new 350 not performing

[80maroonbu]

I am having some performance problems from my new 350 just dropped into my 80 Bu.

1976 block and heads. bored 30 over.
Professional Products highrise intake.
Professional Products Dist.
Quick Fuel Technology Slayer 600cfm Carb
AC Delco plugs
Taylor 8mm wires
290/500 cam
stock exhaust manifolds
2.5 piping into Thrush welded muffs

the engine starts perfect and idles well. in gear idle is kind of low, but doesn't die and stop lights.
problem is, it is not anywhere as snappy as it should be. it will NOT even turn the tires over from a dead stop, in low gear, and on wet pavement.
it will NOT even power brake.
it is timed at 10 BTDC. and I didn't set the carb. although I am sure that it is running rich. I have yet to research on how to adjust the air/fuel in a QFT carb.

any and all help you can give will be greatly appreciated. I am open to all suggestions. thank you in advance.

 

[bigtmoney]

With that cam you should give it about 6 more degrees of timing. Is it 10 btdc on the timing light or is that what you set it to to get it running?

 

[DoubleV]

Based on what you posted, it seems to me you have a poor combination of parts. Big cam ( how about posting all the specs btw ) and a 'high rise' intake ( is this a dual or single plane? ) intake are saying 'high rpm performance', but restrictive exhaust manifolds, a smallish carb, and restrictive smogger heads say otherwise.

What is your measured CR? I'd bet it's a bit low for that cam. Was the cam degreed? If not, then that could be a potential big problem right there. What are your gears and stall? That could be a huge problem too.

 

[lilbowtie]

Dito doubleV - the whole package has to work together, intake,cam,heads,covertor,rearend.

 

[80maroonbu]

ok, sorry guys. I work out of town.

so, just a little history. I didn't build the engine. and now I cant get ahold of the guy that did build it to get proper specs.

I get what you are saying about the cam. it is way too big.
the manifold is a Professional Products Cyclone intake. it is dual plane.
transmission is a stock rebuilt transmission. nothing extra.
I would say that the CR is 8 into low 9. its not high compression.

and I set it at 10 BTDC. but I have reset it to 12 BTDC.

in your opinion, will just a cam change and a tune be ok for now?
I plan on doing that, then block hugger headers, and in time, heads, then upgrade the carb. but for right now, I just need to get it where it runs good. it sounds great while at idle, but driving, it sounds like crap.
I have 5k in the engine and transmission, and its frustrating and discouraging me pretty bad. so, do u think a cam change alone right now will make a decent difference?
I do have a guy that im going to try and get it to next week. this is my only car, and I drive 80 miles one way to get to work every week.
thanks guys.

 

[lilbowtie]

Still missing a lot of info:
What heads? - if stock what's the casting number
What size converter?
What gear?
More info on cam - lift duration @.50 (part #)
What is your total timing set @ ?

 

[hereiam]

heads are where the power is made. I would check them and see what you have. Vortec heads would be a good option. Yes if the cam wasnt degreed then that can be a major problem for power

 

[gbondo57]

I believe the quick, and best spent, would be a set of Hooker 2466 headers. Look them up. Even with poorly selected heads, the cam is trying to breath. The 600 might be a small app, now. But the headers would bring alot of what you have together. Stock manifolds choke the stuff you've built. For a daily driver, low compression is ok. Good luck. M ines a daily driver too. My sons XE comp 350 we built, has 10.75:1 approx. He ran 87 pump against my instructions. New lesson here. When dieseling, at shut off, the crank "whips" back and forth. The balancer neck cracked, and "almost washed out the crank key slot. Jury is still out.

 

[seawolf18]

If its a 76 block and heads they are probably 882 or 993 heads. They would be 76cc chamber 1.94 intake 1.50 exhaust valves. They are also weezy smog era heads that don't flow that great. Was the engine built with flat top or dished pistons? if it was built with regular 4-valve relief flat tops, your compression would still only be in the 8.5:1 range. Thats if the pistons had a stock compression height witch is 1.56" IIRC. A lot of rebuilder pistons have a shorter compression height to compensate for decking the block. The stock pistons sit about .07" below the deck.

If your block wasn't decked and short compression height pistons were used, you compression would be even lower, about 8:1 or even lower. With a large duration high lift cam, the engine would be a dog. The large cam would bleed off even more compression. Do your power brakes work at all? My first engine I ever built, I made these mistakes and it had no power, and the brakes would barely hold it at a stop light.

I would say at a minimum, I would put a different set of heads and a different cam in it. If you don't have headers on it, a set of long tubes would be a very good idea. A good set of vortecs would be an excellent head, but then you would also need to get a different intake manifold, and get the spring pockets machined to accept some high lift ones. Unless you can find a set off Craigslist or a local swap meet that have already been modified. Some other good heads would be some L89 heads or some heads off a 350 TPI. for a cam I would run either a comp XE262 or XE268. I wouldn't go any bigger than a 268 with unless, you have a nice sized stall for your trans and steeper gears in the rear 3.42+

When you get your parts together, use one of the compression calculators floating around on the web. For Iron heads you don't want to go more than 9.0-9.5:1 compression. Aluminum heads 10:1. Thats running premium pump gas.

 

[lilbowtie]

5k in the engine and stock trans - there better be some good stuff inside!!