the valve reliefs? thanks Scott

 

Welcome Scott.

Easy and tough question at the same time, you've got the makings of a nice engine. My first response is a question, what is your intended usage?

I would first take all 4 heads to a competent machine shop disassembled and crack checked, it would be a shame to find out later. Have the guides checked and spring pressures to know what is compatible with the cam you will run, maybe bigger.

Biggest question is compression wanted, goes to pistons and notches. You could put a head on with clay on the piston run it through some revolutions and see what valve to piston clearance you have. With the three components shown, small lift, piston in hole and open chambers it will probably work but your compression will be very, very low.

As far as windage tray, if it is stock pan no extension or baffles definitely yes.

 

Just teasing, but stock pistons in .030 over holes will make this engine a mosquito fogger.

 

1975 360 is a smog motor Low compression.... If you can do mechanical work Check how far down in the hole the pistons are? Probably .050 below which means about 8/1 compression.. Smog holes being pluged doesn't matter but I would use the X heads & have them checked. and have either the intake or the intake side of the head matched to the block CC the heads to 64cc Carefully disassembly, Deck the block .050. A 2500-3000 stall converter and 3.55 gear

 

Hi the 340 X heads have been checked and rebuilt ready to go so I think i am going to use them. I am thinking about swapping to some form of hyper piston, and a whiplash cam from Hughes, also there matched springs, lifters, new pushrods, and my Eagle sir rods then a rebalance, maybe put on the Harland sharp rocker i have in a box some ware but that might be over kill for a cruiser with a 727 and 355 gears. My indented use is just a cruiser that my sun and I can take to cruise Ins.

 

They have Step Dish and Quench Head pistons available.

 

Being that this is just going to be for cruising I went with the Hughes Whiplash cam, meant for stock pistons, double roller timing chain, matching springs, lifters and the X heads. Did not want to go crazy with a mopar 367 Cid stroker in the works, the very slow works.