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| 225 top end choice https://www.slantsix.org/forum/viewtopic.php?t=62180 |
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| Author: | bigcasey123 [ Fri Apr 06, 2018 7:30 am ] |
| Post subject: | 225 top end choice |
So I have been talking about building up my dart for a while now but I never could because I needed it for transportation. Now I have another truck so I can park the dart for a while. I can now make it a little more radical then before because I don't have to drive it every day. So I'm planning on a stock bottom end. It's a 69 so the crank is forged. If the pistons are rough I would replace them. So just a basic bottom end. The top end is where I have questions. I would shave the head (and block if needed) to get to 10:1 compression. Port the head. Get headers. I have a super 6 intake with a holley 500cfm 2bbl carb. So I was looking at cam grinds from ogc and I was reccomened the 819 before but the 215 looks just a little better with higher lift and duration and a 108 Lsa. I'd be okay with a rough cam. I'd like to run the intake and carb I have now though so I want the biggest cam for that carb setup and my stick sized valves. Which is my next question. I'm not on a set budget but I'd like to keep the cost low. Should I go with bigger valves or just port the head. |
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| Author: | DadTruck [ Fri Apr 06, 2018 10:18 am ] |
| Post subject: | Re: 225 top end choice |
when the Engine Builder valves were around, it was an easy and economical choice to almost always go with OS valves. However, without the drop in OS valve option, to keep it simple and easy.. I would stay with the stock valves, spend the money that you saved by not buying valves on a good multi angle valve job,and get a back cut on the intakes, upgrade the valve springs, clean up the port bowl area and call it a day. Have the machine shop check the valve guides for wear, those may need attention and work with them and Oregon cam on spring pressures. |
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| Author: | sandy in BC [ Fri Apr 06, 2018 11:46 am ] |
| Post subject: | Re: 225 top end choice |
Although not drop in: SBC 1.72 intake 1.50 exhaust valves are an inexpensive option. When the machine shop did the work on my head I asked for and received a "bowl hog" They had no problem installing Chev valve springs and retainers at the same time. .....at least they knew SBC head stuff. |
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| Author: | bigcasey123 [ Fri Apr 06, 2018 2:14 pm ] |
| Post subject: | Re: 225 top end choice |
Okay. I'll spend the money on the valve job and good porting. Will any machine shop know the proper way to port one of these or are there special quirks that I may have to take it to somewhere special |
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| Author: | DusterIdiot [ Fri Apr 06, 2018 2:21 pm ] |
| Post subject: | Re: 225 top end choice- a few more comments |
Quote: So I was looking at cam grinds from ogc and I was reccomened the 819 before but the 215 looks just a little better with higher lift and duration and a 108 Lsa. I'd be okay with a rough cam.
I see the 218 but not a 215 in Mech lifter lobes... if you are going for a true 10:1+ then you will need more than the 218...think more along the lines of 1416 with a 108 LSA or 791, 346 also works on a 108 LSA... 346 will have a little lump... Set for about 102-104 intake centerline... be advised the cam will also want a bit more rpm to be in the powerband...so time to ditch the 2.76 highway gears for the 3.23's...If your bottom end is used, you will need to really look it over...10:1+ will want good rings and the deck and head to be flat to make sure the head gasket seals right...it would not bode well to read a post where you got it all back together and lost the rings on a cylinder a few hundred miles into breaking it in... when inspecting things, with the head off, you will want to check the depth of the pistons from the top of the deck at TDC so we can help determine your cut needed for your target SCR. With a .480- +/- lift you will be pushing the limits on the stock valves, going Sandy's route and blending the ports to match the intake will help (you will also be carving out the BBD mating surface to get best flow out of the Holley 0-4412...) I will bet that eventually a clifford intake will be more desired and more porting down the road once you know what this can do...to get the most out of the build eventually...for this build you will need to recurve your distributor for best performance. |
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| Author: | DadTruck [ Fri Apr 06, 2018 3:06 pm ] |
| Post subject: | Re: 225 top end choice |
Quote: proper way to port one of these
like any other, clean up the bowl, a good valve seat and back cut the intake valves,,, on the port arms, other than knocking out casting flash and hobernockles,, pretty much leave em alone also, if the valve lift is much above .450 (IIRC) you will need to trim the tops of the valve stems and are you staying with the stock pistons? If so, that is another reason to stay with stock valves, OS valves will be very shroud limited in a stock bore. one more thing you can do to help valve flow is, after you have the head - block milling done, bolt the head to the block and look into the bores and check the alignment of the combustion chambers to the bores. you may be able to fake the dowel pins / dowel pin holes to better center the head to the bores. once the centering is optimized, look to see if there is an opportunity to better unshroud the intake valve by relieving the combustion chamber close to the valves. |
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| Author: | Rick Covalt [ Fri Apr 06, 2018 4:01 pm ] |
| Post subject: | Re: 225 top end choice |
Project creep is always going to be a problem. Tell us what your end goal is and that Will help us give better advise. |
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| Author: | ceej [ Fri Apr 06, 2018 4:38 pm ] |
| Post subject: | Re: 225 top end choice |
Very few shops know how to port slant heads. The cooling passages are very easy to hit. Do a lot of research before turning somebody loose with a die grinder. Doc has some photos of band-saw cut heads someplace. Have a good look at those, and review them with your builder prior to heading in with the power tools. If you plan to street drive the car after your done, do yourself a favor and forgo the 500cfm 2bbl. Either run the 350 cfm version, or try an Edelbrock 500 AFB. The 350-2v will take a bunch of tuning, the 500-2v a whole bunch more. I doubt you'll need to adjust much on the Eddy. Maybe the pump shot. It'll get better fuel economy running the Edelbrock in most situations even compared to the 350-2v. CJ |
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