What a mess
Thread Starter
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
What a mess
It appears I made a bad choice of cams for my engine, I had a hydraulic go flat so I bought a solid flat tappet in almost the same specs as the hydraulic was. I am have a real hard time now with cam lobe to rod bolt contact, (383) and have given it up as a loss. I am tired of band aid fixes so I am considering the GM Performance ZZ383 crate motor. Are the fast burn heads a good head? Other than the obvious fact I would have to change the balancer that comes on the engine is there any other reasons this engine would not be totally compatible with my '85 and all the intake mods I have?
The crate engine is just over $5,000. and to go through my engine and put on some badly needed good heads I am looking at over half the cost of the new engine. I am about to pull the trigger on this new engine but wanted to hear from anyone who has been there, done that.
The crate engine is just over $5,000. and to go through my engine and put on some badly needed good heads I am looking at over half the cost of the new engine. I am about to pull the trigger on this new engine but wanted to hear from anyone who has been there, done that.
Thread Starter
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
Thread Starter
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
Right now I have nothing in mind, the GM engine had Vortec heads on it. I had 3 different ones I was looking at that Summit carries but two of them have been eliminated for a couple reasons. Most of all the cam profile is not right for an efi engine. I have one more to research at Summit and then unless someone has an idea I will probably just re-do my engine completely. The only reason I was looking at a crate engine in the first place was because by the time I buy all I need to make it right a crate engine is not that much more money. If I do my engine I am looking at new heads, the 128's just won't cut it, rods that are stroker clearance and have capscrews instead of bolts & nuts, and a roller cam are the 3 big dollar items, and there are a lot of smaller things I would change. If you have any suggestions I am ready to listen.
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
So, a factory "roller" motor has other differences besides the cam, lifters, valve train? rods? bolts?
Interesting. I would not have thought there would be ANY differences beyond the valve train components. Apparently there are.
Interesting. I would not have thought there would be ANY differences beyond the valve train components. Apparently there are.
Thread Starter
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
Apparently I did not make myself clear, no the factory engines all have the usual internals. Some of the crate motors other than GM have H beam rods with capscrews and other small variances from the norm but almost all of them have a cam that is not compatible with efi. This was told to me by a couple different company techs. The first engine I was looking at had Vortec heads on it, others had cams way too wild for the street. I may have found a winner though, if I decide to get it I will post it here.
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Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
ok..I get it now.
I can see the need to match things, H-rods and clearances but the cam being EFI compatible is curious. Another one of the ...I wouldn't have thought that made a difference..
shows how little I know about buying whole motors! Mine have always come in pieces...
I can see the need to match things, H-rods and clearances but the cam being EFI compatible is curious. Another one of the ...I wouldn't have thought that made a difference..
shows how little I know about buying whole motors! Mine have always come in pieces...
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
The more overlap you have ( the lumpy idle so many desire ) the more raw fuel goes out the exhaust at idle ,
it fools the O2 sensor into giving a lean reading and so the ECM richens up the mixture
"So rich your eyes water" at idle is a common complaint
Thread Starter
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
ok..I get it now.
I can see the need to match things, H-rods and clearances but the cam being EFI compatible is curious. Another one of the ...I wouldn't have thought that made a difference..
shows how little I know about buying whole motors! Mine have always come in pieces...
I can see the need to match things, H-rods and clearances but the cam being EFI compatible is curious. Another one of the ...I wouldn't have thought that made a difference..
shows how little I know about buying whole motors! Mine have always come in pieces...
If I did not already have my Pro Flo XT I would not care if it had the Vortec heads. I think I have made my choice, a crate engine from ATK.
Le Mans Master
Joined: Oct 2008
Posts: 9,758
Likes: 49
From: Houston Texas
Thread Starter
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
http://high-performance-engines.com/...uct_Code=HP36M I got a better price without the intake, distributor and balancer on it.
Racer
Joined: Dec 2007
Posts: 312
Likes: 0
From: San Antonio Texas
Vetteoz referred to "overlap".....and he's correct. Valve overlap (measured in degrees.....the time that both the exhaust and intake valve of a cylinder are both opened) will result in a 'thumpier' idle and is a cam charactoristic that optimizes power output (at the expense of gas mileage).
The more 'radical' or race oriented a cam is, the more valve overlap it will have.
More duration doesn't always compute to more overlap.....neither does a lower lobe seperation angle.
EXAMPLE:
1. The B-body LT1 cam is about 191/196 duration with a LSA of about 110*.....but overlap is only about 10*.
2. I once ran a 224/230 cam with 114* LSA.....that had a -4* overlap.
If you're familier with Desk Top Dyno, you can enter basic cam specs and it will give you all the valve opening & closing events.....as well as the cam's valve overlap.
KW