hey all, looking at buying a 91 z28, but it has a few small problems. the engine is a 350, bored 30 over, 56cc aluminum heads, -5cc pistons to lower the cr (probably about 10.5-11:1 cr) a bit for the heads, crane 1.5's, 500 (advertised) cam, weind intake, holley 650 carb. claimed 450hp.

the guy says its got a miss above 3000rpms that he believes is b/c the high comp is "blowing out the spark". he claims it needs an msd box for it to run right. i know multiple spark is needed for high rpm engines, and very high compression race engines, but for a relatively mild sbc, my bet would be b.s.! if i were personally going to venture a guess, i'd put my money on a valve out of adjustment, or a mis-degree'd cam. any ideas on if the guys claim might have some validity or some recommendations?

 

A .030" over 350 with flat-top pistons and 5cc valve reliefs, .039" head gasket, .045" deck clearance (the stock .025" PLUS the usual .020" "rebuilder" safety factor), and 56cc heads, gives just a shade under 10.3:1. Entirely manageable on pump gas, and without a bunch of high-$$$$ add-on boxes.

Basically hot-rodder mythology; right on up there with "collapsed lifters" and "it's overheating because the water is flowing too fast to get cooled". Might as well blame it on the space aliens: you'd have the same chance of fixing it by scaring them off, as trying to cure it by fiddling with that other monkey-spank.

Consider:

Back in the 60s, LOTS of motors had ALOT more compression than that, with IRON heads; all we had, was POINTS ignitions; and NOBODY had that problem.

He's basically blowing smoke up your kiester.

Whether he knows what the matter really is or not, he's basically just putting out the diarrhea of the mouth, hoping if he can't baffle you with brilliance he can befuddle you enough with bulls** long enough to get your money and make you go away.

If I were to venture a guess, I'd bet it's the carb or valve float.

Of course, first find out what the cam REALLY IS, by part #. No other "spec" will do: part # ONLY. Get this PO to shut his pie hole about the mythological drivel and give you some facts instead. Find out what valve springs are on it if you can, but usually the ones that come with heads unless otherwise specified, aren't good for much.

If you buy it, start with the simple stuff. Try another carb. If it's still there, try a set of better valve springs.

 

the guy says it has a miss above 3k ???

have you verified that? Have you heard it

get the part # of the cam (where have i heard that before) as well as find out if they are 1.5 or 1.6 rockers and also find out the model valve springs he claims to have used.

Hey, do me a favor and ask sofa if he wants to buy a slightly used dwell meter

 

How "slightly"?

 

well i went to look at the car today. i started it and tried to verify some of the guys claim. i found that the problem really isn't a miss, its more of a bogg. when you try to rev it up, it breaks up and wont rev any higher than ~3k. its got a holley 780 street avenger carb on it, which i'm guessing is WAY too much carb for a relatively mild 350. the thing i find odd is that the car sounds pretty good when idling and up to 3k. very healthy sounding. every once in a while it will idle down and die, but you can save it with a few pumps of the throttle. thats why i'm thinking its now fuel related instead of ignition related. also, they are crane gold 1.5 rockers. do you think it could be an intake leak and its loosing vacuum, or losing vacuum and not opening the secondaries (causing the bogg)?

what do you think the car is worth? like i said its a mild 350. i found it had edelbrock intake, trick flow aluminum heads, richmond 6sp tranny. its got a few little bumps and bruises, paint is overall in decent shape...maybe a 6 or 7 out of 10. has hotchkins bracing all around. interior is a bit of an eyesore with a few tears in the seats, and the plastic has all been painted and is chipping.

 

Vacuum is not an issue at WOT; there is basically no vacuum. So, no.

More likely a carb problem.

If you buy the car, be ready to either rebuild or replace the carb.

Probably not a matter of failing to open the secondaries; if that was what was wrong with it, it would just act like it had a 2-bbl carb on it. More likely, it's opening the secondaries too much too soon, and/or has secondary fueling problems.

The carb isn't "too big". It's within the range of reason. Maybe, bigger than some of us might choose for some applications, but not so big that it's a malfunction. The problem lies elsewhere than just being "too much" carb.

SOunds like there's a few $$$ parts in there. Could be, fixing a messed up carb is small potatoes in the grand scheme. That's usually the case, anyway, even for a car that's still stock.

 

what is the asking price?

It's hard to determine what I would offer from behind a keyboard. Also, are the modes performed to your taste and satisfy your desired application?

If so, then there is some value to you but there may not be value if you were looking for a restored vehicle.

 

well the guy is actually asking 5500 for it, but wants to trade me for a quad that i have 2800 into, so actually i'd only be paying 2800 for it. 5500 to me is WAY too much, but the 2800 is manageable. there's definitely money in the engine and trans that could almost be made back if the whole car doesn't work out. thats kind of my mentality. worth it? it definitely needs some tlc though, but i've kind of been looking for a project for the winter.

 

no, because you would be including another thing of value

If the seller is willing to accept the value of your quad as $5500 then it would be a fair sale. I would not pay more than $2500-$2800 for the vehicle in total, but again, I have not seen nor heard it.

$5500 should get you a vehicle that runs great with a very good interior, no body damage or at least not in need of paint/clear coat. The tires and brakes should also have a minimum of 50% life left.

For $5500 I'll sell you my 4th gen which will spank that car.

 

i never told the guy that i only have 2800 in it, so he's willing to straight trade for it.

thats what i'm thinking too. it needs a little too much work to be worth it (even with what i have in the kfx). id be better off selling the kfx for what its worth and buying a better one.

trade you a kfx....haha....i'm really looking for a 3rd gen. something about those cars that bring back my childhood. i just have a thing for 80's style cars....where are you located anyway