TBI head, having it cut a little. tips?

[big_P]

My 93 Shadow TBI needs a headgasket. I have a head from my 92 Shadow TBI waiting for it. While it's off, might as well bump up the compression for some more power! How much should I have it shaved? .040"? Of course, this will need to run on pump gas. I'll use premium, I don't care.

[allmotor]

Quote:

Originally Posted by big_P My 93 Shadow TBI needs a headgasket. I have a head from my 92 Shadow TBI waiting for it. While it's off, might as well bump up the compression for some more power! How much should I have it shaved? .040"? Of course, this will need to run on pump gas. I'll use premium, I don't care.

I usually take .060 off these heads for street use, then I degree the cam advanced 2°. works great on 92 octane. also run ignition timing 16° base.

[big_P]

awesome. Thanks a bunch.

[HotRodDodge]

But don't forget that you will more then likely need the shorter timing belt if you take that much off.

[Wizard]

Yes, that right, early SHELBY 2.2 110HP cars had 1 less tooth timing belts vs stock belt, different cam spocket to correct misalignment when block is decked so much, plus the spark control computer has knock sensor circuit, yes same kind of computer like my Tulip's, 1987 2.2 carb except mine does not have this knock sensor because it is not a performance engine.

Cheers, Wizard

[allmotor]

ive taken off .060 many times on these heads w/o needing a shorter timing belt. you are correct that when milling the head or block that cam timing needs to be corrected. I have found (approximately -varies slightly for each engine) that for every .030" retards the cam 1°

[Wizard]

Okay, interesting thing to consider for milling off head for higher comp ratio on stock engines. How much increase we would see with this modifications?

By the way, how of a effect with lightly ported on 782 (particularly exhaust) head in combination with head milled?

Cheers, Wizard

[allmotor]

Quote:

Originally Posted by Wizard Okay, interesting thing to consider for milling off head for higher comp ratio on stock engines. How much increase we would see with this modifications? By the way, how of a effect with lightly ported on 782 (particularly exhaust) head in combination with head milled? Cheers, Wizard

porting has ZERO effect on street mild applications. .060 off the head with a stock cam degreed on a carburated minivan gained 20 hp.

[Wizard]

This is nice bump.

I admit that manifolds for carb & TBI is not something that would flow nice.

Suppose I start over and keep it street;

Tall deck 2.5 block skimmed and use early T1 small dish pistons (got clevite .020 over set already) for tight squish, skim the 782 head enough to get the squish. Use 1 piece T1 manifold with megasquirt for neon DIS ingition & fuel injection control.

Since 782 head is poor for high compression without preminum gas, would I have to keep under 9.5:1? The DOHC hybrid is I like to go but this is long awhile till I have money for that drastic.

Then this would look like more than 20hp and increase in torque much needed for caravan.

I enjoy your allmotor's widsoms.

Cheers, Wizard

[allmotor]

what was even more fun with this minivan is I waxed the doors off an 88 omni 2.2 TBI 5 speed.... it was my dad driving the omni (he bought it new and my minivan was an 85/auto) we ran from a stop light and just pulled him like no tomorrow. this was in 1989 I figured it should have been a lot closer being an auto and 800# more weight.

[HotRodDodge]

Quote:

Originally Posted by allmotor ive taken off .060 many times on these heads w/o needing a shorter timing belt. you are correct that when milling the head or block that cam timing needs to be corrected. I have found (approximately -varies slightly for each engine) that for every .030" retards the cam 1°

I had to use a shorter belt when i had my head machined twice on my T1 shadow, bought the MP 1 tooth shorter belt and all was good.

[DaytonaTurbo87]

Every .030 off equals about .5:1 of compression, so go as high as you want.

[Lone Eagle]

You can't take it too high, or you end up with an interferrence engine.

[mock_glh]

Quote:

Originally Posted by HotRodDodge But don't forget that you will more then likely need the shorter timing belt if you take that much off.

The short belts were made for some of the racers who were taking as much as .180 off the (G) heads. 1 tooth on the belt is about 3/8 of an inch. You can get away with about .050 using the stock belt and tensioner pulley. Beyond that you should get a larger diameter tensioner (I got mine from Lambros). Those short belts are rarely necessary.

[Wizard]

What about 782 head milled that much?

Cheers, Wizard