beertracker

It's really not a budget at this time. I plan on replacing the intake manifold, cam, and adding headers. I would like to stick with the Quadrajet if possible. I realize the 6x-8 heads are limiting me. I can look around for 6x-4s and add those later. Would it be possible or cost effective to mill my 6x-8 heads down so they approximate 6x-4s?

Go ahead and give me some links to parts.

Maybe some one can tell me about the Quadrajet carb? I noticed two adjustment screws on the front of it. Is the screw on the passenger front the fast idle mixture screw and the one on the driver front the idle mixture screw?

Thanks,
BT

Thumpin455

The two screws under the front of the carb are the idle mix, they allow fuel to flow when there isnt enough signal for the main circuit to flow fuel. If the main is flowing fuel at idle, the float is too high and it will run extremely rich, you can tell if the boosters are dripping fuel at idle. That is the same with a Holley or Edelbrock carb as well. A good place to start with those is 1.5 turns out, turn them to get the best idle quality, not necessarily the highest vacuum.

Qjets have enormous adjustability, it makes them seem complicated but really they arent that bad. They get a bad reputation from people not knowing what they can adjust or how to do it. Rather than giving you a huge wall of text about Qjets, I highly recommend picking up this book. You can get it from Amazon too.

http://www.cliffshighperformance.com/buy_book_2.html

That book will answer your questions and show you how to rebuild and tune a Qjet. Its worth the price believe me. I dont get paid anything for passing that along, its just the best book I have found on the Qjet and Cliff is willing to help out when he has the time.

The stock intake works better than the Performer, and unless you have ported heads you dont need the RPM intake. Trust me that you dont need a single plane intake, all they will do is load up with fuel, cost you mileage, and make it idle poorly. If you have a stock 4 barrel intake, keep it there is no need to buy another one. It isnt a chevy and the stock intake isnt a POS.

This company has budget based parts that arent overkill for a street engine. You can get complete rotating assemblies from them, and the 4" stroke is an easy swap for a stock block 400 and it will increase your torque considerably. Im planning a 4" stroke engine early next year using one of their crank kits.
http://www.pacificperformanceracing.com/index.html

The rods they sell under the Tomahawk name are a step up from the stock rods, and cost about the same as having the stock ones resized with new bolts. Cheap insurance and you can use the press fit forged pistons with them.
Rods:
http://www.pacificperformanceracing....-bearings.html
Pistons:
http://www.summitracing.com/parts/TRW-L2262F30/

Good cam for a street 400 even with the 6X-8 heads. There is a really nice Crower cam, I can look that up on the Performance Years Forum if you want to know, its a bit more pricey but makes really good power in low compression 400s and 455s.
http://www.summitracing.com/parts/SUM-K2802/
You can use it with stock springs, but I would suggest Comp cams 995 springs.
http://www.summitracing.com/parts/CCA-995-16/

And a gasket set.
http://www.summitracing.com/parts/FEL-KS2617/

That cam with a set of headers, recurve the distributor, and a good tune on the Qjet should put you quite close to the hp mark you want. Its a budget build that if you keep it under 6000 rpm should live a long long time.

Im running these headers on my 70 GTO with a 455 that has ported 5C heads and a similar cam to the 2802 from Summit.
http://www.summitracing.com/parts/SUM-G9020/

For $1580 you can get fully assembled street ported iron heads in almost any casting from KRE. Scroll to the bottom, they do really good work as does Butler Performance and a number of other Pontiac gurus/specialists. Most will run about the same price as KRE though.
http://www.krepower.com/Pontiac_head_prices.htm

beertracker

That's good to know I can keep my stock intake and save a few bucks. Now to start saving and eventually spending! Thanks to all who contributed.

BT

IRONFIST

Hey Bro where are you located? If I see better heads or what not pop up in your area I'll let you know...
I always seem to run into good heads that are too far for me to get so I pass them down.

beertracker

I am located in Houston, TX.

beertracker

Thumpin455 posted:

Good cam for a street 400 even with the 6X-8 heads. There is a really nice Crower cam, I can look that up on the Performance Years Forum if you want to know, its a bit more pricey but makes really good power in low compression 400s and 455s.
http://www.summitracing.com/parts/SUM-K2802/

Thumpin455:

What do you think of these cams I found on ebay. Are they any better for my application than the SUM-K2802 you mention above?

http://cgi.ebay.com/ebaymotors/Ponti...0-455-GTO_W0QQ itemZ190286805913QQcmdZViewItemQQptZMotors_Car_Tru ck_Parts_Accessories?hash=item2c4dfa3b99

http://cgi.ebay.com/ebaymotors/Ponti...ft-400-455_W0Q QitemZ190314026701QQcmdZViewItemQQptZMotors_Car_Tr uck_Parts_Accessories?hash=item2c4f9996c d

http://cgi.ebay.com/ebaymotors/Ponti...t-lifters_W0QQ itemZ190327914012QQcmdZViewItemQQptZMotors_Car_Tru ck_Parts_Accessories?hash=item2c506d7e1c

Thanks, BT

Thumpin455

I think all the links are broken or removed. The XE cams work pretty good in a low compression 400, but for the most part almost any cam has less than 228@.050 intake duration it will work for what you want, but you want at least 218@/050 to see any improvement. There are lots of guys with 2802 cams in their 400s and 455s, its a good street cam. If you want the stock 068 cam or the 744 will work too, the RAIV cam makes it a bit harder to have power brakes in a low CR 400, but it works too. Rhodes lifters tame the bottom end on the RAIV stick. The Edelbrock RPM cam is a RAIV copy, but you can find it cheaper than Edelbrock. Crane makes copies of the stock cams, and those three are the most popular stock cams. The best cam I used in a low CR 400 was the UltraDyne 280/288, you can get it from Bullet Cams, just call and ask for it. Had a 400 with ported 5C heads, similar to your 6X, and the 280/288 and that thing was a beast, almost as much power as the 455 and a nice idle.

beertracker

Thumpin455:

Here is ram air spec cam I found on ebay. It doesn't mention if it's ram air 3 or 4. It's intake duration @ .050" (INT): is 212 since this outside the range you gave (218 to 228@/050) I will stay away from this one.

Ram Air spec cam

Performance hydraulic flat tappet camshaft and lifter kit for 350 389 400 428 455 Pontiac Ram Air engines, 3/2carb hi output engines, 4bbl hi output. SPC7** and 16/HL1951S. Kit includes M-Select camshaft (**temporarily we are shipping Elgin equivalent or Comp Cams equivalent**) and Topline Hylift lifters. APPROX Cam specs are as follows:

* ADV Duration (INT/EXH): 285 / 298
* Duration @ .050" (INT/EXH): 212 / 225
* Valve Lift (INT/EXH): .408 / .406
* Lobe Centerline: 113/118
* Power Range: idle-4500
* If we ship Comp Cam, specs will be different but still offer similar performance
Upgrade your stock cam to a Ram Air spec cam...........

**
So a RAIV cam results in low engine vacuum? I can see how low vacuum is not good for power brakes. I have the selection narrowed down to three cams; SUM K2802, Ultradyne 280/228 or RAM AIR 3 or 4 cam. Can you tell me more about Ram Air cams, can I use stock springs with these? Are they a good choice for my application. Is there a difference between Ram Air 3 & 4 cams from a performance standpoint? I am concerned about the power brake issue with Ram Air 4 cams. Are the Ultradyne 280/228 and SUM K2802 considered ram air spec cams?

Thanks
BT

Thumpin455

That cam is a bit small, it will grunt ok but run out of steam around 4000, you can make more torque with a little more cam, and the torque is what moves you. Maximizing the torque without moving the RPM range up is what you want.

The RA cams like the 041 and 744 are factory cams. The Ultradyne cams have custom ground lobes for Pontiacs, not a chevy lobe profile like most cams. The 2802 is similar to the 744 RAIII and just a little smaller than the 041 RAIV, it has 224/234 .465/.488. The RAIV is 230/240 .516/.516 with 1.65 rockers, its about as big as you want to go with stock low CR heads on a 400. You can run stock springs with these, but to get the most out of it you should change the springs. The Comp 995 works quite well, I run them on all my smaller hydraulic cams. Not too expensive and they will handle more rpm than your bottom end will. The RAIV will severely tax your stock springs.
http://www.summitracing.com/parts/CCA-995-16/


Except for the 041 most will perform relatively close to each other, they are big enough to make more power, but not so big as to move the RPM range or need the head ported. Pontiacs have a high velocity port, its longer than the sbc from the carb flange to the valve, so you need a cam that will work with the ports. You can fill the cylinder pretty well under 5000 and there isnt much need to rev over that, but since you have a 400 you can run a bit more duration than your typical 350 sbc. The RAIV will still work and make good power, but some people dont like the loss of bottom end and choppy idle.

The nice thing about the Summit cam is its cheap and makes good power.

rtpassini

I dont know if your are interested. but i currently have a 67 pontiac 400 that I will be parting out in the spring time. Its too much of a PITA and I will be hopefully putting in a LS1.

Ill have 143 heads, holley 750 carb, a comp cam (really lopey, thats all i know, i can get specs if i ever take it out) and other various things if you interested.

beertracker

My power goal is 360hp. I am not sure which head to go with but I am looking at 6X-4 or maybe 143. I will probably have to mill the 6X-4. Is there a better head to use? What CR or chamber size should I be looking at? I would like to be able to use regular gas. At my power level is it necessary to port the head?

Thanks,
BT

beertracker

Yeah, I am interested in the heads. Email me at gphjstep3@juno.com.

BT

[QUOTE=rtpassini; I dont know if your are interested. but i currently have a 67 pontiac 400 that I will be parting out in the spring time. Its too much of a PITA and I will be hopefully putting in a LS1.

Ill have 143 heads, holley 750 carb, a comp cam (really lopey, thats all i know, i can get specs if i ever take it out) and other various things if you interested.[/QUOTE]

Thumpin455

Almost any head with a 2.11 intake valve will work, but the ones that would work best are 64, 7K3, 96, and the 6X-4 and the small chamber 5C and 4X with big intake valves. 360hp shouldnt be too hard even with a 6X-8, you just need air flow. The D ports flow pretty much in the same range no matter what casting it is, that leaves compression as the main difference. 11 and 15 would work but most of them dont have screw in studs. One thing guys used to do to lower CR with the 72cc heads was to cut a 3 inch diameter .010 deep dish in the top of the TRW style forged slugs, that drops it enough that you can run pump gas no problem. Its simple to do by chucking the piston in a lathe. You can find heads for sale over at PY and almost all the other Pontiac forums.

disc0monkey

iTrader: (10)

the 6x heads are a great port shape. clean them up and you'll be in great shape.

+1 on the Q-JET no way i would ever get rid of it.

beertracker

Ironfist, what hp is your 400? How much did you have milled off the head? Did you use a thin head gasket? If yes, what was the gasket thickness. What are the available gasket thicknesses?

I have found a set of 6x-4 heads that have not been worked on. What CR should I target to get 360hp? I read 6x-4 chambers are 93cc. I also read from Jim Hand's book a valve job will add 2 or 3cc. I don't quite understand why a valve job will add ccs?

I have been experimenting with CR calculators. One parameter is the gasket bore diameter. How much larger is this than the bore; 10 to 20 thousands inch?

I have a stock intake manifold that has D secondary ports. Since I am replacing the cam for a more aggressive one should I change the intake manifold to one with O secondary ports? At my hp level is there a significant difference in flow between the two intakes?

Thanks,
BT

beertracker

Hey Thumpin455:

I have 6X-4 heads milled .040", headers and Summit 2802 cam. What do you think will I need a stall converter?

Thanks,
BT