Hope this isn't too far off topic. I need advice, don't know where to ask, and impatient to boot. Long story short is that Beaver Springs Dragway will be opening soon and I want to get my new motor assembled, in the car and run it a couple times before the Nostalgia Nationals. I have been collecting parts for years now. This is my first experience with aftermarket SBC heads. Bought a set of used aluminum cylinders that only had a few runs on them. No idea what brand, they don't have a name on them. Even though I put new springs, keepers, etc on them, it was way cheaper than fixing a set double hump 461's that needed everything. My old style valve covers fit and I thought my old style intake was gonna fit. The gap looks parrallel, so I'm doubt these have ben angle milled enough to cause this. Are these heads a "tall deck" version of some type? Do I need a set of "intake spacers"? How do I figure what intake fits? Will my Q-jet fit? Is there a manifold short enough to fit under my stock flat hood? Will my SBC distributor still fit height-wise? First photo shows with cork end seal on Fel Pro 1205. Second and third photo shows without cork end seal. At this point, I want to get it running with minimal $ on more parts until I see how this combination works. If anyone can get me started in the right direction, I'd 'preciate it.
Somewhat obviously, you need to raise the manifold. You could always mill the crap out of the heads to drop them to the desired height too. But that would depend on the deck thickness. BUT, what does that do to the bottom of the runner ? Have you measured the manifold runner height vs. the cyl. head runner height ? One simple measurement will tell you what you have. I doubt you have any sort of raised runner head. But obviously something is screwed up. IF...the runners are the same height, make a spacer (manifold to block) to raise the manifold to get the runners to the same location. Then center the manifold and measure the manifold to head gap. Make spacers to fit, remembering you'll need two...gaskets. If this were me, I'd return the heads to the previous owner and buy a proper set of heads. There's a reason the previous owner sold them..! Mike
Most modern aftermarket aluminum heads have what would be considered a raised port when compared to an old stock cylinder head....port roof is roughly .100" taller. That's how they get a lot of the larger port volume, since the pushrod width spacing eliminates just making the port as wide as you want. Don't confuse this with what is actually considered a race "raised port" head, which will have the entire intake port raised 1/2" or more, those are a different animal. Another factor is most old aftermarket aluminum intakes don't have much material above the original stock size port opening, which contributes to the problem. Looks like you've got an old Holley "Street Dominator" single plane?? If you looking for good power, not the best intake choice. Fel-Pro makes intake gaskets that are double thickness, .125" thick, but I can't say for sure that will entirely fix your problem due to the old intake. Fel-Pro #1266 is the thick version of the #1206 port size, and there is a trim-to-fit undersize port version #1245. A modern single plane that will make good power and fit under a stock 64-65 Chevelle stock hood are the Edelbrock Vic Jr, the Holley Strip Dominator 300-25, or the Weiand Team G 7530....but none of those are spreadbore Q-jet pattern. They will all also need a drop base air cleaner to fit. a flat base air cleaner is probably only going to get a 2" tall filter in there. Since your heads also have the Vortec intake manifold bolt pattern, you can go to an modern aftermarket Vortec pattern intake and the port height issue will go away since the manifold will be made for that height. Plus you can get several different versions that will fit a Q-jet....no single planes though, just dual planes. There are no modern single plane intakes with the Q-jet carb pattern....nobody really wants one, so nobody makes one.
Yes, just spent too much time on the internet to learn that SBC intake gaskets come in different thicknesses. Right now I think this should be a simple solution, except the thicker gaskets are out of stock at a large supplier in Ohio. Tempted to try double stacking, but won't. Quite impressed that you could name the intake from that small of a corner. I grabbed the Street Dominator for test fitting, I am running a dual plane Edlebrock in the car now. Right now, my Holley Q-jet is my best carb on hand. Time will tell if these heads were money well spent, I think they will be fine. These heads let me run old style valve covers and use my current manifolds which is why I didn't go with Vortec heads. There was plenty of time to second guess that decision today after I set the intake in place.
I’m going with what squirrel says. The gaskets would have to be a 1/4 inch thick! Sent from my iPad using The H.A.M.B. mobile app
Sorry in advance.. Vortec heads are way off topic.. That being said., the gaskets for vortec heads are very thick plastic embossed with rubber to seal the ports and water jackets. Pick up the gaskets for a 99 chevy pickup with a 5.7 vortec engine.. You will need the proper Vortec intake. Edelbrock sells them. Summit sells a couple of offshore made copies. If you insist on your spread bore carb you will have to run an adapter.. It will add approximately 5/8" height.. The high swirl combustion chamber combined with flat top pistons is a very stout package. Dave Sent from my SM-G973U using The H.A.M.B. mobile app
Double stacking gasket is a common thing too....use Edelbrock GasgaCinch or a similar contact cement to glue them together and they essentially become one gasket. I spotted the single plane lay-out, the vacuum port on the top pf #2 runner and the tail end of the slanted orientation cast-in name script and was pretty sure it was the old Street Dom intake that is more or less the same as the old Edelbrock Torker or Weiand X-celerator. All three aren't very good intakes for power when compared to either a Vic Jr type or a Performer RPM type manifold, although with it's somewhat curved runner shape the Holley Street Dom does get the mixture better aligned with the direction of travel the air makes in the head port itself....the old Twisted Torker is terrible in that regard.. The old short single planes just suck, they don't do anything well except keep the carb from falling into the lifter valley LOL. I'm guessing your heads have both bolt patterns?? Check just below the valvecover rail on the exhaust side of the head above the paired exhaust ports, there may be identifying numbers pinstamped in that location that can lead you to a manufacturer ID. Edelbrock sells a Performer RPM Q-jet vortec bolt pattern manifold, it will have the taller port opening match-up. I believe there are also others who make one too. Chevrolet started the taller port roof thing with the L98 head in the 1990's and it continued with the L30 305" and L31 350" Vortec heads. You said Holley Q-jet carb....I'm guessing this is a List-6210 650 cfm Spreadbore Double Pumper?? Or have you got the bigger 800 cfm version List 6211, 6212, or 6213??
I found an add for double hump aluminum heads without accessory holes. That would get the L79 engine appearance I was hoping for. Yes, my heads have both intake patterns. The carb is the vac secondary version which is also too new by a year or so. I have a square bore that I think is a 650, but mud dauber hornets got in it. It needs cleaned and rebuilt, or upgraded on next years budget.
I bought an aluminum intake for a 400 small block Caprice wagon that a customer had. I found out that it had been milled down and about fell into the valley. I glued 2 sets of intake gaskets together and the bolt holes finally lined up. It ran perfect for a long time so gluing gaskets together will work.
TrickFlow Cylinder Heads and Speedway Motors both sell a aluminum "double hump" look-alike head. TrickFlows is the DHC 175, Speedway calls theirs Camel Double Hump 461. The TrickFlow head flows quite a bit better, the Speedway head would need to be ported to equal the Trickflow. Hopefully your Holley Spreadbore isn't the dreaded "reverse idle" emissions type, a lot of those spreadbore vacuums were...they don't like cam durations bigger than stone stock because the idle screw adjusts air, not fuel for idle. Pain in the butt to modify. Do you remember your carb's List # off the choke horn??
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