Have you checked timing? Are you running lean at WOT? What about moving to a 650 or 750 cfm?

I have the same cam in my son's truck, and it sounds exactly as you stated at startup, smoothes out somewhat after warmup. It pulls hard to 5300 rpm, it has a 650 vac sec carb on it, harder with the 750 on it. Everything is tuned perfectly on it, and we have a blast in it. You would have to put another converter in if you went with more duration. Go over your tuning with a fine tooth comb.

 

Am RPM would be wrong for you basic package. Try something like a 230/235@.050 and .500 lift. The RPM has too much duration in my opinion.

 

XE 284, the cam I wished I'd used. I have a 280H and I could have used just a bit more.

K

 

I`ve used the Summit 1107 in 4 different SBC`s (3-350`s & 1-327) all with about the same pistons and heads you have and it sounds awesome and pulls strong to 6500rpm... I would recommend it to anyone with 9.5 to 1 or higher and an ear for that rhythm that gets your blood going... :thumbup:

BTW it works extremely well with the Vortec heads too... (almost perfect lift spec`s for them)

 

Thanks for the replies. I have several cams to choose from. I like the price of the summit cams.

 

I'd run that XE268 over any of those Summit cams, it should be pulling fine to 6K IMO. I've got an even smaller XE 4X4 cam in a 350 that pulls really well to 5500ish. That Summit cam is going to be a real mut down low compared to your XE and down on power through most of the rpm range. You've got some decent heads there, something else is holding it back I would assume. The performer intake is OK but a performer RPM would be way better. Also set the valve lash at only 1/8 turn preload- it lets the engine rev a little higher if your springs aren't very good. Springs also have a whole lot of effect above 5000 rpm- what springs are you running? Bob

 

Car doesn't pull strong?

4speed57,

When you say the car doesn't pull strong up top, where does it seem to stop pulling?

 

The springs are new ones that I got from Northern Auto Parts. They are good for .500 lift. My engine doesn't have a miss or anything, it just seems when you mash down on it doesn't have the pulling power to put you back in the seat. It almost seems the 4bbl. isn't opening up. I've tried 4 different carbs and it runs the same on all of them. My linkage is good, allowing for full opening. I raced my 57 last year and ran a 15.55@89.9. I thought it would hit at least a high 14. To do a comparison, I had a 79 camaro with a very similiar combination and it ran a 14.64@95. The camaro had a 350 with flat tops, 305 heads with 1.94 valves installed, Crane energizer 278 cam, weiand stealth intake, edelbrock performer intake, headers, 350 turbo, and a 2.73 gear. On paper it looks like the 57 engine was a better combination, had better gearing, and was lighter. The 57 weighs 3400lbs vs. 3600lbs. for the camaro. The camaro would only pull to 5000rpm because of the 305 heads. But in doing so it would run mid 14's. I can't figure out why the 57 is so much slower. Several people told me the wind resistence would have something to do with it. In the 1/8 mile my camaro ran a 9.45 vs. a 10.02 for thr 57. Is my 57 just completely out of tune? The horsepower is down, the camaro is almost trapping 5 mph's more.
Thanks for any help.

 

It sounds like you may have a tuning problem, as others have noted. But after chasing all that down, I wouldn't replace the cam to go with one less streetable. Since you are running 3:55s, I can only assume this is a primarily street-driven car. If you want to wake that motor up, try a different intake and a pair of heads. The Trick Flow (from Summitt) 23 deg, 195 cc heads are really nice pieces for the price. Lots of other nice heads are out there too, but those camel hump heads (I know they're classic, and pretty good) aren't a match for the good aftermarket heads available these days. Dollar for Dollar, you can't beat the vortecs (but some machine shop work would be required). Perhaps Scoggin-Dickey . . . . . .

PatM

 

i think you are complaining about a rough idle hard start cause of a biggish cam. then i think you stated you wanted to go bigger. do you realize that this wont help your problem?

 

Does the car have a good fuel delivery system? I bet you've installed your own line but just in case... I know some of these old cars only had 5/16lines- this would make the car lay down on the second half of the track. What kind of compression is it pumping with a compression test? Something's definately amiss here, your new combo i would think would be way better than the old, especially with the heads. That performer intake could be improved upon though, a Stealth or rpm airgap would help on the high end 6000-6500, the regular performers are good to 5000-5500. A double pumper 750 should also wake it up some-especially since you're running a 4 speed- borrow one and try it maybe. Bob

 

I would like to say that I agree with some of the other people that have posted on this. A good set of heads and a Performer RPM intake would be a better way to go. That XE268 is still a decent sized cam and should be more than adequate.

Heres something I dont understand, why do so many people want a Performer RPM Air Gap over the standard RPM. How much of a power increase do you really get for the added $70 (from Summit)?

 

Heres something I dont understand, why do so many people want a Performer RPM Air Gap over the standard RPM. How much of a power increase do you really get for the added $70 (from Summit)?

I bought a used one for my Son's engine, I've heard they're worth 10hp over the standard rpm, and they look so much better.