502 with a Quadrajet?
07-31-2003, 10:25 AM
#21
Safety Car
Re: 502 with a Quadrajet? (marky mark)
No one wants to spend more than they have to. But, if you have ~$10k budgeted for this, then I think you can do what you want.
I researched a LONG time trying to find a combo that would make me happy AND fit under the stock hood. I wasn't starting from scratch, since the previous owner had this 454 HO in the car, and I didn't want to pull it since it has ~2500 miles on it. So, I had to design part of the combo around what I already had.
The biggest problem with low-rise oval ports is that, from what I found, the only "performance" manifold out there is the single-plane Torker II. I think that's probably a decent intake, but would not be my first choice on a 6000rpm street motor. Thus, the LS6 low-rise dual plane is really a nice one to have. Obviously, that limits you to rectangle port heads, which typically are not as good as an oval port for a motor under 6k rpm (except for the AFRs...which have proven they are better than _most_ oval ports, even in the low(er) revs).
Since you're considering buying a block, I would try and figure how much it would cost to have one built, instead of just buying a crate engine...especially with regards to the cam. Do not handicap yourself by running the crate cam if that is not really the best cam for what you're trying to do. :) Of course, you could just get the crate engine and pull the cam out.
I don't know if its in the budget, but a 502/502 shortblock, AFR heads, and LS6 intake would be cool. You will want to pull the cam that comes in that block, though, and run something different. I nearly stuck with my LS6 intake. It would have kept me from having to buy an L88 hood...but everyone said it would cost me ~20-25hp vs. something like the RPM AirGap intake. On a 502, though, you'd probably get the power back that I would have lost with the 454.
Just an idea.
I researched a LONG time trying to find a combo that would make me happy AND fit under the stock hood. I wasn't starting from scratch, since the previous owner had this 454 HO in the car, and I didn't want to pull it since it has ~2500 miles on it. So, I had to design part of the combo around what I already had.
The biggest problem with low-rise oval ports is that, from what I found, the only "performance" manifold out there is the single-plane Torker II. I think that's probably a decent intake, but would not be my first choice on a 6000rpm street motor. Thus, the LS6 low-rise dual plane is really a nice one to have. Obviously, that limits you to rectangle port heads, which typically are not as good as an oval port for a motor under 6k rpm (except for the AFRs...which have proven they are better than _most_ oval ports, even in the low(er) revs).
Since you're considering buying a block, I would try and figure how much it would cost to have one built, instead of just buying a crate engine...especially with regards to the cam. Do not handicap yourself by running the crate cam if that is not really the best cam for what you're trying to do. :) Of course, you could just get the crate engine and pull the cam out.
I don't know if its in the budget, but a 502/502 shortblock, AFR heads, and LS6 intake would be cool. You will want to pull the cam that comes in that block, though, and run something different. I nearly stuck with my LS6 intake. It would have kept me from having to buy an L88 hood...but everyone said it would cost me ~20-25hp vs. something like the RPM AirGap intake. On a 502, though, you'd probably get the power back that I would have lost with the 454.
Just an idea.
07-31-2003, 10:38 AM
#22
Burning Brakes
Re: 502 with a Quadrajet? (marky mark)
Don't know if I can add anything here. I never ran my motor with the stock cam. I'm using a low rise LS-6 intake with a Holley 3310. My motor is really set up all wrong from what I think it should be.
1-the ZZ cam is probably too big with the stock 8.75:1CR
2-I am running Heddman Huslers with 2" primaries, way too big
3-I am just running the stock(72-75)jetting in the carb
4-Low rise intake, no help there
What I really don't understand is why it runs so well. It will burn the tires well into 2nd gear from a 10MPH roll. I use a drop base AC with 3" element, timing is 12 initial, 35 total, all in by 2600. I will try to get off my azz and get some time slips, or better yet a dyno session. I have about $2K in the conversion including brackets, pulleys, carb, headers, Spals, etc. I also have another $500 in rebuilding the trans and a new converter 1 week after firing it up. :thumbs:
1-the ZZ cam is probably too big with the stock 8.75:1CR
2-I am running Heddman Huslers with 2" primaries, way too big
3-I am just running the stock(72-75)jetting in the carb
4-Low rise intake, no help there
What I really don't understand is why it runs so well. It will burn the tires well into 2nd gear from a 10MPH roll. I use a drop base AC with 3" element, timing is 12 initial, 35 total, all in by 2600. I will try to get off my azz and get some time slips, or better yet a dyno session. I have about $2K in the conversion including brackets, pulleys, carb, headers, Spals, etc. I also have another $500 in rebuilding the trans and a new converter 1 week after firing it up. :thumbs:
07-31-2003, 12:06 PM
#23
Team Owner
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St. Jude Donor '11, '16-'17
Re: 502 with a Quadrajet? (ORVette)
it runs so well. It will burn the tires well into 2nd gear from a 10MPH roll. :thumbs:
06-30-2012, 10:39 AM
#25
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big block with q-jet
I'm still researching / considering all options possible.
One was to get the GM 502/502 and use my low-rise factory oval intake mated with the Quadrajet to clear my stock big block hood ('69, 427/390 car). I know this combo would hurt power somewhat, but how much?
Has anyone tried this or similar build ups with large cube engine and Quad carb?
Also, in looking at other options I noticed that the H.O. 454 & H.O. 502 both have rectangular port heads & 8.75 to 1 compression and a .211/.230 cam. But the 502/502 has the bigger cam, .224/.234 with the higher compression alum ovalports. Now GM must have a reason for this cam difference. Would you think that the larger cam would not work as well in the lower comp / rectangular port head 454/502 (H.O.)? Is it a question of compression ratio or head flow or perhaps both? Anyone tried the larger cam in the H.O. motor?
I ask because another option if I stayed with a GM crate motor would be to acquire the LS-6 intake and use the Holley carb instead. Either 454 or 502 H.O. would then work I believe. This would seem to be a better combo than the 502/502 with a quadrajet, unless I'm mising something (which I probably am)???
Overall summary: Can a Quadrajet work well on a 502?
Any help appreciated!!
Sorry for so many questions!!
Never knew hood clearance issues could take so much time! But I do want to retain the stock bb hood.
Mark :flag
One was to get the GM 502/502 and use my low-rise factory oval intake mated with the Quadrajet to clear my stock big block hood ('69, 427/390 car). I know this combo would hurt power somewhat, but how much?
Has anyone tried this or similar build ups with large cube engine and Quad carb?
Also, in looking at other options I noticed that the H.O. 454 & H.O. 502 both have rectangular port heads & 8.75 to 1 compression and a .211/.230 cam. But the 502/502 has the bigger cam, .224/.234 with the higher compression alum ovalports. Now GM must have a reason for this cam difference. Would you think that the larger cam would not work as well in the lower comp / rectangular port head 454/502 (H.O.)? Is it a question of compression ratio or head flow or perhaps both? Anyone tried the larger cam in the H.O. motor?
I ask because another option if I stayed with a GM crate motor would be to acquire the LS-6 intake and use the Holley carb instead. Either 454 or 502 H.O. would then work I believe. This would seem to be a better combo than the 502/502 with a quadrajet, unless I'm mising something (which I probably am)???
Overall summary: Can a Quadrajet work well on a 502?
Any help appreciated!!
Sorry for so many questions!!
Never knew hood clearance issues could take so much time! But I do want to retain the stock bb hood.
Mark :flag
07-01-2012, 06:08 PM
#28
Burning Brakes
489motor and stock hood
Just my .02....
I wanted a good strong motor but wanted to keep my org block. GoFast built me a killer 489, with "stock" heads, and a nice roller cam. With an old but nicely port Holley street dominator (get one on flea bay), long tube headers and a Holley it dyno'ed at 514 hp, with MacJacks shorties it only put out 496 hp,
I now have it in the car with a Q jet, still not yet fully set up, but it pulls like a train. Traction is a little more of an issue! By the wya, the Q jet has been worked, reworked and worked on again. I must admit it is a nice carb but a little beyond my shade tree mech level and I have little desire to get much more into it. Saving for what I really want, a Kinsler cross ram system that fits under the stock Bb hood.... Trouble is the 5k price tag,......
Btw, David Vizards new book on BBCs is a must read before you make any decisions! There is a lack of intakes for oval port heads to fit the BB hood, hence the old Holley Street Dom. Probably better than a Tor II....
Carbste
I wanted a good strong motor but wanted to keep my org block. GoFast built me a killer 489, with "stock" heads, and a nice roller cam. With an old but nicely port Holley street dominator (get one on flea bay), long tube headers and a Holley it dyno'ed at 514 hp, with MacJacks shorties it only put out 496 hp,
I now have it in the car with a Q jet, still not yet fully set up, but it pulls like a train. Traction is a little more of an issue! By the wya, the Q jet has been worked, reworked and worked on again. I must admit it is a nice carb but a little beyond my shade tree mech level and I have little desire to get much more into it. Saving for what I really want, a Kinsler cross ram system that fits under the stock Bb hood.... Trouble is the 5k price tag,......
Btw, David Vizards new book on BBCs is a must read before you make any decisions! There is a lack of intakes for oval port heads to fit the BB hood, hence the old Holley Street Dom. Probably better than a Tor II....
Carbste
07-01-2012, 06:11 PM
#29
Burning Brakes
I forgot to add, I once drove a vette with a 502/450 and was not overly impressed. Hence the decision to build my old LS 5 into something a little more trick. If you go GM go 502/502. But there are many better routes to go.
10-17-2013, 08:56 AM
#30
Buy a 502 block and get a 4.250 stroke crank for a 540. If you get a GEN VI 502, it has revised water jackets that take either MARK IV or GEN V heads, so you can use your original ported oval port heads with bigger valves and a stock Q jet cat iron intake, have a hyd roller, set compression where YOU want it, etc...then get a worked over 850 Qjet.
10-17-2013, 06:08 PM
#31
Melting Slicks
Buy a 502 block and get a 4.250 stroke crank for a 540. If you get a GEN VI 502, it has revised water jackets that take either MARK IV or GEN V heads, so you can use your original ported oval port heads with bigger valves and a stock Q jet cat iron intake, have a hyd roller, set compression where YOU want it, etc...then get a worked over 850 Qjet.
Am I wrong?
10-17-2013, 08:37 PM
#32
Some 800s flow more than others...and there are mods that can be done (slabbing the throttle shafts, de-burring the main body, installing bigger primary butterflies, removing the outer booster ring on the secondaries, etc...) to increase flow. Edelbrock used to market an 850 cfm Q jet. David Vizard says a Q jet can flow over 1000 cfm with the right modifications.
