467-Ratman

Just starting to work on my big block, 454 and was wondering what cam to use. It has Merlin rectangular port heads, 4 bolt mains, aluminum high rise intake, Crane gold roller rockers. I have heard that CompCams extreme energy cams are good, looking for strong off the line performance, which I have heard from the forum that the big block will smoke the tires at will!!!! Also was going to use my LT-1 Holley 780 carb, but some of you guys said go bigger, 850? Need some help on what carb to get if I don't use the 780.

bence13_33

My suggestion would be go to an 850cfm, at least. I don't think that the 780cfm will get the job done, especially with those heads. What kind of cam are you looking for (hydraulic, solid, hydraulic roller, solid roller)? I'm going with a solid lifter cam because it has the biggest bang for your buck over a hydraulic cam. A roller setup is nice, but they are a bit pricey.

P.S. The Comp Cams XE274 Hydraulic cam is a nice cam.

467-Ratman

I am thinking hydraulic only because it is a pain to re-adjust the lifters! I messed around with my LT-1 solid lifters and I am ready for set it and forget it. What type of 850 carb? Holley , Edelbrock or something else?

DaveP

Tom, is your car a stick? If so, I'd say a 850 mech would do the trick. try the 780 too, it might work too. Depends on what you want. All street, combo, track car? Street tires or DOT's? Make sure the 85o is an annular design, stronger fuel signals in mild/moderate engines.

Do you have a L-88 hood? Single plane intake? Call comp cams, a roller would be the way to go if you have the$$. Iron merlins are good, I'm looking for a set right now myself, Al would be extra nice!!
Do you go to Ubly dragway much?

467-Ratman

My car has a muncie close ratio 4 speed with 3.70 rear gears. Pretty much a street car, but when some punk comes up next to me with a mustang I want to be able to really embarrass him! I live in Bay City, MI. have not been to ubly in a long time, but a good friend of mine loves to go there. Dumb question, but when you were talking about the carb, what is annular?

Techno

I find the speed limit kicks in too early no matter what mod is done so be realistic on your choice.
Decide on what your driving is for first. Don't make the mistake of building an engine that is really meant for the track, then expect it to drive nice on the street.
If I remember rectangular ports are for high end max use, oval were for the street.
You can range the cam you want by where you want the power. Low end, mid, high end. I would eliminate the high end because you won't see it on the street, it will make the car lousy to drive and your using hydraulic lifters. You can skew inside these ranges, I think my cam would be a mid-range

I tried a low end cam, torquer RV. Big mistake. The car did have plenty of torque in the low end but way too much. I switched to a mid range cam and prefer it. I still have to change my valve springs to raise the RPMs up some.
Check the the range of the cam for your driving, they all have it stated. If not then call the company and ask them.

I had a stock Q-jet. 780? I bought a re-manufactured one from california that is 850. I don't think it was worth it. If your engine isn't going to be seeing the top end regularly then its somewhat a waste, and usually isn't actually called for in a street car. Also the cam I have is fairly low in the rpms for this carb.
I am surprised at the number of people who are using 850s This is approaching the too much level for the engine. I must be somewhat on the lonely side of spread bore country also. I think this is the best for the street.

Comp cams #11-313-4 .544 lift 276-284 duration
#99377 crane hi intenstiy lifters. 427 @ 9.5:1 The engine when new idled like crap, after break in it idles very low and smooth. (1200 now 650 -800) I don't know if these lifters have anything to do with it since I haven't run the cam without them.

I also have 4:11s and since I'm not seeing any incredible top end and already have the low end I took this into consideration(this time). I planned on use as a good street car. That was my primary concern. That was why I tried a low end cam. Live & learn.
The RV cam would cause the tires to spin when I turned from a stop, one tire would break and the differential would lock up. This became a real hassle. Too little throttle and you stalled the engine, A little more and the turn was OK, A tad more and the rear end broke loose. This required a lot of finesse to do.

DaveP

Tom,"annular"refers to the type of booster design in each of the 4 barrels of the carb, versus other types such as a "dogleg" or others. Annulars are more sensitive to low speed signals to airflow, such as street driving, and can make a larger carb like a 850 double pumper much more streetable. What type of tire and intake and exhaust are you going to run, Tom??

467-Ratman

Thanks Dave, I currently have BFG 225-70 TA's, The intake is a GM alumiunum high rise dual plane and my exhaust is Flowmaster. It was pretty loud with the 350 motor, can't wait to hear it with the big block.

bence13_33

Tom:
How big are your current exhaust pipes (are you planning on using them)? If they aren't at least 2.5"....don't use them. Running anything smaller than 2.5" pipe with a 454 will smother that rat engine.