ideas for an engine

I just purchased a 1983 crossfire 305 shortblock with a few extras. Does anyone have any good ideas to make this engine really run?

I just purchased a 1983 crossfire 305 shortblock with a few extras. Does anyone have any good ideas to make this engine really run?
Those engines were poor performers in the early 80's, better heads, more compression are called for here, but a performance built 383 stroker will still run it off the road, basically any 305 would have trouble standing up against a decent 350.

yeah you can put a decent cam in there and some better heads and maybe get a decent peak horsepower of over 300 horsepower, but theres no way in hell you can get a torque curve even close to a 350 or the 383 for that matter. i bet it will get good gas mileage though... i would look into the performer package from edelbrock, but thats prolly pretty expensive...

you should have got a 350 and had it turned into a 383, then you could make 500 lb/ft of torque and a decent 450 horsepower pretty easy without needing really high rpms to get it...

first if you want a 383 de-stroke a 400, much much better choice of $$'s spent... for a 305, depends on how wild you wanna be, dome/flat top pistons, wild cam, smaller heads, deck the block, mill the heads and intake, port n' polish, atleast a gasket match cut, full roller rockers at a 1.6 ratio, preformer intake, 2 middle of the road (cfm wise) carbs, stall converter, you can make a 305 a fairly decent moter, but as said thers not as much potential as a 350 or 400 small block

I just purchased a 1983 crossfire 305 shortblock with a few extras. Does anyone have any good ideas to make this engine really run?


I hope you didn't pay alot for it :uhoh:

305's are capable of decent power and can keep pace with a stock 350 after some work, but for the same amount of money and work, a 350 would make more sense.

Unfortunatley tho, the crossfire just plain sucks:sleeping:

You could make it a 359 stroker!!!!

yeah i heard that it takes .060 over to make a 400 into a 383 with the 3.48inch stroke crank. are there still cores out there capable of being bored that much over? my 383 is the more typical 350 bored .030 over with the 400 crank of 3.75 inch stroke. is the difference that the 400 based one revs much higher while the 350 based one makes more lowend torque?

as for the 305, with the right work, it will spank any stock 302 mustang from the 80's

If you build a 305 right and make it a stroker engine then it will do very well, i have the plans and have built a few sprint engines out of 305's if you need help let me know

lol or make a 283 that wraps out at 10,000 rpm!!!

If you take a 400 block and put in a 350 crank you have a 377, if you take a 350 and put in 400 crank you have a 383, if you take a 305 and put in a 400 crank you have a 359

If you take a 400 block and put in a 350 crank you have a 377, if you take a 350 and put in 400 crank you have a 383, if you take a 305 and put in a 400 crank you have a 359

If you put a 400 crank in a standard bore 350, you have a 377. .030 overbore takes it to 383. A 400 crank into a 305 standard bore block yields 328 cubic inches. A .030 overbore yields 334 cubic inches. A 350 crank into a 400 standard bore block gives 372 cubic inches. A .030 overbore yields 377 cubic inches.

I don't know where you got your numbers from!

Standard 305 bore is 3.736 inches. .030 is 3.766 inches.
Standard 350 bore is 4.000 inches. .030 is 4.030 inches.
Standard 400 bore is 4.125 inches. .030 is 4.155 inches.

Standard 305/350 stroke is 3.480 inches.
Standard 400 stroke is 3.75 inches.

The formula for CID is pi/4*bore^2*stroke*# cyl. pi/4=0.7843982

On the 305 stroker, we get:

.7843982*(3.736*3.736)*3.75*8 = 328.45~ rounded to 328
.7843982*(3.766*3.766)*3.75*8 = 333.75~ rounded to 334

Try it!

Ok well i have been racing in the dirt track world for over 10 years, my engine builder has been building for me for that time frame but has also been building racing engines since like 1958 he is 63 now and he said a 350 block 400 crank=383 he said a 350 block bored 60 with 400 crank=388 he said 400 block std bore and 350 crank is 377 and a 305 block bored 60=359 with 400 crank

and from a chevy smallblock book and i quote "The 377 cubic motor is built using a 400-style block and a 350 medium journal crank depending on the size of the 400 block cylinder bores, you get the large bore size of the 400 with the higher RPM capabillties of the shorter 3.48 stroke of the 350 crank.
Another common non-factory combination to build if the 383 but it has different power generation and rpm operating range characteristics. For the 383 you use a 400 crank in a 350 block."

and for the 359. 305 block, 400 crank bored to 307+30=359 cut 150 thousands off the top of the deck of the pistons, cut off the skirt of the pistons use 400 rods, fill the block half full of block epoxy to stregthen the walls of the cylinder and my engine builder said that is how he made a 359 out of a 305

and for the 359. 305 block, 400 crank bored to 307+30=359 cut 150 thousands off the top of the deck of the pistons, cut off the skirt of the pistons use 400 rods, fill the block half full of block epoxy to stregthen the walls of the cylinder and my engine builder said that is how he made a 359 out of a 305

I still don't know where you get 359. I gave you the hard numbers - math doesn't lie. Cutting the deck down does not begat cubic inches - it increases compression ratio. Cutting down the piston crowns lowers compression ratio. Epoxy strengthens the block, it doesn't add CID. Cutting the piston skirts provides clearance for the crank. By overboring to 307 ... even with that number plugged in it still doesn't provide 359 CID (if you're talking boring out to what a stock 307 was - 3.875" bore).

It does provide 353 and if you bore it another .030 it might be 359 - but I wouldn't expect that to live on the street. Once again, it comes down to thickness of bore and a 305 doesn't have thick bores to begin with.

The mod you're talking about is essentially stroking a 307, not a 305. It is what it is - and if you go around throwing credentials about how long you've been doing this, I was building competition small blocks in the late 1980s.

I am just disagreeing with your numbers is all i am not trying to throw anything around i have ran the above engine's had them go through tec at the dirt tracks and came back with the cubic inch's as for a 350 with a 400 crank i am still not sure where you came up with 377??? because every engine builder i have ever talked too said the only way to come up with a 377 is with 400 block 350 crank even the books i have read say the same thing and the same goes for the 383/388 so once agian i am not say you are wrong just wondering where the numbers came from as you said. You asked where i got my numbers and i stated above. My engine builder and the tec officials maybe wrong.

What i know is that we took a 305 iroc block and that is what was done to it, i do know that i ran that engine in my late model for a total of 67 races, we then took it out tore it down rebuilt it and now it is sitting on the stand waiting to be used agian

I am just disagreeing with your numbers is all i am not trying to throw anything around i have ran the above engine's had them go through tec at the dirt tracks and came back with the cubic inch's as for a 350 with a 400 crank i am still not sure where you came up with 377??? because every engine builder i have ever talked too said the only way to come up with a 377 is with 400 block 350 crank even the books i have read say the same thing and the same goes for the 383/388 so once agian i am not say you are wrong just wondering where the numbers came from as you said. You asked where i got my numbers and i stated above. My engine builder and the tec officials maybe wrong.


My numbers come from the formula that is used to derive CID. As I said, the math doesn't lie.

Then that means that the books on chevy smallblock engine building and chevy high performance engine building and chevy smallblock parts interchange, and smokey yunick are all wrong :(

Like i said before i would never call somone wrong, I was just going off of what i read and what i have been told and what i have been built, then had tec officals tell me at the track

yeah silicon is right about the 377, (4.000 bore and 3.75 stroke= 376.96 c.i.) as well as the 400 bored .030 one (4.155 bore and 3.48 stroke= 377.52 c.i.)

i believe that a 400 bored 60 over with a 350 crank makes a 383 as well as the more typical 350 bored 30 over with a 400 crank.

(4.185 bore and 3.48 stroke = 383.2 c.i.)
4.030 bore and 3.75 stroke = 382.64 c.i.)

Then that means that the books on chevy smallblock engine building and chevy high performance engine building and chevy smallblock parts interchange, and smokey yunick are all wrong :(

Not at all, in fact they all back me up. Go read them again, the proof is in the text.

Ok i think i have figured out my problem i went looking through all my old engine blocks (blown up engines in the back of the shop) and have discovered that i have never built a 388 or 377 with a std bore block so therefore you are right :) but i was also right in the sense i belive that a 400 block 30 over with 350 is 377 and a 350 block 400 crank is 383 if you take 350 block out to 60 and put 400 crank 388.. so i am sorry to disagree but all the engines in the past i was never told what you said about sizes and that is because none of the are std bore

well, you were in the right ballpark anyways. them little overbores dont make much more cubes anyways... the only differences are the stock 350 bore with the 400 crank being a 377, while the .030 over is 383 and .060 is 388.... not enough cubes to really argue over lol

I have talked to very few people in dirt track racing at our track that run std bore engines :( most of the ones we have wont go std and need to be bored to so degree

So what would happen if you stuck a 3.500 stroke crank into a 30 over 350 with six inch rods what would the ci be

do they make 3.5 inch stroke cranks? i bet it's possible if you got your own unground crank and had a machine shop custom grind it. are you talking about the 3.48 inch stroke of the 350's crank? i dont think that the 6 inch rods would make any more stroke themselves, i think they would just require moving the pin farther up in the piston to keep it from coming out of the block. correct me if im wrong, im kinda a newb to this sort of thing. i do know that a .030 over 350 that uses its original crank will be a 355 in the end. thats with the 3.48 inch stroke crank that makes a 350

p.s. i think that the 6 inch rods would keep the stroke the same but would have better angles than the shorter rods for less wear and tear and would stay at tdc a little bit longer, or so it seems...(im just going on my common sense here, which is usually wrong, so dont quote me lol)

if the peak piston speed is less with the longer rods, wouldnt that let a person run a slightly higher compression ratio on the same octane without detonation? probably not a huge difference though

Well, the Chevy 350 is 4x3.48, the Ford 351 is 4x3.5 - so I'd say the 3.5 stroke crank would be good for one extra cube. :)

You can offset grind a crank to obtain a slightly different stroke, so 3.48 to 3.5 is doable, but it's a whole lot of nothing.

NASCAR Cup engines are typically 4.125x3.35 to obtain the 358cid max engine size with the best bore/stroke ratio for high RPM.

And longer rods...