spark plug gap question

[markmitchinnh]

As many of you may have read I installed a 1995 4.3 in my 89 Astro I used the TBI system from the 89 engine. My question is do I gap the spark plugs per 89 4.3 specs or do I use the 95 specs to gap them? The difference is .35 for 89 and .45 for the 95

[1Gary]

Gap it to the 89 spec because your using the 89 induction system.

It is one of the things your going to have to deal with given in reality a mongrut swap you have.The hp spec I would think is the same as a 89.

[Smiliesafari]

Gary is probably correct. However, I always liked the larger gap because of the larger spark that it produced. At one time, back when HEI first came out, there were gaps that got set at .060. If you have ever used a HEI tester you could see how big the spark really was. It was impressive.

[markmitchinnh]

Thank you both. as for the hp specs thats fine after I move to California I will try another V8 swap at least now I know what I will need I am starting to collect the parts already. This time I am going to buy a rebuilt engine instead of a used one.
I will need the best stock GM cam for horsepower if anyone has a recommendation. I plan on using a Edelbrock TBI intake and a modified rebuilt TBI and a custom chip. everything will have to be passable for California emissions. This will most likely be with vortec heads simply because California laws.

[doyoulikeithere]

I think you will find trouble meeting epa specs for cali if you use 4 bolt vortec heads on a 89 tbi system, due to the lack of any EGR valve porting to the intake manifold, in the 4 bolt vortec heads. 6 bolt heads have the EGR port up the middle to the intake manifold. 4 bolt heads do it externally and there is no port up the middle to the EGR. It can be done, but you probly need to adapt a Vortec's externally ported style EGR to the TBI style system.

[markmitchinnh]

I believe the vortec TBI intake by edelbrock is EGR delete so yes I would have to purchase the pipe and such from GM to use the EGR system. Thats fine. I have a list of things I will have to buy such as the passenger side exhaust manifold with the EGR accessories. But Thank you for the input.

[1Gary]

Will you make up your mind if you moving or not. Gezzz Mark.

[markmitchinnh]

We are definitely moving but when is the big question.

[doyoulikeithere]

I believe the vortec TBI intake by edelbrock is EGR delete so yes I would have to purchase the pipe and such from GM to use the EGR system. Thats fine. I have a list of things I will have to buy such as the passenger side exhaust manifold with the EGR accessories. But Thank you for the input.

Actually, looking at all of the 4.3 V6 edelbrock manifolds, I am now curious which one you intend to bolt to "Vortec" heads. And, I am confused by your terminology...

Most people refer to the 4 bolt heads as vortec, and the 6 bolt heads NOT as vortec. So for clarity sake, lets refer to only the 4 bolt heads as true "Vortec"
(Granted 93-95 CPI engines used 6 bolt heads with valve covers stamped "Vortec" but most folks dont really consider these as 'true vortec heads' b'cuz they are a lot different than the 4 bolt heads)

As far as I can tell, edelbrock does not make a TBI manifolf for the 4 bolt vortec heads, but they do make #3713 to fit the 6 bolt pre vortec heads, and it does have an EGR mount. Only bolts to a 6 bolt head.

If you wanna use a 4 bolt vortec head with an edelbrock manifold, you will probly have to use the #2114 4bbl manifold and a TBI adapter plate. No EGR on that set up... Just FYI, I did not see any TBI manifold for a SBC V8 on the edelbrock website. Vortec or not. Do you have a model number I could look up?

Can you clarify for me please? I dont understand what you actually meen by "Vortec Heads"

[markmitchinnh]

I was talking about a 5.7 future build when I was referring to the edelbrock intake. My 4.3 is done as much as its going to be. with the exception of tuning and tune up parts.

[doyoulikeithere]

Just FYI, I did not see any TBI manifold for a SBC V8 on the edelbrock website. Vortec or not. Do you have a model number I could look up?

Can you clarify for me please? I dont understand what you actually meen by "Vortec Heads"

[markmitchinnh]

Oh I'm sorry I got two separate engines builds mixed, The only TBI intake for vortec heads is from GM. its like close to 400 bucks. The vortec heads for a V8 chevy are 1996 and up however there were some of the older non vortec heads on early 1996 engines so I have been told. Casting number 12558062 Vortec head has 3 small humps, aka "sawtooth", on the end of the head. Casting number 10239906 Vortec head has one large single hump on the end of the head.

[markmitchinnh]

I build a basic stock Vortec 350 back a few years ago with a 4 barrel intake and an adapter for the TBI. Thats what I was thinking when I wrongly answered you. My apologies.

[doyoulikeithere]

I build a basic stock Vortec 350 back a few years ago with a 4 barrel intake and an adapter for the TBI. Thats what I was thinking when I wrongly answered you. My apologies.

Hey no worries, I was just trying to get your meaning is all...
And, yes, 96 seems to be the year for BOTH the V6 and V8 to have switched to the true "Vortec" heads (with 4 bolts each)

Thanks for the clarification.

[markmitchinnh]

My 1995 4.3 has six holes per side on the intake but the combustion chambers are still kidney bean style I don't know exactly what would make them true vortec or not though.