I know there is one on ebay. Don't take this the wrong way I just can't afford $325 for an intake manifold now, so I'm planing and doing what I can with my current budget. I got ahold of a 66 MT motor and understand that it came with the spreadbore intake. I unfortunately didn't get the intake from the prior owner. I'm kicking myself now because I just watched one go on ebay for $41, and didn't bid.ou: So my questions are: Is it worth paying for the spread bore intake manifold? What should I expect to pay for one? Is there anything different on the MT motor that would stop me from using a different intake manifold?
Doug, It is the 66 MW (425) engine that came with a spread bore standard, and some 66 MR (401) GS Skylark engines had the spread bore as an option. This was the only year this manifold was available, and it was roughly on 30,000 engines. I don't know how many of these are left, but you can bet the majority have been melted into Toyotas. I think you are going to find that they go for around $200, and then there is shipping (it is not light). The Nailhead spread bore used a Quadrajet carburetor that flowed about 750 CFM. This was compared to the earlier square bore AFBs that flowed in the 500s. The Nailhead 401/425 spread bore, square bore and dual 4 bbl manifolds will fit any 401 or 425 from any year (some special brackets for attachments will be needed or will need to be fabricated). The 364 manifolds will not fit the 401 or 425, and the 401/425 manifolds will not fit the 364. Cheryl
I have 1 left of the 3 that I had. I dont care for the qjet carb, so I will sell it for $175 plus shipping. they weigh 35lb.
Hi Doc, my 66MW 425 has a squarebore 4 barrel manifold. I don't know if it is original on the engine or not. Can I expect similar flow performance by doing your mods to the plenum dividers or is a spreadbore manifold still a better option? Will a 750cfm Edelbrock or similar be restricted by the square bore manifold or does it not matter in the end as long as the carb base matches the manifold? Thanks in advance Ross
Ross, i have one of the spreadbore manifolds for sale but IMHO is that the modified sq. bore manifold will flow just as much or more. In the past I have run the big holley 3 bbl. carbs on them. [950 and 1050 cfms] Throttle response is crisp. To put a big holley on the sq.bore manifold you will have to come up with an adapter for the base plate. i made my own out of 3/8 '' hot rolled steel. It is stronger than alluminum But to answer your question, the mod is well worth the effort, and the 750 will work well. I was sent to school on the holleys and just prefer them because to me at least they are easier to work with. When I put the mod on my 64 riv i used a holley 600 cfm ''cigarbox'' carb. Btw my 64 riv had the sq bore manifold with a carter afb.
Pretty much covered, but closer to 50,000 of these were 'out there' at one time. I think these also now have the Barrett-Jackson/ebay $ thing happening to them. I like this setup and the qjet is fine-good power and milage compared to the afb..and I run both in big Buicks-
If you take a really close look at a Q-jet manifold, you'll see that the secondaries of the Q-jet are centered on the manifold, whereas the carb itself is centered on the square bolt manifold. I'm running a later Q-jet on mine. It came off a Pontiac Trans Am that had the 403 Olds motor in it. It has an electric choke and all of the linkage is above the base of the carb. It flows closer to 850 cfm. The original AFB was rated at 625 cfm. A friend of mine in Denver has had both a 2x4 66 Riv and a Q-jet 66 Riv. On the strip, the Q-jet was quicker than the 2x4 setup, but the 2x4 setup would run faster than the Q-jet. Both had the same transmissions and rear end ratios. There's lots of controversy about which is better, but IMHO, it all boils down to what's easier to tune and maintain. ergo for me it's the Q-jet. Ed
Cheryl, I'm still learning my nailhead facts so any help is greatly appreciated. I found the block ID #s on Buicks.net and so I checked my motor. If I read correctly, it appears that my project motor is a 1966 "MT,"(link below). Buicks.net show a note that says the MT has 340 hp. I'm not sure their numbers are right or if these would be the correct codes for my motor. I was told the motor was from a 66 skylark. I don't know if it was a GS. I measured the bore and it is 4.1875 so it is a 401. If Doc's mod gets similar flow at a much better price that sounds like the better beal to me. http://www.buicks.net/shop/reference...ification.html
The MT is a standard 401 used in most of the big Buicks in 1966. It originally came with the Carter AFB. Was it red or green? For 1966, standard engines were green, optional hp engines were red. There have been cases where a 401 engine with a MT (or LT for '65) stamping have made their way into Skylark GS's. Sometimes the factory restamped them with the proper LR/MR code, sometimes they didn't.o No: I have to try that manifold trick Doc. ...anything for a few more tenths!:TU:
Walt, Just for grins, when you do the mod, and then run at the strip , tell me the difference on the time slip. All I have is the seat of my pants. Hehe, and there aint much there, he he. Wonder what it would do if a man opened up a dual quad manifold that way?????? I notice that all the speed equipment companys design the intakes that way [eelco, ebrock, ect.] evidently they thought it was worthwhile to do that. naturally, one would have to use their brain and modify any adapter/spacer that goes under the carb if needed.
Walt thank you. I think you have answered my id question. Mine is green under all the dirt and grease from sitting on a spare tire in a barn for years. Doc, I wonder what opening up a spread bore would do...?
Doug, i wondered that myself. The qjets used to have a part underneath them that would get loose and fall down into the engine with disasterous results. i think that one of the spread bore holleys would work ok with a modified manifold. i dont think that it could hurt to do a spread bore manifold.
This is what Greg Gessler does when he ports them. Pic is from Bill Stacey (Buickstreet.com) from a few years back.
