Help!!!!!

[Captainkirk]

Given what you have - I'm no fan of having to mix fuels on a car that runs on the street. I build primarilly street engines that run on pump gas. Yours would be no exception. So this is what I'd do and why:
- Use the forged crank - you will internally balance it and it's got the heaviest counterweights making it the best candidate.

That decision has been made already!

- Take the pistons and either mill off the domes if possible - as was mentioned - just flip one over and look. A flat top with an open chamber head is where I'd want it.]
- Static ratio no higher than 10:1. Prefer 9.8:1 if it's doable.

Not contradicting myself here, but if I were to go with flat tops, wouldn't I be better just saving up the Almighty Dollars for a set of, say, Keith Black Flat-tops? Not sure how this would affect my CR with the 67cc bowls, though...

- Use the ported Js. The oldschool Tony can keep the 1.88s. They will need to be sunk to be run - use at least 2.02s and if the seats are bad I'll go as large as 2.05s assuming the porting is good and they can use it. If you think the 2.02s are too large take a look at any modern 4 cylinder that has 2 times the valve area and 1/4 of the displacement. I'll bet you the cost of the engine that you can't feel any loss of torque directly related to a larger intake valve.

If I decided to go with the flat-top KBs, and was gonna run 2.02's....why wouldn't I want to just use the X-heads I have that are already 2.02'd? JUst asking. Yeah, I know the J's are ported, but I could probably get the X's ported for what I would spend having 2.02's installed in the J's, not to mention my CR would be higher....

- Buy an Edelbrock RPM Air Gap. I'll bet that same dollar amount that you will feel a loss of low end by not using this intake - and it will still make the same or more power up top.

Is there test data to back this up, or is this from personal experience? Everyone has a favorite, and there's so much out there it's hard to choose.....

- lose the smaller Holley . Buy something that gets you up around 750 in the oldschool cfm ratings, or 670 in the modern wet-flowed stuff (like the Street Avenger or HP series Holleys).

The reason I chose the 650DP in the first place was using the flow formula in the Holley Carbs & Manifolds book which indicated a 750 would be too much flow, especially with manual secondaries. Has that opinion changed over the years? Seems a lot of things have.......

- Keep the factory distributor but recurve it for your package. Get a Standard Ignition control module for it.

Not the Mopar Performance module? If not, why not?

- Buy a cheapie set of headers at minimum or a nicer set if the $$ is there. Either will work, the more expensive stuff makes a little more power (not much) but is easier to get in and will not be damaged by road dips or speed bumps.

Yeah, will probably go with budget headers....

- You said the heads were ported - have them flow tested and post the results before I can recommend camshaft. Also tell us what they have/had for rocker gear.

If, and I say IF....I decided to go with the X heads, it wouldn't matter about the porting because I could have them ported and flowed at the time of rebuilding. But yeah, I see your point. Especially if I decide to run the J's.

Thanks for all your input!!!!:hello2:

 

[moper]

Let me preface by saying there are lots of good guys here - these answers are "in my opinion" based on my use since the mid 80s. Others have skinned this cat in other wasy so there's no "one perfect plan".


Not contradicting myself here, but if I were to go with flat tops, wouldn't I be better just saving up the Almighty Dollars for a set of, say, Keith Black Flat-tops? Not sure how this would affect my CR with the 67cc bowls, though...
It's budget - you already have pistons you can use for about $100 of milling assuming they have a thick dome.

If I decided to go with the flat-top KBs, and was gonna run 2.02's....why wouldn't I want to just use the X-heads I have that are already 2.02'd? JUst asking. Yeah, I know the J's are ported, but I could probably get the X's ported for what I would spend having 2.02's installed in the J's, not to mention my CR would be higher....
The cost of valves will be the same for each head. The valve job, guides, spring seat work, etc - same for each head. The porting will be more if you use the Xs, not to mention the milling of the deck surface to reduce the chamber to 67cc. Port-wise - the X and J are the same deal. So again - budget in mind - use the ones that arae already done unless you flow test them and they're crap anyway.

Is there test data to back this up, or is this from personal experience? Everyone has a favorite, and there's so much out there it's hard to choose..... Data from a couple of manifold shootouts, and my own personal "butt dyno" testing.

The reason I chose the 650DP in the first place was using the flow formula in the Holley Carbs & Manifolds book which indicated a 750 would be too much flow, especially with manual secondaries. Has that opinion changed over the years? Seems a lot of things have.......
The formula didn't - but the way the carbs are tested has and that plus a lot of advancements in fluid dynamics and internal engine physics has led to some other thinking. IMO, the 650's too small. Using todays thinking - 650cfm is calculated without adding a fluid. Carburetors don't only flow air. So if you add in the gasoline, drop the cfm by about 15%. That drops the cfm that carb is rated for down to around 580cfm. If you were to use a modern Street Avenger DP - say a 670, it is rated with the fuel included. So a 670 Avenger is comparable to a 750 old-school 4150. The 650 wil work - but IMO you will get better all-around performance from a 750cfm 4150 or 3310, than the 650cfm.

Not the Mopar Performance module? If not, why not?
MP orange modules pull out timing at higher rpms and some later units have issues with premature failure. The Standard LX-101 does not take out timing and has a good coil saturation. I've run them to 7200 before (not intentionally...lol) and it will run clean that high. The Std is virtually identical to the higher dollar "special" FHO modules. The best scenario would be a multispark unit with adjustable curves like the MSD Pro Billet.

 

[Captainkirk]

That explains a lot......THANKS!