Summit cam okay with low comp 400?!?
 

I bought a 81 Trans Am with what I believe to be a '76 400 , XA code block
Whoever put this engine in this car (originally a 301 Turbo WS6 euro-export car) modded the engine before it went in.
I don't know if they only did some bolt-ons or if they went deeper into the engine, like overbore and so on.
Heads are 6X-8's (orginal to the engine) don't know if the've been worked - think stock
Intake is a Edelbrock Torquer II
Carb is a 3310-3 Holley 750 vac.secondarys
Headers of unknown make
Roller rockers
Cam is unknown, probably not stock
The T/A has it's orginal 3.08 Posi with discbrakes

The T/A runs okay, but the header gaskets leak so I need to take them out before I car really drive it.
It idles okay not really choppy or anything.
Anyway, with the 3.08 rear it does about 2.500 rpm on the freeway.
Acceleration is nothing to write home about, although I must say I haven't pushed it very much into the higher RPM range. I kept it below 3.000 rpm.

From what I know the Torquer II has a range from 2500-5500 rpm (!?!)
And I think the Holley 3310 is also a little too big. (plugs are pretty wet)

I just want to have a spicy cruiser, not a race car. So I want as much low end torque I can get. I'm not interested in high rpm horsepower.

I was thinking of putting on a stock '73-'76 4bbl egr intake (I've got 2, that's why) with an Edelbrock 600 cfm carb 1405 (smaller I know, but european fuel prices are way worse than stateside), and putting in a new timing chain, a new Summit 2801 cam, and leaving my roller rockers as they are.
I already got all these parts so that's why I'd like to do this.

Is this a good plan?, anybody got experiience with a similar combo?

erik

Hello Erik,

Hoe bent vandaag u???

The K2801 and stock intake sounds like a great modification. The Edlebrock carb would be a good choice, although a Q-Jet might get better fuel economy...Robert

anyone got any experience with the combination I'm thinking off?

IMO, go for it, I like that cam in a street car but find a late 70s Pontiac carb, it will bolt on the factory intake, the Holley or Ecarb will not. sell the torkr and holley to someone who wants to look like a hot rod LOL
that Holley if in good shape will probably work great even with an adapter but I think youll get better mileage with the qjet. I dont see a 600 Ecarb being any improvement at all

Definately, The 2801 cam will work fine, I like the Comp Xe series in real low comp engines especially smaller cubes like 400's IMHO i'd use the Comp XE268H cam and 1.5 Full Roller rockers, 68-72 Iron Intake, seen one today for cheap, but 73+ will work Ok, A Q-jet from 67cruiser for around 325$ is Very hard to beat and he builds a very good carb, Exhaust if you can add some oversized Ram air manifolds from PY or RARE or Headers , Upgrade to an HEI or Pertronix, New Tune Up parts and Go, probably get around 325-340hp on the cheap and be good on Fuel with the Q, Please Don't use a E-carb!

I ran a similar combo, I went one size smaller on the cam and used a Q-jet carb:http://forums.maxperformanceinc.com/...1&postcount=22

If I should get a Qjet, what Qjet should I get then?!?
Anymodels/series that are best suited for this application?

I don't think I need a 800/850 cfm Qjet for this mild combo....

I just put the K2801 in a 72 400 with 7K3 heads and I like it.
I looked at the Comp XE268H but Comp says you cannot run stock springs and must have an adjustable valve train.

The Summit cam will be ok and is cheap. If I were to pick a cam I would choose the XE 256 Compcam. It is superior to Summit grind and will out perform it as well. It will put you into the 14's easy. You can run the factory valve springs if there in good shape.
212/218 dur .447/.455 lift on a 110 LSA which is better for a low compression motor vs 112LSA. Strong torque low and midrange. I do not think another cam out there will out perform it in the parameter that you describe.
Keep the headers , just replace the gaskets with a copperseal type.
Dump the Holley when you can afford and buy a Qjet.
Good luck

ran low 8's comp 400,5C head,2801 with 68 intake and ram air manifolds to low 14's in my 72 formula and it was actually stronger runner than my new 406,60916 cammed higher comp motor

The 1977-1979 Olds/Buick Pontiac Q-Jets are great. The linkages can be changed to Pontiac easily when you install new throttle shaft bushings...Robert

800 Q will work great!

quote
"I don't think I need a 800/850 cfm Qjet for this mild combo...."

that is true but the later 800s will be a much better fit on the late manifolds. choke heat, throttle linkage, etc
keep in mind the qjets secondary air valve only opens as far as engine manifold vacuum opens them in spite of the actual secondary bore plates being wide open. this makes the qjet self regulating as far as cfm. that along with the very small primary bores makes the qjet very fuel thrifty whether accellerating or just cruising. It is actually demand based self regulating as far as actual cfm. It feeds only the amount of air and consequently fuel, that the engine actually can use at a given speed and load. The factory used a 800 on the 455SD motor as well as the puny 301. Basically the same carb although each with appropriate calibration. It worked fine for both.

Actually, There is nothing wrong with keeping the Holley if you already have it. They work just fine on the dual plane (street) Edlebrock Performer intake or the Tomahawk single plane offered by Ken @ PPR.

On a 3310, I would use a .070" primary jet to start off with, a 10.5 X 5.0 in/Hg two-stage power valve, a .028" discharge nozzle, 'Black' accelerator pump cam in position #2, a 'Purple' secondary diaphragm spring.

I would use as much of the stuff that you already have. The Holley works great when properly tuned, You can move up to something different later if you like...Robert

Pontiac used 800's on all thier mid to late 70's V8's.
Even the 301's.
Basically all the same except for jetting.

The Summit 2801 cam works great in a 400, 8:1 up to 9.5:1 runs great! I have ran as well as 13.3'[email protected] mph in mild/stock-ish 400 ci 400 2nd gen's birds with that cam. Definitely use the Qjet intake with heat riser/egr blocked off and find a 800 Qjet from a 76-78 Pont 350 or 400 use a 72/44 or a 73/45 jet/rod primary combo, Trans Am or Bonneville ,etc..
Use a recurve kit in the HEI with the lightest springs and set total timing at 34-38@1600-2000 rpm and don't use the vacuum advance and 160 degree thermostat. You should be well pleased with the performance!!

Larry
13.3's - I would like to know the engine combination please. I know you did not run that with a 8.1.1 compression motor. Please elaborate the specs.

I know guys with 10.1.1 compression 400's and 3.42's in 2nd gen birds and they are not running that fast. They are running in the 13.5 range in the 1/4. Basic 10.1.1 400 motor , Qjet, factory intake, with stock 13 heads/exhaust (Ram air manifolds) and a 60916 cam. 75 Trans am automatic.

Back to the 2801. Its decent cam and will make decent power in the right combination. Erick has 6X8 heads
and a 3.08 gear. His compression is not even at 8.1.1
The XE 256 is the way to go for him. I rode in a 80 Trans am with 3.08 gears, 400 with log manifolds that was a total dog. The guy put in a XE 256 and it was
a huge difference. Strong low end and midrange torque. VERY STRONG. This guy used to get thrashed by civics and mustangs all the time. He has no problem staying ahead of new mustangs GTs.

Just my 2 cents worth

It's dynamic compression (DCR) that makes the difference, not just high levels of SCR by itself. In fact, SCR has little to do with DCR. I built an 11.25:1 SCR 327 SBC that only had 160 psi cranking compression and the DCR calculated out to only about 8.25:1 or so.

I know of one 8.80:1 Pontiac 400 with an XE 274 that makes an honest 380 HP...Robert

I said 8-9.5:1 , my mid-low 2nd 70-1/2 T/A was a undecked 70' 400 block with cast 8 valve relief replacement pistons. Regular Felpro blue gaskets and #12 big valve heads( my compression was no more than 9:5, probably less. stock 70 intake and 750 Qjet, th350 , with 2800 11" , repop HO/RA manifolds ,2-1/4 pipes, 3.55 gears. I did not say his exact combo would run 13's , merely what I have done with that cam in a comparable combo. Another buddy at the same time, had a 78 t/a , 400, with 2801 summit cam, small valve #15 68 heads, headers, iron intake, qjet , 3.23's , th350/11"... we were dead even at all speeds , every time we raced. Another one.. 80 Formula ,SUMMIT 2801, 400 , 8-valve relief cast pistons, 3.23's , th350/stock converter, log manifolds, #62 heads with matching 69 Qjet intake.. it went 13.7@102 on street tires in the 80's., Another one.. 76 t/a 400 8-valve relief pistons. low-compression..summit 2801, #11 heads , small valves.. 8.0-8.5:1, th350/stock converter, log manifolds, 2.56 gears, no track time , but it ran very well. Had some hwy races with motorcycles and 454 1/2 swb pick ups.. did well against them..Probably ran 14's...
I am not calling any better than 14's for low compression combo, but with a sharp tune ,.. it can be ok... Lots of Comp Cam cheerleaders out there, but I and my friends are not.. Summit Cams have a great bang for the buck and also Doug Herbert is cool too..
Lots of cars are dogs , if the owners are not experienced or knowledgeable tuners or drivers for that matter.. Thats normal.. and man .. ditch that Torker II !!!
All I can say is a 2801 in a 400 works great and has predictable results and economy/idle quality better than a 110 ls Comp.. 112ls ..remember street car.. my car ran a best of 13.3 ..it turned slower times on other trips too..13.5,13.7..just mentioned the better ones.
This guy should try to find some cheap 68 small valve #17's or at least some 6x-4's or 73-74 #46's ..raise it up from 7.6:1 to 8.1-9:0 depending on which heads.

Chalk up another vote for the Summit 2801 cam in an 8.5:1 motor. With 3.23 gears even a heavy '73 Grand Am will light 'em up from a stop and run forever. Other cams may be more appropriate to the combination, but it's hard to beat a simple cam like that except for maybe one of the factory grinds when it comes to "know it's gonna work" type situations.