Engine build gone wrong! What combo due I need?

SonicStangGT · Jun 29, 2008

I'am building my 4.6 back with stock 96 cobra flat top pistons with flycuts. Also installing Comp 278's. My problem is that when I'am trying to degree them I can't even get through a whole revolution without the intake valve having PTVC. What piston combo can I use so that I don't have any PTVC. Any help would be great as I need my car running in two weeks for beach vaction. Thinking about buying a set of stock cams because like an idiot I sold my stock stuff, just so I can put it back with no issues. I would rather use the Comp cams, Help!

SaleenGT2001 · Jun 29, 2008

what has been done to the heads? have they been cut at all? there was a similar problem at the shop a few weeks back with the 278's.

why did you use a stock piston?? i hope this is not a forged engine build.

good luck with it. i'm guessing i may see your car at Mustang Week.

darkside03gt · Jun 29, 2008

are you using aftermarket cam gears? I would check your timming marks again because im pretty sure you shouldnt be having issues. I'll bet your off by a tooth or so.

SonicStangGT · Jun 29, 2008

Not forged, just a cheap N/A build for now till I due boost. I have comp Adj. cam gears. The machine shop said all he did was resurface them. Yeah, Iam staying at Holden beach about 35 to 40 minutes north of Mrytle Beach. Been trying to get ready forever, but the machine shop fell behind and had my stuff for 2 months.

SaleenGT2001 · Jun 29, 2008

i have heard bad things about the adjustable gears. try the stock ones if you still have them

SonicStangGT · Jun 29, 2008

Still have them, I have heard bad things about the fidanza adj gears, and also the **** 278's. Wish I would have bought the 270's, maybe even the 262's. If I can get my hands on a set of stock cams there going in for now.

CobraRed_96_GT · Jun 29, 2008

flat top pistons and 278's? Even with flycuts you're asking for trouble. It's not the lift that's the issue, just all the factors of the 278 - which has been known to PTV even on 99+ pistons heads. Maybe you'll find someone with VT (CMS) Stage II cams that will want to trade

SonicStangGT · Jun 29, 2008

Would love to have a set of stage II cams instead of the 278's.

darkside03gt · Jun 29, 2008

why did you buy 278s? those are a little big for a n/a street engine. Try and find some stock pi cams for now. here are some being sold by dss racing they have 4 days left on the auction. I would offer them $100 and see if they will end it early and send them to you

http://cgi.ebay.com/ebaymotors/_Car...hash=item260256280631&_trksid=p3756.m14.l1318

SonicStangGT · Jun 29, 2008

yeah, I seen them on ebay, thanks. I really didnt know what I was buying, I wanted them for the rough idle, did'nt know the problems they were going to cause.

BobHyatt · Jun 29, 2008

SonicStangGT said:
yeah, I seen them on ebay, thanks. I really didnt know what I was buying, I wanted them for the rough idle, did'nt know the problems they were going to cause.

Just unplug two coils and the idle will be rough enough, and you will have saved a ton of money. That's the _wrong_ reason to buy a new cam. Like buying a new pacemaker just because you like the color. There are good reasons and bad reasons for doing most anything. This is a bad reason...

SonicStangGT · Jun 29, 2008

Your sarcasium does not help, The rough idle is not the only reason I bought the cams, also wanted to gain power. If you look at comp cams on there requirements for the 278, it has valve springs, intake,exhaust, gears and a tune. The rough idle is the reason I choose over the 270 and 262. Unplug two coils is retarded, I guess that will help me get my car running , thanks.

CobraRed_96_GT · Jun 29, 2008

SonicStangGT said:
Your sarcasium does not help, The rough idle is not the only reason I bought the cams, also wanted to gain power. If you look at comp cams on there requirements for the 278, it has valve springs, intake,exhaust, gears and a tune. The rough idle is the reason I choose over the 270 and 262. Unplug two coils is retarded, I guess that will help me get my car running , thanks.

they show those requirements cuz they are PI cams; and even then some people run into problems so it's a good idea to search around on boards first. And you're putting them on NPI internals which the cam isn't not made for, that's why they have 262h's and 272H's.
Furthermore, with stage three cams you lose a very good amount of low end power, but that's made up for in the high rpm's - yet only if you make use of it through ported heads and springs that allow around 6400rpms+. So on stock heads i'd bet stage II's (maybe even stage I's) show better track results than stage III's, especially when shifting at stock redline.

mogs01gt · Jun 30, 2008

Those cams are going to cause major issues with a Cobra shortblock. You will probably have to run a larger head gasket to get that combo to work without changing the cams out. You could run a .070 gasket and you shouldnt have PTV contact.

I run a Cometic .070 with my flat tops. Technically its not the correct way of doing it but it works.

96SCstang · Jun 30, 2008

i hate to tell you this but i see no way of those cams working with your lower end. the cobra flat top pistons are really the big issue here, and there isn't gonna be anything you can do but put in different cams. i would go with a stage II with your setup. if you need the car in two weeks and you have the money just hurry and buy stage II's and put them in. you dont want to have to pull everything apart again to put in cams again after you put in PI's for awhile. just my two cents though. good luck....sometimes it can be a real PITA to do an engine build. just take your time and do it right the first time. dont rush to make unrealistic deadlines. it's not worth blowing up in two weeks cause you missed a little thing cause you were in a hurry.

BobHyatt · Jun 30, 2008

SonicStangGT said:
Your sarcasium does not help, The rough idle is not the only reason I bought the cams, also wanted to gain power. If you look at comp cams on there requirements for the 278, it has valve springs, intake,exhaust, gears and a tune. The rough idle is the reason I choose over the 270 and 262. Unplug two coils is retarded, I guess that will help me get my car running , thanks.

You only gave _one_ reason. hence my comment directed at it. But in going forward, you do realize that a bigger cam can actually hurt performance? Isolated additions don't work well. If you increase duration/overlap/lift, you have to increase airflow, or you lose power and torque.

that was my point... going to a 278 in an otherwise stock motor is going to produce a weaker motor...

SonicStangGT · Jun 30, 2008

Thanks for all the help, thing I'am going to pick up a set of stockers, because I really want to find the right combo for the 278'S since I already have them. Does anybody have any idea on what piston I could use with these cams, would rather due that then buy new cams. Not really sure what I'am going to due, but I will not half ass it, I would rather wait than risk anymore damage. Thanks again.

SonicStangGT · Jun 30, 2008

Also I dont have stock heads, they have been ported and also had a 5 angle valve job.

SonicStangGT · Jun 30, 2008

What due any of you think about these cams, will they work with my shortblock.
http://cgi.ebay.com/ebaymotors/_Car-Truck-Parts-Accessories__4-6-SOHC-Ford-Mustang-Camshafts-LIVERNOIS-2V-Cams_W0QQitemZ120278628452QQadnZCarQ20Q26Q20TruckQ20PartsQ20Q26Q20AccessoriesQQadiZ2865QQcmdZViewItem?hash=item120278628452&_trksid=p3756.m14.l1318

CobraRed_96_GT · Jun 30, 2008

SonicStangGT said:
What due any of you think about these cams, will they work with my shortblock.

If you tell us what you're looking for i'm sure we can find something that'll suit your build. That cam is barely a stage 1 N/A, 2 less intake and exhaust and 1 degree broader LSA than a stage 1 comp cam (262ah) - don't waste your time there. I'd say either get PI cams while you recoup - or get stage II CMS's which for sure wont PTV.

Engine build gone wrong! What combo due I need?

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