I have a 1969 Firebird with a 428 that was built up by the previous owner. The engine was originally in a Grand Prix but was bored and built to be a drag racer. The spark plugs I have it in now are AC Delco R44S but they no longer make this plug. The plugs are very fouled and need to be changed.
Most auto part sites recommend the AC R43S for this engine but I'm afraid this plug may run too cool for a built-up 428 engine. Any suggestions on a good plug to use for this car? The car will only be used for street cruisin' and will no longer drag race.
The previous owner supplied me with the below specs:
1969 Firebird Specs: 1968 428 4 bolt 40 over TRW pistons 58-62 Forged rods RPM Limit 6200 430 Chrysler rear Cylinder heads #16 Valve screw in studs Poly locks Ultradyne 288-296 cam Street dominator mid-rise manifold Holley 750 double pumper
Are the colder plugs fouling? I have 44S in there now and they get carbon buildup. I was thinking maybe putting 45's in. The carb is probably running too rich too.
Problem is this car was built to go really fast for a short amount of time and not cruise the street. It drinks gas like it's free!
Are the colder plugs fouling? I have 44S in there now and they get carbon buildup. I was thinking maybe putting 45's in. The carb is probably running too rich too.
Problem is this car was built to go really fast for a short amount of time and not cruise the street. It drinks gas like it's free!
Thanks for your input!
I am not getting the carbon buildup. Between the carb and timing you should be able to take care of that.
I was looking at your setup. If you are trying to make your bird more street friendly? I would look at both carb and intake. That intake doesn't work well on the low end on mild street motors. The carb is a lot of carb. You could downsize both and I bet your low end torque will go up. Just my two cents.
Yeah, I agree with the others. I'd make some changes.
(1) I'd change to a stock iron intake and a GOOD Q-jet. Will also make it look more original.
(2) I'd change the cam. Something like an 068 clone or a Summit 2801 is plenty of cam for a 428 street cruiser. Will have more low end torque, vac, and a smoother idle. That 288/296 cam has 231/239 @ .050 lift, with a 110 LSA. That's similar to an 041. The UD chart I'm lookin at shows the power range of that cam to be 3000-6800. That's a lot of cam, even for a 428. Looks good for racing, but not for street cruising.
(3) 4.30 gears are way too much for the street. Probably need 3.23 max. Or, go with 3.08 if you do a moderate amount of 70mph cruising--2.73 for lots of 75mph cruising.
Of course, these are just one guy's opinions. I'm no expert.
I'm not an expert either, but that sounds like good advice. You could use one of the Edelbrock performer intakes, or the performer rpm if you don't have access to a stock one. I wouldn't go and buy a new carb unless you have one available, a 750 cfm carb is not bad for a 428, the double pumper can be tuned to your engine and if you keep your foot out of it you should get better milage. I've always thought low end torque as opposed to high rpm horsepower was the way to build if not racing at high revs, a milder camshaft will give you better street manners. But we don't know what the compression ratio of you engine is, If it's high you may need a large camshaft to reduce the dynamic compression ratio and reduce cylinder pressure. What are the numbers of your cylinder compression tests?
Thanks for the advice and suggestions. I will definitely take some of your advice and do some tweaking over the winter months.
I agree on the rear end. It needs to go if it's going to be a street cruiser and I'll have to look around to see what's out there. Maybe I can find someone interested in the rear end locally at the track. I know they're in high demand in certain circles.
The carb will either be changed or rebuilt. I'm thinking possibly just switching it out with a Street Avenger. Not sure on compression ratio. Haven't tested it yet.