higher compression

[Rusty]

I had stock heads an all in my old engine but my new one is a 78 z28 block (dished pistons) with some SS Monte carlo 305 heads, i've got the thick felpro head gaskets but i'm not sure on the exact compression, I've got an MSD street fire coil (60,000 Volts) but i was wondering if you guys had any suggestions on better spark plugs for a C/R in the 10's

[harleyboy]

someone told me one time that the compression would be about 10.5-11.5 but cut out at around 5000 rpm's but like mine don't see that high of rpm's.

[ZR1BLAZER]

i would go with the common champion plug. you can try and gap it to .045 instead of .035

[stroker1]

Use an Autolite 25 gapped at .040" to start with. If that rattlles bad and nothing else seems to help, go to Autolite 24. Keep the engine cool, keep the air inlet drawing cool air, and block off any exhaust cross over the intake may have. Better to use an intake with no exhaust crossover if possible, or an Airgap intake or the Professional Products intake with the Airgap design.

You'll hate them heads one day!!

[Scuba]

I did the math eariler on a 305 o headed 350, depending on the gasket thickness your dancing around the 10.37 to 1 area with a stock piston (four valve dished ). With Iron heads and a stock cam run a good cooling system and like stroker said block as much heat coming into the intake as you can. Also back you timing off a hair, not to much but a degree or two, it will help with detonation if it becomes a problem. 10.37 to 1 dosen't sound like that much with all the newer cars and trucks running that, but the difference is they are also fuel injected and run reverse flow cooling systems that cool the heads first. Im not saying your going to have problems but if I could throw my 2 cents in I would think about going to a little more aggressive of a cam to knock your dynamic down and it will give ya more power to to.

[coppergmc]

Is that the 601 casting heads? I think mortec has them at 53cc or something like that. What volume in ccs are the stock dish pistons and wonder how far down in the hole they usually are? If I'm thinking correctly, you may not have to worry about it much. Does this look about right?

.041 X 4.166 gasket =9.16cc
.021 X 4.03 deck = 4.39cc
piston = 18cc
head = 53
4.03 X 3.48 swept = 727.54

812.09/84.55 = 9.60:1

A cam something like comp's 270 magnum should be about right. 224@.050 with .470 lift. It'll work with your stock converter. I use spray foam and JB weld to block off the cross over on an intake one time like stroker was talking about. Worked good.

[harleyboy]

well I am fixing to buy some seals for my 305 heads and put the on my 350 there is a lot of different opinions on it but in todays economy hey do what you have to do.

[Rusty]

wow well... umm... i have NO crossover, the EGR is blocked at the heads and the 10.36 sounds about right, i haven't seen the pistons but they told me they were dished (got it from a friend that had it in his monte carlo) I doubt a stock 78 Z28 would have a huge dish (like 18cc's) but i haven't a clue.. if i can get it started i'll have more info.. I'm hoping that coil helps me out, the air that comes in should be pretty cool (open element on the top of the tbi)
his plugs were destroyed and i couldn't see the numbers, I think my old plugs should be at .45 gap, I'll see if I have any detonation issues when i get it started, I'll get there wed, i'll tell you guys if i've got problems
oh and its a TBI so i have a little reliability on the timing ;)

[stroker1]

wow well... umm... i have NO crossover, the EGR is blocked at the heads and the 10.36 sounds about right, i haven't seen the pistons but they told me they were dished (got it from a friend that had it in his monte carlo) I doubt a stock 78 Z28 would have a huge dish (like 18cc's) but i haven't a clue.. if i can get it started i'll have more info.. I'm hoping that coil helps me out, the air that comes in should be pretty cool (open element on the top of the tbi)
his plugs were destroyed and i couldn't see the numbers, I think my old plugs should be at .45 gap, I'll see if I have any detonation issues when i get it started, I'll get there wed, i'll tell you guys if i've got problems
oh and its a TBI so i have a little reliability on the timing ;)How do you have a TBI with no exhaust cross over? Has it been JBwelded, welded, of stuffed with brillo pads and foam?? Never seen a TBI without a crossover unless it was some trick aftermarket stuff.

[Scuba]

My math was off sorry, for some reason I figured with a 56 cc head.

4.0 x 3.48 x pie x 8 = 43.750 CI
58cc x .061 (conversion) = 3.538 CI
11cc x .061 = .671 CI
.041 x 4.100 x pie = .5281 CI
.02 x 4.0 x pie = .2513 CI

Total engine displacement = 48.7184 CI
head, piston , gasket, deck = 4.9884 CI

48.7184/4.9884 = 9.766 to 1

Coppergmc was closer than I was sorry for the mix up if I would of took more time I would of seen it. You can buy intake gaskets that have block offs for the cooling system I believe that you can get small Aluminum block off plates for them as well.

[Rusty]

its a carb motor/intake, the friend i bought it off of is a retired stock car driver that built his engines himself, now he sells them :P

[Rusty]

scuba thats exactly what i put in (had to replace the intake), I've been getting them since i got a set by mistake

[stroker1]

oh and its a TBI so i have a little reliability on the timing ;)Make up your mind, is it TBI or carb??

[Rusty]

its a 454 TBI on a stock style quadrajet intake

[Scuba]

Just throwing this out there if you wanted to try. I did some light porting and bowl blending and a redneck valve job on those heads on a buddys TA form the 80s, It made a significant difference I was pretty supprised. Im not talking push you back in the seat scaring little old ladies performance but it was noticeable. I also port match the intake, Ya it was a lot of work for a 305 head, I had about 40 hrs in it all said and done. But it made him fall in love with the beast all over again and saved him some a good chunk of money also (free heads and beer for the porting).

[Rusty]

hah nice, I'll think about that for later scuba, right now i just wanna see it run again, I was going to start it last night but i realized it has the small flex plate, I'm going to try and take out the trans rather than dismantling all my hard work