I spent some time searching some Hemi topics on here and thought I would share a pair of 354 Hemi heads I recently built for a project I'm working on. I call them "Heinz 57" Hemi heads because they use a SBC intake valve, Pontiac exhaust valve, and a LS Beehive spring - a little of this.....a little of that. The sole goal was to lighten up the valvetrain while using shelf parts for a street performance oriented head. I took some stock 354 heads, installed some bronze Hot Heads 11/32 guides (thick liners could be used with stock guides), performed a good quality valve job (proper and matching seat depth is critical), and did a light surfacing to the heads to clean up. There was some extra machining to do on the guide OD to make a LS spring seat work properly using a spring pocket cutter and also machined for PC seals. I don't run seals on the exhaust side on Hemis, not enough oil there. The LS springs in general usually take a 1.800 installed height so matching that with a 5.160 length valve you end up with a nice setup that can still work with stock rocker arms. I used a PAC Beehive spring that I could get a little more seat pressure on for a final 1.770 installed height in this particular case. The SBC valves range in size from a 1.94-2.125 if desired at this length, just need porting done to compliment the valve size. The exhaust is a 1.770 and fits the exhaust throat size nicely when using a radius seat cutter. The exhaust ports are plenty big and flow around 190-200 cfm @ .500 lift with mild port cleanup which is sufficient for a mild street motor. Be sure to smooth the ledge on the short side radius. I did do a mild port job on the intake side and they flow 280cfm @ .500 lift. Nothing trick here like raising the roof just opening up the bowls to the last angle of the valve job (5 angle in this case) and widening at the pushrod walls a bit without breaking through. Just proper and sensible porting techniques. If you happen to break through no big deal just get a .014 wall bronze tube to sleeve it back up and seal with red loctite before installing. It may require you to use a reamer in the hole first for sizing, you need a slip fit. A 5.160 length is the longest you can possibly go with stock rockers so you really have to understand your boundaries here! The sweep pattern isn't optimal compared to aftermarket roller rockers but it does work without issue. I spent a long time mocking it up and checking geometry using non adjustable rockers. I think this is a really neat setup to do for a street motor and the springs can handle .600+ lift pretty easy if desired. If you need more spring pressure for a more aggressive hydraulic roller or solid flat tappet cam then you could look at the LS Dual Spring kits.These heads are going on a 10:1 354 Hemi that we are using to get some licensing passes done at Bonneville (if it will ever dry up). I did a custom grind hydraulic flat tappet cam for it that was a 236° @ .050 with .522 lift on a 110° lobe separation Thanks Chase at Crane! Anyhow just wanted to share a simple setup that I think many on here could use for their Hot Rod Hemi.
Wow, thanks for providing such real world detailed info. On the Pontiac exhaust valves - are they used just because they are the right diameter (1.770)? And are they the same length as the intakes (5.160")?
Those are the exact reasons. Basically opening up a vendors catalog and looking for something in the range for diameter and length. I'm glad you appreciate what I put out there, I have a feeling it will be a very popular way to build these heads. I build alot of Early Hemi heads so figure I would share a real world setup.
We will have to agree to disagree on the 0.600" lift as being practical with stock rockers. There is just too much rocker tip movement (sliding) across the tip to be a good thing. .
Nice work and that should work out nice for a strong street engine. While I don't have a Hemi, appreciate you sharing the info for others, as well as the basic philosophy of how you came about the mix of parts.
Thanks for sharing, this is great information. Question on the 1954 heads with the factory hardened seat inserts. Can these inserts be reworked to the 1.77 valve diameter or do the seats have to be replaced? How large can the diameter under the valve seat area be opened up with out compromising the inserts?
As long as the seat condition is fine I use the stock seats. They except this size just fine, even up to a 1.800. A 1.850 valve I may also fit but there really isn't a need for that size in a street motor, a blown Nitro motor sure. The only time I replace the seats are when Nitro is used but those heads are on a different level than something like this. The throat of the seat could be opened up as long as you keep the ratios correct. Typically the throat size or ID of 87%-90% of valve diameter on the exhaust side. Street performance stuff I err on the small side. I have gone 92% on the exhaust side but that was a extreme case for racing applications only. A typical valve seat cutter will not work to achieve that at 92% and even a struggle at 90%.
402bossman Little help if possible please... first 392 hemi... R these 2 valves good? 1] FORD Intake: 460 (1976-97) PN : S3168 Head Diameter - 2.083 Length - 5.1750 (but you said '5.160 max') Stem Diameter - 0.34190 (Chrome) 2] GMC/Pontiac Exhaust 350/400/428 (1967-70) - PN: 01-01097 Head Diameter - 1.775 Length - 5.090 Stem Diameter - 0.3410 (Chrome) Thanks,ed
On the exhaust side I do limit the lift (usually .530 or less) but the intake side can handle it just fine.
So I have gotten many PM's and phone calls over this thread and I would like to add a little more to it in hopes to clarify some things. Valve Springs: The LS valve springs in general are a nice fit whether a beehive or a dual spring. Just be aware if you use a beehive you need to have a mild lobe profile on the cam with a heavier 11/32 valve or limit your intended MAX RPM. Most beehive springs were designed around a very light valve so check valve weights in grams, I try to stay close to 115 grams where I can. Just be aware there are many variables that affect what is considered a safe weight especially when considering retainer and lock weight as well. It is also very important to run the best quality valve spring possible like PAC valve springs especially using a Beehive. When in doubt just go to a Dual LS Spring. Retainers are available to convert to 11/32 stem from the normal 8mm LS setups. The original heads in this thread have worked successfully to 6500 RPM running the Ohio Mile to date and wear looks great. Stem Height: The major thing when running a 5.160 valve - Stem Height is the real concern here. The way I do a valve job is most likely far different vs everyone else. I sink the valve job a bunch on the intake side so I can have a rather large top cut so the stem height (spring pad to valve stem tip measurement) will be far different than most. Or the other side is maybe the heads you have have been gone through many times and the seats sunk a bunch. The Stem Height measurement or spec is the real important number vs actual valve length since the valve job depth can be a variable. I may run a .050 shorter valve to compensate for stem height in my case. So this will bring it to the geometry side, 5.160 is pushing it to the outer limits. I will need to go look in my notes what the stem height number is that I would consider MAX and update. In the event that the geometry gets pushed too far using stock rockers and stands the other option is I offer Hard Anodized Billet Aluminum stands that move the shafts up +.100 and out +.150 to give better geometry and correct this.
Thought I would share an update to my original post. This setup has ran at the Ohio Mile and at Bonneville to get licensing passes completed up to 150 MPH. Ultimately it will end up in a street hot rod of his. It has successfully turned 6800 RPM on a regular basis without any issues. I also have developed an Offset Rocker Stand Kit to correct the geometry for this longer valve and for cams with much more lift. It's a complete kit (no need to chase down the other parts needed) that reuses the stock shafts and rockers, top notch deal!
Very cool....... Any chance you could post pictures of the port work you did on those heads???? Thanks!
I don't remember if I took pictures of this particular set, however I developed something even better. http://www.smithbergracing.com/?page_id=342
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